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Climate Technology Partnership Workshop
jointly organized by KEMCO, U.S. EPA and NREL
14-15 June 2004, Seoul, Korea
Gas Generation and Recovery
Model Developed for Thailand and
Feasibility Study for Cheong ju
Presented by David L. Howard
Based largely on presentations developed by
Brian Guzzone of U.S.EPA LMOP and Alex Stege of
SCS Engineers
Korea Energy Management Corporation
Presentation Outline
• Factors affecting a site’s potential for landfill
gas utilization
• Using the factors to perform feasibility study
at Cheong ju landfills
• Using the factors to analyze potential of
landfills for a country - Thailand
• Possible follow on steps after completing
initial analysis with the models
Korea Energy Management Corporation
Potential Landfill Gas Project Sites
• Factors affecting a site’s
potential for landfill gas
utilization
– Site location
– Waste quantity and
composition
– Waste disposal rates: past
and future
– Climate and moisture
– Other considerations
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Disposal Site Location
– Landfill serves
population which
generates significant
quantities of waste
– Landfill open or is
recently closed
– Facility with power
needs located near
landfill
– Landfill located near
power grid
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Site Location
• Site acceptance
– Landfill gas utilization
project is to be
accepted by the local
government and
community
– Demonstrates
commitment to
improving local
environment
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Waste Disposal Rates
• Waste quantity
– >0.3 million metric tons of
waste in place and >0.5
million metric tons capacity
• Waste composition
– Higher organic waste % =
higher methane production
• Waste age
– Older waste produces less
methane
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Site Conditions
• Status of Landfill Operation
– Open or recently closed
• Landfill Type
– Managed Landfills
• daily cover, compaction
• leachate management
• liner
– Dump Sites Present challenges
• Poor design and management
• Fires
• Scavengers
• Landfill Depth
– Greater than 5 m preferred
– Greater than 10 meters is optimal
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Climate and Moisture Levels
• Climate
– High rainfall at sites
contributes to rapid waste
decay
– Sites with low rainfall have
slower waste decay
• Management of Moisture
in the Landfill
– Leachate management
– Landfill stability
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Other Considerations
• Geology/ Hydrogeology
– Presence of liner and/or clay
soils beneath site
• Temperature
– Methane production is
maximized between 35-57
degrees Celsius
• Other factors:
– Landfill design
– Site-specific factors
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Utilization Options for Landfill
Gas
• Are there uses for the
energy recovered?
• Direct use
• Electricity generation
• Gas processing
• Emerging technologies
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Are There Uses For The Energy
Recovered?
• Ask yourself these questions, are there….
1) Residential areas that could use a supplemental source of
fuel?
2) District heating plants that can use medium quality gas?
3) Industrial facilities nearby that can use medium quality gas?
4) Medium-quality gas distribution networks?
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Are There Uses For The Energy
Recovered?
• Additionally...
5) Are high-quality gaseous fuels very costly, making gas
processing potentially cost effective?
6) Are there electric power distribution systems that do (or
can) obtain power from project such as landfills?
7) Would you consider gas recovery as a lost-cost alternative
approach for reducing methane emissions even if it is not
profitable in its own right?
Korea Energy Management Corporation
Identify Other Favorable Options
• Find Supportive
Project Partners
–
–
–
–
–
Regulatory agencies
Utility companies
Governmental agencies
Private industry
Adjacent land owners
and residents
– Multi-lateral banks
– Financial institutions
Korea Energy Management Corporation
Cheong ju Landfill
• In 2002, SCS Engineers, a U.S. EPA
contractor conducted a feasibility
analysis of the two Cheong ju landfills
• Purpose of the study was to determine
options for developing LFG projects at
the sites
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Criteria Used for the Analysis
•
•
•
•
•
•
•
•
•
Reviewing Solid Waste Management Practices
Reviewing Site Information
Preparing a Landfill Gas Recovery Estimate
Preparing a Landfill Gas System Concept
Evaluating Energy Utilization Options
Reviewing the Institutional Framework
Reviewing Emission Reduction Credit Criteria
Performing an Environmental Effects Assessment
Performing an Economic Evaluation
Korea Energy Management Corporation
Model Used to Estimate Gas
Production
• Q = Lo R (e-kc - e-kt)
• Where:
–
–
–
–
–
–
Q = Methane generated in current year (m3/yr)
Lo= Methane generation potential (m3/Mg of refuse)
R = Average annual waste acceptance rate (Mg/yr)
k = Methane generation rate constant (1/yr)
c = Time since/to landfill closure (yr)
t = Time since landfill opened (yr)
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Economic Analysis
• Once the gas production is estimated
– Collection system is modeled
– Utilization options analyzed
– Potential for generation of carbon credits
assessed
– Economic analysis included
• Cash flow analysis
• Net Present Value analysis
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Economic Analysis
continued
• Evaluation of economic results strategy
– Minimising the initial capital investment that is
necessary to implement the initial LFG recovery
system.
