Sofware Manual 120713

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ETI Macro Distributed Energy Project

DE Tool User Guide

11 July 2012

Megan Jobson and Gbemi Oluleye (The University of

Manchester)

Paul Woods (AECOM) Chief Technologist

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Tableofcontents

Executive summary ............................................................................................................................. 6

1 Introduction ................................................................................................................................ 7

1.1 Installing the software ........................................................................................................ 9

1.2 Summary ........................................................................................................................... 10

2 Tool Inputs ................................................................................................................................ 11

2.1 Demand profile ...................................................................................................................... 11

2.2 Other user inputs ................................................................................................................... 12

2.3 DE systems ............................................................................................................................. 14

2.4 Performing sensitivity analysis with the tool ......................................................................... 15

2.5 Heat distribution .................................................................................................................... 15

3 Tool Outputs ............................................................................................................................. 17

3.1 Operating schedule of DE solution......................................................................................... 17

3.2 Design economics................................................................................................................... 19

3.3 Carbon dioxide (CO2) emissions ............................................................................................. 19

3.4 Energy Flow and DE Centre Efficiency ................................................................................... 20

3.5 Redundancy Analysis .............................................................................................................. 20

4 Counterfactual Modelling ......................................................................................................... 21

5 How to Use the Tool ................................................................................................................. 24

5.1 Design of new energy centres ................................................................................................ 24

5.2 Operational optimisation of existing energy centre/ tool in simulation mode ..................... 24

5.3 Project options ....................................................................................................................... 25

5.4 Design Options ....................................................................................................................... 25

5.5 Entering User Inputs............................................................................................................... 26

5.6 Design Approach .................................................................................................................... 28

5.7 Model Inputs .......................................................................................................................... 29

5.8 Creating superstructure ......................................................................................................... 30

5.8.1 Creating superstructure for new design ............................................................................. 30

5.8.2 Building model for existing DE solution .............................................................................. 33

5.9 Running the Optimisation ...................................................................................................... 35

5.10 Viewing results ..................................................................................................................... 36

5.11 Error check ........................................................................................................................... 36

5.12 Model Anomalies ................................................................................................................. 37

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5.13 Error messages ..................................................................................................................... 37

6 Conclusions and recommendations .......................................................................................... 38

6.1 Conclusions ............................................................................................................................ 38

6.2 Recommendations ................................................................................................................. 38

References ........................................................................................................................................ 39

Appendices ........................................................................................................................................ 40

Appendix A: Description of worksheets in tool............................................................................ 40

Appendix B: Energy price present value ...................................................................................... 43

Appendix C: Carbon price calculation ........................................................................................... 44

Appendix D: Solar heater model .................................................................................................. 45

Appendix E: Flowchart for selecting number of DE systems ....................................................... 46

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ListofFigures

Figure 1 Model flow chart 8

Figure 2 Cell/worksheet colour codes 9

Figure 3 Format for energy demand 11

Figure 4 Energy demand profiles 12

Figure 5 User input: fuel price 12

Figure 6 User input: electricity tariff and tariff structure 13

Figure 7 User input: grid emission factors 13

Figure 8 User input: Project data 14

Figure 9 Format for DE systems 15

Figure 10 DHN model inputs: pumping energy and heat loss 16

Figure 11 DHN model inputs: cost 16

Figure 12 Operating schedule for design with thermal storage 17

Figure 13 Operating schedule for design without thermal storage 18

Figure 14 Design solution configuration (with thermal storage) 18

Figure 15 Tool output: DE centre economics 19

Figure 16 Tool output: DE centre emissions 19

Figure 17 Tool output: Energy flow and DE centre efficiency 20

Figure 18 Tool output: Redundancy Analysis 20

Figure 19 Counterfactual model input: gas boiler 21

Figure 20 Counterfactual model input: air source heat pumps 22

Figure 21 Counterfactual user inputs 22

Figure 22 Counterfactual model outputs 23

Figure 23 Using the tool: design of a new energy centre 24

Figure 24 Using the tool: simulation mode 25

Figure 25 Using the tool: optimisation options 25

Figure 26 Using the tool: design options 26

Figure 27 Using the tool: site information 26

Figure 28 Using the tool: energy demand data 27

Figure 29 Using the tool: energy profile 27

Figure 30 Using the tool: cost data 28

Figure 31 using the tool: grid emission factor 28

Figure 32 Using the tool: design approach electricity production 29

Figure 33 Using the tool: model inputs (selection of DE systems) 29

Figure 34 Using the tool: number of each type of DE system in the superstructure 30

Figure 35 Creating superstructure: Step 1 30



Figure 38 Creating superstructure: Step 4 (continued) 32


Figure 40 Creating superstructure: Step 5 (continued) 33

Figure 41 Building model for existing design: capital cost sheet 34

Figure 42 Building model for existing design: deleting excess units (Part 1) 34

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Figure 43 Building model for existing design: 'calculations ' sheet 35

Figure 44 Building model for existing design: deleting excess units (Part 2) 35

Figure 45 Running the model 36

Figure 46 Error messages in the WB! Status page 37

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Executive summary

The UK is committed to reduce carbon emissions by up to 30% by 2020 and by up to 80% by 2050

(Climate Change Act, 2008). Distributed Energy (DE) has gained interest over the past few years as a

way to maximise the efficient use of fuels to produce electricity and heat near the end users, and

therefore to reduce carbon emissions.

