SY Anaerobic Digestion Toolkit

This project is supported by the Sustainable Development Fund

and East Midlands Development Agency

A TOOLBOX GUIDE FOR ASSESSING THE FEASIBILITY

OF AN ANAEROBIC DIGESTION PROJECT DEVELOPED FOR

THE BENEFIT OF A COMMUNITY OR FOR A SINGLE FARM

Prepared by Methanogen ltd Tooracurragh Ballymacarbry Co.Waterford Ireland

With the advice & assistance of The Andersons Centre

[email protected] and

Rutherford Renewables [email protected]

mailto:[email protected]


AD Development Toolbox March 2010

DISCLAIMERS FOR SY AD REPORT This report was commissioned by Sustainable Youlgrave and produced by Methanogen & Associates. Neither they nor the Peak District National Park Authority accept liability for any costs or losses arising as a result of the use or reliance upon the contents of this report by any person. The content of this report does not constitute legal advice, nor does it necessarily represent the views, aims or policies of the Peak District National Park Authority. This Guide has been part funded by the East Midlands Development Agency Limited (emda). The purpose of the Guide is solely for general interest and should not be used as a substitute for advice. The emda logo on the front of this Guide is for the purpose only of recognition of emda’s contribution to the cost of the Guide and its preparation. This Guide or any part of it is neither endorsed by emda nor represents emda’s views. Emda makes no warranty, representation or promise as to the accuracy of this Guide’s content. Emda hereby excludes all liability for any loss howsoever caused to the fullest extent permitted by law.

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Contents Introduction................................................................................................................................... 3

Defining different types of Anaerobic Digestion (AD) situations.............................................. 4 How to use this document........................................................................................................... 5 Acronyms used in the document................................................................................................. 7

Chapter 1 - Introduction to AD ................................................................................................... 9 1.1 What is Anaerobic Digestion?.......................................................................................... 9 1.2 Technical Matters................................................................................................................ 11

1.2.1 Feedstock .................................................................................................................... 12 1.2.2 Maintaining a Good Process ...................................................................................... 14 1.2.3 Quality and type of outputs ......................................................................................... 15 1.2.4 Integration of the digester into surrounding systems ................................................ 17 1.2.5 Capital and operational (including maintenance) costs............................................ 21 1.2.6 Management............................................................................................................... 21 1.2.7 Layout of site.............................................................................................................. 22 1.2.8 Storage ....................................................................................................................... 23 1.2.9 Sites .............................................................................................................................. 24

1.3 Technology providers ........................................................................................................ 24

Chapter 2 - Deciding whether to develop an AD ..................................................................... 25 2.1 Identifying what is the primary purpose of the digester ..................................................... 25 2.2 Determining the size of AD ................................................................................................ 25 2.3 Choosing an optimum mix of Feedstock .......................................................................... 27

Chapter 3 - External effects of AD ............................................................................................ 28 3.1 Agricultural Effects........................................................................................................... 28 3.2 Environmental Effects ...................................................................................................... 29 3.3 Social Effect on Other Businesses & the Community ....................................................... 31 3.4 Community Development .................................................................................................. 33 3.5 Health................................................................................................................................ 36 3.6 Waste Management........................................................................................................... 37

Chapter 4 - Undertaking a feasibility study for an AD project.............................................. 39 Stage 1 research ........................................................................................................................ 39 Stage 2 - Assessment of information ........................................................................................ 41

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4.1 Farm Assessment .............................................................................................................. 42 4.2 Assessing a community CAD ........................................................................................... 43 4.3 Regulations ....................................................................................................................... 45 4.4 Finance.............................................................................................................................. 45

4.4.1 Supports ...................................................................................................................... 45 4.4.2 Banking ....................................................................................................................... 46 4.4.3 Local currency ............................................................................................................ 47 4.4.4 Investors...................................................................................................................... 48

4.5 Crucial internal & external factors related to development of AD................................... 49 4.5.1 Internal......................................................................................................................... 50 4.5.2 External....................................................................................................................... 50

4.6 Factors pertinent to an on-farm AD .................................................................................. 51 4.7 Factors pertinent to a community digester........................................................................ 52 4.8 Public Consultation........................................................................................................... 53 APPENDIX 1 Options for the use of Biogas? ......................................................................... 55

Heat Only .............................................................................................................................. 55 Electricity production ........................................................................................................... 55 Biogas Cleaned to Biomethane............................................................................................. 56 Future uses for biogas .......................................................................................................... 58

APPENDIX 2 Options for the use of Digestate Products........................................................ 59 Land bank for utilising the digestate .................................................................................... 60

APPENDIX 3 Technology Types ............................................................................................ 61 APPENDIX 4 Technology Providers ...................................................................................... 64 APPENDIX 5 Farm Assessment Form.................................................................................... 70 APPENDIX 6 - Possible Business Models for a Community CAD......................................... 73 APPENDIX 7 Agricultural Considerations ............................................................................. 77

Farm Business....................................................................................................................... 77 Nutrient management............................................................................................................ 78

APPENDIX 8 Environmental Effects..................................................................................... 80 APPENDIX 9 Details concerning Regulations........................................................................ 85 APPENDIX 10 Getting connected.......................................................................................... 95 APPENDIX 11 FINANCE - Banking.................................................................................. 100 APPENDIX 12 FINANCE - Grants .................................................................................... 106 APPENDIX 13 - Checklists................................................................................................... 107 APPENDIX 14 - Bibliography of very useful reading ........................................................... 111

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Introduction

Defining different types of Anaerobic Digestion (AD) situations Different situations require different AD technologies. Technologies also vary according to the feedstock, the prime focus of the project, the type, quality and use of the outputs and the applicable regulations. There is a wide variance in understanding and use of the following types of digester system. It is therefore necessary to define the terms as they will be used within this document.

On-Farm Digester - is a digester designed to improve the management of the farm. An on-farm digester processes feedstock (manure and crops) produced on that farm. However, additional off farm material may be imported to co-digest with the feedstock produced on-farm, but the total amount of liquid digestate produced is utilised to meet the fertiliser requirements of the farm and the digester is operated as part of the farm management system.

Shared digester - is similar to an on-farm digester, the only difference being that the digester is utilised by two or more farms, in a similar manner to an on-farm digester.

On-site digester - is a digester designed to provide improved waste management and/or energy for the business on the site (e.g. dairy, abattoir etc). Some additional feedstock may be imported to improve the process or to increase the energy output to meet the on-site needs.

Stand alone business digester - this type of digester is developed primarily to maximise the financial return for its owner, and can be located on a farm or elsewhere. The objective is to maximise revenue from gate fees and from the sale of electricity, and so often very little or no manure, is processed. Typically, these digesters are large (>500kW), the location is such that most of the spare heat often cannot be utilised, and the quality of the processed material is considered sufficient so long as it meets regulatory requirements.

Centralised digester - this type of digester usually processes the manure and possibly crops from 3 or more farms, along with biodegradable wastes. In many ways it is similar to the stand alone business digester, except that the farms involved usually have a shareholding and manure and crops are co-digested with the feedstock that can earn gate fees. Because of the farmer involvement there is usually more emphasis put on producing a high quality fertiliser product in the digestate. The digester may provide a function of re-distribution of nutrients between farms.

Community digester - this type of digester is similar to the centralised digester, but it has other functions and parameters as well. Although the digester must be capable of financing its development and operation, the effect that the digester has on the surrounding community and environment are considered equally as important and considered in the overall assessment of the project. The number of jobs created, the amount of additional money in circulation in the local economy, the amount of transport miles, whether production costs on farms can be reduced, whether ground/surface water quality could be improved etc. would be considered while developing the project. In other words the digester is developed for the welfare of the surrounding community, as well as the project owners.

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This document refers only to on-farm and community digesters as defined above. Therefore, it is only concerned with digester systems that use a wet anaerobic digestion process and process feedstock, with a combined average of more than 5% dry matter, when loaded into the digester, are considered to be relevant to this document.

How to use this document This document is to serve as a guide for communities, farmers and individuals who are considering whether anaerobic digesters might have something to offer them. There is a lot of information on AD available through the internet, and from technology companies. Many people have said that when they have completed some research into AD, they are more confused than when they started. This guide is valid in March 2010, after that some aspects may change. This guide is designed to;

• provide some basic information on AD and associated technology and help you to understand enough to be able to ask the right question to get the information you actually need

• assist you in deciding what you might want from an AD and to determine the optimum size of AD for your individual situation

• decide how to integrate the AD into existing management systems

• know how to collect some basic research data to know if the AD is viable

• know how you might be able to finance your project and to decide what business structure might be suitable for your AD

• help you to know what regulations and other issues you may have to comply with and to know where to go to get the information you need to develop an AD project

• know what options and procedures there are in getting connected to the electricity grid

This guide is intended to guide you through the initial steps of assessing the feasibility of developing an AD. It is not meant to dampen your enthusiasm, but as AD development is not an easy business, particularly if it is to be well integrated and bring about wider benefits, it is important to realise it is not to be undertaken by the feint hearted!

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Why this Toolbox Report has been Developed

Sustainable Youlgrave (SY), a community environmental group from Youlgrave in the Peak National Park in Derbyshire, approached the East Midlands Development Authority (emda) and the Peak District National Park Authority (PDNPA) Sustainable Development Fund (SDF) for funding to undertake a detailed feasibility study to assess the potential for utilizing anaerobic digestion within their local area. SY requested tender proposals from companies interested in undertaking this study. A team led by Methanogen Ltd, consultants who specialise in community AD and their associates, the Anderson Centre, farm business consultants and Rutherford Renewables, were employed by SY.

During discussions, held during the tender process, it became clear that these funding agencies receive several applications each year, for feasibility funding to assess both on-farm and community based projects. Much of the work required to complete a feasibility study is generic to all AD projects. However, this information does not normally become publically available because a specific feasibility study will also contain an amount of information that is confidential. Feasibility studies also contain details that are specific to the situation where the study is undertaken, and could be misleading if transferred to another situation.

Therefore, it was decided to provide the information relating to the feasibility study for SY, in two parts, namely

a) This Toolbox report which will be publicly available, and includes all the generic information relating to developing an AD project to serve the needs of a community or a farm. It also provides details on the process of assessment that is required to establish whether there is potential for an AD or not. This information should enable, other community groups, like SY, or individual farmers to undertake a preliminary assessment of the potential for AD themselves, prior to having to engage professional consultants and/or look for funding.

b) A report into the potential for AD in the Bradford Valley, which will be a confidential document

The Coalition Government has issued an Environmental policy item which calls for a 'huge increase in AD systems nationwide'. It is hoped that this Toolbox report will enable the development of well integrated AD projects, where the value of the wider benefits, social, agricultural, environmental and health, that AD can bring, can be realised.

When AD projects are developed as businesses where only the internal returns are considered, typically most of these wider benefits are not realised because they have no value to the financial bottom line of an AD project. That is why it is crucial to enable community and agriculturally based AD development, which do realise the wider benefits because they are of value to the project owners/developers.

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Acronyms used in the document ABPR Animal By-Product Regulations

AD Anaerobic Digestion

CAD Centralised Anaerobic Digestion

CHP Combined Heat and Power

DECC Department of Energy and Climate Change

DEFRA Department for the Environment, Food and Rural Affairs

EA Environment Agency

ECA Enhanced Capital Allowance

EP Environmental Permit(ting)

FIT Feed in Tariff

FYM Farmyard Manure

GHG Green House Gas

HACC Hazard Analysis and Critical Control Points

HSE Health and Safety Executive

kWh Kilo Watt Hour

MWh Mega Watt hour

LATS Landfill Allowance Trading Scheme

LEC (Climate Change) Levy Exemption Certificate

MSW Municipal Solid Waste (garbage)

MW Mega Watt

NERS National Electricity Registration Scheme

NM3 Newton m3.refers to the volume of gas at air pressure and 0oc

NVZ Nitrate Vulnerable Zone

OFGEM Office of Gas and Electricity Markets

PAS 110 Publicly Available Specification 110

PPA Power Purchase Agreement

PPC Pollution Prevention Control

QP Quality Protocol

RDA Rural Development Agency

RDPE Rural Development Programme for England

REA Renewable Energy Association

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RHI Renewable Heat Incentive

RO Renewables Obligation

ROC Renewables Obligation Certificate

SP(S) Single Payment (Scheme)

VFA Volatile Fatty Acid

WML Waste Management Licence

WMR Waste Management Regulations

WRAP Waste and Resources Action Programme

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Chapter 1 - Introduction to AD

1.1 What is Anaerobic Digestion? Anaerobic digestion is a natural process of microbiological conversion of organic matter in the absence of oxygen.

An anaerobic digester (AD) provides the means to process most types of clean biodegradable material, to improve the fertilizer value of the material and to produce energy. AD has the potential to provide many environmental benefits, not least a net reduction in greenhouse gas (GHG) emissions, and to also bring social benefits. AD can be a key part of the sustainable development of an area. However, if AD is not developed carefully and with consideration of the effects on its surroundings it can create adverse effects.

Figure 1~ Diagram showing requirements of an Anaerobic Digester Operation

SCHEMATIC OF A DIGESTER

Electricity

Liquor Fertiliser

Fibre

Heat

Gas Holder

Separator Pasteuriser

Abattoir sludge

Sewage sludge

Food processing

Food waste

Green waste

CHP Crops

Digester

Animal manure

The AD process will occur at most temperatures below 70oC when air is excluded, but typically there are two temperature ranges used for commercial operation of digesters. Mesophilic range occurs from 30-44oC and Thermophilic range from 45-60oC. The higher the process temperature

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the faster the process to the upper point and the higher the rate of gas production and the lower the capital cost (as the digester can be smaller). However, the faster the process is the more attention it requires.

1.2 What the process produces Biogas - typically contains 60% methane and 40% carbon dioxide, with trace amounts of other gases and is saturated with water vapour. However, the proportions of methane and carbon dioxide vary significantly. The biogas produced can be used in a boiler or cooker to provide heat only, or used in a Combined Heat and Power (CHP) unit to produce electricity and heat, or it can be upgraded to natural gas quality and used as a vehicle fuel or injected into the National Gas grid. See Appendix 1 for more detail on possible uses for the biogas

Digestate - three forms of digestate material can be derived from the AD process:

• Whole digestate is the processed material as it is unloaded from the digester. This will be a pumpable material which should not be more than 12% dry matter (DM). Some dry AD systems may produce a partly digested material with higher DM, but this is not the same as whole digestate. Whole digestate contains a mix of, fibres derived from the structural components of feedstock, minerals, anaerobic organisms and water.

• Separated liquor: the liquid resulting from passing whole digestate through a separator to remove the coarse fibre.

• Separated fibre: the fibrous fraction resulting from passing whole digestate through a separator.

The nature of the whole digestate and any separated fractions is affected by:

• The choice of input materials (particularly as regards nutrient content and structure);

• AD system and process configuration;

• Any pre-treatment or post-treatment. For example, pre-processing such as thermal hydrolysis acts to open the structure of the feedstock, allowing the process bacteria better access so that more carbon is transformed to biogas.

A centrifuge can be used instead of a separator. A centrifuge produces a liquid and a solid but this is not the same as separated liquor and fibre because the process of separation is different and as a result the properties of the solid and liquid fractions are different. Separation is the removal of the coarse fibres from the liquid fraction. The liquor will still contain a significant amount of small fibres and solids. The fibre will be fibrous and relatively dry and crumbly. Centrifuges separate the liquid from the solids, and a floculant is used to ensure the liquid contains as little solids as possible. The liquid then has a very low phosphate content, and the solid fraction is more like a cake and is usually somewhat sticky.

Most separated fibre can be subjected to a further aerobic stabilisation phase to produce a high quality horticultural product. It is not normally possible to aerobically stabilize centrifuged solids

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without the addition of another fibrous material to open it up to the air. A centrifuge has a much higher capital and operational cost, than a separator.

In this document only the fibre and liquor from a separator are considered. Further details concerning digestate products can be found in Appendix 2.

1.3 Technical Matters It is important to have some understanding of the technical issues when discussing a digester project with a technology company. The most common cause1 of difficulty in the development of farm digesters was identified to be a lack of understanding between the technology company and the farmer which resulted from poor communication. In essence this lack of communicatarose because engineers and farmers use different language and have different objectives and approaches. It is important that the developer explains what they want to achieve, in a way that the technology company understands, and that the technology company helps the developer to determine what they do want and what the technology is actually capable of doing in a language familiar to the AD developer.

ion

Figure 2 - An on-farm digesters of 150m3 - A concrete tank digester clad in wood

Some basic explanations are provided under the following headings

1 As recorded in a survey of over 40 farm digesters developed in UK between 1976-96

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• Feedstock

• Maintaining a good process

• Quality and type of outputs and how they will be utilised

• Integration with surrounding systems

• Capital and operational (including maintenance) costs

• Management

• Layout of site

• Storage

Appendix 3 provides more technical details concerning the choice of technology available. Once you have considered what your objectives and requirements are, and have talked to a couple of technology companies, it is a good idea to go to see a few digesters that operate in a way similar to what you hope to build, and talk with the operator about how they have got on with their digester, and what they would change if they could.

1.2.1 Feedstock It is possible to process any type of biodegradable material in a digester. The type, quality and mix of the feedstock, to be processed, will determine the type of technology required for pre-conditioning the feedstock and loading the digester. The design of the digester system and the type of technology used within the digester system and, if the digestate is to be separated, for the separator too, will be related to the intended feedstock. This is why if there is likely to be a subsequent change in the type, quality or mix of the feedstock, to that which was initially identified and agreed with a technology provider, it will generally result in a process guarantee becoming invalid. Therefore it is important to allow for anticipated later changes in feedstock in the original design

Materials, such as plastics, stones, sand, undesirable chemicals etc can contaminate a feedstock and cause problems in the digester system, therefore measures should be taken to either prevent these getting into the feedstock or technology and methods utilised to remove the contaminant prior to digestion.

Solid feedstock such as farmyard manure, poultry litter, silage, hay, crops and food products can be digested. However, they will require to be either mixed with a liquid to enable loading by pumps, or to be loaded by an auger system directly into the digester. It may be advantageous to chop the feedstock before loading to improve access for the process bacteria, thereby improving gas yield and improving digestate quality.

If the type of feedstock has a high dry matter content then only certain types of technology can be used for mixing and heating the digester. Some digester systems re-circulate liquid digestate to assist in loading or to keep the digesting material at a sufficiently low dry matter content. If liquid digestate is re-circulated, ensure that ammonia levels in the digester do not increase to a level that inhibits gas production or results in the deterioration of digestate quality.

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The more watery the digesting material is the more likely it will be that heavy materials (e.g. grit, stones) will settle on the floor of the digester, and materials that float (e.g. straw, plastics, most food) will form a mat across the surface of the digesting material. Therefore, if the feedstock is watery, or the hydraulic retention time2 is longer than normal, the risk of floating and settling layers will be greater. It is possible to have equipment, designs or management systems that facilitate the prevention or removal of these separated layers. If such layers form and are not controlled the working digester volume will reduce. This leads to a reduction in the quality of the digestate, unless throughput is reduced, and will reduce gas yield and quality. Eventually the digester will have to be emptied and cleaned and the process restarted.

Figure 3 An on-farm AD at Turiff - glass lined digester tank with a green membrane roof

If a digester processes feedstock that originates from an animal (e.g. manure, milk) or contains parts of animals (e.g. meat) then the site must be licensed by DEFRA in accordance with the Animal By-Products Regulations. These Regulations stipulate the inclusion of certain technology processes and management systems, depending on the type and amount of feedstock processed and the location of the site.

The longer feedstock is stored before being digested the lower its gas potential will become.

2 Hydraulic retention time (HRT) is the amount of time the feedstock is kept (on average) within the digester.

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1.2.2 Maintaining a Good Process The more stable a digestion process, the less management input is required. A digester that produces a high rate of gas production requires careful monitoring and a steady mix of feedstock with little variation, because the process can deteriorate easily. Conversely a digester that has a lower rate of gas production3 and a high proportion4 of manure (or other buffering material) can cope with a wide variation in feedstock, changes in temperature and requires little monitoring or chemical addition.

Feedstock The type, quality and mix of feedstock will affect the ability to maintain a good process. Some feedstock (e.g. food, fats, vegetable oil) readily release gas, but can result in the gas becoming trapped in the digesting material resulting in foaming5. Too much high gas potential feedstock can also cause an imbalance in the chain reaction of the digestion process, reducing gas quality, increasing acidity and eventually resulting in loss of process.

Some feedstock has a high Nitrogen content (e.g. meat, poultry slurry, grain) this Nitrogen becomes transformed into Ammonium salts during the digestion process as the readily available carbon gets transformed into biogas. When the amount of Ammonium salts in the digesting material build up beyond certain levels they have an inhibitory effect on gas production, can cause changes in the chain reaction of the digestion process and eventually will lead to a loss of process altogether.

It is therefore generally accepted that it is better to co-digest feedstock that has a high gas potential and/or high Nitrogen content with feedstock that is already populated with suitable process bacteria, has a high carbon content and slow gas release, such as manure.

Mixing Effective mixing is essential to maintaining a good process. There are a wide variety of types of mixing systems, some of which include re-circulation of the digesting material to assist mixing. A detailed explanation of mixing systems is provided in Appendix 3. Essentially there are two kinds of digester mixing, namely large bubble gas mixing and mechanical mixing. In general mechanical mixing tends to become difficult when the digesting material has a dry matter content above 10%, whereas large bubble gas mixing tends to become less effective when the digesting material dry matter content is below 3%.

A mixing system should be able to ensure complete and even mixing of the digester contents and encourage biogas escape from the digesting material. A good mixing system should also prevent settling and floating layers, otherwise there should be a method of removing these layers within the digester. The mixing must also be able to distribute the heat evenly throughout the digester whether heating is internal or external to the digester.

3 If gas production is <1.75cu m per digester volume 4 >60% by dry matter content 5 During ‘foaming’ the digesting material can expand to many times its normal volume.

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When assessing the energy required for mixing any additional measures employed to assist mixing or heating should be included. Some digesters can achieve effective mixing with as low a power requirement as <2 watts per cubic metre of digester volume.