– Maximising LFG recovery rates (within the
limitations of the above item) by focusing on
selected portions of the disposal area.
– Maximising the value of the Emission Reduction
Credits.
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Application to a Nationwide Analysis
• At about the time the Cheong ju feasibility
study was complete, EPA with the World
Bank analyzed landfill gas potential in
Thailand.
• The evaluation used many of the same
tools to provide a country wide data base
of the economic potential of landfills
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Approach
• Thailand landfill gas model based on
USEPA’s LandGEM
• Thailand landfill gas model outputs:
– Estimates landfill gas generation rates
– Estimates landfill gas recovery potential
• Evaluation of suitability of site
conditions based on responses to
World Bank disposal practices survey.
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USEPA’s Thailand Landfill Gas
Model
• Model inputs - site specific information:
– Historic and projected waste disposal rates
– Average annual rainfall
• Model inputs - regional information:
– Thailand waste composition
• Model equation estimates annual landfill gas
generation
• Model estimates annual landfill gas recovery
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Key Model Inputs
• Annual waste
disposal rates
• Methane decay
rate (“k”)
• Methane
generation
potential (“Lo”)
• Collection
efficiency
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Model Inputs – Disposal Rates
• Mass of waste disposed each year
– Historical disposal data estimated using
data obtained from World Bank
– landfill practices survey of municipalities
– Estimated future disposal rates account for
site capacities
– Possible regional or provincial disposal
sites scenario
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Model Inputs – Rate Constant (k)
• “k” – refuse decay rate constant
(units = 1/year)
– Sets rate of waste decay and methane
production
– Influenced by waste moisture – use annual
rainfall
– High rainfall at Thailand sites (900 – 5000
mm per year) create very high k values
– High k values confirmed by Chiang Mai
University study
Korea Energy Management Corporation
Model Inputs – Methane
Generation Potential (Lo)
• “L0” – methane generation potential
(units = m3 methane per metric tonne
[Mg] of waste)
– Total amount of methane one tonne of
waste produces
– Thailand Lo estimate based on Bangkok
waste composition
Korea Energy Management Corporation
Model Inputs – Collection
Efficiency
• Collection efficiency =
Amount of landfill gas collected
Amount of landfill gas generated
• Collection efficiency based on:
– Type of facility (landfill vs. dump)
– Type/design of collection system
– Extent collection system covers waste volume
– Waste characteristics – permeability
– Collection system operation
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Methodology – Model
Equation
• Landfill gas generation equation:
Landfill gas generation = 2 k L0 M e-kt
where:
k = refuse decay rate (1/yr)
L0 = methane generation potential (m3/Mg)
M = mass of waste deposited per year (Mg)
t = age of waste (years)
Note: This derivative of earlier model shows generation
in one year.
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Methane
Rate Constant (k)
• Range of observed values:
– 0.01 1/year (desert landfills) to 0.45 1/year
(“bioreactors”)
• Estimated range of k values for Thailand
disposal sites:
– 0.065 to 0.15 (1/yr)
• Estimated k value for Cheong ju site
– 0.085 (1/yr) based on rainfall analysis
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Methane
Generation Potential (Lo)
• Range of observed values:
• 0 - 312 m3 methane/Mg of waste
• Estimated Lo value for Thailand disposal
sites:
– 78 m3CH4/Mg
– Based on average organic and solids content
• Estimated Lo value for Cheong ju
– 39 m3CH4/Mg
– Based on average organic and solids content
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Projected LFG Recovery
Rate
• Landfill gas recovery = landfill gas
generation x collection efficiency
• Collection efficiency Thailand sites:
– Engineered and sanitary landfills: 60%
– Open and controlled dump sites: 50%
• Collection efficiency Cheong ju
– Based on planned system: 75%
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Evaluation of Suitability of Landfill
Site Conditions
• World Bank survey of sites-Thailand
– Management practices
• Daily cover , compaction of waste
• Presence of clay or plastic liner
• Presence of leachate drainage system
– Environmental conditions
• Leachate adequately contained
• No fires
• No scavengers living on landfill
– Depth of waste: > 5 m
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Modeled Thailand Sites
Central Region:
• 11 landfills, 5 dump
sites
• Sites with largest landfill
gas potential currently:
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–
–
–
Bangkok-Kampangsean
Bangkok-Ratchathewa
Nonthanburi
Pathum Thani
• Sites with largest future
landfill gas potential:
– Bangkok-Kampangsean
– Bangkok-Ratchathewa
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San
Suk
Sample Model Output – BangkokKampangsaen Landfill
Landfill Gas Generation and Recovery
Bangkok- Kampangsaen Landfill
Gas Flow at 50% Methane (m3/hr)
25
15,000
20
15
10,000
10
5,000
5
0
1990
0
1995
2000
2005
Generation, k=0.08
Generation, k=0.15
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2010
2015
2020
Recovery, k=0.08
Recovery, k=0.15
2025
2030
Project Generation Potential (MW)
30
20,000
Sample Model Output – Megalo
Exhibit 4-1
Landfill Gas Generation and Recovery Projection (Flow)
Megalo Landfill, Cheongju, South Korea
1,200
LFG (m3/hr)
900
Generated
Recovered
600
Passive
300
0
2001
2006
2011
2016
2021
Year
Korea Energy Management Corporation
2026
2031
2036
2041
Overview of Results
Thailand
Existing Sites:
Size of Potential Landfill Gas Facilities
0.5-1 MW
2 sites
4-10 MW
2 sites
Suitability of Landfill Conditions for
LFG Developm ent
not
assessed
low
3 sites
5 sites
0.2-0.5
MW
13 sites
high
24 sites
<0.2 MW
39 sites
medium
24 sites
Potential Regional or Provincial Sites:
2
landfills can accommodate regional waste (1-8 MW)
8 landfills can accommodate provincial waste (0.2-7 MW)
Korea Energy Management Corporation
Existing Sites
Potential Projects at Large Disposal Sites*
Site Name
Bangkok-Kampangsean
Bangkok- Ratchathewa
Project
Capacity
(MW)
Project
Duration
(Years)
10
15 (2004-2018)
4
16 (2004-2019)
0.5
23 (2004-2026)
Nonthaburi
0.7
10 (2013-2022)
Nakorn Ratchasima
0.5
12 (2004-2015)
Nakorn Pathom
0.4
23 (2004-2026)
Pathum Thani
0.4
10 (2004-2013)
Hat Yai
0.4
16 (2004-2019)
0.2
35 (2004-2038)
Phitsanulok
0.5
14 (2013-2026)
0.2
42 (2004-2045)
Kampang Phet
0.3
31 (2012-2042)
Songkhla
0.2
50 (2004-2053)
*Includes sites with capacities > 1,000,000 tons
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Landfill
Suitability
for Project
medium
high
low
high
high
high
medium
low
high
Potential Regional Sites
Potential Projects at Potential Regional Sites*
Site Name
Chiang Mai
Ubon Ratchathani
Project
Capacity
(MW)
Project
Duration
(Years)
Landfill
Suitability
for Project
2-5
5-8
2-5
1-2
2-3
1-2
20 (2008-2013)
14 (2014-2027)
14 (2028-2041)
14 (2008-2012)
11 (2013-2023)
14 (2024-2032)
high
*Assumes disposal site will receive all waste from the home province and
neighboring provinces.
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low
Confidence Levels for Model
Results
• Sources of Uncertainty:
–
–
–
–
Methodology – model accuracy
Data quality
Collection efficiency
Other factors
• Estimates in the range of +/- 30 %
• Model accuracy improved by field studies
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Options for follow up:
Field Testing Program
• Field testing at
potential
project sites
• Install test wells
• Perform testing
and monitoring
• Field Testing
Issues
• Confidence
Levels
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Install Test Wells
• Install vertical extraction wells or horizontal
collectors in the landfill
• Flare recovered gas to control discharge
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Perform Testing
and Monitoring
• Balance the well
field
• Recover gas
continuously
during testing
period
Monitor gas quantity and quality at the
flare station and at each well
 Review test results

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Field Testing Issues
• Advantages:
– Provides site-specific data
– Provides information on
landfill leachate levels
• Disadvantages:
– Cost increase
– Potential inaccuracies
– Limited information on
seasonal variations
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Confidence Levels for Field
Testing Program
• Sources of inaccuracy:
– Estimating total landfill gas flow from field test
• Landfill gas from only portion of site during field test
• Need estimated waste volume under influence of
test wells
– Recovery during test may not be sustainable
over long term
• Can extend testing program to improve
accuracy
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Options for follow up:
Feasibility Study
• Recommend feasibility studies for potential
project sites
– Refine landfill gas recovery projections by calibrating
model to results of field test
– Project developer likely to require feasibility study
– Feasibility study can include evaluation of project
financial information
Korea Energy Management Corporation
Summary
• Information on landfill gas recovery rates
critical for finding suitable project sites and
sizing equipment
• Analysis can be done for single sites or all
sites in the country
• Follow-up studies at potential project sites
may be warranted
– Field testing
– Feasibility studies
Korea Energy Management Corporation