The ETI Macro DE project aims at evaluating future opportunities for technology development with

respect to Distributed Energy in zones with electricity demand of up to 50 MWe. The purpose of

Work Package 4 (WP4) within the ETI Macro DE project is to develop the methodology for the design

of optimised macro DE solutions or energy centres, and to implement this methodology in a

software tool.

The design tool generates the design for an optimised energy centre and estimates costs for DE

solutions (the energy centre and district heating network, DHN) to meet the heat requirements of

each characteristic zone.

The design methodology within the software tool allows the systematic design of DE solutions which

satisfy aggregated thermal and electrical demands. The design involves selecting which supply units

will comprise the DE solution and specifying the best operating schedule to guarantee minimum

total annualised cost (capital and operating costs). The lack of software packages in the market with

these functionalities made a case for required the development of such a methodology and software

tool.

This report summarises the principles of the design tool and explains how to use the software.

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Chapter1

1 Introduction

The DE tool is a complete modelling software package created in MS Excel for design of new

distributed energy centres and operational optimisation of existing energy centres. Deliverables 4.1

and 4.2 of the ETI Macro DE project provide comprehensive descriptions of the modelling and design

approach, assumptions made, etc.

The software tool was created in MS Excel, as it is a user-friendly and familiar environment.

Calculations required for solving the mixed integer linear optimisation problem (MILP) are carried

out with the Excel add-in Whats Best!. Whats Best! is a compilation of solvers for different

optimisation problems (linear, non-linear, mixed-integer, etc.), which can be used directly within

Excel spreadsheets or called from Visual Basic. Research experience with What's Best! within the

Centre for Process Integration, at the University of Manchester, is that it provides a powerful

approach for solving large mixed-integer linear problems, i.e. linear problems involving many

discrete decision variables. Note that a Whats Best! license is required to run the design tool.

The tool has two modes: design and simulation. In the design mode a DE solution is designed given

the aggregated thermal and electrical demands of a characteristic zone, available DE systems, and

other economic parameters such as electrical tariffs and asset life. The results in this mode will

include the DE solution configuration and its capital cost, the operating schedule for the best

performance, thermal storage requirements, net operating cost of satisfying heat demand, total CO2

emissions, and consumption of fuels of various types.

In simulation mode the user can simulate and optimise the operation of a specified existing DE

solution. In addition, the user could evaluate a DE solution and carry out sensitivity analyses with

respect to fuel type, fuel price and power tariffs. In this mode the DE solution is fixed, and the

operating modes of the DE systems are optimised in order to maximise the performance of the

energy centre in each time band. The results in this mode includes the operating schedule for the

best performance, net operating cost of satisfying heat demand, total CO2 emissions, and

consumption of fuels of various types, if applicable. It is assumed that the investment in the

equipment has already been made in this case.

The software tool also addresses feasibility of a design (i.e. the ability to meet the peak thermal

demand and satisfy average thermal requirements for all time scenarios) as well as optimality, with

respect to a range of performance objectives, subject to relevant constraints, e.g. carbon dioxide

emissions.

The approach selected for design of DE solutions involves many integer variables (related to the

number of DE systems and the number of time bands), as well as continuous variables. There is also

a large number of constraints (e.g. 50% < load < 100%) to take into account. Despite that, key

relationships can be represented using linear functions, which makes the problem relatively easy to

solve using a suitable optimisation algorithm.

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How do I use DE Tool?

Figure 1 provides an overview of the modelling approach applied in the tool.

Figure 1 Model flow chart

Inputs into the tool include aggregated thermal and electrical demand (demand profiles), DE

systems, fuel prices, electricity price, emission factors and DHN parameters. The superstructure

created using the available technologies and the peak thermal demand is reduced to the best

solution by MILP optimisation for minimum cost.

The tool provides information on;

the operating schedule for the design,

economics of the design

carbon dioxide emissions from the centre

energy flows in the energy centre

performance of counterfactuals these are reference technologies, namely stand-alone gas

boilers and air source heat pumps, against which DE is to be compared.

Peak

demand

DE systems

Fuel price

Constraints Minimum part load for DE systems

System heat balance

Energy balance for thermal storage

Create

superstructure

for design

MIL

P o

pti

mis

ati

on

Demand

profiles

Demand represented using 39 time

bands

Other Inputs

Electricity tariff and structure

Grid emission factor

Fuel emission factor

Heat distribution losses

Project life time

Heat

distribution

costs

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Cell colour coding

The user enters data into shaded cells and worksheets. All other cells and worksheets that do not

require input data are protected to prevent the user from accidentally deleting a formula or

reference cell. Appendix A contains description of all worksheets in the tool. The DE tool colour

coding chart for input and output cells is presented in Figure 2.

Input and Output cells/worksheets

Yellow cell User input

Yellow worksheet Model Input

Green worksheet For user input

Red worksheet Tool output

Blue worksheet Locked/protected worksheet

Figure 2 Cell/worksheet colour codes

1.1 Installing the software

To install the tool check that What'sBest! is available and installed and macros are enabled.

The What'sBest! license can be purchased and installed on a desktop PC or a laptop with Microsoft

Windows 7, Vista, or 98, Windows NT 4.0, Windows XP and an already existing Microsoft

Excel version 2002 or higher version 2007 with about 40 MB of free disk space.