Process Heat A steady and suitable process temperature is also important in maintaining a good process. The higher the temperature the faster the process works and the more sensitive the process becomes to changes of any kind. Digesters are usually operated at any temperature between 30-60oC. Typically Mesophilic digesters are operated in the range 36-42oC and Thermophilic digesters at 48-55oC. It is best if the operational temperature chosen is maintained within +/-1oC, which is why digesters are fed little and often and sometimes the feedstock is pre-heated (or cooled) before loading. However, if the process is robust it will withstand much greater swings of temperature without much negative effect, and this may be necessary to fit in with another management system (e.g. once per day feeding).

The amount of heat required to maintain the process temperature will depend on the temperature of the feedstock before loading, how well the digester is insulated, whether the digesting material is re-circulated, and the choice of process temperature. Heat is provided typically by either pre-pasteurising the feedstock, or by internal heat exchangers (where hot water is pumped through pipes or radiators inside the digester) or by external heat exchangers, where the digesting material is pumped through a double skinned pipe system where heat from hot water is transferred through the shared pipe wall into the digesting material.

Different digester technology providers have preferences for different types of heating systems for a wide variety of reasons. It is important for them to explain those reasons and to discuss the method of heating proposed to understand whether it suits your situation. It is important that the type and capacity of heating system used will provide you with the capability to increase or reduce the heat transfer rate, from the heating system to the digester contents, as required, should the rate or type of feeding change or the digester process require it. You should identify what the capital, operational and maintenance costs are likely to be and what other functions the method of heating provides.

1.2.3 Quality and type of outputs

There are two important outputs from a digester, biogas and digestate. Both products of the anaerobic digestion process can be further processed to produce additional products. If any of the feedstock is considered to be a waste, then UK regulations classify both the biogas and digestate produced as waste products. However, if the digestate meets the requirements of the PAS 110 and Digestate Quality Protocol6, then it can become a product and no longer is considered a waste.

Biogas The biogas can be burnt in a boiler to produce steam or hot water, or in a cooker/range, or in an engine (with heat reclamation from the exhaust and engine) that drives a generator to produce

6 PAS110 (Publicly Available Specification) and Quality Protocol are available on http://www.biofertiliser.org.uk/

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both heat and power (a CHP unit) or be cleaned and used as a vehicle fuel or refined further to natural gas quality, to be injected into the gas grid or used as a higher grade vehicle fuel. It is also possible to use the biogas as the energy for a cooling/refrigeration system with absorption chiller technology.

There are many different types of technologies for each gas use, and several different designs within a type of technology. Each option has its own merits and difficulties. Each option should be evaluated on the basis of which energy form can be utilised in your specific situation and assessed for its efficiency. What technology to use to utilise the biogas is a different question to ‘is AD viable’ and the biogas options should be financially assessed separately to the AD. More details on the options to use the biogas are in appendix 1

Figure 3 - A bus depot in Sweden with buses refuelling overnight with biogas

Where biogas is burned in a CHP engine to produce electricity and heat, a boiler is normally used as a back-up to use the biogas in case of servicing or breakdown of the CHP engine. If biogas is produced at a greater rate than it can be used and all the buffer storage capacity is full then the biogas flared, in order to prevent the methane content of the biogas escaping to atmosphere. Storing biogas has a significant cost.

The quality of biogas from a digester can vary significantly in methane content (typically from 40-75% methane) and still be burnable and it may contain contamination of trace elements (e.g. sulphur). The quality depends on the mix and type of feedstock, the actual hydraulic retention time, the minimum retention time, the process stability and the process temperature. Generally the biogas quality is best when a stable process is established with a slightly longer then normal

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HRT, using a multi stage process to extend the minimum retention time, and where a certain amount of fat/oils are in the feedstock (3-5% depending on the mix of feedstock)

At most AD facilities the biogas needs to be cleaned of sulphur before it is used in a CHP. Cleaning can be achieved effectively by several means, the lowest cost being the injection of a small amount of air into the gas, while it is stored over some digestate. However, if the gas store is integral to the digester with gas mixing, air injection should be avoided, because the air will be driven into the digesting material and have a negative effect on the process.

Digestate The whole digestate can be used directly after digestion as a fertiliser product or separated to remove the coarse fibres from the liquid, thereby producing separated fibre and separated liquor. If the whole digestate is stored before use or separation, it could be stored in an open topped tank, as it will form a crust in storage, which will keep ammonia loss during storage at a low level7. However, it will require agitation before removal from storage.

There are several different types of design of separator. The design of separator should be matched to the type of whole digestate being separated and to the qualities of the separated products that are required. For example a belt press usually has a slow throughput, but can separate almost any kind of digestate; a drum press has a high throughput, but will have difficulty with fine solids or greasy digestate; whereas a screw press requires a digestate that contains fibrous material, but will then produce a drier fibre than other types of separator.

If the separated fibre is to be aerobically stabilised after separation, then it must be fairly dry and fibrous to allow the air into it. Otherwise a medium, such as coconut fibre, should be added. The separated liquor should be stored in a covered tank to prevent loss of nitrogen during storage. Generally a liquor storage tank will not require agitation before emptying, because the coarse fibres have been removed by separation.

1.2.4 Integration of the digester into surrounding systems A digester should make life better for those that work with it or are associated to it, otherwise the AD project will not be considered a success. If an AD is not well integrated it can cause damage to its surroundings and as a result could be closed down. Therefore, the digester project should be well integrated with the existing systems it will interact with, and the individual interests and concerns of those involved must be fully considered. For example every farm is worked on a different regime and has a different layout and equipment. The manner in which the manure is transferred to the digester must fit in with that individual farm system, and make things easier for the farmer.

Main considerations for integrating an on-farm digester a) How is manure currently managed and stored? Can it be diverted before it is transferred

to the storage? If so then it may be possible to utilise the existing storage for the

7 The Environmental Permit for the biogas facility defines when storage can be uncovered - see standard rules SR2010No15 – The “On Farm” permit allows uncovered storage, whereas AD using outside feedstock do require covered storage

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digestate. If not then either the current manure management system needs to be altered or additional storage will be required.

b) How will the manure be transferred to the digester? In most situations it is important that the amount of time required and cost (to a lesser extent) to manage the manure is reduced by having a digester, rather than increased, otherwise the digester becomes a nuisance.

c) There should be a method of diversion for the manure, should the digester be unable to be fed, because the animals will keep on producing it.

d) How will wood, string, stones etc, often found in manure, be kept out of the digester?

Figure 4 - An on-farm AD situated for easy slurry management

e) Will you grow crops or import other feedstock? If so there needs to be sufficient storage

space nearby and a suitable loading system, or the digester system needs to be capable of being batch loaded. If animal by-products (e.g. food) are to be imported the risk of disease transfer to your herd must be considered.

f) If waste is imported and digested, an environmental permit is required to spread the digestate or the digestate product will have to have met the requirements of certification to the PAS110 digestate specification and Quality Protocol. In both cases records of applications will have to be kept and Regulations adhered to.

g) Vehicle movements will have an effect on those that live near to the digester site, therefore the size and type of vehicles used should be such that the disturbance is minimised.

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h) The feeding and unloading of a digester can be fully automated, but some farmers prefer to be about when machinery is operating (e.g. the separator). So the method of operation should fit with your preference.

i) Do you want to be able to undertake most of the maintenance and servicing yourself? If so then the technology used should be such that you can do this (e.g. plug in timers and controls rather than computer controlled systems).

j) How much time are you able to give to your digester each day? Remember that digesters, like an animal can get sick, or machinery can break, so it is important to keep a watchful eye regularly on the system and process and catch problems (and have time to rectify them) before they develop into nasty ones (the same as with an animal).

k) How will the digestate be used? Separated liquor is the best product for grassland, whole digestate and separated fibre are better for arable crops, silage ground, or where more Phosphate and/or organic matter is required. There are different requirements for storage and spreading of each type of product. See appendix 2 for more information.

l) Is it desired to have a digestate fertiliser that has a nutrient content to meet crop/soil needs? Then a mix of feedstock must be used that will provide the right nutrients to balance the nutrient content of the digestate products to match your farm needs.

m) Do the maths concerning farm nutrient needs and the total nutrient output of the digester, and if you have an excess of nutrients identify where they can go and what costs/income might be attributed to exporting digestate.

n) How will the biogas be utilised and what are the costs of doing so? It may be easier and more cost effective to pipe the biogas to the points of use rather than laying insulated hot water pipes, particularly if concrete yards or roads have to be crossed.

o) The new Environmental Permit Exemption T24 which is low cost and easily applied for is applicable for a digester <1,250m3. Therefore it is worth considering whether to keep the digester size below this capacity.

Main considerations for integrating a community digester

All the considerations for an on-farm digester are relevant for a community digester other than points h) & j) and also:

• Collection of manure and delivery of digestate products to farms must fit with each individual farm regime as far as possible. It is possible to deliver slurry or digestate by pipe. But large bore (>8”) pipes must be used to transport manure to ensure they don’t become blocked, and these are expensive to install if the distance is not short, and the manure should be conditioned before entering the pipe. Digestate, in particular separated liquor, can be delivered through small bore (1.5”) pipes.

• In most cases farmers will be willing to lend their manure to the digester to allow the energy to be taken from it as the level of available nitrogen will increase. Most farms will want to receive at least as much nutrient back as they provided in the manure. However, some farms

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may not as they are producing too much nutrients for their land/crops to fit within the NVZ requirements.

• Farmers involved will have to be agreeable to comply with the environmental permit relevant to their operation or for digestate, the PAS110 and Quality Protocol requirements.

• Vehicles used to transport must be suited to the local road network and to the farm access for the manure and digestate stores. These vehicles could be owned by the CAD or local contractors could be used.

• Transportation using fossil fuel produces greenhouse gases, therefore the mileage travelled and the type of transport used is important not only for cost reasons but also to maximize the net savings of greenhouse gas emissions created by the anaerobic digestion process.

• Bringing waste from a distant source leaves the project vulnerable to losing the waste if another treatment facility is developed between your digester and the source of waste.

• If food wastes are used, then the plant will have to be compliant with Animal By Product Regulations which increase capital costs and complexity of operation. Does the additional energy in food waste balance out these costs?

• What are the benefits to the community of the digester project?

• Odour, noise, dust, litter and visual effect are also important to manage in a such a way to minimise the effect on the locality

• How will the biogas be used? The cost of access to the National grid, may determine the scale of the project, but what is the cost and the accessibility for utilising the heat? Will other businesses be developed to utilise the energy produced?

Figure 5 - Interior of a reception hall at a CAD facility in Denmark

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1.2.5 Capital and operational (including maintenance) costs The capital and operational costs for different digester systems can vary significantly, so shop around! Be sure that all the parts of a digester project are included in a quotation. Determine what the energy demand for the system is and what maintenance and replacement costs can be expected for each major piece of equipment.

Visit or contact the reference plants of the technology provider, to establish whether the equipment replacement periods and costs given to you are just theoretical, what the operational costs really are, whether there have been any technology or process difficulties (and who or what caused them as quite often it is the operators fault or lack of knowledge), and how the technology provider supported them if there were. The control system can have monitoring and/or phone alerts for key parameters, these services come at a cost, so decide what is necessary for you.

Remember that differences in feedstock and management will place different requirements on a digester system, so two sites might not be directly comparable.

If you plan to use more than one contractor or supplier, to construct your AD, be sure that equipment provided or the way it is installed is compatible. Also be sure that any guarantees given are valid if someone else is involved or other equipment is used. Generally process guarantees cannot be claimed upon, because there are so many variables within a digester system, but they make financiers feel happier.

1.2.6 Management Before choosing a digester system, you should decide who is going to manage and operate the system and how much time will be available to do this. A robust farm digester, if integrated well into the farm system and where the biogas is used for heating only could take as little as 10 minutes per day to operate and about 10 days per year to maintain and service. The digestate will need to be spread but there may be savings in time and costs compared to the amount of time currently spent in manure and farm management. However, the more complex the digester system and mode of operation the more time consuming it will become.

Good management, as with many things, is the key to success. While learning about the digester, over the first 2 years, it is important to have good back up from the technology provider and to have contact with other digester owners, so that you can ring up for advice. You should insist on a training and follow up service as part of the contract. It is also possible with some technology companies to arrange a remote monitoring capability so that a diagnosis can be made by the supplier without having to request a site visit. However, such services are often very expensive, and tend to be a disincentive to you learning how to operate your own digester properly. It is important to treat your digester more like an animal than a machine. The process is alive and if operational parameters remain steady and you observe of a change in the process, or the rate of gas production, it is a sign that some piece of equipment is not working correctly or that the feedstock has changed.

Nothing happens quickly in a digester, most serious problems arise because changes are not observed early enough, or the system or process is being misused. Very often one small unobserved problem then causes a series of other problems to arise and the digester process can

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then be difficult to settle down again. So regular checks of equipment and operational parameters should be undertaken, and equipment serviced in accordance with manufacturers guidelines.

It is important that all those people who are in anyway involved in the supply of feedstock, understand how important it is to maintain the quality of the feedstock (e.g. dosing all of the animals on a farm with antibiotics and supplying that manure undiluted, or the sudden use of strong disinfectants at a food processing factory will have a quite severe negative effect on gas production. However, if these contaminants are always present in the feedstock, at a reasonably low level, the bacteria will adjust to some extent and although gas production may not be maximised the process will remain stable). It is advisable to have a written feedstock supply agreement with the supplier, making it clear what qualities in the feedstock the supplier will achieve and maintain.

1.2.7 Layout of site It is good practice that any digester site should be laid out so that there is a one way flow of material from intake of feedstock to removal of the digestate products. Procedures should be in place and care should be taken to ensure that unprocessed feedstock cannot contaminate the digestate products either directly or via personnel or equipment. This is mandatory for any digester that processes feedstock that contains or might contain meat.

There should be sufficient space around the digester and other equipment for easy access for maintenance and operation. Nearly all digesters have to be cleaned out at some time over their lifetime (hopefully not more frequently than 10 year intervals) so this should be considered before construction. It is advisable to protect all equipment against damage from vehicles, if they enter the site.

The site should be easy to keep clean, and any spill or litter that occurs should be able to be contained and cleaned up easily. Unloading areas should be designed to be able to contain any spills that might occur, be easy to clean and not encourage vermin.

Figure 6 - Liquid waste being delivered by pipe link directly into holding tank in Sweden

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1.2.8 Storage

Of feedstock In the ideal situation, feedstock should be loaded into the digester as fresh as possible, to obtain the optimum gas production, minimise nutrient loss, and to not cause a negative effect on the process (e.g. food becoming acidic before loading). It is possible to design a digester to operate with no feedstock storage, even when deliveries are in bulk loads. However, if a steady gas production rate is important, then the diet of the digester should be kept as constant as possible. Therefore, if different feedstock is being co-digested and/or there are bulk deliveries of feedstock, there may need to be some storage for feedstock at the digester site.

All feedstock storage must comply with the requirements of environmental permitting and with the good agricultural practice guidelines. If the feedstock, needing storage contains animal by-products, then the storage and handling systems must be compliant with the requirements of the Animal By-Products Regulations.

Of digestate Liquid digestate products cannot be applied during the closed period in winter, similar to slurry or other liquid materials within NVZ regions. Therefore, long term storage is required. While digestate is in storage it must be protected from sunlight (to prevent ammonia loss), by some sort of a cover. Whole digestate will form a crust which is generally sufficient, however, a crust will not form on the liquor. So either the tank must have a fixed rigid or flexible cover, or a ‘barrier’ of some sort (e.g. straw) should be floated on the top of the stored liquid. It is possible for this tank cover to have a dual use of creating a gas store and cleaning space.

Separated fibre can be spread throughout the year just like farmyard manure. However, if it is stored then the fibre should be covered, whether stored in the field, on a yard, or in a shed, to prevent loss of nutrients.

Where several farms are receiving digestate from a digester, as is the situation with a community digester, there is usually a short term storage for digestate on the digester site. This storage acts as a buffer between production and removal from site. Long term storage is typically on the receiving farms, but not necessarily in the farmyard, as new storage should be built near the fields where the digestate is to be used. When a vehicle goes out with a load of digestate to a farm it returns with a load of manure, from either that farm or another farm, which keeps transport costs down. Also when the time comes for spreading, all the farms want to have digestate available to spread and by having the digestate in stores near the fields where it will be used, reduces road traffic and damage, because farmers don’t have to tanker the manure to distant fields, and reduces the time required. Careful planning is required with a centralised AD project to determine the optimum positioning and size of long term stores.

In Denmark, where there are several centralised digesters, farmers who have land near to each other, agree to share a storage tank. Sometimes the cost of these stores is paid for by the digester company, and the farmers either lease space, or buy back the storage over time (with the savings made from reduced artificial fertiliser use). All digestate storage must comply with the requirements of environmental permitting and with the good agricultural practice guidelines.

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Figure 7 - A covered digestate store

1.2.9 Sites Choosing a site for the AD is of paramount importance because, not only is it financially important to minimise the distance that feedstock and digestate are carted and to utilise the heat and/or biogas locally to keep down the cost of pipework, but also it is important to consider location to minimise the environmental impact of the AD. For example, having an AD within a dip or even partially buried is ideal, to reduce the impact to neighbours but could raise the chances of unnoticed leakage into water courses etc. Reducing the environmental impact of an AD will also simplify the environmental permitting procedure as the plants that have a lower environmental impact will have easier route through the environmental permitting legislation.

Farm assurance bodies have been relatively quiet on the location and siting of AD within a farm system that they audit, however, they will require assurances that the food ingredients that are being produced on these farms are exposed to no risk of any kind of contamination with feedstock or digestate.

1.3 Technology providers A full list of technology providers known to have representatives active in the UK are listed in Appendix 4 along with more detailed description of different types of technology available. A check list of questions to ask concerning technology is in Appendix 3.

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Chapter 2 - Deciding whether to develop an AD

2.1 Identifying what is the primary purpose of the digester It is important to first identify what are the priority things that you want the digester to do, because that focus will affect the type of technology required and the way the digester is operated. For example if the most important thing is electricity production, then it would be preferable to use feedstock that contains good energy potential and to operate the digester in a way that gas production is kept at a fairly level rate. Whereas, if the focus is primarily improving farm management, then the feedstock mix and quality will be determined more by utilising the resources within the farm and the need to produce a digestate that best matches the farm need for fertiliser rather than just trying to maximise energy production.

Generally everyone who considers developing a digester would like all the following benefits, but they should take time to consider how they would rank them in order of importance and identify why that benefit has more importance than another.

• waste management

• farm management

• energy production – and what kind of energy – gas, electricity, heat, vehicle fuel or a combination

• fertiliser production

• odour control

• protecting health

• environmental control – for soil, air, greenhouse gas reduction, water quality

• rural development – helping to maintain existing businesses and creating new opportunities and jobs

Detailed explanations of how AD can improve management and provide benefits in these different areas can be found as you read through this document and the appendices.

2.2 Determining the size of AD In recent years it has become normal practice, particularly by AD technology companies, to size digesters by the electrical output of the project. This is because there has been widespread development of crop based digesters in Germany and in other EU countries. Typically these digesters have an electricity output of 500kW or more. Another reason the electrical output of an AD has become the focus of sizing an AD is because Government financial supports are related to the electricity output. It is a better practice to size a digester by determining the cubic capacity of the tank, that is needed to contain the feedstock for long enough to get sufficient carbon conversion (from feedstock to biogas) and produce a stable digestate product.

The focus of any financial support tends to drive any market in that direction. Recently WRAP has offered capital grant support to AD that process waste only, to help the UK to meet its targets

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of diverting biodegradable waste from landfill. As a result large waste only digesters are being built, even if these are likely to be difficult to operate due to process instability.

Figure 8 - A 500kW on-farm digester in Germany processing grass, slurry & some maize

When determining the size, location and purpose of the digester that you should build, it is important not to be distracted by financial supports or policy targets, or to become ‘greedy’ after seeing the revenue that might be generated from gate fees. All these factors could easily disappear in the future, therefore a project should not be entirely reliant on them. The life of an AD project is at least 30 years, therefore to take 10 years to pay back the capital is entirely reasonable. The assessment of any AD project should review the long term viability and resilience to external changes. This is not the typical way of assessing a business proposition in today’s economy, where short term gains and market conditions are the focus.

It is strongly advised that you size your AD to the feedstock that is readily available in your locality. There is no doubt that transport costs will significantly increase over time, and other AD projects are likely to be built across the country. These factors create a serious risk to an AD project that relies on getting waste or manure from any distance away, or has to take digestate to some distant place to be utilised.

It is possible to grow crops for AD, and currently because of depressed prices for food products at the farm gate, and because of the current financial supports for electricity, it is financially viable to grow crops for digestion. The question is will it still be viable if any of these factors change, and if it becomes no longer financially viable to grow crops, what else is available to keep the digester going. For a community perspective there is always the question of whether widespread mono-cropping for energy production is good for the landscape and the environment.

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2.3 Choosing an optimum mix of Feedstock There is much difference of opinion about what is an optimum mix of feedstock. This can be confusing. There is no set rule about determining an optimum feedstock mix, because it depends on what you want the digester to do and how much you are willing to spend to keep it operating. However, there are a few factors that should be considered when trying to determine the optimum mix for your situation.

Fresh manure or human sewage is easy to digest because it contains a wide spectrum of process bacteria already, and the conversion of the material within the digester into biogas occurs at a rate that helps to maintain a balanced process. Therefore a feedstock mix that contains more than half (by dry matter) of these materials will ensure a robust process can be maintained and that will be able to cope with ‘shock loadings’ from time to time.

• As a general rule feedstock that has a high potential gas yield is considered to be a volatile feedstock

• Mesophilic digestion process works slower than the Thermophilic process, so it is inherently a more stable and robust process.

• Higher temperatures, whether Thermophilic digestion or during the pasteurization process, will tend to make volatile wastes foam or may release ammonia too quickly, which can cause ammonia poisoning within the digester. Therefore if higher temperatures are involved early in the AD system the amount of volatile feedstock processed should be controlled carefully.

• Some feedstock requires the consistent addition of minerals to aid digestion and gas production. This adds cost to operations and may have a negative effect on the digestate quality.

• It has recently become apparent that the AD process in most food waste only digesters begins to change over time. This is a concern because when this change occurs the volatile fatty acids take a structure that cannot be broken down by the bacteria, so that gas production rate decreases and the digestate is not sufficiently processed for use in agriculture.

