Building Value for Landfill

8/3/2019 Building Value for Landfill

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Landfll Design and Management

Building Value or the Landfll Gas StreamDyfed Evans, Dr. Robert Gregory and Simon Copping

With much o the Worlds Waste manage-

ment strategy still ocused on landflls, the recovery

o landfll gas or use as an energy source has become

a signifcant business, where either renewable energy

or greenhouse gas drivers exist. Accordingly, it seems

likely that landfll gas capture considerations will

become more dominant in design o landflls.

In the UK, the landfll gas business is predominantly

owned and operated as an enterprise separate rom thewaste disposal and landfll management operation.

This means that many o the lessons learned in the UK

or integrating waste management and landfll gas

operations concurrently have application elsewhere in

the world. Some o these lessons have come through

work undertaken to analyze recoverable landfll gas

energy potential, or purposes o setting a fnancial

value on that potential.

Gas Capture FactorsThe amount o landfll gasprimarily a mixture o

the greenhouse gases methane and carbon dioxide

that can be expected to be captured rom a landfll

depends on several actors, including:

How effectively the landll is sealed against

leakage o landfll gas through the base, sides or top

o the waste mass.

How quickly the landll has been lled. Over

time, the methane-generating capacity o waste

declines, and so, i the cell is flled slowly, its methane

potential may have mostly dissipated by the time the

gas collection system is installed.

In existing landlls that are being retrotted for

gas capture, the age o the landfll and the type o

waste are major determining actors in the amount o

gas that can be captured.

Iil, b lbl li ill i ii lfll

. LandILLs thatare aLready desIgnedand operated wIthLandILL gas captureIn mInd wILL have anadvantage In thIs newarea o competItIon.

22 WasteAdvantage Magazine April 2011

General view o gas engines.Images courtesy o Golder

Associates.

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Depth of the waste. Methane can be more easily captured if the waste

mass is deeper, wet but not waterlogged, and with a smaller surace area,

compared to a wider, shallower waste mass that is poorly drained.One of the biggest factors in methane capture has to do with the nature of

the waste stream itsel. Construction waste tends to produce little methane

compared with much o the municipal or commercial waste stream.

Faster AttenuationAs waste management practices shit more towards diversion o organics

into separate treatment streams, there is a reduction in the methane

producing capability o the remaining stream. As a result, the revenue

producing capacity o landflls is becoming attenuated. This means thatinstead o being described by gas generation curves with exponential post

closure tails showing revenue possibilities two or three decades into the

uture, the declining portion o the curve may be steeper, illustrating aster

attenuation.

Hot SpotsOne of the considerations to be made in valuing landll gas streams is the

potential cost of not managing landll gas production adequately, seen as

increased potential or osite gas migration, odor and, in extreme cases, the

potential for re. Deep-seated hot spots, sometimes referred to as landll

fres, can develop due to particular types o waste or by the ingress o air

into the waste mass leading to heating and smoldering o the waste mass

in situ. Once established, these hot spots become difcult to extinguish.

B V lf g s

General view o a gas fare.


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Collecting and Managing the GasAnother actor to consider is the cost o collecting and managing the gas.

Collection can be done through a sacrifcial-pipe system, in which horizontal

perorated pipe is laid at various levels throughout the landfll as it is flled,

connected to a collection network. A more robust system, installed ater a waste

cell has been flled, comprises o a network o vertical pipes installed throughthe landfll in an optimal pattern to collect the landfll gas. The ideal system

uses both concepts.

All o these fnancial considerations are largely dependent on the incentives

available to help them along. Fnancial credits or generating energy rom

renewable sources, such as the UKs Renewables Obligation, and other

programs such as the Clean Development Mechanism, permit options that may

not at present be fnancially viable in certain jurisdictions such as much o the

U.S., where there are currently ewer signifcant fnancial supports available.

The Valuation ProcessWhere the fscal and regulatory environment makes landfll gas to energy

practical, the valuation process contains three steps:

1. The valuation o the resourcedetermining the volume o the landfll,

the nature o the waste in it including how much organic waste there is,

whether the landfll is capped or i rainall is able to percolate through it,

moisture content and other actors, which determine the landfll gas potential.

In addition, the records o the landfll operator are examined to see what waste

has been deposited, and in which parts o the landfll. From this, a prediction

can be made or the amount o gas available or power generation.2. Examine any gas collection inrastructure on site, together with the

technology used to convert the gas to energyrom gas feld collection

efciency to the electrical efciency o the plant, other loss actors, the level o

maintenance, and any investment required to bring the operation to a suitable

level o eectiveness.

General view o gas collection inrastructure.


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3. Determine the operations level of environmental compliance, as well as

fnd out i any capital investment needs to be made to maintain compliance.

Financial advisors are then able to use this inormation to set a monetary

value on the business, using numbers that are based on the best availablescience.

In landfll design and management, many o the parameters are already set

the nature o the waste, the size and shape o the landfll, and other actors. This

means that many aspects of the landll are pre-determined. However, there

are still many actors that can be decided by the operator, and many o these

decisions can make it easier or more difcult to collect the methane produced

by the landfll.

Increasingly, given concerns about energy shortages and global climate

changeincluding the need to reduce methane, a powerul greenhouse gas

will drive considerations more towards landfll gas capture. Landflls that are

already designed and operated with landfll gas capture in mind will have an

advantage in this new area o competition. | WADyfed Evans is a Principal o the Leeds, UK ofce o Golder Associates. He has

18 years o experience as a consultant, working on land impact and due diligence

projects. He has managed such projects across a number o industrial sectors including

waste management, oil and gas, chemical, electronics, manuacturing, specialty

chemicals, paper-pulp, mining, electronics and automotive industries. He has also

undertaken the design o numerous characterization and remediation projects or the

redevelopment o contaminated and industrial sites. He can be reached at +44 1937837 800 or via e-mail [email protected].

Dr. Robert Gregory is a Principal in the companys Nottingham, UK ofce. He

has an international reputation within the industry and his career has included more

than 23 years o landfll site auditing, permitting, landfll gas resource assessment and

environmental compliance. For the regulator, he has delivered applied research in support oevidence-based regulatory guidance, drating o regulatory guidance documents, training

on waste management and landfll gas modeling, including producing the GasSim

landfll gas model. In 2006 he served as Review Editor o the Waste Management

Chapter o the Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment

Report into Climate Change. This report was instrumental in the IPCC being jointly

awarded (with Al Gore) the Nobel Peace Prize 2007. He can be reached at +44 115

937 1111 or via e-mail [email protected].

Simon Copping is a Principal in Golders Maidenhead, UK ofce andis UK

and Eire Business Development Leader. He is a Senior Engineering Geologist with

more than 20 years o experience working in the UK and abroad on a range o

waste management and mining projects. Simon has a broad engineering background,

having led the design, development, construction and project management o a range

o waste handling, processing, treatment and disposal acilities. Simon has also

provided commercial, technical and environmental due diligence support to a number o

waste management company acquisitions in particular the modeling and mapping o

theoretical to actual gas generation and recovery values or renewable energy portolio

assessments.He can be reached at +44 1628 586 200 or via e-mail atscopping@

golder.com.

WasteAdvantage Magazine April 2011 27

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2011 Waste Advantage Magazine, All Rights Reserved. Reprinted rom Waste Advantage Magazine. Contents cannot be reprinted without permission rom the publisher.
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