It can be enabled by checking the What'sBest! add-in using the Tools/Add-Ins or Excel Options dialog

box. If What'sBest! does not appear in the current list of add-ins, the Browse option can be used to

locate it. The add-in file WBA.XLA, or WBA.XLAM, is typically found in the Library subdirectory or the

WB subdirectory on the C: drive. The What'sBest! functions are only available when the What'sBest!

add-in is active within Excel.

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To enable macros, follow the steps below:

1. Start the Excel application.

2. Choose the Microsoft Office Button.

3. Choose Excel Options.

4. In the categories pane, choose Trust center.

5. Click on the Trust centre settings box.

6. Select the Enable all macros tab in the ribbon check box

7. Choose the OK button to close the Options dialog box.

1.2 Summary

This manual provides guidance on using the ETI Macro Distributed Energy design tool developed at

the University of Manchester. This guide describes the main inputs and outputs of the tool, explains

the modelling of counterfactuals, and presents step-by-step instructions on using the tool.

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Chapter2

2 Tool Inputs

Tool inputs are divided into two; user inputs (Sections 2.1 and 2.2) and model inputs (Section 2.3).

Performing sensitivities on tool inputs is described in Section 2.4.

2.1 Demand profile

Aggregated yearly thermal and electrical demand are represented using 39 time bands consisting of

7 time bands on a weekday, 6 time bands on a weekend day and 3 seasons in a year (Winter,

Summer and Transition). Data for each time band include the average thermal and electrical

demand, the duration of the time band and the number of days per year to which the time band

applies. The definition of the time bands can be adjusted by the user; however, the maximum

number of time bands is 39. The format for entering the thermal demand is shown in Figure 3. Note

that the electrical demand can be entered in a similar format.

Figure 3 Format for energy demand

The user needs to provide information about the peak and baseload energy demand for the three

seasons as the peak thermal demand is used to determine the capacity/number of units in the

superstructure (Deliverable 4.1). The annual demand profile can be generated by clicking Calculate

on the Energy demand data page of the tool. An example is shown in Figure 4.

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Figure 4 Energy demand profiles

2.2 Other user inputs

Other inputs include fuel prices (Figure 6), average electricity price (Figure 7), the grid emission

factors (Figure 8), and information on the project such as the energy centre life time and discount

rate (Figure 9). The energy prices in Figure 6 and 7 represent the present value for energy prices

(with carbon price added) for a 2010 baseline calculated from energy price projection for the project

lifetime, as shown in Appendix B. The carbon price represents a penalty for CO2 emissions added to

the fuel price to encourage design of CO2 reducing DE schemes; Appendix C contains information on

how carbon price can be calculated.

Figure 5 User input: fuel price

Contained within the tool are nine fuels, as shown in Figure 6. The user enters the fuel price1 in

p/kWh and the tool converts the price to standardised units. The values shown in Figure 6 represent

the present value for energy price (Appendix B).

1the basis for fuel price is Gross Calorific Value (GCV), also known as Higher Heating Value (HHV)

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Figure 6 User input: electricity tariff and tariff structure

The electricity market structure can be flat or variable. If the structure is flat, a single electricity price

is required for all the time bands; otherwise, either a dual tariff is required reflecting peak and off-

peak electricity price or multiple tariffs may be defined according to the time band. The user is

expected to specify the market structure and electricity price.

Figure 7 User input: grid emission factors

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The grid emission factor2 for both export and import of electricity, as shown in Figure 8, is required

by the DE tool. The user can use different emission factors in each time band. The grid emission

factors entered should represent the period of interest to the user and be averaged over this period.

For example if the average CO2 emissions over a 25 year period are required, then the inputs should

be an average of the projections over 25 years.

Figure 8 User input: Project data

Information on the project economics, namely project life and discount rate, is required to annualise

costs, as shown in Figure 9. The tool calculates and applies the annualisation factor, based on these

inputs. It is important that these same values are used in the processing of fuel costs used as inputs.

2.3 DE systems

The tool currently has 17 technologies of various capacities, as shown in Table 1.

Table 1 DE systems available in tool

Technology Available sizes (thermal capacity, MWhth)

1 Gas engine 0.47 1.62 2.29 4.42 5.24 6.95 7.00

2 Gas turbine 8.38 15.23 18.39 22.78

3 Gas boiler 0.25 1.40 3.50 7.00 10.00 20.00

4 Diesel engine 0.52 1.39 5.15

5 Biodiesel engine 0.52 1.39 5.15

6 Landfill gas engine 0.47 1.39 2.74

7 Fuel cell (natural gas) 0.19 0.50 0.90 1.80

8 Solar heater 0.1 2.10 6.00 10.50

9 Heat pump (waste heat) 3.17 4.00 4.15 4.75 37.05

10 Large scale combined cycle gas turbine

(LS-CCGT)

38.53 54.55

11 Dual fuel engine 2.20 3.31 6.88

12 Energy from Waste (EFW): incineration 12.00 39.00

13 EFW anaerobic digestion (AD) 0.27 1.40 4.06

14 Biomass combined heat & power (CHP) 6.36 58.35 87.58

15 Biomass gasification 11.69 20.42 49.73

16 Biomass boiler 0.84 1.00 3.00

17 Ground source heat pump 2.00

Each technology (apart from solar heaters) is entered in the format shown in Figure 5. (The format

for entering solar heaters is in Appendix D.)

2 the present value for the grid emission factor can be estimated by taking an average over the project life.

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Figure 9 Format for DE systems

The user may not need to change the inputs for these DE systems. If new technologies are to be

included, these can be added to the library by replacing an existing unit while maintaining the

format.