• The mixing and heating system must be suited to the feedstock mix

• If the feedstock mix has a watery consistency, it is advisable not to use feedstock types that have long fibres or contain grit or heavy particles, as these will separate out in the digester into a floating mat or sediment on the base of the tank. These separated layers will be difficult to move and will continue to build up.

• The thicker the consistency of the feedstock mixture in the digester, the less likely there will be separation of layers but the mixing system must be capable of moving such material.

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Chapter 3 - External effects of AD

3.1 Agricultural Effects A digester will have significant effects on a farm business, whether it is an on-farm or a community digester. The common effects are;

• a 50-70% reduction in artificial N fertiliser purchases, even when only manure is processed. If feedstock other than manure is co-digested then there will be further saving of N and other types of fertiliser purchases.

Figure 9 - Meeting the crop nitrogen need on one hectare of grassland Raw slurry Liquor from slurry Liquor from digestate Total N in slurry kg 170 170 170 Total N in other AD feedstock kg 0 0 80 Availability of N 30% 90% 90% Available N kg 51 153 225 Crop need 225 225 225 Top up from artificial N kg 174 73 0 Cost at £652/t art. N (100%) £111 £53 £ 0

• The ability to operate an effective nutrient management plan will be greater, because digestate is homogenous, so a sample is representative of the whole, unlike manure. Also the nitrogen availability to plants is certain.

• Generally there is no need to lime.

• Weed seeds are destroyed by the process of anaerobic digestion, so it is possible to return fields to having negligible amounts of weeds in them

• There is less risk of lodging in arable crops as root structure is enhanced

• In many cases there is a reduction in costs related to managing the manure

• There will be better plant root development and the plants will interact more effectively with the soil. This results in many benefits such as less poaching and vehicle damage, less need to reseed pastures, a better uptake of minerals, in particular the minor minerals which are needed for health and strength of the plant (and consequentially the animal/human that eats the plant), a more open soil structure, easier to till, increase in earthworms and less flooding and water logging of soil

• Better silage quality. Farmers that use digestate have found their silage quality has improved and there is much less wastage

• Higher protein (by dry matter content) in winter wheat8.

8 Danish Agricultural Advisory Service Annual Report of National Field trials in 2002

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Figure 10 - A permanent meadow fertilised with digestate

Further details on the characteristics of digestate products can be found in Appendix 2

3.2 Environmental Effects All anaerobic digesters have a significant effect on the environment. The extent and whether this effect is positive or negative depends on the configuration of the project and its management. If the project is designed, integrated into its surroundings and managed to optimise the net environmental benefit, then the overall improvement to the environment from installing an AD can be significant.

At the current time, the AD project cannot realise any financial value, apart from that of reducing carbon emissions by replacing fossil fuel used for electricity generation, from optimising the environmental benefit. Therefore most AD project developers are not concerned about the effect on the environment other than to be able to meet environmental regulations. This is one aspect where a community AD project can differ, because its focus is not solely on ensuring the project trades positively, but also on improving conditions for the community as a whole. Therefore the value of the external benefits should be calculated, where possible, and considered when evaluating the feasibility of the community AD project.

Environmental benefit is difficult to quantify. More research is required to be able to quantify all the environmental effects of designing and operating an AD in different ways. However, there is some research data available which has been produced in Denmark, where they have had community digesters for over 20 years. The data in Figure 10 has been used by Risoe National Laboratory in Copenhagen, to provide socio-economic analysis of centralised AD. It is important to realise that these figures can change for better and worse, depending on how an AD project is configured, managed and outputs are utilised.

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Climate change and greenhouse gas (GHG) emission reduction are very important and pressing issues of this time. Anthropogenic emissions affecting global climate change comprise, amongst others, the gases carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O). Animal manure and slurry management is a major source of GHG emissions (CH4, N2O) in the agricultural sector, only beaten by rice cultivation and enteric fermentation. AD of manure and the capture of the biogas produced, usually provides a net reduction of GHG emissions, when all factors are accounted for. AD is currently the most promising way to reduce GHG emissions from agriculture and especially from animal and dairy production.

Figure11 - Value of some of the environmental externalities for a 4,000tpa slurry only digester (440LSU ), producing 20kw electricity and 16kw spare heat

Benefit Amount of output Value per unit Value for AD £pa

CO2 saved by reduced Grid loss 12.1t/yr 550kg/MW hour

electricity 180

Electricity C02 saved 9 87t/yr 550kg/MW hour electricity 1,315

Heat CO2 saved 33t/yr 241kg/MW hour electricity 481

CH4 pa manure storage saved10 400t/yr 100kg CO2 equiv./t 600

manure N2O saved 23.2t/yr 5.8kg CO2 equiv./t manure 345

CO2 of energy saved by less artificial fertiliser being

required 74.8t/yr 18.7kg/t manure 1,122

Kg N to water saved pa (£3.36/kg) 2,760 25% of art. fertiliser

saved 9,108

Total benefits to environment £13,151

AD facilitates the establishment of an environmentally sound manure management system on farm. The AD process transforms carbon from the digesting material into biogas. The nitrogen that was bound to the carbon as organic nitrogen becomes mineralized (60-80% of the total nitrogen content in form of ammonium [Banks et al., 2007]). In this form it has the potential to replace artificial fertilizer use. As most of the mineralized nitrogen is in forms of ammonium nitrogen, the nitrogen becomes ‘locked onto’ the soil particles until soil conditions are suitable for plant growth. This nitrogen then becomes available to plants to use as they grow. Digestate application also stimulates plant root growth, which helps to reduce soil erosion and damage and keeps the soil in a more open structure. This makes digestate much more predictable, minimises

9 Valued at €15/t CO2 10 Stored for 4 months on average in outside stores

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nitrogen loss through leaching and erosion and is in line with the development of good agricultural practices.

In untreated animal manure, over 50% of the nitrogen is in organic form. When this is spread on the land, the organic nitrogen has to be mineralized to nitrate, in the soil, before the plants can utilize it for growth. The timing of this conversion is uncertain and depends on temperature and soil conditions. Therefore, there is the possibility that nutrients will be leached from the soil as the nitrogen conversion may occur at a time when plants are unable to take nutrients up. The spreading of artificial nitrogen fertilizer can also create nitrate leaching if the plants aren’t growing at a sufficient rate to utilize the applied nitrate and N2O emissions can occur if soils are very wet after application.

The amount of the organic nitrogen content in manure and wastes that are land spread untreated that is taken up by plants is uncertain, so that organic nitrogen is not accounted for when planning the nutrient needs of crops in any one year. This practice means that at least an amount of nitrogen equivalent to the amount of organic nitrogen applied is guaranteed to be ‘lost’ into the environment, whether this nitrogen actually comes from the manure or the artificial fertilizer application. Therefore using digestate has the potential to at least halve the amount of nitrogen being lost to the environment compared to normal agricultural practices.

There could be other environmental benefits such as reduction in ammonia emissions (depending on the management system used), reduced odour, increased organic matter in the soil and a more open and resilient soil which therefore is less prone to flooding. The value of these benefits has not yet been quantified. See Appendix 8 for more on the environmental effects of AD

3.3 Social Effect on Other Businesses & the Community Any type of development has some level of effect, either positive or negative, on other businesses and the local community. The amount of social benefit or disadvantage arising from an AD development will depend on the individual situation and the manner in which the AD is developed. Because the value of most social benefits cannot be realised within a project, as they are ‘externalities’, generally a project developer will not bother to maximise them. A community owned project should have more focus on maximising the social benefits.

The following would be considered as social effects:

• job creation and new incomes – there is an obvious benefit for the person who gets the new job or income stream, however there is also a benefit for the wider community because at least some of that new wealth will be spent locally, creating further jobs and incomes. Research has determined that about 0.4 ‘knock-on’ jobs are created from every new job created in the biomass sector.

• positive effects on other industries and businesses, e.g. improvement of water quality in rivers could improve fish numbers and be positive for tourism businesses, or by providing an local outlet for food waste at a lower cost could help to lower school and hospital costs.

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• negative effects on other industries and businesses, e.g. a poorly managed AD taking in food waste will be likely to smell, creating an unpleasant environment that makes people not want to be nearby.

• new business opportunities, either for existing or new businesses to service the AD and to utilise the AD products.

• a decrease in other businesses turnover eg as the digestate will reduce the demand for artificial fertiliser, those businesses selling artificial fertiliser will have a lower turnover.

• an increase or decrease in vehicle movements associated to the AD and supplying farms, will effect those living nearby and the safety on the roads.

• visual effect

• level of involvement. If local people have some sense of ownership or involvement in an AD project it can help to improve community spirit and interaction. Where a large scale AD development is ‘imposed’ upon an area and there is no local benefit, it is likely to generate anger and discord amongst local people.

The table below identifies some of the social value that can be obtained from an on-farm AD

Figure 12 - Value of social externalities for a 4,000tpa slurry only digester (440LSU), with total capital cost of £202,000, producing 20kw electricity and 16kw spare heat

Effect Value Impact £ per year

Wages from capital spend 30% of capital cost £60,748

indirect + induced incomes from capital labour spend 40% of direct income £24,299

Increase in farmers income pa Averaged over 15 yrs £14,065

Income created from servicing 1% of digester cost £1,625

indirect + induced incomes from ops labour & farmer 40% of direct income £6,276

Avoided import oil equivalent11 10t/yr 0.16 tons per MWh e £3,750

Net avoided import of N fertiliser pa 11t/yr 2.75kg/t slurry at £1000/t £11,000

Grid losses saved 22MW/yr 15% of output @ £160/MWh £3,520

11 $50/barrel and 7.5 barrels/ton oil

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Enjoyment Farming is a way of life that often doesn’t provide large profits. Most farmers farm because it is a way of life they like. However, in recent years some of the pleasure of farming has been eroded. This is because there is increased paperwork and marginal profitability on many farm systems. As a result the enjoyment of farming has disappeared for some farmers.

AD will not solve all these difficulties, but it has the potential to provide the farmer with a level of independence from the ‘treadmill’, make manure management no longer a messy and tiresome job, and helps the farm and animals to function more naturally. An on-farm digester is a new animal that most farmers come to ‘love’.

3.4 Community Development The development of an AD facility can be an isolated enterprise with minimal or no interaction with other parts of the community. Alternatively it can be developed to provide a valuable service to farms and businesses in the locality, generate an income for the community and local people, and become a vibrant hub for community development. The outputs from AD are multiple and it can create opportunities to benefit the wider economy and community. The following three diagrams illustrate how AD can be one of the central pillars of economic activity in a local area.

Factory

Finance

LabourFarms

Businesses

fertiliser

Little activity

energy

waste

waste

Emigrationenvironmentaldamage

environmentaldamage

environmentaldamage

Figure 13a - how a community in decline, where the parts function separately & only externally

This first diagram (figure 13a) reflects that in today’s society, a large amount of business is undertaken in isolation from other nearby businesses or residents. Computers, phones and other forms of communication and electronic information transfer, now mean that people can operate their businesses from virtually anywhere in the world, regardless of where their clients are based. This is particularly true of the service sector, and increasingly so for manufacturing businesses as

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well (hence business emigration to developing countries). The diagram above illustrates the potential for isolation even in a busy location. This is the bleak situation that most communities find themselves in today.

CAD

Factory

Finance

LabourFarms

Businessescheaper waste

wagesfertiliser

manure

energy

loan

Figure 13b - A reviving community with more local interaction & money transactions

The second diagram identifies the connections that could be made with the local economic community when developing an AD plant. The interaction comes from supplying electricity to local factories and houses, supplying heat to community buildings or commercial uses, taking food waste from businesses instead of their sending it to land fill. A community AD will require employees, the number depending on its complexities and size, which provides local employment. A skilled workforce is necessary for most of the jobs, and such ‘quality jobs’ are hard to find in rural areas. By employing local staff there would more likely be a genuine interest to see the AD project work well.

Farms of course have a two way link with the CAD, with the manure being digested, and the farm taking the digestate as fertiliser, essential for the success of the AD plant and also offering major saving to the farming operation. Other businesses might be involved through owning shares, taking surplus heat to warm the offices, or even using the heat to generate cooling.

This third figure (below) illustrates that this inward investment can generate further value at every point in the business cycle. Linkages between businesses tend to generate additional linkages making the local community into a vibrant hub of sustainable economic activity. Greater movement of resources and money, within a community, instead of letting these resources drain out to distant economies generates additional local opportunity from within. For example, the enhanced local business network and greater employment will lead to more money remaining within the local community, thereby adding to the justification for local services such as a local shop, more children at the school, a bus stop or route, leading to greater community sustainability.

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Figure 13c - A community developing further with a CAD

CAD

Factory

Finance

LabourFarms

Businesses cheaper waste

wagesfertiliser

manure

energy

Buy more Save more

Employ more

Buy more

Buy more

loan

new loan

More opportunities within – Growing business for all

Examples of how AD can create local opportunities

• Manure feedstock will need moving from its point of origin, the farmyard, to the digester and the digestate has to be moved out to the storage tanks in the fields where the digestate will be spread. This is an opportunity for a local farm worker, or haulage contractor to develop a business, or expand an existing business to supply this service. A tanker vehicle, be that a tractor and trailer or a tanker lorry would be necessary. Today several farms have surplus workforce, because they have at least two generations of the same family operating it. Few farms make sufficient income to make sufficient profit for more than one family to take drawings and leave sufficient money for reinvestment. To support additional generations as their families grow, the farm size must increase, the workforce decrease, or other off farm enterprises need to be developed.

• A community CAD provides the opportunity for a local authority to change its domestic waste collection policy. Many authorities have considered the option of separated kitchen waste collection. Not only would this offset the landfill tonnage but also provide a useful revenue for the CAD and provide work from the refuse collection.

• Many CAD facilities will separate the digestate into liquor and fibre fractions. There is the potential for someone to develop an enterprise marketing the fibre. The fibre can be further processed to produce a high quality compost or nutrient rich soil conditioner. The markets for

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which a good value could be obtained for the fibre would include market gardening, small scale landscape gardeners, golf courses and other recreational grounds or to sell to private gardeners. Branding the fibre as a local product might be one way of adding value to it.

• There are currently not many community-owned ADs outside Denmark. CAD could therefore generate considerable local, national and even, international interest. People interested in renewable energy or in building a CAD of their own would travel long distances to see what has happened in your community. Some will visit the CAD and may want to remain in the area for lunch, or stay in the hotel or see how buildings are operated that the CAD provides heat to. A rise in the number of visitors to the area will raise the spend in the nearby shop or pub. It could create potential for tourism ventures and so on. A visitor’s centre could be built at the AD. The venue, if well designed could be used for conferences for the renewable energy industry or, for that matter other events too.

• Selling the electricity locally rather than to the National Grid would enhance the return to the CAD whilst also making cost savings to the local householders and businesses.

• If the heat is not utilised, it is a waste of a resource. If there are no obvious nearby uses for the heat, or they would all incur excessive cost to install, why not encourage local business generation (possibly with grant aid) to capture the heat and make use of it. Examples of low cost heat capture might be:

a) to dry fire wood or chip thereby minimising the time needed to dry it by open storage. 1-2 years is normally required to dry wood in open stacks. This is a long time to have capital tied up.

b) Building a row of green houses to utilize the heat (and possibly CO2) to produce vegetables or flowers out of season

c) The heat could be a justification for a new enterprise where the heat is useful but of secondary interest. An example is a swimming pool where energy costs have prohibited its development or a large shed to house indoor enterprises like go-carting. Heating these buildings would make the experience more enjoyable in wintertime and aid their success.

• The Renewable Heat Incentive will come into effect in April 2011. It is likely that this will provide an income from heat produced, weather from a boiler or from the heat element from CHP. This income may be sufficient to cover the investment in a heat network such as a district heating network to nearby housing, construction of greenhouses or to be utilised in providing hot water to clean down cattle sheds.

3.5 Health

AD has been used for over 100 years in the sewage treatment industry because the process destroys harmful bacteria. Spreading digestate that is properly digested significantly lowers risk to health of humans, animals and plants compared to spreading undigested feedstock of all types.

There are harmful bacteria in all manure and biodegradable waste, although generally amounts are not sufficient to cause disease transfer. Spreading untreated manure on different farms with the same species of livestock or spreading any waste has the potential for disease transfer.

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Research has shown that during the AD process harmful bacteria are destroyed. The higher the temperature and the longer the duration in the digester, the greater the destruction.

However, in a continually mixed digester that is fed at frequent intervals, there is always a risk of by-pass and some feedstock will only have been processed for as long as the period between feeding the digester, which may only a few hours. 5 hours at a temperature of 57oC provides sufficient pasteurisation for most feedstocks including cooked food and manures. To ensure destruction of nearly all harmful bacteria that cause disease, some feedstock, particularly that containing raw meat, must now be pasteurised (70oC at 12mm for 1hr) within an AD system. Where pasteurisation is required by regulation12, there is a requirement to be able to verify the time, temperature and size particle.

Figure 14 - Tanker collecting digestate for delivery to a farm in Finland

3.6 Waste Management AD is generally accepted to be the most energy efficient and environmentally benign method of transforming manure and biodegradable wastes into valuable fertilisers. Following sustainable principles, what comes from the ground should be returned to the soil to grow the next crop. However, this ‘recovery and return’ should be undertaken efficiently, minimizing the losses from and inputs to the process and safely, minimizing any health risk or environmental damage. AD

12 See National ABP Regulations in appendix 9

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systems can provide the means to do this, so long as the size, location and design of AD project is appropriate to the feedstock supply.

A digester that is built primarily for waste management will focus on maintaining a robust process that can withstand shock loading of different waste streams. This is different to an AD built primarily for gas production, in which the feedstock mix and rate is kept as even as possible to ensure steady gas production.

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Chapter 4 Undertaking a feasibility study for an AD project The following points should be considered when assessing the feasibility of an AD project whether the proposed AD is to be small or large. However, in certain circumstances not all the following points will need to be considered. How much research is required into each item will depend on the size of the proposed AD development.

Stage 1 research Identify what is the developer’s main purpose of building an AD

• Resource assessment should include –

a) identification of the amount of farm material available and the current manure management system on the farms with reference to collection and storage facilities, timing of availability, access, alterations that might be necessary etc

b) identification of the amount and type of suitable biodegradable waste (e.g. food processing waste, dairy sludge, sewage sludge) that is available

c) Will crops be used as a feedstock? If so what and from where? For each type of feedstock it is important to establish

quantity

quality (content of dry matter and a rough identification of type)

possible seasonal variations

price available for treating or cost to obtain

present use/disposal (possibly including price of disposal)

existing or forthcoming legislative requirements.

likelihood that supply may cease do to competition or changes is production or land use

d) What mix of the available feedstock will provide a stable process and the right quality and quantity of by-products without causing capital and operational costs to rise to a level that cannot be supported by the project?

• Transportation of feedstock –

a) How will the feedstock be moved from its source to the AD plant?

b) How will material be moved to the collecting point at the supply farms? If moved by gravity or automatically, will this require new equipment or modification to existing system? If so what is required and at what cost?

c) If vehicle used to transport, who will do it and at what cost?

d) What type of vehicles will be used and how many traffic movements per day?

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• Unloading and storage of feedstock

a) What type and size of storage will be required at the AD to allow for variable supply and operational requirements?

b) Will feedstock need to be ‘cleaned’ of contaminants, or receive other conditioning or be mixed prior to loading? If so how?

c) Can existing facilities be used (if there are any)?

d) What measures are required for hygiene measures and odour and other environmental control measures?

• By-Products – it is important to establish what by-products will be produced and how they will be utilised. Do they require further treatment or facilities? Do they require storage? What are the legislative or public acceptability requirements etc?

a) Biogas – is there a use for the biogas and if so will it be for heat only, heat & power production or for vehicle fuel? What technology will be required?

b) Digestate – will the digested material (digestate) be used as it is or separated into fibre and liquid?

c) Will the fibre be composted on site?

d) Will the liquid be utilised as a liquid fertiliser? If so is there sufficient land bank available or will liquid be treated to water dischargeable quality?

e) Will a nutrient management plan be required/utilised?

• Markets – establish which of the by-products will be used on site and which will need to find other outlets (including disposal)

a) Do markets already exist for the by-products? If so where and what is required to be able to reach them?

b) If markets do not exist, what is required to develop one?

c) How reliable are these markets and what and who are the competitors?

• Public acceptability – It is important to establish what the local feelings are concerning an AD development. This could involve provision of information, public consultation, door to door contact etc.

• Permits, licences and permissions – Identify what permits, licences and permissions may be required, what is needed to do so and have discussions with the relevant authority

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Figure 15 - A CHP unit

Stage 2 - Assessment of information Once the above items have been researched the size of plant can be determined. An assessment can then be made of;

• what technology is available and suitable and at what cost

• what the skills and labour requirements are, whether these can be provided by existing personnel or will new people be required, if so whom and from where

• training – who will provide training to the personnel necessary to run the plant

• service and backup –what is required and from whom

• finance – establish how the plant will be financed, is the finance available, at what cost and what will be required to obtain that finance

• insurance – what insurance will be required or desired, from whom is it available

• risk assessment –

a) What can go wrong and how will it be overcome?

b) How vulnerable are prices/costs to change - and what happens if they do change?

c) What happens if another AD or competitive process is built in the vicinity?

Once all the above have been completed a business plan and financial prediction can be made.

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It may be necessary at any step of Stage 2 to consider changing one or more parameters (e.g. the amount of one of the feedstock streams). A single parameter change will probably mean that other parameters and conditions will also have to be changed. Therefore the Stage 2 assessment will then have to be undertaken again. If possible it is best to enter as much information as possible into a spreadsheet, so that the parameters can be adjusted and the results will flow through.

4.1 Farm Assessment The farm assessment required will be the same whether an on-farm or community AD is being considered. A farm visit takes 1.5-3 hours depending on the complexity of the farm and the interest of the farmer. It involves walking through the farmyard and buildings, to understand how the animals are managed, when they are housed and how the manure is collected and stored. The types of crops grown, the land area for each crop, the amount and type of artificial fertiliser used, the timing of applications and the type of soil should be identified. Ideally the farmer marks out the land belonging to the farm and that which is rented, on a map (showing field boundaries) of the area. The value of growing grass or crops for the digester should be discussed and it should be established whether the farmer has any interest in doing so.

All relevant data should be recorded on a standard form (a sample form is in Appendix 5). The aim is to allow the conversation to flow naturally during the visit, so it is best not to fill in the form until after the visit. It is important that the farmer feels the assessor is interested in his farm and will keep any information provided confidential. Otherwise much of the required information may not be forthcoming. Each farm is individual in the way it is operated and should be treated so. The assessor should therefore have at least some understanding of farming and farming issues, as well as a thorough knowledge of AD.

Explanation has to be provided to the farmer about how a digester works and how it would change the farm, how it might fit within that farm, and why a feasibility study was being conducted. The purpose of the conversation, other than to obtain factual data about the farm and explain AD, is to gain an understanding of what is important to that individual farmer about their farm and their concerns about farming and their future. This process of discussion and two-way exchange of information is crucial to identifying what might be possible. AD is only suitable for a particular farm, if it would actually improve the farm management and make things easier and financially better for the farmer. Every farm and farmer is different and their individual situation, management system, concerns, needs and hopes must be understood and considered if a proposal is to be workable in the long term.

If a farm digester is being considered then the potential site should be identified, and the alterations that might be required to the manure management system to integrate the digester should be discussed with the farmer. If a community digester is being considered then the accessibility of the farm for a vehicle to collect the manure from the farm should be considered and what measures may be needed to facilitate collection. In both situations where the storage of the digestate is going to be and what type of storage should be discussed.

Once the information is recorded on the forms along with a sketch of the building layout and manure storage, then any missing information can be obtained by a subsequent phone call. The individual datasheets should be used to prepare a spreadsheet for each farm. This approach

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allows analysis of a farm situation against an on-farm AD business model to see whether a particular farm is suitable to have its own digester. It will also allow computation of farm data to assess how much feedstock from farms might be available for a community digester. The spreadsheet can be used to calculate what would happen should a parameter change.

4.2 Assessing a community CAD A site for the digester needs to be identified where;

• there is adequate room for the whole facility and trucks to turn,

• the heat can be utilised,

• the grid connection cost will not be prohibitive,

• there is good road access to the site,

• there is enough farm and non-farm feedstock available within an acceptable distance,

• most importantly it will not impose on those living nearby or on the landscape,

• it will not present an undue bio-security risk.

Figure 16 - Centralised Anaerobic Digesters (CAD) in Denmark

Determining the size of digester to build can be quite arbitrary because there are many factors involved but it is important to define at least one limiting factor as soon as possible in the assessment. Otherwise there is too much ‘chicken and egg’ syndrome involved. The following factors should be considered:

• How much manure and crops are available within a 3-4 mile radius and what ratio of farm to non-farm feedstock will be used?

• How much non-farm feedstock is available within a distance that is acceptable, typically a 20 mile radius is advised to minimize future operational and financial risk from competition. Determine the type of non farm feedstock and what gate fee can be levied. All centralised ADs

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require non-farm feedstock to finance the project as there are many additional costs when compared to a farm digester. Some non-farm feedstock may not be suitable for AD or may require additional capital and operational cost to condition it before digesting. Some feedstock may not be acceptable to the farmers who will utilise the digestate.

• How much energy can be used - particularly relevant for the heat use?

• Planning or permitting limits

• How much land is available to utilise the nutrients produce, in particular those in the liquid digestate? 3-4 miles is generally the maximum distance that is economic to transport liquid digestate.

The important factors defined by the community (refer to list in chapter 2) and the benefits they want from the project, should form the basis of the feasibility study. The project should be regularly proofed against these important factors as it develops, to make sure that the project still meets them and that other factors or information gained has not changed the focus. For example it is tempting to allow the project size to grow or to change the ratio of manure to non-farm feedstock, when large amounts of feedstock that can earn a high gate fee are identified.

It is really important to remember, that the more non-farm feedstock the AD processes, the more vulnerable the project becomes to competition for that feedstock. There are plenty of examples in Europe where projects have failed because of losing a paying supply of feedstock to another project, or where gate fee value has dropped considerably due to the increased number of treatment facilities. It is therefore advisable to limit the distance the feedstock has to travel, so there is less likelihood of another facility being built between your project and the source of the feedstock. Another way to protect the availability of the paying feedstock for your AD is to build a relationship with the feedstock supplier, or allow them to invest in your project to some level.

The mix of feedstock is important to maintaining process stability, the type of technology required, the energy and digestate quality outputs. Generally the lower the proportion of manure in the mix, the more operational costs will rise and the more the process will have to be monitored. Experience has shown that 70% manure to 30% other feedstock (by dry matter content) is a very good ratio for a community digester, and produces good quality digestate that does not exceed the amount of nutrients needed by the farms in the area.

As the community-wide benefits of the AD project are relevant to the project, where possible the value of the externalities (community benefit) should be added in to the assessment of the viability of the project (e.g. helping to keep farming businesses viable in the area would mean that the net benefit to each of the farms will be added into the financial assessment).

The road network accessing the supplying farms must be considered. If there is additional large vehicle traffic on small roads it could cause a safety issue and be a nuisance to those living on the road. The type of roads and manure storage accessibility will determine what type of vehicles can be used to move manure and digestate. The type of vehicle used will affect the financial assessment of the project, and whether local contractors can be used to provide a transport service.

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If there is no obvious user for the heat produced, then possibly a heat-using business could be developed in conjunction with the digester facility. The assessment of whether to develop such a business should be made as a separate business case.

How the company that owns and operates the digester is to be established should be considered. There are many types of business models; which model to choose will depend on many factors. Examples of possible models are provided in the appendix 6. It may be necessary to attract a large investor, but as a general principle, the control of a community digester should remain with the farmers, as it is their land that will be using the digestate, so they should be the decision makers. If local people are encouraged to invest, even at a very small level, it is a great way to get the support of the community.

4.3 Regulations There are lots of regulations that can be relevant to an AD project depending on its location, the way it is developed, the type of feedstock and its size. Appendix 9 provides more detailed information on each regulatory requirement and when it is applicable. The list below identifies what might be applicable.

• Environment Agency Permits - facility, waste carriers and spreading

• Animal By-products Regulation

• HACCP Management

• NVZ Regulations

• Planning

• Grid connection

4.4 Finance Appendix 11 provides more details on all the following sections on financing an AD project

4.4.1 Supports

There are capital grants available that an AD project can be eligible for. However, the source and availability of and the eligibility criteria for these grants changes over time. Due to State Aid criteria it is possible that although a project may be eligible for two or more supports, if one support is applied another cannot be. Therefore, it is important to check all possible sources for current availability and to read the small print, to ask many questions and not to give up easily. Sometimes if you change the proposal slightly you may become eligible or ineligible.

There is a support measure related to electricity production called the ‘Feed-In Tariff’ (FIT). This financial support is available to any AD project that generates electricity, whether that electricity is consumed on-site or sold off site. It favours on-site consumption and small scale (<500kW) projects.

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4.4.2 Banking

An on-farm digester that processes only the manure from that farm, or manure and a non-waste feedstock (e.g. silage) is not usually difficult to finance, unless the farm is already carrying significant debt. The farmer usually will have a ‘track record’ with their bank, and so long as this is a positive story, and the figures ‘stack up’, banks are available that will lend the money required against the security of the farm asset and a contract regarding the FIT if electricity is being generated.

Figure 17 - A 140m multi-tank on-farm digester made of reinforced concrete

A CAD does not generally have any collateral assets beyond the operation on the ground. As these assets have little resale value and because AD is a relatively new technology in UK, the loan will be against forecasted cash flow. This will make borrowing money far more difficult and maybe expensive as the risks are perceived as higher. So the banks will probably want at least the following criteria met

• Robust and long term energy & feedstock contracts

• Proven technology

• Expert operation and management

Obtaining long term contracts for the electricity should not be difficult. If there is a use for the heat a long term contract should suit both the CAD and the customer. However, even though the majority of the feedstock might come from local farms, the majority of the biogas and the revenue for the project will come from the paying feedstock. Therefore, the bank will consider it very important to have secure arrangements concerning this feedstock.

It is most unlikely that long term waste supply contracts will be available from waste collection companies because they cannot guarantee they will have the waste in the future. It may be possible to interest a waste supplier or waste management company to secure an outlet for its waste into the future, by coming to an arrangement, such as through taking a shareholding, in the AD project. Although the income from gate fees would still not be guaranteed, if the bank is confident that it is in the interests of both the waste supplier and the AD facility to maintain their agreement, they may accept this instead of a guarantee of gate fee income.

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Another alternative is that the CAD develops a waste collection service, or enters an agreement with a small waste collection company to collect specifically on their behalf. This approach has already been used by some European AD projects and composting facilities. This approach means the CAD can guarantee waste supply to itself, so long as it can offer the service at a price that is competitive with its competitors.

4.4.3 Local currency Local currencies have been used in UK and other countries for many years and are particularly successful in times of economic recession. Local currency is being used in Germany to help finance renewable energy projects, since the collapse of the world economy. A local currency greatly helps the liquidity of money in a local economy, and stops the ‘drain’ of money out of the area on purchases from far away, thereby helping to keep small, local businesses trading. There are several models that can be referred to but local currency use is continually developing and there is no ‘typical model’ to follow. Who issues the local currency has to be decided, but it needs to be a body that people believe will be able to repay them when they need to ‘cash-in’ the local currency for the standard tender, or the local currency needs to be ‘backed’ by something of tangible value.

Renewable energy projects are ideal for backing such currencies, because if someone needs to ‘cash-in’ the local currency for standard currency (sterling) then they can do so by purchasing electricity or heat from the project. This ability to cash-in creates a confidence in the users of the currency and so many businesses and individuals become willing to trade in the currency instead of sterling. But the currency can obviously only be used in the local economy, thereby generating more business locally. It is possible to issue a local currency, the value of which is guaranteed by the AD company. There are already local currencies operating in UK, but most of them are not backed by ‘something real that can be paid for’ to realise the sterling value

The experience so far in Germany is that very few people actually cash-in the local currency. However, the possibility that people will cash-in the local currency is a risk because the repayment time is unknown. This is why a local currency should be used to replace bank borrowing rather than investor shares. Because if a large amount of local currency was cashed in at one time, it should be possible to repay it by taking out a bank loan.

The AD company could issue the currency, either by itself or in conjunction with the local community representative group. The currency would be ‘sold’ for pounds to individuals and businesses in the local area, thereby raising sterling capital for the project (instead of borrowings). With the agreement of local businesses and contractors, some or all of the local services and goods used to construct the project could be paid for using the local currency. The currency is then in circulation and is used by individuals and businesses to pay each other for goods and services exchanged. If the area is a tourist venue, then visitors could also be encouraged to buy local currency and use it to pay for whatever they purchase, during their visit, at businesses that were participants in the scheme. This would tend to increase their ‘spend’ while visiting the area, as using a local currency is a novelty currently.

How, and to whom, the AD company trades the electricity and heat it produces will affect the simplicity of operation of the system. If the AD company is set up to sell the heat and/or electricity directly to any end user then anyone can ‘cash-in’ their local currency directly with

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the AD company by purchasing energy. However, what is more likely is that the AD company will sell the energy produced to a third party, whether that is an energy supplier or a single large customer. If this is the case then that third party would need to agree to be part of the process of ‘cashing in’.

Figure 18a - How an AD and CHP can be connected to utilise the energy

Figure 18b - Insulated heating pipes used to transport hot water

Another possibility is that the currency could be backed by waste disposal. If it is proposed to collect biodegradable waste from local businesses who have to pay for waste disposal it would be possible to allow payment in part in local currency, to the level of the cost of the gate fee charged by the AD. Unless the AD company collects the waste itself, this arrangement would require the collection company to be willing to participate.

A third party, such as an electricity supplier could be happy to participate because it would help to create ‘loyalty’ from the local people to that supplier (rather than to its competitors). If the third party does participate then if at some time an individual or a business needs to realise pounds for the local currency it holds, it can pay the electricity supplier or waste management or whoever, with the local currency. Then that third party pays the bill invoiced by the AD company for the electricity sold to them or the gate fee for disposing of waste at the AD.

It would also be necessary to identify what the legal position is concerning using a local currency and liability for tax. In Germany they just issued the currency and used it and the Federal Government has not interfered because they see the advantage for them from businesses developing and thriving. There are already local currencies operating in UK, but most of them are not backed by ‘something real that can be paid for’ to realise the sterling value

4.4.4 Investors

Like with any business, having investors who buy shares in a limited company, is a low risk way for the project to raise capital, because the investor carries the risk of the company remaining viable. It is considered that there are four main categories of investors relevant to a community CAD project:

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• Venture capital

• Local investors

• Supplying farmers

• Other interested parties (e.g. waste supply company, energy customer etc)

Venture capital (VC) investment usually has many requirements to enable them to either insure against their risk or to minimise that risk. Therefore the requirements of obtaining VC can be as onerous as obtaining an unsecured bank loan. A high rate of return (interest rate) is usually required to attract VC. Therefore for most AD projects VC should be used to provide only a small proportion of the capital required. An advantage of VC is that the investors usually want a quick return and want an exit mechanism by year 5. At this time if the project is trading profitably it could re-finance easily and cheaply, using a bank loan. This means that the ownership of the AD can return to local people at this stage. A local VC investor, who is interested in the AD project or in supporting the community, may not have such onerous requirements. Generally a VC investor with a significant share wants to have a position on the Board of the company so they have some say in the company operation so they can protect their money. This could provide valuable business experience to the company, but it could also change the modus of operation away from community and farmer’s aims.

Another source of investment is local people. Many community projects offer shares to local people in small denominations. This allows individuals to invest relatively small amounts of money, which allows people to support a local project and to feel involved. The level of return on the investment generally doesn’t have to be much higher than can be earned from an investment at a building society. For the project it raises some capital, but perhaps more importantly it reduces the risk of opposition to the project.

Another source of capital raised by shares is to require all farmers supplying feedstock to have to make some level of investment. This helps to secure the manure feedstock, maintain quality of the manure and raises capital. Farmers tend to be willing to invest an amount that reflects the benefit to their farm they will receive from the project over time, therefore the rate of return on the share need not be high. This is a means to internalize some of the external benefits of AD (i.e. the benefits that accrue on the farms involved. Farmers who supply feedstock to the CAD in Denmark are required to make some level of investment in the CAD as a commitment to the project. Individual amounts are not significant, maybe equivalent to a few thousand pounds, but the cumulative amount raised would provide a significant amount of capital. An investment by the farmers should also ensure that they have a significant say in the way that the AD is operated.

4.5 Crucial internal & external factors related to development of AD AD is not the perfect business diversification answer for all farms or waste management businesses. There are many prerequisites that are absolutely necessary to ensure the viability of an AD plant, let alone for it to become a great business and environmental opportunity. The crucial ones are discussed here.

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4.5.1 Internal

An AD project has a wide range of outputs and effects. To maximise the returns from AD it is important to be able to realise a value for as many as possible of these outputs and benefits, whether internal or external to the project. It is also important to minimise the costs related to the outputs and also the costs of operation, maintenance and negative effects.

Any enterprise if badly managed, can quickly become a financial and environmental liability. With on-farm AD plants, once they are up and operational, they are often relatively straight forward to manage but still require attention to maintain and keep ‘healthy’; just like a cow. CAD plants though are far more complex with more connections to third parties. There are several people providing feedstock and taking the digestate for use elsewhere, so much of the necessary supply chain moves into the hands of third parties, creating relationships that require careful management.

The most important skill necessary to develop an AD, either on-farm or CAD, is enthusiasm. If there is not somebody keen enough to personally see something turn into action, then stop now. Too many studies have led to nothing for this reason alone. It is difficult for consultants to identify this resource with certainty, but few would argue on its critical nature.

AD is capital intensive, so access to sufficient funds is critical, whether this is personally available funds that are currently unemployed, or financiers who will be either investing or loaning capital. Sufficient space is required at the AD site to facilitate vehicle movements where necessary, including space to turn and unload and load delivery vehicles. The digester and other tanks should be sited to allow top covers to be removed and emptying and maintenance to occur (even if this only happens once every 10 years). All equipment should be positioned to facilitate maintenance and replacement.

4.5.2 External

Site location and scale of project are key to whether local people accept the project, the costs of operation and its resilience to future competition. Bigger is not automatically better, even if the financial bottom line says it is.

Figure 19 - A well landscaped on-farm AD

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Land to utilise the digestate must be established at the early stage of the feasibility study to ensure that there is sufficient land available to use the digestate. If the site is in an NVZ (and that’s most of England), the calculations should take this into account when assessing total area required to spread on. If the land is not on one single site, where the digestate can be spread via an umbilical pipe and pumping system, then some of it will have to be transported by lorries. Careful costing will be necessary as this can very quickly become uneconomical and throw the entire project off course.

A consumer for the energy from the biogas is clearly necessary, in whatever form is most suitable. On the assumption that the biogas is used for electricity generation, a suitable grid connection point needs to be available nearby too. If the nearest is more than a few hundred meters away, this could be uneconomical. Also, if the heat produced during generation cannot be used near to the location, financial returns will not be maximised and the AD would not really be considered a sustainable development.

The value of as many as possible of the externalities relating to the project should be realised and internalised for both the community and the project’s benefit. This may mean involving those that gain benefit from the externalities within the project (e.g. supplying farmers, waste companies, local people) as investors or having an arrangement with a company that has to pay for carbon, so that they can gain value for the greenhouse gas emission abated by the project; or getting a grant for the value of other environmental benefits; or issuing a local currency that stimulates local business and helps to finance the project.

4.6 Factors pertinent to an on-farm AD An on-farm digester has a high capital cost and although a farm may be able to raise finance for this cost, it may mean that the farm has less finance available to it for other enterprises

Time is required each day to manage and operate the digester. It is another animal that needs to be cared for, and another machine to be serviced.

It takes about 2 years to really understand how a digester works, and you never stop learning.

Farm energy Many farms use considerable amounts of energy, directly for vehicle fuel, electricity and heat and indirectly in the products they consume, in particular artificial fertiliser, animal feed and plastics. All farms produce products that can provide energy, such as manure, crops and wood. AD provides a method of realising the energy potential, although materials that have high lignin content (e.g. wood) are not normally digested.

• The cost of energy is rising and is likely to continue to do so. Therefore the more ‘bought-in’ energy and products that can be replaced by energy and outputs produced on the farm, the more the farm can keep control of its production costs. Efficient use of energy is important, whether the energy is produced by fossil fuel or by renewable resources, and will become more so. Therefore, wherever possible, digesters should be designed, located and sized so that;

a) any spare heat or electricity produced can be utilised,

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b) the energy used to manage both the feedstock and the digestate products should be kept to a minimum,

c) the digestate should be used to replace as much artificial fertiliser as possible

d) if crops are grown as an AD feedstock then there must be a net energy gain when all energy requirements and outputs are considered

4.7 Factors pertinent to a community digester

• Long term storage required on farms could be paid for by the digester project.

• The AD facilitates safe nutrient re-distribution between farms so this allows a farm to export surplus nutrients or import additional nutrients if needed.

• Transportation of the manure to distant fields is organised by the digester project instead of being a farm cost.

• There is likely to have to be some farm alteration to fit in with the digester, involving farm costs.

• You have to work as a team with others and lose a certain amount of control.

• A community CAD can take a long time to develop, 3-5 years would be typical, there is a lot of work and can be frustrations along the way, it is not easy for a community group to sustain this input of time and enthusiasm. It can be done, but it is important to decide how at the beginning, rather than run out of steam in the middle. One possible way to keep enthusiasm is to co-develop some smaller projects at the same time in the area, which come to fruition much quicker, and allow people to realise something is happening and making a difference.

• Typically grant funding is available for feasibility studies into community developments which finances the fact finding and analysis part of AD development. If the results of this stage are favourable and the development of the AD project continues, the next stage is difficult to find finance for. There can be significant costs incurred (>£200,000 would not be unreasonable), securing a site, applying for planning and obtaining other permissions and grid connection, going through the due diligence process for finance, travelling to see other AD projects etc. There is no security that the project will actually reach the build stage, and so investors and banks will not provide finance for this stage.

Currently it would also appear that funding agencies do not provide finance for this stage either. Hopefully this will change. Some AD technology companies have financed this stage in the past, to enable them to get a sale. Unfortunately this practice caused many technology companies to develop cash flow problems and close or sell the business. It is also not an advisable practice for the community, because you are tied in to one supplier, which limits choice and may result in a loss of control over how the project develops. So a community may need to raise funds from local people and events or find a supportive individual, for this stage.

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4.8 Public Consultation It is important to communicate, as early as possible, with those people who will be affected by a proposed AD project, no matter what size or complexity of the project. Experience shows that where public consultation has started early in a project development, and the developer has taken notice of people’s concerns and comments where possible, or explained honestly why it is not possible, then public opposition is negligible, and the planning application process becomes a straight forward process.

AD is still a relatively unknown technology for most people. There have also been some very bad development processes related to waste treatment, including proposed large AD facilities, where the public have felt excluded from the process, or have felt they are being given misinformation. As a result people naturally resist the development due to fear and not wanting their life changed. Many people call this the NIMBY (not in my back yard) syndrome. But to be honest why should someone put up with something that is imposed on them and might make their life less pleasant, when there is no benefit for them, or they feel it is totally unrelated to their life.

It is advised that the following procedures should be followed with regard to public consultation:

1. Information gathering

2. Assessment of the information gained,

3. Decide the rough shape of the AD project, and identify how it will interface with and effect things outside the AD site

4. 1st consultation - which explains the findings and what is proposed and why

a. For an on-farm AD this may only entail talking to neighbours, generally when they learn that the manure will no longer smell when spread, and there will be little additional traffic they will be supportive, if not then find out what bothers them and try to get the answers for them.

b. For a community AD this would probably take the form of an open meeting where local people are invited to come. The meeting hall is set up to allow people to walk around and view posters to learn about the proposed project and to meet with consultants, community people and maybe someone who knows about AD technology or already operates one. At this early stage this approach to consultation has been found to be preferable to a formal seated meeting, because individuals can privately discuss their concerns more freely, with the consultants or community representatives, and no one member of the public can take control of the meeting. All concerns and suggestions should be noted, and where people request more information this should be provided either at the meeting or subsequently.

5. Concerns and suggestions made should be considered and either included in the project development, or a response should be given to the individual who made it. In this way people feel they can have a valued input, do not feel they are being ignored or ‘walked upon’ and generally become supportive of the project.