2.4 Performing sensitivity analysis with the tool

All tool inputs (both user and model) can be changed; however their formats need to be maintained.

Changing inputs that affect the superstructure (Figure 1) require the superstructure to be re-created.

How to create the superstructure is described in Section 5.8.

2.5 Heat distribution

Heat produced by the energy centre is distributed to end users via the District Heating Network

(DHN); this system of transmission and distribution pipes with heat exchangers and pumps is used to

transfer the heat from the energy centre (where it is produced) to the end users. The model for the

DHN cost was developed within the ETI Macro DE project. Its detailed description is in the D.H.N.

Design and Algorithm Verification document prepared by Mooney Kelly NIRAS (MKN). The DHN cost

is not an integral part of the optimisation; however, the cost of distributing heat, distribution losses

and pumping energy required by the network is accounted for in the tool. In order to estimate the

heat loss and pumping energy, the user needs to input the heat loss and the pumping energy as a

percentage of the annual thermal demand, as shown in Figure 10.

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Figure 10 DHN model inputs: pumping energy and heat loss

The calculated network cost (using the algorithm developed by MKN) should also be included as an

input to the DE tool. Figure 11 presents an example

Figure 11 DHN model inputs: cost

The annualised cost of the network is added to the total annualised costs for the energy centre to

give the total annualised cost of the DE solution. Dividing the total annualised cost of the DE solution

by the thermal demand gives the cost of heat delivered to end users in /kWh.

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Chapter3

3 Tool Outputs

The methodology for the design of distributed energy centres is described in Deliverable 4.1

(Deliverable 4.1, February 2011), where optimisation is used to capture trade-offs in the design. In

summary, the design is subject to optimisation, given an objective function and a set of constraints

(e.g. to ensure the system attains energy balance, as explained in Deliverable 4.1). A globally optimal

solution is obtained, providing a design and operating schedule.

Tool outputs refer to the design, the operating schedule, design economics, carbon dioxide

emissions, energy flows, global energy efficiency and results of redundancy calculations at the global

optimum.

3.1 Operating schedule of DE solution

The operating schedule, as shown in Figure 12, shows which technologies would be operated and

their output in each time band.

Figure 12 Operating schedule for design with thermal storage

For the particular design shown in Figure 12, where the thermal demand is satisfied and all

electricity generated is sold to the grid, the DE solution consists of gas boilers, gas engines, dual fuel

engines (using natural gas and diesel as fuels) and EFW Anaerobic Digestion. In some time bands, the

heat generated does not satisfy the thermal demand; instead, heat is provided by the thermal

storage unit. Conversely, in some time bands, surplus heat is produced, to provide stored heat.

Figure 13 shows a design where thermal storage has been disallowed. In this case the thermal

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demand (represented by red lines and X markers) is met in every time band as none of the heat

produced is diverted to storage.

Figure 13 Operating schedule for design without thermal storage

The selected DE solution is reported by the tool on the Results page. Figure 14 shows an example

of an optimised DE solution.

Figure 14 Design solution configuration (with thermal storage)

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3.2 Design economics

The economic analysis of the energy centre includes the total annualised capital cost, total operating

cost (sum of fuel and maintenance cost), revenue from electricity sold to the grid and cost of

importing electricity. The cost of heat delivered to users by the energy centre is an output of the

tool. All tool outputs are shown on the Results sheet of the tool, as shown in Figure 15.The cost of

heat delivered is the minimum price at which heat can be sold for the energy centre to break even.

Figure 15 Tool output: DE centre economics

The capital cost includes cost for replacement of DE systems during the project life. Other

assumptions related to the energy centre economics are described in Deliverables 4.1 and 4.2.

3.3 Carbon dioxide (CO2) emissions

The DE centre CO2 emissions can be categorised into;

emissions from fuel burnt to satisfy the energy demand (fuel CO2 emission)

emissions corresponding to imported electricity from the grid (CO2 emission debit)

avoided emissions corresponding to electricity sold to the grid (CO2 emission credit).

The sum of the fuel CO2 emissions and emission debits less emission credits is defined as the global

CO2 emissions. All four emission types are reported by the tool, as shown in Figure 16. The global

CO2 emissions per unit of heat delivered is also an output of the tool.

Figure 16 Tool output: DE centre emissions

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3.4 Energy Flow and DE Centre Efficiency

In the DE tool, heat and electricity produced, as well as fuel consumed by the energy centre, is

calculated for the optimum design, as shown in Figure 17. From the energy flows, the DE centre

overall energy efficiency (defined as the ratio of total useful energy to the fuel consumed) is

calculated.

Figure 17 Tool output: Energy flow and DE centre efficiency

3.5 Redundancy Analysis

To ascertain the ability of technologies in the DE solution configuration to meet the peak demand

when CHP units are unavailable, a redundancy analysis is carried out on the energy centre design.

The installed heat capacity of boilers and other technologies selected is compared to the peak

thermal demand, as shown in Figure 18. Both the energy flows from the centre and redundancy

calculations can be used to assess the contribution to energy security of the energy centre.

Figure 18 Tool output: Redundancy Analysis

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Chapter4

4 Counterfactual Modelling

In order to assess the potential contribution of macro-scale DE to Great Britain (GB), it is necessary

to compare the performance of DE solutions to other non-DE approaches for delivering heat in GB.