6. An on-farm AD project can then usually choose a technology supplier and go to planning at this stage.

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7. A community CAD will have several more steps to complete before it will be ready to apply for planning. However, as further information becomes available, or there are significant changes to the project, further public meetings should be held. Even if nothing significant happens for a while, the public should be kept informed on the project on a regular basis, say every 3-4 months, either at a special meeting re the AD or at another community gathering. This makes people less afraid that something might be happening behind their backs and helps to keep them supportive.

8. An on-farm AD project could take as little as 3 months to research and bring through planning. It could take another 6 months to build and commission. So within one year from considering the idea of building an on-farm AD the project could be fully operational, all depending on its complexity and neighbours’ support.

9. A community CAD will take longer to research and develop, because it is a larger AD, involves several people and in most cases will have to process a waste for which a gate fee can be charged, to enable it to become financially viable and attract the investment needed. 3-5 years would be typical. In this timeframe conditions can change. Therefore, it is really important to have regular communication with people in the community to maintain their support

For all AD projects it is important to identify real benefits that those affected will benefit from.

Figure 20 - Digestate being spread on grassland

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APPENDIX 1 Options for the use of Biogas?

Heat Only Biogas can be used, as it is produced from the digester in a gas boiler to provide heating and/or hot water or in a kitchen range cooker to provide heating, hot water and cooking. The equipment used needs to be corrosion resistant, and is usually cast iron or stainless steel. Standard natural gas equipment can be used, but usually the jet size in the burner is increased to allow more gas through, as biogas has only about two thirds of the calorific value of natural gas. Condensation boilers are not really suitable for biogas though, because they take too much heat from the exhaust. The exhaust should be vented fairly hot with biogas because it is a wet gas that contains some level of sulphur; this combination is more likely to cause corrosion once it cools.

The heat only option is, in most cases, the cheapest option for utilizing the biogas at any scale. It is probably the only option for small on-farm digesters (<250cu m biogas/day). However, to be a viable option there needs to be a use for the heat and the cost of equipment and pipes to deliver the gas (or hot water) should be assessed against the cost of providing the same amount of heat in a different manner. There is no need to disconnect an existing fossil fuel boiler from a heating system, as the biogas boiler could be either connected into the existing system as well, so that either boiler can be used, or a heat exchanger can be used to interface to independent systems (this option is more suited to connecting in a district heating system).

Figure 21 - A cooker operated on biogas

Currently the value of the biogas is purely the avoided cost of alternative heating. A Renewable Heat Incentive Scheme is being discussed by Government at the moment. If this is introduced then it is likely there will be some way of rewarding the replacement of fossil fuel with a fuel from a renewable resource, like biogas. This would provide additional income.

Electricity production Biogas can be used in a combined heat and power generator (CHP) to produce electricity and heat. A CHP currently provides the most efficient conversion of the biogas to energy. However, there is quite a wide range of efficiency with different makes of CHP. Also some CHP produces more electricity and less heat than others. The amount and cost of maintenance and operation, and life of the CHP, can vary very significantly with different makes. It is important, therefore,

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to identify what criteria you want your CHP to have and what you want it to do, and then to shop around carefully.

Most CHP units now come set up in a container, with connection points to be joined into the rest of the AD system. There is an advantage in buying the CHP like this because it will usually have been tested before leaving the factory, the electrician and plumber on the AD site will be able to connect it, rather than having to have a specialist to put the CHP system together, and the price will include most of the parts needed. Even so it is wise to get the CHP supplier to tell you exactly what additional equipment etc will be required to connect the CHP up before purchasing. Some CHP units will include gas cleaning systems to protect the engine, others won’t. Some have integral flares for excess gas, some CHP units can be operated on diesel or biogas and so can be used for back up heating as well.

Some of the heat from the CHP can be used to heat the digester. The amount of spare heat for other purposes will depend on the type of feedstock, the AD system design, the gas production rate and the efficiency and outputs of the CHP. There will generally need to be an alternative source of heat to the CHP to provide heating for the digester when the CHP is not operating.

When looking to get connected to the electricity grid, you will be asked for a lot of technical information about the CHP. Generally the CHP company should be able and willing to provide this information and communicate with the electricity purchaser. However, many CHP are manufactured in Germany and the grid and safety rules in Germany are very different to the UK.

Biogas Cleaned to Biomethane The term biomethane is used for biogas that has been cleaned of impurities and has had most of the carbon dioxide removed, so that it has a methane content comparable to that of natural gas. There are a number of well proven technologies to do this. Most of the equipment available for cleaning and upgrade is expensive and is therefore only suitable for large AD producing over 300m3 per hour. However, smaller scale equipment (from 50cu m/day upwards) is now available in the UK, Austria and Finland, and farm scale filling stations for vehicles are being developed. Unfortunately because demand for this small scale equipment is still low, it is still relatively expensive and still needs further development before it is fully commercialized.

Figure 22a - How a car can be altered to operate on biogas and petrol

Figure 22b - A biogas filling station outside a farm

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Biomethane can be used as a vehicle fuel or injected into the natural gas grid and used for any purpose natural gas is used for. Injection to gas grid is in its infancy in the UK. Before injection can take place, some adjustments to the quality of the gas may have to be made including the further removal of oxygen and the introduction of small amounts of propane plus an odorant; there also needs to be metering and a compression unit. Some gas network operators have shown great interest in promoting the biomethane injection option including the possibility of assisting in the capital financing of project, however this would require government approval to pass these costs on to their customers.

Biomethane has been used for fuelling vehicles in Sweden for many years now, most commonly in captive fleets (e.g. buses & taxis) where the vehicles can be refueled overnight at their depot. However, there are many cars available, throughout the EU, that operate on a duel fuel basis using petrol or natural gas. It just requires a flick of a switch inside the car to change fuels. These cars can also be run on biomethane.

Biomethane is classed a fuel from a renewable resource under the Road Traffic Fuel Obligation (RTFO) Scheme in UK, Biomethane suppliers can gain certificates from vehicle fuel supply companies and biomethane users will pay reduced excise duty when purchasing the fuel. Because of the Renewable Energy Directive, biomethane gets double rewards because it is made from waste. Unfortunately the RTFO certificates have proved almost worthless in the first year of operation of the Scheme so the only real incentive is the reduced duty on the fuel. The Scheme may be adjusted as a result in the future. For bus fleets which are enjoying duty free diesel, gas is simply not an option. However, some transport fleets have changed to compressed natural gas for reasons of economy and reduced noise and pollution, and in this area, biomethane could be used as a substitute.

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Biogas, as produced by the digester or as biomethane, can be piped over long distances, depending of course on whether the cost of trenching and pipes can be justified. However, it is much less costly to pipe the biogas than to pipe hot water, which needs two water pipes (outward & return) and that need to be well insulated.

There will be times at any AD when all the biogas cannot be utilized as planned. The uncontrolled release of biogas from any AD is highly undesirable as it is a greenhouse gas. There are a number of options available, to be able to avoid biogas release to atmosphere.

• A boiler can be installed along with a heat dump system so that surplus biogas can be burnt and the heat created can be lost into the atmosphere.

• The biogas can be flared. In this means the biogas is burnt in a purpose built flare, which is usually positioned slightly away from the rest of the system, or on top of the CHP container. The flare usually operates automatically when pressure in the gas store reaches a certain pre-determined point

• The biogas can be stored. Biogas is a bulky gas. Large storage facilities are very expensive, occupy a large space and may create planning issues. For example, a 500cu m store would be full in less than 1 ½ hours with a 1MW electrical CHP unit or in 15 hours for 100kW CHP. Therefore biogas storage should act more as a ‘buffer’ between production and use, or if it is desirable to generate more at certain times of the day than at other times in a 24 hour cycle.

• Compressed biomethane can be stored in gas bottles like other gases.

Future uses for biogas

• Fuel Cell – Biogas can be used in a fuel cell unit, there is one of 250W capacity operating in Germany using Molten Carbonate Fuel Cell technology – however this technology is still under development and is more of an option to be considered for the future rather.

• Hydrogen production - As there are four parts of hydrogen to every carbon atom in methane, biogas is a good source of hydrogen. Using hydrogen for energy is happening, but it will be a few years yet before it is commercialised

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APPENDIX 2 Options for the use of Digestate Products The fully digested feedstock is called whole digestate. Whole digestate can be further processed by a separator to produce fibre and liquor. All three digested products are valuable fertilisers, because the nitrogen availability for plants is higher than in the feedstock. Each of the three fertiliser products has different qualities and should be used appropriately, according to the crop being grown.

Figure 23 - Nutrient content of cow slurry compared to digested slurry as whole digestate, separated liquor and separated fibre

cow slurry whole liquor fibre DM % 8.0% 3.8% 1.8% 24.0% Total N - kg/t 5 5 4.4 10.2 Available N - kg/t 1.75 3.25 3.9 3.06 Organic N - kg/t 3.25 1.75 0.5 7.14 Available N as % total N 35% 65% 90% 30% Phosphate - kg/t 0.8 0.8 0.27 5.6 P : available N 1: 2.2 1: 4.1 1: 14.4 1: 0.55

The liquor is the best fertiliser for grassland and for top dressing growing crops. This is because the coarse fibres have been removed and the liquid leaves almost no surface residue. This means the liquor can be used on grazing grass and silage ground even when the grass has begun to grow. This is a big advantage as it creates many more spreading windows in the year and farmers don’t have to spread by the calendar but can spread when the ground and growing conditions are right. The Nitrogen availability is typically over 90% in the liquor and there is a crop response in about three days after spreading, if there are growing conditions. The Phosphate content in the liquor is low, which means more of the crop Nitrogen needs can be met using liquor than with slurry. Liquor is also ideal for land that has a high soil P status.

The EU Nitrates Directive does not allow a stocking rate that produces more than 170kg of Nitrogen per hectare, or the application of more than 170kg manure-N per hectare. However, it is permitted to spread Organic- N, from sources other than livestock manure in excess of 170kg/ha so long as the total amount of available Nitrogen, (from both organic and artificial fertiliser) applied does not exceed crop needs or 250kg/ha per rolling 12 months. Figure shohow all the Nitrogen needs of grassland could be met by co-digested liquor, and the resultanreduction of costs that could be gained.

ws t

The liquor and whole digestate can be spread by low trajectory splash plate, dribble bar, trailing shoe or shallow injection. Trials13 conducted in Denmark showed that surface application gave the best growing results. The nitrogen in these liquids can be easily lost to air as ammonia, but research14 in Denmark showed that where digestate stores were covered and surface application

13 Danish Agricultural Advisory Service Annual Report of National Field trials in 2002 14 (Research results presented by Henrik Ortenblad at Biogas in Europe conference in 1995)

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was undertaken, the loss of ammonia was less with digestate than with normal management of slurry, because there was less need for agitation before removal from storage and the material remained on the surface of the ground for significantly less time. Liquor can be easily pumped down small bore pipes as it has the consistency of water, so depending on the layout of the farm it is possible to deliver the liquor to fields by pipe rather than by tanker, which would save both transport costs and damage to fields.

Figure 23 - Meeting the crop nitrogen need on one hectare of grassland Raw slurry Liquor from slurry Liquor from co-digestTotal N in slurry kg 170 170 170 Total N in other AD feedstock kg 0 0 80 Availability of N 30% 90% 90% Available N kg 51 153 225 Crop need 225 225 225 Top up from artificial N kg 174 73 0 Cost at £652/t art. N (100%) £111 £53 £ 0

The whole digestate and separated fibre are fertilizers that are well suited to arable land and silage ground, where the organic matter is required to maintain soil quality and there is a higher need for Phosphate. Similar to slurry, when whole digestate and fibre are added to the soil, available nitrogen is required to release the organically bound nitrogen. However, because the amount of available nitrogen is high (70%) in the whole digestate, the net availability of nitrogen to the crop from the soil does not diminish as with slurry, nor is there a sudden rush of availability as with artificial nitrogen.

Land bank for utilising the digestate In most cases farmers will be willing to ‘lend’ their manure to the digester to allow the energy to be taken from it as the level of available Nitrogen will increase. However, most farms will want to receive at least as much nutrient back as they provided in the manure, although some farms may not, as their animals are producing too much nutrients for their land/crops. In this later case the AD provides a method of re-distribution of nutrients in a safer manner from an animal health point of view.

If the cow slurry from 2,000LSU that are housed for 6 months of the year are used to provide the manure feedstock for a community CAD, they would provide 50t/day spread over the whole year (18,200tpa). If the ratio of manure to other feedstock was 70 : 30 by dry matter and on average the other feedstock is twice as high in dry matter, there would be an additional 5,000tpa from this waste. If the supplying farms were to be stocked at the maximum stocking rate permitted (2 LSU/ha) there would have 1,000ha of land between those farms. Digested food waste would typically have about 3kg/t of available nitrogen. Therefore all the digestate could be used on the supplying farms without exceeding the grass needs for available nitrogen and without exceeding the Nitrates Directive

If Phosphate levels are high in the soils around the digester then Phosphate in the form of the fibre can be cost effectively exported from the area. The value of the nutrients in the fibre would, in most situations, probably at least cover the cost of transportation.

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APPENDIX 3 Technology Types The diagram and photo in figure 25 below show a plug flow digester. This is a mechanically mixed digester that is suited to high solid materials. The digester in the photo is used to process biowaste, a mixture of green waste and food waste.

Figure 25 Plug Flow

outflow

feedgas takeoff

motor &gearbox

end view

Blacksmith type‘Plug flow’

digester

There is a limit to the size of an individual digester, because of the torque limitations the mixing axle and the motor and gearbox. The feedstock is loaded at one end, the paddles on the axle are placed in a spiral formation so that the digesting material is slowly ‘corkscrewed’ through the digester. The heating is from hot water which is circulated through the mixing paddles nearest to the feeding point. The digested material is unloaded from the opposite end. These digesters can be used in series with one of the other digester designs to provide more capacity.

Another couple of approaches to mechanically mixing a digester are shown in figure 26 below.

In this case the tank is cylindrical and is mixed either by a centrally mounted paddle, or alternatively by paddles mounted on a horizontal axle. Propeller mixing is another alternative (not shown here). Generally these types of digesters have a conical base because there is always some settling of grit, and there is an extraction point at the point of the cone, where the grit slides down to and is then removed. Typically these digesters also include re-circulation of the digesting material to assist the mixing system. This allows the heating to be on this re-circulation system to maintain digester temperature. Fresh feedstock is mixed with the re-circulating material, so the heat in the digester remains quite stable. However, quite a lot of energy is required to mix and re-circulate.

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Figure 26 mechanical mixing

heatx

silt removal

motorgas take

paddle

Side mounted paddles

Mechanical mixedCSTR digesters

Mechanically mixed cylindrical tank digesters, generally have membrane like those in the photo below. These roofs are double skinned, the outer skin being held extended by the use of air pressure and the inner skin dilates to allow for storage of the biogas above the digesting material.

Heating of a mechanically mixed digester usually occurs externally to the digester by way of a heat exchanger through which the digesting material is pumped. Alternatively, pipes, carrying hot water, are fixed around the internal surfaces of the walls of the digester

Figure 4 - gas mixing

x x x

v v

v

mixing effect

xx

xx x

xx

xx

xx

one port@2-5sq mbase area

tank base

Mixing pipeCompressed biogas

Gas mixedOn-Farm digester

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Gas mixing can be used in any shape or size of digester, so long as it is at least 3 metres deep. To achieve gas mixing, some of the biogas produced is drawn off through a compressor, which compresses the gas, which is then released periodically through pipes that are fixed to and end on the base of the digester. Typically there is one pipe end spread evenly every 2-5sq m across the floor of the digester. As the large gas bubble rises it expands and collects up the small gas bubbles being formed by the bacteria in the digesting material. When the gas bubble reaches the surface of the digesting material it causes a large eruption that breaks the surface as it falls back and drives the material at the top back into the digesting mass. There is generally no requirement for a silt removal system, because the material at the bottom of the tank is continually lifted by the gas and mixed, so that the silt remains in suspension and is removed from the digester when material is unloaded.

Heating is generally achieved by using heat exchangers mounted inside the digester through which hot water is circulated. One mixing port is positioned below a heat exchanger to ensure the moving material passes through the exchanger and there is good heat transfer

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APPENDIX 4 Technology Providers

BEKON Energy Technologies GmbH & Co. KG www.bekon-energy.de Feringastraße 9 85774 Unterföhring Germany tel: +49 (0)89 9077 9590 fax: +49 (0)89 9077 95929 e-mail: [email protected]

UK partner: James Lloyd (CEO), HotRot Composting Systems Ltd, Milbank, Mundford Road, Weeting, Norfolk IP27 0PL, tel: +44 (0)1842 816909, fax: +44 (0)8707 053055, e-mail: [email protected]

The BEKON group companies cover various fields of environmental engineering. BEKON Energy Technologies GmbH & Co. KG is the expert company in dry digestion, which offers complete planning and construction of the biogas

Biogas Nord UK Ltd. www.biogas-nord.com Owen Yeatman Biogas Nord UK Ltd. Henstridge Trading Estate Templecombe BA8 0TN Somerset UK tel: +44 (0)1963 365 252 fax: +44 (0)1963 364 792 e-mail: [email protected] UK subsidiary of German company Biogas Nord AG, founded in 1995, which has experience with digestion of waste waters, agricultural waste, and co-fermentation of municipal or industrial wastes. Very small-scale plants up to large-scale facilities have been completed. Generally proposes installation of a two phase digestion system; both digesters fully mixed and operated in mesophilic or thermophilic temperature range; Standing cylinders made of reinforced concrete; Digesters covered with double membrane. Biogen-Greenfinch Ltd. www.biogen.co.uk Milton Parc, Milton Ernest,

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http://www.bekon-energy.de/



http://www.biogas-nord.com/



Bedfordshire, MK44 1YU tel: ++44 (0)1234 827 249 e-mail: [email protected] Specialist in food waste digestion. BIOGEN is part of the eco-technology sector of the Bedfordia Group of companies. The technology is based on experience in design of prefabricated sewage sludge digesters, on-farm biogas plants in Scotland, and R&D with household kitchen residuals, supermarket waste, etc.; Reference plants include seven on-farm biogas plants in Scotland, 5,000 ton/year biowaste for source separated organics in South Shropshire.

Bioplex Technologies Ltd www.bioplex.co.uk Bioplex Technologies Ltd Unit 5, The Cobden Centre Folly Brook Road Emerald Park Emersons Green Bristol BS16 7FQ United Kingdom tel.: +44 (0)117 301 4409 fax: +44 (0)845 602 0066 e-mail: [email protected] The Portagester® is a mobile and modular anaerobic fermenter, which can hygienically treat waste material in less than four days. It operates as leachate bed reactor with pasteurisation and hydrolysis and was developed by Bioplex Technologies Ltd as part of a process which digests solid waste materials. The liquefied organic material is then digested in a second reactor. Bioplex Ltd ([email protected]) - Portagester is a two stage, high solids, multivessel, mobile and modular AD; Uses a single or multiple thermophilic anaerobic first stage or phase with pasteurized feedstock; Portagester can collect feedstock, digest contents and transport treated material to end user; Reference plants include Rathdowney, Ireland for catering and retail waste; and Derry for source separated MSW.

Celtic Composting www.celticcomposting.com Celtic Composting Systems Limited was established in Ireland in 2001 as a full-service company that designs, builds, operates and finances state-of-the-art biological treatment facilities (mostly composting but also AD) for local authorities, industry and agriculture. Celtic Composting Systems are the Irish and UK representatives of Krieg and Fischer Gmbh (www.kriegfischer.de) who are a German based biogas engineering firm. Krieg and Fischer have almost 20 years of

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http://www.bioplex.co.uk/


http://www.celticcomposting.com/

http://www.kriegfischer.de/


experience in the design, build and operation of biogas facilities and have been involved in the construction of approximately 120 biogas plants worldwide.

EnviTec Biogas UK Ltd. http://www.envitec-biogas.com John Day Colton Road Rugeley Staffordshire, WS15 3HF tel.: +44 (0)1889 584459 fax.: +44 (0)1889 578088 e-mail: [email protected] or [email protected] EnviTec Biogas UK is the UK subsidiary of German company EnviTec Biogas AG. EnviTec iogas AG covers the entire value chain for the production of biogas. In Cornwall, in 2008 the company will build an 844 kW plant at Penare Farm, Higher Fraddon, near Truro, where there is a 600-sow farrow-to-finish unit.

Fre-Energy Ltd www.fre-energy.co.uk Chris Morris Fre-Energy Ltd was formed in 2008 and has only built one large on-farm/waste digester. However, the technical Director has 30 years of AD experience. The company also supplies key components including gas holders, heat exchangers, mixing systems, pasteurizers, digester vessels. The technology supplied by Fre-Energy Ltd has been used in more non-sewage works digesters in the UK and Ireland, including tiny home digesters, on-farm digesters, and large commercial facilities, than any other make of technology. They are willing to allow a project owner to reduce costs, by undertaking some of the construction.

Hesse-Schmack Biogas AG www.schmack-biogas.com Bayernwerk 8 92421 Schwandorf Germany tel.: +49 (0)94 31 751 0 fax: +49 (0)94 31 751 204 e-mail: [email protected] Active since 1995 in the biogas sector, the company provides support during the planning phase and builds complete biogas systems. Previously part of Hese Umwelt GmbH, Gelsenkirchen, Germany, a company specialised in waste management and waste treatment (in Britain: e.g. mechanical & biological waste treatment plant for the City of Leicester and Biffa Waste

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http://www.envitec-biogas.com/



http://www.fre-energy.co.uk/

http://www.schmack-biogas.com/



Services), Hese Biogas GmbH presently now belongs to Schmack Biogas AG, Germany, and is specialised in AD plants for treatment of residual bio waste, food waste and agricultural substrates. UK agent Paul Wayman

Kingdom Bioenergy Ltd 15 Brandon Ave, Woodley Reading RG5 4PU, UK Tel: 0118 326 9779 E-mail: [email protected] Skype name: djfulford in Reading, UK The company has constructed a pilot plant, which has been developed for farm use. The design of this AD is based on an underground masonry design that has been used extensively in Nepal has been developed. This uses pre-cast insulated panels that can be made cheaply in a factory. The panels can be slotted together on site, allowing rapid construction with limited labour. This type of AD has been made in huge numbers (hundreds of thousands and even millions) in countries such as India and China.

Kuttner (UK) Ltd 29 Miller Road Ayr KA7 2AX Scotland Contact: Robin Szmidt 01292 283 543 mobile 07952748549 work [email protected] Active Compost Limited ([email protected]) - Works in association with Kompogas of Switzerland; Small to large-scale installations - typically treating 12,000 to 25,000 tons/year; Installations include source segregated feedstock as well as organic fraction of MBT plants; Process uses horizontal plug-flow reactor with low-speed agitation. Operational sites in Austria, Switzerland, Germany and Spain.

Marches Biogas Ltd Email: [email protected] 45 Beech Road,

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mailto:[email protected]?subject=Enquiry%20via%20Regen%20SW%20Member%20Directory


Shipham, Winscombe, BS25 1SA Contact: Russell Mulliner Telephone: 07786381890 Farm scale biogas plants. Design and build small plants on BiogenGreenfinch technology. Small company , very personal service.

Methanogen (UK) Ltd. http://www.methanogen.co.uk/ James Murcott Methanogen (UK) Ltd. The Nurton Linley Shropshire SY9 5HW tel: +44 (0)7980 541 520 e-mail: [email protected] 30 years of AD experience. Company supplies key components including gas holders, heat exchangers, mixing systems, pasteurizers, digester vessels. Has completed largest number of non-sewage works digesters in the UK and Ireland, including many on-farm digesters, treating manures, food waste and green waste.

Monsal Ltd. www.monsal.co.uk Oak House Ransom Wood Park Southwell Road West Mansfield NG21 0HJ United Kingdom tel: +44 (0)1623 429500 fax: +44 (0)1623 429505 e-mail: [email protected] Monsal is a specialist environmental technology company providing engineered solutions for the water and waste sectors. Many Monsal components are operating in the UK, incorporating thermal pasteurization and biological hydrolysis pretreatment. Components and complete digestion systems are available.

Muckbusters – SeAB Energy http://www.seabenergy.com/products/anaerobic-digesters/ SEaB Energy Brandon Thatch Annex

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http://www.methanogen.co.uk/


http://www.monsal.co.uk/

http://www.seabenergy.com/products/anaerobic-digesters/


Charles Lane Ringwood BH24 3DA Small containerised plant – no working examples can yet be seen, but prototypes available in Ringwood

WELtec BioPower GmbH www.weltec-biopower.de WELtec BioPower GmbH Zum Langenberg 2 49377 Vechta Germany tel: +49 (0)4441 999780 fax : +49 (0)4441 999788 e-mail: [email protected] WELtec, set up 2001 by German agricultural systems manufacturer WEDA and Stalkamp, provide complete AD systems using stainless steel vessels, including equipment for solid substrate handling, pasteurisation, CHP units. Most projects are in Germany, but the first units in the United States, in Japan, Sweden, in The Netherlands and in the United Kingdom have already been put into effect. An agent for UK is available.

Xergi Ltd [email protected] address UK representative : Jorgen Fink Xergi Ltd. is a 100% subsidiary of Xergi A/S who is owned equally by Aktieselskabet Schouw & Co. and Hedeselskabet A/S. The group is engaged in consultancy, service, operations, contracting, and trade within forestry, landscape, landscape gardening, environment, and energy. Xergi is a contractor and O&M operator with more than 20 years of experience within development, delivery, operation and maintenance of turnkey energy and environmental plants. The biogas and manure separation activities of the company are focused on exploitation of energy and nutrients in organic waste, while effective energy transformation of biogas, natural gas and landfill gas is the main element when it comes to power, heating and/or cooling solutions. During the past 20 years Xergi has gained wide experience in elaborating and accomplishing solutions which help the customers’ in covering their present and future needs.

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http://www.weltec-biopower.de/



APPENDIX 5 Farm Assessment Form Name

Address

Farm access

Livestock

Number Type of manure Type of housing Which mths housed

Other organic material

Type How much When produced When available

Manure management

Type of housing Number housed Bedding system When produced

Manure Collection System

Slurry management Procedure Daily

Other

Water Collection System

Will alterations will be required- Design Operations

Manure Storage Current Capacity – Vol

Months

How is manure delivered to store

Would additional storage be required for digestate?

Amount

Type

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Are you agreeable to this?

Would additional storage be required for fibre

Would you want back the same amount of digestate

Farm Layout Sketch

Current Spreading Practice Manure

Amount Where Spread* When Rate/acre

*Type of crop

How is the manure spread?

By whom?

Do you bring in other manure/organic material as a fertiliser? If so

Amount What Where spread* When Rate/acre

*Type of crop

How is this spread?

By whom?

Do you use artificial fertiliser? If so

Amount What Where spread* When Rate/acre

*Type of crop

Would you like to meet most of your fertiliser requirements with digestate?

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Would you like to use fibre, if so where?

Would you prefer a balanced fertiliser (one pass)?

Land Area & Current Use

Acerage Crop Land type* Nutrient status Last tested

* wet or dry

Do you operate a nutrient management programme?

Why?

If so who creates it?

Are you party to a management scheme (Organic etc)?

Other Questions What are the most important factors to you in the way you manage your farm?

What are your current concerns about farming?

Do you plan any changes to your farm or what you farm?

What are your current concerns about manure management?

What are your current concerns about nutrient management/pollution?

Would you be interested in your own digester? What are your current concerns about owning a digester?

What are the benefits that you envisage you will get?

Which of these is the most important to you?

Would you be interested to investigate further the possibility of being involved in a co-digestion project?

What are your concerns about being involved in co-digestion

Would you like to be part of a finance package for the work needed on your farm?

Have you ever visited a biogas plant?

Would you like to visit some plants?

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APPENDIX 6 - Possible Business Models for a Community CAD There are a number of business vehicles through which a community based project could be developed. However, a public company limited by shares appears to be the most appropriate for a number of reasons. It facilitates:

• The issuing of shares to farmers, other businesses and private individuals giving them ownership rights and a say in the running of the project.

• Having different levels of privileges relating to different kinds of shareholding.

• A public AGM where audited accounts have to be presented each year.

• Placing of a levy on profits for the purpose of funding other community projects

The experience of the many Danish co-operative CAD facilities provide good guidance for the organisational structure of a community AD project. All farmers supplying slurry are expected to be shareholders. The amount of the farmer investment should be related to the farm benefits they will receive over time for their farms, but the state of the farming industry should also come into the equation. The way the AD project is configured will obviously affect the calculation of the amount of investment suitable. It is important that the farmers have at least 51% of the control of the company. This is because it is their land that will receive the digestate and so they should have the control over the quality of that material.

CAD Board 15 supplier farmers £150,000

Large Investors £618,000

Bank loan finance

SY Community development

4% of equity finance 0.9% of cap.costs 2% of dividend

39% control

77% of equity finance 18% cap.costs 92% of dividend

£10,000 each 4.3% cap.costs

68.5% Cap cost

initial efforts

Loan repayment

10% net profitretained

51%

control

10% control

6% dividend 10% levy On net profit

Grant

8.7%

Figure 28 - an example of a possible organizational structure for the community AD company

Local people & small investors £30,000

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The farmers, as a group, will supply the majority of the feedstock, so it is also important that they realise the importance of sending good quality feedstock. If they have made an investment they are going to take more interest in how well the facility operates. The return on the farmer’s shares need not be as high as for other investors, because they do also get other benefits including reduced fertiliser costs, additional storage capacity, and nutrient management planning.

Many types of community projects offer the opportunity for local people to purchase small amounts of shares, because it is a good way to generate local interest and support for the project. This approach does not usually raise significant amounts of investment, but even 250 people buying £50 of shares each generates £12,500.

This AD project will be for the benefit of the community as a whole, and the local community group may have undertaken or driven much of the early work related to a community project, if so it is reasonable that the community gain benefit from the CAD project. It is very common in community owned and promoted projects that a ‘community levy’ is placed on net profits before share dividends are decided upon and paid out. The money raised by this levy is then used to fund other community projects. The amount of the levy might vary from year to year depending on the profits made and the amount of reward required to attract and maintain investment.

Company management As with any Limited Company there would be a Board of Directors, who would oversee and make the decisions concerning the operations of the company. As there will be many investors and interested parties involved in this community AD project, it is recommended that each ‘grouping’ would be able to elect at least one Director to the Board. Each grouping would have its own meeting of members and Director to discuss any important issues. The grouping Director would then represent the interests of that grouping at the Board meeting.

Other company structure options considered Option 2 ~ the Standard Limited Company Option

This option puts all the financial responsibility into one corporate body and allocates the shares evenly to whoever purchases them. It would be exposed to gradual imbalances of control of shareholding percentages, and the value of the shares would vary depending on the success or not of the project.

• The management of the CAD would be controlled by the company

• The Company would be owned and led by shareholders

• A board of directors would be recruited

• The Return on capital would be equal to all shareholders

• The Liability exposure would also be equal to all shareholders

• Farmers would pay service charge to participate either per year or per load of slurry/digestate

• Each supplier would have a supply agreement/contract

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• A 5-year initial commitment would be required for farmers, as the farming community would be essential to both supply the slurry/FYM and also take the digestate,.

Option 3 ~ Community Owned Green Energy Co. (COGEN)

Like the previous option but with a few differences:

• Capital would be via a CoGEN

• Private local investors as before

• A Bank loan would be necessary (again with minimal collateral)

• Grant funding would be applied for

• The electricity buyer could be a shareholder, this would commit them to the project financially.

• Landowner / Farmers would also be asked to take a shareholding as in and for the same reasons as in option 1. The farming community would be essential for the success of the project.

• Management; A Board of project interests would be appointed.

• Operation; Supply agreements would be written out to:

o sell slurry

o buy digestate

o Other services

• Community involvement would be encouraged

Option 4 ~ the Co-operative Finance Model

The Structure would be in the form of a cooperative.

• A Maximum share holding per member would be £20,000, this would keep the equity split even throughout the interested parties.

• Shares would have a fixed value

• Shares would only be redeemable at face value

• Profits & losses distributed per share

• One member one vote not 1 vote per share so somebody with a £500 share would have the same say as a member with a £20,000 share

Finance

• The Bank injects full project finance over fixed term

o Guaranteed feedstock

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o Long term energy contract

o Professional management

o Proven technology

o Project management

Torrs Hydro New Mills has proved this system to be successful.

Torrs Hydro New Mills Limited www.torrshydro.co.uk was established for the specific purpose of owning the Torrs Hydro Electric scheme by Torr Weir on the River Goyt in New Mills in the High Peak of Derbyshire. A share of the revenue from the scheme will help Torrs Hydro achieve its aim to help regenerate the community and to promote the environmental sustainability of the New Mills area. The project was started in 2006 by Water Power Enterprises, a social enterprise whose mission is to set up small-scale hydro plants and reduce carbon emissions. They helped us start up, apply for grant funding and project managed the building phase.

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http://www.torrshydro.co.uk/

http://www.h2ope.co.uk/


APPENDIX 7 Agricultural Considerations

Farm Business A digester will have significant effects on a farm business, whether it is an on-farm or a community digester. The common effects are:

• A 50-70% reduction in artificial N fertiliser purchases – even when only manure is processed. If feedstock other than manure is co-digested then there will be further saving of N and other types of fertiliser purchases.

• Ability to operate an effective nutrient management plan, because digestate is homogenous, so a sample is representative of the whole, unlike manure. Also the nitrogen availability to plants is certain.

• Generally there is no need to lime

• Weed seeds are destroyed by the process of anaerobic digestion, so it is possible to return fields to having negligible amounts of weeds in them

• Less risk of lodging in arable crops

• In many cases there is a reduction in costs related to managing the manure

• There will be better plant root development and the plants will interact more effectively with the soil. This results in many benefits such as less poaching and vehicle damage, less need to reseed pastures, a better uptake of minerals, in particular the minor minerals which are needed for health and strength of the plant (and consequentially the animal/human that eats the plant), a more open soil structure, easier to till, increase in earthworms and less flooding and waterlogging of soil

• Better silage quality. Farmers that use digestate have found their silage quality has improved and there is much less wastage

• Higher protein (by dry matter content) in winter wheat[1].

• The need for liming agricultural land will be reduced as digestate has a more alkaline pH than slurry.

A well designed AD plant will offer a contribution to the operation of a farm business above and beyond the greater fertiliser value and the profitability of the plant as a free standing enterprise but hopefully also make more efficient use of existing farm business resources. For example, an AD plant that fits neatly into a business will make good use of spare labour, at otherwise quiet times in the year when agricultural activities are not at their peak work load, and machinery that is not used all the time. This could help optimise these resources. Unfortunately there has been no research done yet to quantify how much an AD can save in farm management costs, but farmers who do have digesters will claim these benefits above.

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Nutrient management Digestate is an homogenous fertilizer, that can be spread evenly, therefore it is possible to accurately keep to a farm nutrient management plan.

• The AD process transforms the readily available carbon in the feedstock into biogas. As a result the Nitrogen that was organically bound to that carbon becomes mineralised into forms of ammonium, and is readily plant available after application, typically 3 days in growing conditions.

• When slurry is land spread, the readily available carbon requires available nitrogen (in the slurry and/or in the soil) to break it down and release the organically bound nitrogen. This can takes weeks/years and is unpredictable.

Available Nitrogen - Whole digestate 70%, separated liquor 90-95%, separated fibre 30%

Digested and separated liquor is the best digestate fertilizer for grassland and growing crops, because it runs down the leaf, leaving almost no surface residue (unless it is spread in very strong drying conditions). Also grassland, which has a well developed root network, requires little organic matter addition to maintain good soil. The liquor has more than sufficient fine solids to meet this need. The liquor can also be spread on growing grass, so there become more spreading windows for application to silage ground and it can be spread on grazing land throughout the spring and summer.

The liquor and whole digestate can be spread by low trajectory splashplate, dribble bar, trailing shoe or shallow injection. Trials15 conducted in Denmark showed that surface application gave the best growing results. The nitrogen in these liquids can be easily lost to air as ammonia, but research16 in Denmark showed that where digestate stores were covered and surface application was undertaken, the loss of ammonia was less with digestate than with normal management of slurry, because there was less need for agitation before removal from storage and the material remained on the surface of the ground for significantly less time. Liquor can be easily pumped down small bore pipes as it has the consistency of water, so depending on the layout of the farm it is possible to deliver the liquor to fields by pipe rather than by tanker, which would save both transport costs and damage to fields.

The whole digestate and separated fibre are fertilizers that are well suited to arable land and silage ground, where the organic matter is required to maintain soil quality and there is a higher need for Phosphate. Similar to slurry, when whole digestate and fibre are added to the soil, available nitrogen is required to release the organically bound nitrogen. However, because the amount of available nitrogen is high (70%) in the whole digestate, the net availability of nitrogen to the crop from the soil does not diminish as with slurry, nor is there a sudden rush of availability as with artificial nitrogen.

15 Danish Agricultural Advisory Service Annual Report of National Field trials in 2002 16 (Research results presented by Henrik Ortenblad at Biogas in Europe conference in 1995)

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Clover Clover fixes nitrogen from the air into the soil, and so is a good source of nitrogen addition for grassland. Experiences from farms, show that applications of digestate does not diminish the amount of clover in a field, unlike the addition of artificial nitrogen.

Phosphate management The Phosphate tends to the fibre fraction as it adheres to the solid material. Each digestate product has different nitrogen to phosphate ratio. This means that a digester and separator can provide a farm with a method of managing the nutrients produced by the animals in a way that suits the soil and crop needs. This is particularly important on dairy farms where significant amounts of concentrates are fed and where the soil in some of the fields has a high soil P index.

Table showing typical division of nutrients in digestate products with separation

Whole digestate

Separated liquor

Separated fibre

DM, % 4 1 30 total nitrogen, kg/t 5.15 4.49 9.5 available N, kg/t 4.12 4.13 4 Phosphate, kg/t 1.16 0.37 7.8 N:P ratio 4.4 12.1 1.2

Need for lime Digestate reduces the need to lime fields. Digestate that has been properly processed has an alkaline pH of typically 7-8pH. Digestate is best applied at low rates and a number of times throughout the growing season. This generally results in maintaining the soil pH at or above 6.5pH (neutral). If the soil pH is alkaline the conditions are more suited to increased microbiological activity which facilitates the conversion of minerals in the soil to the form plants can use. Farms that use slurry and/or artificial fertilizer tend to have soils that become acid and hence they have to add lime in some form.

Adding lime to soils that have a high molybdenum content, results in inhibition of copper and selenium availability, which are essential minerals for health. The experience of farmers who utilise digestate instead of lime to maintain soil pH, where there is high soil molybdenum, is that they do not find a problem concerning selenium and copper availability.

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APPENDIX 8 Environmental Effects All anaerobic digesters have a significant effect on the environment. The extent and whether this effect is positive or negative depends on the configuration of the project and its management. If the project is designed, integrated into its surroundings and managed to optimise the net environmental benefit, then the overall improvement to the environment from installing an AD can be significant.

Benefit Amount of output Value per unit Value for AD pa €

C02 saved by reduced Grid loss 12.1t/yr 550kg/MW hour

electricity 180

Electricity C02 tpa saved 17 87t/yr 550kg/MW hour electricity 1,315

Heat CO2 saved 33y/yr 241kg/MW hour electricity 481

CH4 pa manure storage saved18 400 100kg CO2 equiv./t 600

manure N2O saved tpa 23.2 5.8kg CO2 equ. /t manure 345

CO2 of energy saved by less artificial fertiliser being

required tpa 74.8 18.7kg/t manure 1,122

Kg N to water saved pa (€3.36/kg) 2,760 25% of art.fertiliser

saved 9,108

Total benefits to environment 13,151

At the current time, the AD project itself cannot realise any financial value for the project for optimising the environmental benefit, apart from that of reducing carbon emissions by replacing fossil fuel used for electricity generation. Therefore most AD projects are not concerned about the effect on the environment more than meeting environmental regulations. This is one aspect

17 Valued at €15/t CO2 18 Stored for 4 months on average in outside stores

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where a community AD project differs, because its focus is not solely on ensuring the project trades positively, but also on improving conditions for the community as a whole. Therefore the external benefits should be internalised, where possible, when evaluating the feasibility of the community AD project.

Environmental benefit is difficult to quantify. More research is required to be able to quantify all the environmental effects of designing and operating an AD in different ways. However, there is some research data available which has been produced in Denmark, where they have had community digesters for over 20 years. The following data has been used by Risoe National Laboratory in Copenhagen, to provide socio-economic analysis of centralised AD. It is important to realise that these figures can change for better and worse, depending on how an AD project is configured, managed and outputs are utilised.

Value of some of the externalities for a 4,000tpa slurry only digester (440LSU19), with total capital cost of €202,000, producing 20kw electricity and 16kw spare heat

There could be other environmental benefits such as reduction in ammonia emissions, reduced odour, increased organic matter in the soil and a more open and resilient soil which therefore is less prone to flooding. The value of these benefits is not currently known.

If waste is co-digested there could be additional environmental effects, such as a reduction of methane emission from landfill (calculated to be 28kg CO2 saved per ton biowaste even when allowing for capture and use of methane at the landfill). There would also be nutrients in the waste that would replace more artificial fertiliser. There may be an increase or decrease in the transport miles depending on whether the digester was located between the waste source and the previous disposal point. A typical figure used for transportation at centralised AD facilities, in Denmark (2005), is 1kg of CO2 equivalent emissions for each ton of feedstock processed. However, in the W.S.Atkins report ‘a review of the environmental effect of CAD (1996)’ a medium efficient heavy good vehicle was expected to produce 0.99kg of CO2 per km travelled.

It can be seen that the potential value of environmental benefit even at a small on-farm AD of 175cu m capacity could be significant at over €13,000 per year, even when processing only the manure produced at that farm. However, these benefits would reduce quickly if the system was not built to optimise the benefits. For example if the digester has to have its roof removed with any frequency, or the biogas is not collected from the digestate while it cools down there will be significant methane emissions; or if the digestate store is not covered or proper care is not taken at spreading there will be ammonia emissions; or if the digester is very large the power may not be able to be used locally and there will be less savings in grid losses; or if feedstock is transported long distances to the digester.

Odour Biodegradable waste and manure produces unpleasant smells when it is stored or moved, due to the process of decomposition. In a digester the process of decomposition occurs in a closed vessel, and the gases emitted during the process are collected and burnt. Well digested material therefore has a much less unpleasant smell than undigested material and the duration of that

19 Cattle housed for 6 months of the year

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smell after land spreading is much shorter. The smell shadows below of digested and undigested manure show this change graphically.

Odour shadows after spreading20

5 minutes

12 hours

Digested slurry

Untreated slurry

Wind-direction

The AD process is a closed process so odour is not emitted from the process itself. However, there is the potential for an AD facility to produce bad smells by other means such as

• Feedstock reception, handling, cleaning, mixing, preparation transfer and spillages.

• Emissions of biogas and exhausts from combustion (if there is no H2S removal from the biogas)

• From digested materials directly after unloading from the digester, during separation or sometimes from storage areas

The degree of nuisance created by odour varies according to the type of storage, waste type and age, abatement measures installed, management techniques and location. The odour may arise at a low level from several diffuse sources or at a high level from a single source. The main components of odour nuisance from an AD are, sulphides, mercaptans, ammonia and (volatile) fatty acids

When feedstock is transported, handled, stored or conditioned it will usually emit bad smells. These can be controlled by careful design and good management techniques, such as

• Delivery vehicles should be clean and leakproof on arrival, and washed clean of any debris that might become lodged on the vehicle during delivery, before it leaves.

20 Research undertaken by Danish Institute of Agricultural Sciences

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• Liquid feedstock can be delivered through pipe connections directly into closed holding tanks.

• Spillages during delivery or handling should be should be avoided but if they occur they must be cleaned up as quickly as possible

• All feedstock should be stored in appropriate storage as soon as possible after delivery, and not left sitting outside

• Any strongly malodorous feedstock should be delivered, handled and conditioned inside an enclosed reception hall. All doors should be closed when activities are taking place.

The reception hall should:

• Have automated vehicle doors that are closed after the vehicle enters and before unloading commences

• Be maintained under negative pressure to prevent external release of odour, aerosol, dust or ammonia. Typically there should be 3-4 air changes per hour. The extracted air must be treated to remove contaminants to acceptable levels or utilised in combustion

• Use atomisers to mask odour, if odour levels are high or if exterior doors are opened frequently

However, some feedstock does not emit bad smells so other types of reception facilities could be used.