The business as usual approach is to provide heat using stand-alone boilers to meet residential

and commercial heating demands. In the future, it is also expected that individual air source heat

pumps may become an attractive low-carbon technology option which could replace conventional

boilers. These alternatives, against which DE is to be compared, are referred to as counterfactuals.

Counterfactual technologies refer to baseline heat supply systems. The DE tool contains models for

two systems:

Natural gas boilers, as are currently predominantly used in the UK to satisfy domestic and

commercial heat demand

Air source heat pumps, which may offer a low carbon alternative to boilers in the future.

The DE tool includes models for gas boilers and air source heat pumps, for 2010, 2020 and 2030, as

shown in Figures 19 and 20.

Figure 19 Counterfactual model input: gas boiler

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Figure 20 Counterfactual model input: air source heat pumps

The user inputs needed to estimate cost and emissions of the counterfactuals are shown in Figure

21. Costs and emissions associated with the counterfactuals are calculated on the Counterfactuals

page of the DE tool; Figure 22 provides an example.

Figure 21 Counterfactual user inputs

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Figure 22 Counterfactual model outputs

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Chapter5

5 How to Use the Tool

5.1 Design of new energy centres

To design a new energy centre, the user should specify the project objective and provide site

information on the Start page of the tool shown in Figure 23.

Figure 23 Using the tool: design of a new energy centre

Once the problem objective is selected, appropriate settings are automatically selected. The user

should then specify the optimisation objective, which will be discussed further in Section 5.3.

5.2 Operational optimisation of existing energy centre/ tool in simulation mode

If the user needs to optimise an existing energy centre, this option should be selected on the Start

page of the tool, as shown in Figure 24. In this case the DE tool optimises the operating schedule of

the centre. Then the user needs to specify the optimisation objective (see Section 5.3).

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Figure 24 Using the tool: simulation mode

5.3 Project options

Once the user has specified how the tool is to be used (i.e. design mode or simulation mode), the

optimisation objective needs to be selected. Three objectives are defined, as shown in Figure 25:

Minimum cost: Global optimum is reached at minimum total annualised cost

Minimum cost with constraint on carbon emissions: user constrains the CO2 emissions to a

maximum of some percentage of the emissions of a counterfactual gas boiler. Then the

optimiser satisfies this constraint at minimum cost.

Minimum cost with constraint on capital investment: the user specifies the maximum capital

investment for the design that minimises the total annualised cost.

Figure 25 Using the tool: optimisation options

5.4 Design Options

The user can decide to allow thermal storage and/or heat dumping in the design. Allowing thermal

storage in the design allows CHP units to continue running when electricity prices favour production

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of electricity and thermal demand is low. The excess heat produced is stored until needed (within a

24 hour day). Assumptions related to the thermal storage model are presented in Deliverable 4.1.

Heat in excess of demand may be produced if the heat dumping option is selected. The cost of

dumping heat, e.g. to a cooling tower, is not taken into account. Grid emission factor inputs are used

to determine credits for CO2 emissions associated with electricity generated (claiming rate) while

heat is rejected (i.e. dumped without being used to satisfy heat demand) see Figure 26.

Figure 26 shows how these two options are represented in the tool:

Figure 26 Using the tool: design options

5.5 Entering User Inputs

User inputs refer to inputs required for a basic run of the tool in either design mode (for new energy

centre design) or simulation mode (for an existing energy centre). User inputs need to be entered in

the correct format. All user input cells are marked yellow; these include:

On the Start page, site information, referring to data about the site, as shown in Figure 27.

Figure 27 Using the tool: site information

Energy demand data (including annual energy demand, peak energy demand and demand in

time bands for both electricity and heat). The annual energy demand for both electricity and

heat need to be entered in the Start page of the tool. The heat and electricity demand in each

time band are entered in the Energy Demand Data page of the tool. The same format as

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shown in Figure 28 is used for both thermal and electrical demand. The energy profile for a year

is generated by the tool by clicking calculate buttons for both thermal and electrical demand,

as shown in Figure 29.

Figure 28 Using the tool: energy demand data

Figure 29 Using the tool: energy profile

Cost data: information on cost of fuels and electricity tariff/tariff structure need to be specified

on the Economic Data page of the tool, as shown in Figure 30.

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Figure 30 Using the tool: cost data

Emissions data: information on the grid emission factor should be provided on the Economic

Data page of the tool, as shown in Figure 31.

Figure 31 using the tool: grid emission factor

5.6 Design Approach

The user needs to choose how electrical demand will be handled in the design of the energy centre.

Three options are provided:

All electricity produced can be sold to the grid (in this case, power requirements for DHN

pumping are imported from the grid),

Aim to satisfy the electricity demand of the zone (electricity produced satisfies electrical demand

of the zone),

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Allow electricity sales and purchase (where the electricity generated is more than the demand,

electricity is sold to the grid; where there is a deficit in electricity production, electricity is

bought from the grid).

The user needs to specify the approach to be applied in the design by ticking the option on the

Start page, as shown in Figure 32.

Figure 32 Using the tool: design approach electricity production

5.7 Model Inputs

Model inputs include the DE systems to be considered during design and the maximum number of

each type of unit that can be installed.

The inputs of models of existing technologies in the tool (worksheets marked yellow) need not

be changed by the user. If the user intends to perform some sensitivity studies, e.g. on fuel

prices, or if the user wishes to include new technologies, existing values can be replaced by the

user. The format shown in Figure 5 should not be changed. The user can select which

technologies to include in the design from the DE systems page by checking or unchecking the

appropriate boxes, as shown in Figure 33.