• Typically there will be some methane and ammonia emissions during separation, and a risk of spillage from the process. Therefore

• The separator/decanter should be in an enclosed, well-ventilated area, with the air being extracted and combusted

• The area where the separator is sited should be concreted with a slight slope to allow discharge of spillages and wash water into a drainage sump

If the digestate is fed to the separator from a holding tank, that holding tank should have a gas tight cover, and the biogas be collected, and the tank should be mixed to minimise settling out of solids pre-separation

Care needs to be taken to limit the potential odour emissions, in particular ammonia and in some cases methane, from storage of digested materials.

• Storage tanks that receive digested material before it has cooled to at least ambient temperature, should have gas tight roofs and the biogas should be collected and utilised

• Storage tanks for cooled digestate should be covered, to minimise the risk of ammonia emission

• Storage of material that is not sufficiently processed for any reason, such as it has not been retained in a well functioning digester for at least the HRTshould be protected from vermin and have odour and methane emission control

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• Whole digestate storage tanks will require agitation prior to emptying. There is likely to be significant air emissions during this process, and there should be measures in place to manage these emissions. In most situations the separated liquid will not require agitation before removing from storage.

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APPENDIX 9 Details concerning Regulations Environment Agency Facility Permits The Environmental Permitting (EP) Regulations came into force on 6 April 2008, combining Waste Management Licences and Pollution Prevention and Control in England, making them more straight forward. Where a biogas plant already had a PPC permit or a Waste Management Licence before that date, it will automatically have an Environmental Permit, containing the same conditions as before.

If waste inputs are accepted into the Biogas Plant, the following operations require EA authorisation:

• Storage and pre-treatment

• Anaerobic digestion

• Post treatment

• Use of digestate materials

• Combustion of biogas

With Non-waste inputs, only the following may come under EA authorisation:

• Post treatment

• Use of digestate materials

The first decision is whether you have a plant of a size which requires a full Environmental Permit or not. For small facilities there is the option of a “Simple Exemption” for on-farm anaerobic digestion; it is known as the T24 exemption, which allows up to 1,250 cubic metres of plant tissue, horse and farmyard manure and slurry to be stored or treated on site at any time. If you are running a Community Digester then you can digest a maximum of 50 tonnes at any time of manure, catering and green waste at an off farm location.

The thermal rated input of the biogas should not be more than 400kW. At 35% efficiency, this means a CHP of about 140kW electrical. The T24 exemption doesn’t have any limits on the storage of manure/slurries in the farms’ existing manure stores/slurry pits, unless the storage facilities form an integral part of the AD activity itself i.e. place a lid over the slurry pit and pump the gas off for burning. In these cases the quantity limits would apply but in those situations where manure/slurry is transferred from the point of storage to the AD unit the 1,250 cubic metre limit will only be applicable to the volume of the digester. The Exemption is apparently going to be very cheap (£30) with on line registration.

If your plant is bigger than the 1,250m3 digester capacity and is only taking the following types of waste, you will need an On-Farm Environmental Permit (SR2009 No21)

• sludges from washing and cleaning − food processing waste, food washing waste

• plant tissue waste - husks, cereal dust, waste animal feeds

• animal faeces, urine, manure including spoiled straw

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• wastes from the dairy products industry

• biodegradable materials unsuitable for consumption or processing

• solid and liquid dairy products, milk, food processing wastes, yoghurt, whey

• sludges from on-site effluent treatment

If your plant is bigger than the 1,250m3 digester capacity, and you want to digest a wider range of feedstock including Animal By products then you will need an Environmental Permit:

• SR2009 No20 Anaerobic digestion facility including use of the resultant biogas

You may also need:

• SR2009 No22 Storage of digestate from anaerobic digestion plants

And if you spread the digestate you will need:

• SR2009No09 Mobile Plant for land spreading

Or else undergo certification to the new PAS110 and Anaerobic Digestion Quality Protocol

These permits are new and there is a transitional period for the implementation of the regulations which ends in October 2013. So it is worth keeping an eye on any changes that may take place.

Waste Carriers Licence Only a registered waste carrier can transport waste. The information available to become registered as a broker or carrier is laid out by the Environment agency in this web-link here:

www.environment-agency.gov.uk/business/sectors/wastecarriers.aspx. Registration costs £149 then £102 annually thereafter.

HACCP Management Hazard Analysis and Critical Control Points (HACCP) is a procedure that identifies the possible hazards associated with the process, analyses how they can be avoided, sets limits to minimise the risk of the hazards occurring, and develops a strategy of action in case the hazard does occur. Critical Control Points are points in the process that can be monitored and measured, so that if operation is not within the stated range, action can be taken to rectify the problem. An example might be temperature, feedstock quality or throughput rates. The ABP Regulations require CCP

Animal By-Product Regulations If there is any chance that animal by-products other than slurry or manure might form part of the AD feedstock, then an Animal By-Product Regulation (ABPR) licence is necessary. This regulation augmented controls on animal by-product uses following the devastating foot and mouth outbreak in 2001. Its aim is to protect the public and animal health from any risk of diseases. Meeting this regulation is not cheap, simple or easy. If there is any intention to follow this route, then it should be fully planned to this effect before construction.

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http://www.environment-agency.gov.uk/business/sectors/wastecarriers.aspx


Table providing examples of how ABP and EA licensing may apply

Waste Standards Animal Health approval EA Licensing

Livestock manure None under ABPR No21 Exemption Milk and bellygrass Yes Licence required

Other category 2 waste

133C at 3 bar pressure for 20 mins Yes Licence required

Green waste Not an ABP No Licence required Wwtp sludge or Not an ABP No Licence required other waste not

containing any meat or ABP

Not an ABP No Licence required

Catering waste National Yes Licence required Category 3 (other

than catering waste) EU Yes Licence required

Category 1 Not allowed for AD

If different types of feedstock are combined then the requirements to be met are those required for the feedstock with the most stringent requirement

There are three categories of material under the ABPR regulations;

• Category 1 (high risk material) includes the ‘high risk’ parts of the carcass including spinal column and brain tissues because of the risk of containing Spongiform Encephalopathy (BSE). Category 1 materials cannot enter an AD plant under any circumstances.

• Category 2 This category includes fallen stock, milk, bellygrass and manure. The fallen stock material can be digested but only after they have been rendered at 133oC at 3 bar pressure for 20 minutes. These materials are identified with a black stain.

• Category 3 (low risk material) is food waste that is not fit for human consumption. This could include out of date foods (meat, dairy, eggs), leftovers and so on. This has to be pasteurised before it enters an AD plant. The heat can be sourced from the CHP generator. Reports suggest this can enhance methane generation and recovery by denaturing the fibrous material of the feedstock. They are not fit for human consumption. This is the category that is most commonly anaerobically digested.

There are also materials that have no animal matter in them at all and are therefore not categorised as ABP. All types of material must remain identifiable at all times. If materials from

21 Although an ABP licence is not required, the local animal health officer must be informed that the AD is to be developed and used to process either manure only or manure and other materials that do not contain animal by-products (eg vegetables, waste water treatment sludge etc)

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different groups become contaminated, the entire batch must be treated as if it was all the higher risk category material.

Milk from the farm the AD plant is on may be used as a feedstock without any additional ABPR requirements, but milk from cows on antibiotics could damage the micro flora balance of the digester. Milk from another farm or dairy is a category 2 ABP and must be treated accordingly

The UK has adopted a national standard for catering waste. The national standard does not apply to supermarket food waste, only food waste from households and other kitchens (eg hotels). To enable flexibility to be able to handle all types of biodegradable waste, adoption of the EU standard is recommended.

Standard Minimum Temperature

Minimum Time Maximum Particle Size

EU Standard 70oC 1 hour 12mm National Standard Either 57oC 5 hours 50mm Or 70oC 1 hour 60mm

The National Standard,

Can only be used if only catering waste that contains no meat is processed

Or the material is stored after pasteurisation for a minimum of 18 days. (This storage could be in an AD with a HRT of at least 18 days)

The EU Standard for Biogas Plants

The following are the important parameters for a biogas plant to be approved under the EU Animal By-Products Regulation:

• The particle size of all material must be smaller than 12 mm.

• All material must be pasteurised, either before or after anaerobic digestion, at 70oC for one hour.

• The plant must include a source of back-up heating for the pasteurisation unit.

• Measures must be taken to prevent recontamination of the digestate with raw waste.

• Samples of digestate must be verified to have no salmonella in 25 gm and limits of enterobacteriaceae.

• Digestate may not be applied to pasture land, being defined as land on which ruminants graze within 3 weeks and pigs within 8 weeks.

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Obtaining an ABP licence To be ABPR compliant, an operator must be licensed.

This link www.defra.gov.uk/animalh/by-prods/wastefood/compindx.htm opens the DEFRA on ABPR including application forms for a permit and Frequently Asked Questions. The application form and guidance document specifically for composting and biogas operations, available at www.defra.gov.uk/corporate/regulat/forms/Ahealth/by-products/abpr1.htm.

There is no cost for ABP certification other than those necessary to ensure the business conforms. There are significant management and administrative responsibilities in order to achieve ABP requirements, resulting in additional costs. ABPR compliance also involves additional machinery and measures requiring capital to set up and more running costs. It may not be feasible for an existing AD business to ‘upgrade’ at a later date to accommodate feedstock other than what it was designed for, as the buildings and other facilities might need locating differently, for example to allow better vehicular access, space for pasteurisation units, segregation of waste or cleaning of vehicles and operational areas.

It will probably take several weeks to get an AD validated to ABPR. Once the application is submitted, if the Animal Health inspectors are satisfied that the plans will meet the regulatory requirements, they will visit the site. If the site does not meet the requirements, they will write after the visit explaining what the shortfall is/are. You will then have the opportunity to amend this and re-apply. It is therefore prudent to contact the Local Animal Health Office at an early stage for assistance with the complex and demanding criteria.

Health and Safety Executive (HSE) The Health and Safety Executive has no specific guidance or requirements for AD businesses. It notes though that every business is obliged to carry out a risk assessment of health and welfare of employees or visitors (regardless of whether there are any employees). Details of this self-auditing procedure are outlined in a leaflet called ‘Five steps to Risk Assessment’ downloadable from www.hse.gov.uk/pubns/indg163.pdf. For specific requirements, contact your local regional office, locations being listed here: www.hse.gov.uk/contact/maps/index.htm.

Introduction to Nitrate Vulnerable Zones (NVZ’s) Nitrate Vulnerable Zones (NVZ’s) were first introduced in England in 1996 as part of the Nitrates Directive Action Programme. NVZ measures are a way in which nitrate pollution from agriculture can be controlled. 55% of England was designated as an NVZ on 1st January 2009 as previous restrictions did not result in sufficient reductions of nitrate pollution.

New rules now apply to anyone occupying agricultural land in an NVZ. The official Defra NVZ booklets should be referred to for detailed guidance on these rules. The following text is a summary to the key NVZ rules specific to the handling and spreading of materials from the AD process.

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http://www.defra.gov.uk/animalh/by-prods/wastefood/compindx.htm

http://www.defra.gov.uk/corporate/regulat/forms/Ahealth/by-products/abpr1.htm

http://www.hse.gov.uk/pubns/indg163.pdf

http://www.hse.gov.uk/contact/maps/index.htm


AD By-Products

The AD ‘digestate’ is extremely useful as both a fertiliser and a soil conditioner.

The liquor produced as a result of separating the digestate usually contains a high level of available nitrogen (70-95%). Sampling of the material in line with Defra’s standard protocol procedure will confirm whether or not this is the case.

The solid fraction should be ‘stackable’ and should not slump when heaped. Sampling of the product is recommended to determine the nutrient content of each batch, but where this is not possible it can be assumed that the product contains a relatively low level (30%) of readily available nitrogen and a high level of Phosphate (>5kg/t)

The exact amount of nutrients in the digestate depends entirely on the nutrient content of the feedstock, the consistency of the feedstock, the duration in the digester and how the digestate is separated.

Livestock Manures

It is important to distinguish between ‘organic’ manures and ‘livestock’ manures within the scope of the NVZ rules. Organic manures include any natural material that contains nitrogen e.g. AD digestate, food waste, compost, sewage cake, vegetative products (including livestock bedding), as well as livestock manures. Livestock manures only refer to unprocessed livestock excreta.

Digestate that contains animal manure is still identified in the NVZ regulations as livestock manure. The NVZ restrictions and requirements still apply to the relevant proportion of digestate that is manure (eg the maximum application rate of N - There is a whole farm livestock manure loading limit 170kg N/ha/calendar year, rising to 250kg N/ha for those farms with a derogation).

Spreading Rules

Spreading organic manure must be performed when field conditions allow to ensure cross compliance rules aren’t breached. Anybody spreading any organic manure must have a farm ‘risk map’ in place. This shows information including non-spreading areas and land that has a low run-off risk. Assuming field conditions are suitable to undertake spreading and / or organic manure incorporation, the following spreading dates apply:

Organic manure must not be spread at a rate which results in the total organic nitrogen supplied exceeding 250 kg/Ha in any 12 month period. This maximum organic manure application level therefore applies to any form of AD digestate.

Prior to an application of organic manure (or any manufactured nitrogen fertiliser), a nitrogen plan must be in place for the crop receiving the material. This plan should indicate the nitrogen requirements of a crop (from any source) on a field by field basis so it is important to determine the crop available nitrogen value of different organic manures prior to any applications. Available nitrogen applications from all sources should never exceed the advised crop nitrogen requirement.

Organic manures that are spread on bare soil or stubbles must be incorporated into the soil as soon as practicable or within 24 hours if the land is sloping or within 50 metres of surface water.

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Liquid AD material must always be incorporated into bare soil and stubbles with 24 hours unless a band spreader or injection system has been used to apply the product.

From 1st January 2012, slurry must not be spread using equipment that has a trajectory higher than 4 metres. Liquid AD digestate should be considered as ‘slurry’ in this instance.

Closed Spreading Periods

For Organic Manures with High Readily Crop Available N

(Non-separated AD digestate, Liquid AD digestate, slurry etc):

Sandy or Shallow Soil 1st Sept to 31st Dec Grassland

All Other Soils 15th Oct to 15th Jan

Sandy or Shallow Soil 1st Aug to 31st Dec Arable

All Other Soils 1st Oct to 15th Jan

For Manures with Low Readily Crop Available N

(Solid AD Digestate, FYM etc):

Any Farmland Any Soil No Closed Period

Storage Rules

Liquid material from the AD process is subject to the organic manure closed spreading periods. The rules applicable to FYM are applicable to separated fibre. These include:

• organic manure located in field heaps must be of a ‘stackable’ consistency

• they cannot be located within 10 metres of surface water or a land drain, and 50 metres from a spring, well or borehole.

• They cannot be located on land that may become waterlogged or flooded

• They must be relocated after a period of 12 months on the same site and not return to that site for at least 2 years

• The location of field heaps must also be identified on the farm’s ‘risk map’ (see above).

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NVZ Rules and AD Digestate Summary

Analyse AD liquor and solid material to determine the crop available nitrogen value of each

Unless testing proves otherwise, liquid material from the AD process should always be considered a high crop available nitrogen product, whilst solid fractions should be a low crop available nitrogen product

A ‘risk map’ must be held and regularly updated for the farm

Ensure that the closed organic manure spreading periods are adhered to

Ensure that organic manure applications rates do not exceed 250kg/N ha in any 12 month period

Never apply more nitrogen (from any source) to a crop than is required

Ensure that spread organic manures are incorporated into bare soil and stubbles within the necessary timescales

Adhere to the relevant storage rules that apply to liquid and solid organic manures

Using the Digestate

When the Digestate Standard and Quality Protocol is in operation, the Biogas Plant operator has the opportunity to choose between following the Environmental Permitting route and applying for the Digestate Specification based on PAS110.

Using an Environmental Permit

Have to show there is beneficial use on agricultural land - Registered Exemption, Para 7, annual review and comply with various conditions including:

• Annual prior notification, with certificate of benefit and risk assessment

• Secure storage to 12 months, away from watercourses, wells etc

• No more than 250 tonnes/hectare/12 months

• Compliance with the ABP Regs

Pay a fee of £500 per 50ha of land that is spread on.

Digestate Specification PAS 110 & Protocol

The purpose of the PAS110 and the Quality Protocol is to remove a major barrier to the development of AD by encouraging markets for these digested materials. It creates an industry specification against which producers can verify that the digested materials are of consistent quality and fit for purpose. The underlying principle is that only source separated biodegradable

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materials can be accepted within the scheme; this reduces the laboratory testing regime to a manageable level and for example greatly reduces the risk of the presence of a wide range of harmful organic compounds

The Quality Protocol has the following three main purposes:

• to clarify the point at which waste regulatory controls are no longer required;

• to provide users with confidence that the digestate materials they purchase conform with an approved standard;

• to protect the environment (including soil) and human health by describing acceptable best practice for the use of quality digestates in agriculture, forestry (excluding horticulture other than soil-grown horticulture) and in land restoration.

The Renewable Energy Association is running the Scheme Rules for the Specification and Protocol. Biogas plants which successfully pass the PAS110 and Protocol, will no longer be subject to Environmental Permitting Regulations, since the Digestate will cease to be waste and instead be classed as a product. This has two main benefits, firstly removing the need to make applications to the Environment Agency, which at present is expensive, time consuming and inflexible, and secondly to remove the “waste” tag from the digestate; this will overcome resistance from retailers and some quality labels which are very sensitive to the nature of any soil additives that may cause concern to the public or to food buyers.

How to reach PAS110 certification and what would it cost? The best place for guidance through the standard is the Renewable Energy Association (07973 111 972).

Planning Requirements for AD If an AD facility is to use only farm sourced feedstock and digestate will only be spread on that farm, then it could be treated as permitted development as long as the conditions can be met: (http://www3.winchester.gov.uk/SHARE1/www/planning/permitted_development/pd2.htm#6)

Planning permission will be necessary for all other installations because AD is not considered within the agricultural planning guidelines, rather an industrial/waste treatment process. Outline planning permission is not available for waste-processing sites. Planning consent will also therefore be required if an AD plant wants to change its feedstock range, for example, including non-farm waste streams.

The location of the local planning offices can be found here: www.planningportal.gov.uk/england/genpub/en/,

The cost of making a planning application will vary with the building size and type of application. An outline application costs £335 per 0.1 hectares and full application costs are more sophisticated. Overall though, the cost of the application will be in the professional planners’ fees required to put the plans together. This may run to several thousands of pounds.

Planning Considerations

Several points need consideration before applying for planning consent. These include:

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http://www3.winchester.gov.uk/SHARE1/www/planning/permitted_development/pd2.htm#6

http://www.planningportal.gov.uk/england/genpub/en/


• Distance from neighbours

• Surface and ground water aquifers

• Flooding risk

• Area of Outstanding Natural Beauty or National Park

• Visual impact ~ will it be intrusive to anybody?

• Traffic movements, will the local road network accommodate any increase in traffic?

• Access ~ is the access safe and adequate?

Planning applications should take consideration of the Planning Policy Statements PPS7, ‘Sustainable Development in Rural Areas’, PPS 22, ‘Renewable Energy’ and PPS1 ’Delivering Sustainable Development. They provide guidance on what is important in the planning application. These documents are freely downloadable from the communities website at www.communities.gov.uk/planningandbuilding

Business Rates Any non farming business where a product is sold off farm will be subject to business rates. Therefore if a product from an AD is sold off farm it will be liable to business rates. The cost depends on its rental value. Premises subject to rates are given a ‘rateable value’ by the Valuation Office Agency. Local Authorities use this assessment to calculate business rates. The size and type of premises are considered as well as how they are used suggesting both the physical and electrical capacity of the plant would be assessed. It may therefore be worth considering setting up a separate business from the farm for the AD, if AD products are to be sold off farm.

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http://www.communities.gov.uk/planningandbuilding


APPENDIX 10 Getting connected Grid Connections & Assumptions The first decision concerns the type of conversion of the Biogas to useful energy. This can be:

• Gas boiler for use of heat on site

• Electricity export to Grid and local Heat via CHP on site (or pipe to remote CHP)

• Cleaning the Biogas to methane for vehicle use or injection to Gas Grid

It is assumed that the CHP option will be adopted in most cases in this report, so the following electricity use options would be available:

• Generation for own supply only without export option (Non synchronized connection)

This is used where the output of the generator is less than the normal electricity import of the site. A changeover panel is used, which isolates supply from the Grid network whilst the generator is available, but re-connects to the grid in the case of a generator interruption.

• Generation for own supply with export (synchronized connection)

Used when the electrical output of the generator is more than the lowest load taken by the site. When exporting electricity the output of the generator has to be synchronized to the frequency of the Grid network

• Generation for export only

Entire output exported to Grid Network. A new separate connection for export is required and a survey of the network to confirm that it can handle the increased energy flow. Additional reinforcement of the Grid may be required.

Changing an existing on site network For a Biogas Plant, external connection to the Grid will normally be to the low voltage distribution network operated by the DNO (Distribution Network Operator) which in the Peak District is E-ON. The National Grid operates the high voltage transmission network. For generators up to 1000kVA the distribution can be handled on the Low Voltage (415 volts) network but larger generators will need Medium Voltage (11,000 volts)

Indicative costs of changing the existing onsite network - at low voltage can be:

• £25 kVA for network modifications and changeover switch

• Maintenance of the electrical equipment £800 per 1000kVA per annum

Establishing new connections to the Grid Network A network study is required to ensure that the new point of connection (POC) will not adversely affect the network due to reverse power flows. These studies may cost between £1,000 - £5,000

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and take about 3 months. Very small export of <50kw would not normally require this service. Following the study a formal connection application would be made to the DNO.

Costs for connection to Grid The actual cost for grid connections depends very much on local conditions. Some sites may be situated a long distance from any possible Low Voltage (415 volts) network, whilst others may be adjacent or already connected. Amounts of £30,000 - £40,000 are not unusual.