Figure 33 Using the tool: model inputs (selection of DE systems)

Inputs related to the number of units of a particular technology in the superstructure: the user

can select the number of units of a particular technology to be included (in the superstructure).

The default is determined by dividing the peak thermal demand by the highest rated capacity of

each technology this information can be found on the Energy systems page of the tool, as

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shown in Figure 34. The user may change this number before building the model (explained in

Section 5.8).

Figure 34 Using the tool: number of each type of DE system in the superstructure

5.8 Creating superstructure

Creating the superstructure essentially creates the overall model that is to be optimised. While

building the superstructure the user is advised to close all other Excel workbooks.

5.8.1 Creating superstructure for new design

If the project objective is design a DE centre the steps below are necessary to create the

superstructure to be optimised and this should be done after completing Sections 5.1, 5.3, 5.5 and

5.7 (which deals with selecting technologies to be included in the superstructure).

Steps to creating superstructure for new design

The steps necessary to build a suitable superstructure:

1. On the Start page, the user should Save and proceed to input data, as shown in Figure 35.

Figure 35 Creating superstructure: Step 1

2. On the Energy Demand Data page, having entered required user inputs, the user should click

on Save and proceed, as shown in Figure 36. A message box pops up showing the peak thermal

demand.

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3. On the Economic Data having entered relevant inputs in yellow cells and the electricity market

structure, the user should Save and Proceed, as shown in Figure 37. A message box would pop

up showing the maximum power production. Note that the choice of market structure is

important as the electricity price has a strong influence on the design.

4. Some messages pop up, as shown in Figures 37 to 39. The first message confirms the maximum

power production. The second message box notes that models should be updated whenever

fuel prices change. The third message box directs the user to the DE systems page.


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Figure 38 Creating superstructure: Step 4 (continued)

5. On the DE systems page, as shown in Figure 39, the user may add technologies to the

superstructure or remove them from the design. This step allows the appropriate settings to be

saved.


6. To create models, the user should click the command button beneath the DE system of interest.

Technologies can be excluded from the design, by deselecting the model and clicking the

command button beneath the DE system of interest. Once satisfied with the technologies added

to the superstructure, the user should click on Save and proceed to create the superstructure.

Note that creating the superstructure could take some time, even hours, depending on the

maximum number of units for each technology, an example of which is shown in Figure 40. The

number of units can be adjusted by the user from the default settings. If any changes are made

to the technology models or inputs such as fuel prices, then the superstructure will need to be

re-created.

33

Figure 40 Creating superstructure: Step 5 (continued)

After completing step 5, click save and proceed on Figure 39. The user is directed to the start page

where Sections 5.4 (selecting design option) and Section 5.6 (selecting design approach) can now be

completed before running the optimisation (Section 5.9 below).

5.8.2 Building model for existing DE solution

This is applicable if the tool is in simulation mode where the project objective is Optimise an existing

DE centre. The steps below should be followed to build the existing model that is to be optimised. In

this case, only the operating cost is optimised as the DE solution is fixed.

Steps to model existing DE solution

1. On the Start page, the user should Save and proceed to input data, as shown in Figure 35

above.

2. On the Energy Demand Data page, having entered required user inputs, the user should click

on Save and proceed, as shown in Figure 36. A message box pops up showing the peak thermal

demand.

3. On the Economic Data having entered relevant inputs in yellow cells and the electricity market

structure, the user should Save and Proceed, as shown in Figure 37 above. A message box

would pop up showing the maximum power production. Note that the choice of market

structure is important as the electricity price has a strong influence on the design.

4. Some messages pop up, as shown in Figures 37 to 39 above. The first message confirms the

maximum power production. The second message box notes that models should be updated

whenever fuel prices change. The third message box directs the user to the DE systems page.

5. On the DE systems page, as shown in Figure 39 above, click on Delete models to save

appropriate settings this is required especially if the tool was previously used to design new

energy centres.

6. In this step, technologies in the energy centre should be specified by ticking relevant boxes. If

technologies in the centre are not in the library of DE systems (Table 1) the user can substitute

the systems in the library, while adhering to the format shown in Figure 5. New CHP units should

34

replace existing CHP units while new heat only units should replace existing heat only units for

consistency in calculations.

7. For handling the number of units in the design refer to the flowchart in Appendix E.

Figure 41 Building model for existing design: capital cost sheet

Figure 42 Building model for existing design: deleting excess units (Part 1)

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Figure 43 Building model for existing design: 'calculations ' sheet

Figure 44 Building model for existing design: deleting excess units (Part 2)

Having followed the flowchart in Appendix E, the user is directed to the Start page, where Sections

5.4 (selecting design option) and Section 5.6 (selecting design approach) can now be completed

before running the optimisation (see Section 5.9).

5.9 Running the Optimisation

After completing the steps outlined above for creating superstructure for new design (Section 5.8.1)

or modelling an existing DE solution (Section 5.8.2) and assuming all model inputs are correct, the

user is ready to run the optimisation by clicking Run on the Start page. The optimisation usually

takes around 5 minutes; it may take more or less time.

Calculations

36

Figure 45 Running the model

On clicking Run, message boxes ask the user to confirm optimisation settings and that the

optimisation is ready to run. The user can view the progress of the optimisation on the pop-up

window as shown in Figure 42. The optimisation can be interrupted if it has been running for some

time and the user observes that the objective is not changing.

Figure 46 Running the model: Optimisation progress

5.10 Viewing results

The optimisation stops once the global optimum has been reached (as shown in Figure 43) or if the

optimisation is interrupted by the user. On clicking OK, the user is directed to the Results page.

The design, its operating schedule, project economics, carbon dioxide emissions associated with the

design, energy flows in the centre and results of redundancy calculations for the energy centre can

be viewed.

Figure 47 Viewing results: Global optimum

5.11 Error check

The DE tool performs an error check on the energy demand, as shown in Figure 44, to ensure

demand in time bands (entered in MW) add up to the annual thermal demand of the zone (in GWh).

The check could be beneficial when the user decides to change the time band structure.

Figure 48 Error check: energy demand aggregation

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5.12 Model Anomalies

While the model is reasonably robust, there are several issues the user should be aware of when

reviewing the results of the optimisation. These are reported below and on the WB! Status page.

A feasible design may not be obtained. An infeasible design may arise if the optimisation is too

highly constrained. For example, the number of units in the superstructure may have been

specified in such a way that the capacities of the units cannot satisfy the thermal demand. If

design feedback is Infeasible design, the user should check the number of units allowed for

each technology to ensure there is sufficient thermal capacity to satisfy the thermal demand.

Input errors will naturally give rise to output errors. A significant potential source of error is that

when fuel prices are changed, the DE systems associated with these fuels need to be re-

modelled (re-included in the superstructure) before the optimisation is re-run.

The optimisation may not converge for some time (e.g. hours) there may be not change in the

objective. In this case, the user can interrupt the optimisation and proceed to view results.

5.13 Error messages

The optimisation may stop abruptly without user interruption. This suggests a bug in the software; it

is recommended that the user closes other excel files, checks all inputs, re-creates the

superstructure for the heat units and runs the optimisation again. Error messages and warnings can

be viewed on the WB! Status page in the tool, as shown in Figure 45.

Figure 46 Error messages in the WB! Status page

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Chapter6

6 Conclusions and recommendations

6.1 Conclusions

This DE design tool was developed at the Centre for Process Integration, at the University of

Manchester in line with the requirements of the ETI Macro DE project. The DE tool has been used in

diverse ways within the project, including for design of new energy centres and simulation and

optimisation of an operational plant. The tool was applied extensively to explore the concepts of

using time bands to represent variable demand, to design DE centres for characteristic zones

identified during the project, to evaluate the impact of DE in future scenarios, and to assess DE

technology developments. The tool has thus been used extensively, and has had its robustness and

user interface enhanced during this process. Nevertheless, it has been developed primarily as a

research tool, rather than as commercial software. As pre-prototype software, it is expected that

users will have a good understanding of distributed energy and of aspects of the modelling.

The software manual summarises the features of the tool and describes how the tool can be used

for both design of new distributed energy centres and operational optimisation of existing energy

centres. Steps required for entering inputs, running the model and checking results are outlined.

Error messages associated both with the model (model anomalies) and with the tool are described.

6.2 Recommendations

Future recommendations with regards tool improvements are categorised below;

User interface: It is recommended that the user interface be developed further to provide a

smoother process for setting up and running design cases.

Automated data entry: If the tool is to be used for multiple designs, designing an interface to

automatically enter input data would be useful.

Automated output: A design interface to automatically record tool output would be valuable if

many designs are to be developed.

Heat distribution network: Currently the heat distribution network cost is an input; heat losses

and pumping costs are estimated. The design and optimisation of the heat network is not part of

the DE solution optimisation. It is recommended that the heat network design and DE centre

design are considered simultaneously.

Heat storage: Currently, the energy balance must be balanced in each 24-hour period.

Therefore, any heat stored must be used within that period. Extending the model to consider

longer periods (e.g. 48 hours, to accommodate weekends, or much longer periods, to consider

larger scale heat storage) would extend the scope of the tool considerably.

Multi-objective optimisation: The tool optimises by minimising the total annualised cost, taking

into account constraints related to carbon emissions. If a multi-objective optimisation approach

were developed, the flexibility and applicability of the tool could be greatly enhanced.

39

References

Deliverable 4.1 Macro DE Project: Description of design methodology and tool effectiveness,

February 2011

Deliverable 4.2 Macro DE Project: Application of Energy Centre Design Tool to Characteristic Zones,

March 2012

Macro DE Project Technology Library (WP 3.2), June 2011

Mooney Kelly NIRAS. (2012, March). D.H.N. Design and Algorithm Verification Report Rev. 3 for the

Macro DE project.

UK Governments Interdepartmental Analysts Group (IAG) guidance, 2011. Valuation of Energy Use

and Greenhouse Gas Emissions for Appraisal and Evaluation. DECC and HM Treasury

40

Appendices

Appendix A: Description of worksheets in tool

Sheet Name Description Comment

Start Sheet contains general information

about the design

Yellow cells for user input

Energy demand data Demand input for both electricity

and heat is entered on this sheet and

profile can be generated by clicking

Calculate.


Economic data Sheet contains information on

project data, fuel prices and grid

emission factor


DE systems Sheet contains:

All technologies in the tool

Default values for number of units

of each technology in the superset


(default already set)

Counterfactuals Contains models of reference

technologies. i.e. gas boilers and air

source heat pumps


Results Contains tool outputs such as cost,

carbon emissions, etc.