Connection Cost

Depends on the distance from the generator and the point of connection and costs for reinforcement of the DNO network upstream of the connection. For example, cable trenching and reinstatement in open ground would be £20 per metre plus low voltage cable and joints at £15/metre. Some of this work can be carried out by an Independent Connection Provider

Grid Reinforcement Costs

These are shared between the generator and the DNO according an OFGEM formula

On-Going Use of system Costs

Distribution Use of system tariff (DUOS) charges are payable

The Connection Process to DNO Contact with the DNO in the early development stages of a generation project is important to ensure that the connection date can be met. Sufficient time should be allocated to the development stages of a project as it can typically take 18 – 24 months from first contact with DNO to energisation of the connection (at 11,000 and 33,000 Volts). Large connections at 132,000 Volts may take longer to commission.

DNO will need to carry out technical assessments before a generating unit can be connected to the network. The staged connection process for distributed generation is summarised as follows:

Stage I Feasibility Study

Studies are carried out to determine the impact of the proposed generation on DNO’s existing network. An indicative budget estimate is given to the customer, which will be subject to further study and a number of conditions.

Stage II: Formal Connection Offer

Based on a satisfactory outcome in stage I and on instruction from the customer, detailed design work is carried out to produce a connection charge and connection offer. Further technical studies including Stability Studies (for large connections, normally over 5MW) are completed as necessary. DNO start the process to obtain any necessary planning permissions and/or consents. For larger projects, DNO will make Tender and Contract applications for necessary plant, equipment and construction works.

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Stage III: Project Completion & Commissioning

Following acceptance of the connection offer and subject to consents and planning permission, the project will proceed to completion and commissioning at agreed timescales. The customer has the option to carry out contestable work elements. It is possible that some small connections will not require any physical works to be carried out to DNO’s network (eg – single Photovoltaic installations).

There are costs associated with the above work, which will be charged to the customer. A fee for the initial Feasibility Study and any external costs to cover consultants for stability or other technical studies are payable prior to the work commencing. The fee charged will depend on the size, type and location of the proposed generator. DNO’s time and resource costs beyond stage I will normally be recovered in agreed stages in line with DNO’s expenditure. If the project does not proceed for whatever reason, the customer/developer will be asked to settle any abortive costs. For most small connections (typically below 500kW), the process is normally condensed, with Stage I and II combined into one.

Planning Permission and Other Consents The types of consents and permissions required for substations, overhead lines and underground cables necessary to make a connection can be summarised as follows.

Wayleaves/Easements: Required from private landowners where an overhead line or underground cable is to cross his or her land. Underground cables laid in the public highway only require the consent of the Local Authority.

Local Authority Consent: Planning permission is required for new substations of a certain size. However, the substation required for the generator connection would normally be included in the planning application for the whole site. The Local and County Authority must be consulted on new overhead lines and they will make comment to the DTI.

DTI Consent: Section 37 consent under the Electricity Act 1989 is required for most new overhead lines. The views of the local planning authority, local people and statutory bodies such as the Environment Agency, Countryside Agency and English Nature/Countryside Council for Wales can be brought into the decision making.

Environmental Statement: This must be produced for new overhead lines with a voltage of 132,000 Volts or above and at lower voltages, if called for by the DTI (however this is rare).

Substations and cables constructed in certain area’s (eg an SSSI or close to a watercourse), will also require the consent of the Environment Agency and English Nature/Countryside Council for Wales.

Other bodies that may have to be consulted or may wish to provide comment (especially on overhead lines) include, English Heritage/Welsh Historic Monuments Executive Agency (CADW), Campaign to Protect Rural England/Campaign for the Protection of Rural Wales, The County Archaeological Officer and local Wildlife Trusts.

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Technical Considerations The connection of distributed generation to the electricity network will, amongst other factors, affect the power flow, voltage profile and fault level* within that network. The impact of this is assessed during the early stages of a project’s development. In some cases, the impact of the new generator(s) will be adverse and require either reinforcement of the electricity network or operating/output constraints to be enforced at certain times of year or during abnormal network operating conditions.

* Fault Level: Can be viewed as the magnitude of energy, which will need to be interrupted by circuit breakers during a failure/fault on the electricity distribution system. Generating plant normally increases the fault level in the electricity distribution system.

Connection Costs and Regulatory Framework Recent changes to the Regulatory framework have introduced a common approach for connection charges associated with both demand and generation connections. These are detailed in the Connections Charging Statement which may be downloaded from the Information for Supplies area of their website.

Typical Connection Sizes & Connection Voltages The connection voltage for a site can influence the cost of connection and in general the higher the voltage, the higher the cost and this is due to the general increase in size and insulation requirements of plant and equipment as the voltage increases. DNO’s network operates at the following phase voltages: 400V, 11kV (6.6kV in some area’s), 33kV (66kV in some area’s) and 132kV. As an approximate guide, the size of the generator connection and the likely connection voltage is set out on the next page. Be aware, that there will be some overlap between the voltage boundaries and that many site specific geographical and technical parameters can influence the connection voltage to be used. Occasionally in remote rural locations for example, it may be more feasible, both technically and financially, for a 3MW wind farm to be connected at 33kV, where you would normally expect this size of generation to be connected at 11kV.

Generator Size (3-phase) Location: Urban or Rural Typical Connection Voltage0 – 0.25 MW Rural 400V 0 – 0.5 MW Urban 400V 0.25 – 4.0 MW Rural 11,000V 0.5 – 7.0 MW Urban 11,000V 4.0 – 20.0 MW Rural 33,000V 7.0 – 20.0 MW Urban 33,000V + 20.0 MW Urban + Rural 132,000V

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Relevant Documentation/ Essential Reading for Prospective Generators:

• The Distribution Code of Licensed Distribution Network Operators of England and Wales: Section DPC7 is particularly relevant for the connection of Embedded or Distributed Generation.

• Engineering Recommendation G59/1: ‘Recommendations for the connection of embedded generating plant to the regional electricity companies’ distribution systems

• Engineering Recommendation G75/1: Recommendations for the connection of embedded generating plant to public distribution systems above 20kv or with outputs over 5mw

• Engineering Recommendation G83/1: Recommendations for the connection of small scale embedded generators (up to 16a per phase) in parallel with public low-voltage distribution networks

• Engineering Technical Report 113: Notes of guidance for the protection of embedded generating sets up to 5MW for operation in parallel with pes distribution systems

• DTI Report K/el/00318/rep Technical guide to the connection of generation to the distribution network

• G59/1, G75/1, G83/1 and ETR 113 are available to purchase from the Energy Networks Association, 18 Stanhope Place, London, W2 2HH. (Tel: 020 7706 5100). Report K/EL/00318/REP is available via the DGCG’s (Distributed Generation Co-ordinating Group) website listed below.

Useful Websites

www.ofgem.gov.uk

www.energynetworks.org

http://www.decc.gov.uk/

www.distributed-generation.org

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http://www.ofgem.gov.uk/

http://www.energynetworks.org/

http://www.decc.gov.uk/

http://www.distributed-generation.org/


APPENDIX 11 FINANCE - Banking

Triodos Bank Triodos Bank finances companies, institutions and projects that add cultural value and benefit people and the environment, with the support of depositors and investors who want to encourage corporate social responsibility and a sustainable society.

Their mission is stated as:

• To help create a society that promotes people’s quality of life and that has human dignity at its core.

• To enable individuals, institutions and businesses to use money more consciously in ways that benefit people and the environment, and promote sustainable development.

• To offer our customers sustainable financial products and high quality service.

Contact:

John Stevens, Renewables and Environment team specialising in AD.

[email protected]

0117 9809647 07824 877 384 Triodos Bank Brunel House 11 The Promenade BristolBS8 3NN

The bank is interested in investing in AD, and there are already some projects running. The type of facility which principally interests them is the food waste Merchant CAD facility taking feedstocks from reliable sources, preferably with a long term municipal (house) collection contract, at least as long as the term of the finance. Feedstock capacity of 30-50k per annum costing around £7-10m. Input of farm slurries together with the food is encouraged, with the proviso that the bank does not want to support high intensive farming operations; it has close links with the Soil Association.

The bank provides Project Finance not Asset finance. They do not secure loans on the value of the AD plant, because, apart from the CHP unit, there is no realisable value in the reminder of the installation. They could however, secure the loan on other farm assets, not connected with the plant.

Project Finance works on the basis of repaying the loan from the expected income from electricity export, and gate fee.

A company would have to be formed for the project, which would be ring fenced for the project only, but there could be shareholders from many individuals or organisations. The security for the loan is a charge on the assets of the company in the form of cash and shares. In the event of

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the company not being able to meet interest payments, Triodos would take over the management and try to rescue it.

Interest is charged on a rate over the Base Rate (not on Libor as in many other banks). This makes the finance cheaper than other banks. The minimum rate at present for a project is 3.5% which is made up of ½ % base rate, plus 3.0% for the bank, but this can vary upwards with the risk of the project. The bank lends the money normally over a 7 – 10 year period, and will provide the necessary cash to build the plant without repayment being started until the plant is fully operational. The bank wishes the next 6 months interest payments to be in a deposit account on a continuous basis, and if this is achieved, lower interest rates apply.

The basics of a successful investment will depend on:

• Long term secure feedstock contracts with reliable suppliers preferably with a BBB-minus Standard & Poor rating. Long term Local Council Contract is preferred.

• Power purchase agreement with a secure energy company (eg - E-ON)

• Both Power purchase and feedstock contracts to match the loan period of 7 – 10 years

• Technology provider must be well established in field

• Operational management to be experienced and efficient

Triodos has plenty of available funding for projects, but the limiting factor is the time taken in due diligence – AD is complex. Therefore they concentrate on the best projects; they consider that AD has quite a risky profile.

Conclusion:

The bank is principally interested in investments in large merchant AD plant with guaranteed food waste feedstock inputs and energy export contracts.

Co-operative Bank

Contact: Chris Shearlock

Sustainable Development Manager 6th Floor New Century House Corporation Street Manchester M60 4ES Telephone: 0161 827 6209 Mobile: 07989 600 459 Facsimile: 0161 827 6230 Email: [email protected]

Website: www.co-operative.coop

Contact: Chris Matthews

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http://www.co-operative.coop/


Renewable Energy & Asset Finance – deals with projects in detail

Tel: 0161 829 5283

The bank normally invests in projects under 5MW installed capacity

The Co-operative bank can finance projects in three ways:

• Normal bank loan

• Grant to an Industrial & Provident Society

• Investor in an Industrial & Provident Society

1. Normal Bank Loan. This would consist of Project Finance under the same conditions as outlined for the Triodos Bank above. The interest rate would be negotiated, but would be based on a percentage above base rate or libor. Security for the loan would be a long term power purchase agreement and secure contracts to supply the feedstocks.

2. Grant to an Industrial & Provident Society - in 3 months time, the bank will be looking to receive applications for grants of maximum £50,000. A scheme would be eligible if it was planned to be a co-operative. A grant and an investment could be combined.

3. Industrial & Provident Society An industrial and provident society is an organisation conducting an industry, business or trade, either as a co-operative or for the benefit of the community. An IPS has share capital based on value shares, which can only be redeemed at face value. The profits and losses of an IPS are thus distributed among members. The share typically acts as a "membership ticket", and voting is on a "one member one vote" basis. The maximum individual shareholding is currently set at £20,000. The share capital may be withdrawable share capital, an unusual form of finance which is treated as equity but may be withdrawn subject to specified conditions. It is registered under the Industrial and Provident Societies Act 1965. A co-operative would be the most likely structure for a shared Biogas Plant.

The Co-operative bank could invest in the IPS, and this would obviously be on a different basis to the individual limited total of £20,000. It could lend up to the full cost of the project.

Main Features of IPS Co-operative

Democratic Member Control. Co-operatives are democratic organisations controlled by their members, who actively participate in setting their policies and making decisions. Men and women serving as elected representatives are accountable to the membership. In primary co-operatives members have equal voting rights (one member, one vote) and co-operatives at other levels are also organised in a democratic manner.

Member Economic Participation. Members contribute equitably to, and democratically control, the capital of their co-operative. At least part of that capital is usually the common property of the co-operative. Members usually receive limited compensation, if any, on capital subscribed as a condition of membership. Members allocate surpluses for any or all of the following purposes: developing their co-operative, possibly by setting up reserves, part of which at least would be

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indivisible; benefiting members in proportion to their transactions with the co-operative; and supporting other activities approved by the membership.

Autonomy and Independence. Co-operatives are autonomous, self-help organisations controlled by their members. If they enter to agreements with other organisations, including governments, or raise capital from external sources, they do so on terms that ensure democratic control by their members and maintain their co-operative autonomy.

Education, Training and Information. Co-operatives provide education and training for their members, elected representatives, managers, and employees so they can contribute effectively to the development of their co-operatives. They inform the general public - particularly young people and opinion leaders - about the nature and benefits of co-operation.

Co-operation among Co-operatives. Co-operatives serve their members most effectively and strengthen the co-operative movement by working together through local, national, regional and international structures.

Concern for Community.

Co-operatives work for the sustainable development of their communities through policies approved by their members.

Local Derbyshire example of an IPS Co-operative funded by Co-operative bank:

Torrs Hydro New Mills Limited

90 Market Street

NewMills

High Peak

Derbyshire

England

SK22 4AA


Torrs Hydro New Mills Limited was established for the specific purpose of owning the Torrs Hydro Electric scheme by Torr Weir on the River Goyt in New Mills in the High Peak of Derbyshire. A share of the revenue from the scheme will help Torrs Hydro achieve its aim to help regenerate the community and to promote the environmental sustainability of the New Mills area. The project was started in 2006 by Water Power Enterprises, a social enterprise whose mission is to set up small-scale hydro plants and reduce carbon emissions. They helped the start up, application for grant funding and project managed the building phase.

Tax Relief Statement

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http://www.h2ope.co.uk/


HM Revenue and Customs have ruled that the share offer will qualify for the Enterprise Investment Scheme (EIS). HM Revenue and Customs describe the income tax relief:This is available to individuals only, who subscribe for (although this can be through a nominee), shares in an EIS qualifying company. There has to be a minimum investment of £500 worth of shares in any one company in any one tax year. The relief is 20% of the cost of the shares, to be set against the individual’s income tax liability for the tax year in which the investment was made.

Further example: Baywind

http://www.baywind.co.uk/baywind_aboutus.asp

Baywind Energy Co-operative Ltd is an Industrial & Provident Society and was formed in 1996 on the lines of co-operative models successfully pioneered in Scandinavia. The first two Baywind projects enabled a community in Cumbria to invest in local wind turbines. The original board of directors included 7 members of the community from Ulverston and Barrow. Baywind's aim is to promote the generation of renewable energy and energy conservation. To date, members have received a competitive return on their investment from the sale of electricity.

The first share offer in 1996/97 raised £1.2 million to buy two turbines at the Harlock Hill wind farm. In 1998/99 the second share offer raised a further £670,000 to buy one turbine at the Haverigg II wind farm site. Preference is shown for local investors, so that the community can share some of the economic benefits from their local wind farm. For example 40% of existing Baywind shareholders live either in Cumbria or Lancaster with a wider number from the Northwest Region.

Equity Funding Hg Capital

2 More London Riverside

London SE1 2AP

Contact: Emma Tinker

Tel: 020 7089 7955

Mobile: 07876 68 55 67

This company has made investments in AD, but only on the basis of a single investment into several plants built by the same company.

Minimum project size is probably around 250kW electric capacity (if power is produced). Tonnes input depends on which waste stream. The key is less to do with individual project size and more overall size across a number of projects - for Hg we look to be able to do quite a large portfolio over time. A single standalone project would be too small.

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http://www.baywind.co.uk/baywind_aboutus.asp

http://www.baywind.co.uk/baywind_windfarm.asp?ID=WDF1&catID=3

http://www.baywind.co.uk/baywind_windfarm.asp?ID=WDF4&catID=3


The main thing they look for is a team experienced at managing and operating projects successfully. Other things follow.

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APPENDIX 12 FINANCE - Grants ETF The Environmental Transformation Fund (ETF) is to bring forward the development of new low carbon energy and energy efficiency technologies in the UK. The fund formally began operation on 1 April 2008, and is jointly administered by Defra and BERR. A strategy for the Environmental Transformation Fund, setting out how the fund operates, is available on UK environmental transformation fund: strategy . The ETF has UK and international elements. Funds within the UK element of the Fund will total £400 million during the period 2008/09 to 2010/11. The ETF funds the schemes which relate to AD.

Environmental Transformation Fund (ETF) Anaerobic Digestion (AD) Demonstration Programme – this £10 million fund, administered by WRAP, closed for applications on 9th December 2008 and applications are currently being assessed by WRAP. It is to support between three and six AD projects which between them, meet the five key aims of the programme. This is a one off fund, so is not expected to have any further rounds.

Other funds

The Fifth Round of the Bio-energy Capital Grants Schemefunded by DECC has application windows. After the current awards, Capital Grants funding from WRAP is closed until 2011. In the future, the balance between innovation and routine processes will be looked at. WRAP is aware that farm scale projects were not addressed in the last round.

Under the Rural Development Programme for England 2007-2013 (RDPE) Anaerobic digestion is eligible for support (along with a range of other measures). The RDPE is managed by the Regional Development Agencies. East Midlands Development Agency EMDA is the main RDPE for the Peaks district.

Big Lottery Fund’s Changing Spaces – Local Food – For composting, but may apply to AD. £2,000 - £500,000. Match funding of between 30% - 10% required.

EON Source Fund – Small scale renewable energy projects – Maximum £30,000.

EDF Energy Green Energy Fund - £5,000 for feasibility studies and £30,000 for installations. Community based projects favoured.

Ashden Awards – for renewable energy schemes.

Energy Saving Trust – Community renewable energy

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http://www.berr.gov.uk/files/file47575.pdf

http://www.berr.gov.uk/files/file47575.pdf


APPENDIX 13 - Checklists Questions for yourself The most important question is: Do you have somebody dedicated and committed to see things happen? Do they have appetite to make decisions and the energy to manage a project into reality?

Next, what are you considering AD for? What will its purpose be?

To reach a decision on viability, the following questions need answering: Preparatory issues

• do you have sufficient skills in the team to complete the planning stage?

• Is the team sufficiently organised?

• Is the purpose and end-game clear in everybody’s minds?

• If it is not primarily a financial project, how will success be measured?

• Financial returns are easily measured, others are not.

• Profit is necessary to achieve any other objective so where is the balance?

• Does the team contain enough commitment and determination to grind through the nitty-gritty?

Feedstock questions:

• What is your feedstock?

• What tonnage is available?

• What biogas yield is likely from it?

• How secure is its supply? And quality?

• Does it have a changing monthly profile? E.g. slurry in summer

• What restraints does the feedstock present (dry/wet, tonnage, contamination etc)

• Therefore how much potential revenue might you expect under ‘good’ working conditions?

• Do you require additional feedstock for; extra volume, more energy, balance the current feedstock mix, supply a quiet period of the year?

• Where is it and what is the cost of connection to it?

• How far is the feedstock from the ideal location and what would the cost of delivering it be? How would you achieve that?

Outputs

• What outputs will you be producing,

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• what priorities will you place on each one?

• Do you have a market for the biogas or its products in mind? Can you make use of all the co-products including all the heat?

• What are the relevant costs and returns of each option (financially or other)

• How far are the relevant connection points?

• What capacities can each accommodate?

• Are any of these factors limiting?

• What is the cost of connections?

• Is there enough land to accommodate and benefit from the digestate?

• Are there other plans for dealing with it?

Technology

• Which technology will you require (e.g dry/wet, meso/thermo, single digester/multiple)

• How much capacity will be required?

• Cubic meters digester

• kW CHP

• cubic meters digestate storage

• feedstock storage?

• What other capital items will be required with the feedstock and outputs proposed?

• Do they fit in the footprint available and is there sufficient space for operations and movement?

Regulatory Issues

• Will you be using wastes?

• Will you be importing off farm products or wastes?

• Will it be food waste?

• Will you be hauling the wastes? Waste Carriers Licence

• Are you within an NVZ?

• will EA permits and exemptions be required

• Will you be using third party wastes? QP might be required if so

• Will you be using food waste? ABP required if so

• Planning issues

• Environmental Impact Assessment

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Business issues:

• Does the organisation’s balance sheet have the strength to take on a major capital investment? If a community group, where is the capital (and collateral) going to come from?

• Are there sufficient supporters of the project if it means a team effort,

• Have you identified who the critical members are?

• Land occupiers,

• feedstock suppliers,

• biogas buyers.

• What will be the implication if one of these goes out of business or out of favour

• How can this be prevented

• What is the plant going to cost

• What will the operational and overhead costs be?

• Cost of haulage of feedstock and digestate

• Have you calculated the risks?

• What is the biggest risk?

• How could you add value to the plant?

• Private electricity sale

• Secondary heat sales

• Sale of digestate fibre

• What will the biggest costs be, how can they be managed?

• What is the return on turnover (a risk measurement)

• What is the first limiting factor of the plant? (what is stopping it being bigger/ more profitable/ more reliable etc?

Financing issues

• Grant funding?

• What might the implications of accepting a grant be?

• Bridging finance from start of build to being operational

• How will you make the application?

• Do you know who to approach?

Structural Issues

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• Do you have a location in mind for the plant?

• where is the plant likely to go

• why?

• Do you have sufficient land to accommodate the digestate spread?

• what will the nearest residents think of it?

• What benefits will they receive from it?

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APPENDIX 14 - Bibliography of very useful reading • The conference proceedings for the ‘Future of Biogas III’ which was Intelligent Energy

Europe funded http://www.ramiran.net/doc07/Biogas%20III/preprog.pdf

• Anaerobic Digestion of farm and food processing residues - good practice guidelines ‘ funded by ETSU http://www.mrec.org/biogas/adgpg.pdf

• ‘Utilisation of digestate from biogas plants as biofertiliser" prepared by the IEA (International Energy Agency) biogas group Task 37. Download from the Task website - http://www.iea-biogas.net/.

• Redman G. of The Andersons Centre. 2010. A detailed Economic Assessment of Anaerobic Digestion Technology and its suitability to UK Farming and Waste Systems. Published by the NNFCC http://www.theandersonscentre.co.uk/Clients_and_Links.asp

http://www.ramiran.net/doc07/Biogas%20III/preprog.pdf

http://www.mrec.org/biogas/adgpg.pdf

http://www.iea-biogas.net/

http://www.theandersonscentre.co.uk/Clients_and_Links.asp

SY Anaerobic Digestion Toolkit

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