Scroll down page to view

all results

Operating costs For model calculations Minimum user

intervention

Capital costs For model calculations Minimum user intervention

Gas engines Contains model input for gas engines Model input can be adjusted but format may

not be changed

Calculations gas engines Model calculations for gas engines Minimum user

intervention

Gas turbines Contains model input for gas

turbines

Model input can be

adjusted but format may

not be changed

Calculations gas turbines Model calculations for gas turbines Minimum user

intervention

Boilers Contains model input for gas boilers Model input can be


not be changed

Calculations boilers Model calculations for gas boilers Minimum user

intervention

Engines ULSD (diesel engines) Contains model input for ultralow

sulphur diesel (ULSD) engines

Model input can be


not be changed

Calculations engines ULSD Model calculations for ULSD engines Minimum user

intervention

Fuel cells Contains model input for fuel cells Model input can be


not be changed

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Calculations fuel cells Model calculations for fuel cells Minimum user

intervention

Engines B100 (biodiesel)

Contains model input for B100

engines

Model input can be


not be changed

Calculations B100 engines Model calculations for B100 engines Minimum user

intervention

Engines LEG (landfill gas) Contains model input for LEG

engines

Model input can be


not be changed

Calculations LEG engines Model calculations for LEG engines Minimum user

intervention

Solar heaters Contains model input for solar

heaters

Model input can be


not be changed

Calculations solar heaters Model calculations for solar heaters Minimum user intervention

Heat pumps Contains model input for heat

pumps

Model input can be


not be changed

Calculations heat pumps Model calculations for heat pumps Minimum user

intervention

GSHP Contains model input for gas source

heat pump (GSHP)

Model input can be


not be changed

Calculations GSHP Model calculations for gas source

heat pump (GSHP)

Minimum user

intervention

Dual fuel engines Contains model input for dual fuel

(gas/diesel) engines

Model input can be


not be changed

Calculations Dual fuel engines

Model calculations for dual fuel

engines

Minimum user

intervention

LS-CCGT Contains model input for large scale

combined cycle gas turbines (LS-

CCGT)

Model input can be


not be changed

Calculations LS-CCGT Model calculations for large scale

combined cycle gas turbines (LS-

CCGT)

Minimum user

intervention

EFW Incineration Contains model input for energy

from waste (EFW) by incineration

Model input can be


not be changed

Calculations EFW incineration Model calculations for energy from waste (EFW) by incineration

Minimum user

intervention

EFW-AD Contains model input for EFW anaerobic digestion (AD)

Model input can be


not be changed

Calculations EFW-AD Model calculations for EFW

anaerobic digestion (AD)

Minimum user

intervention

Biomass CHP Contains model input for biomass

CHP

Model input can be


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not be changed

Calculations biomass CHP Model calculations for biomass CHP Minimum user

intervention

Biomass gasifier

Contains model input for biomass

gasifier

Model input can be


not be changed

Calculations biomass gasifier Model calculations for biomass

gasification

Minimum user

intervention

Biomass boilers Contains model input for biomass

boilers

Model input can be


not be changed

Calculations biomass boilers Model calculations for biomass

boilers

Minimum user

intervention

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Appendix B: Energy price present value

User input for electricity and fuel price are discounted (over the project life) and annualised (using

the annualisation coefficient) to give the equivalent present value for the base year.

A step by step guide is presented below:

1. Information on energy price projection on an annual basis for the project lifetime is required (UK

Governments Interdepartmental Analysts Group (IAG) guidance, 2011).

2. Using equation B.1, calculate the discount factor for every year from the start year of the project

to the project lifetime:

= () (B.1)

where DR is the discount rate and n is the year

3. For each year under consideration discount the energy price using the discount factors

calculated in Step 2, as shown in equation (B.2):

=(! ) () (B.2)

4. Calculate the annualisation coefficient by summing the discount factors for every year for the

project lifetime as shown below;

#$

= ()&'()*+,*,-./ (B.3)

5. Calculate the present value for the energy price using equation (B.4); this gives the price of

energy used in the tool. (Note that the carbon price can be added to this value.)

! 0$ = ( )123456789:579;5&

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Appendix C: Carbon price calculation

The carbon price can be included in the energy price present value as a ways of indirectly driving CO2

reducing distributed schemes.

Equations for estimating the carbon price for fuel(s) and electricity are presented below.

1. Carbon price for fuel estimation;

#0> ? '@ABC =? 0$D#E$F ,/*JKL5 C M 0$$F,@N/@AB O 0.1 (C.1)

0$D#E$F ,/*JKL5 =

(D#E$F ) S$F

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Appendix D: Solar heater model

Figure D.1 Solar heaters: Representation in tool

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Appendix E: Flowchart for selecting number of DE systems

Start

Enter number of units on DE

systems sheet (Figure 40)

Is number of

units the

same for all

capacities of a

technology?

Yes No Enter maximum number of units on DE systems sheet

(Figure 40)

Proceed to Capital cost

sheet (Figure 41)

Delete rows of excess units

created as shown in Figure

42 for a typical gas engine

(note the row numbers)

Proceed to Calculations

sheet, as

shown in Figure 43

Delete entire rows using the

same row number as in

capital cost sheet (Figure 44)

Proceed to DE systems

sheet

Click command button beneath

technology of interest on DE

systems sheet (Figure 39)

On DE systems sheet

click Save and proceed

(Figure 39)

End

Click command button

beneath technology of

interest on DE systems

sheet (Figure 39)

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