korea energy management corporation climate technology partnership workshop jointly organized by...

Korea Energy Management Corporation

Climate Technology Partnership Workshopjointly 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. HowardPresented by David L. HowardBased largely on presentations developed by Based largely on presentations developed by

Brian Guzzone of U.S.EPA LMOP and Alex Stege of Brian Guzzone of U.S.EPA LMOP and Alex Stege of SCS EngineersSCS Engineers


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


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


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


Site Location

• Site acceptance– Landfill gas utilization

project is to be accepted by the local government and community

– Demonstrates commitment to improving local environment


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


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


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


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


Utilization Options for Landfill Gas

• Are there uses for the energy recovered?

• Direct use• Electricity generation• Gas processing• Emerging technologies


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?


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?


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


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


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


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)


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


Economic Analysiscontinued

• 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.


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


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.


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


Key Model Inputs

• Annual waste disposal rates

• Methane decay rate (“k”)

• Methane generation potential (“Lo”)

• Collection efficiency


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


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


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


Model Inputs – Collection Efficiency

• Collection efficiency =

Amount of landfill gas collectedAmount 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


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.


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


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


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%


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


Modeled Thailand SitesCentral Region:• 11 landfills, 5 dump

sites• Sites with largest landfill

gas potential currently:– Bangkok-Kampangsean– Bangkok-Ratchathewa– Nonthanburi– Pathum Thani

• Sites with largest future landfill gas potential:– Bangkok-Kampangsean– Bangkok-Ratchathewa

San Suk


Sample Model Output – Bangkok-Kampangsaen Landfill

Landfill Gas Generation and RecoveryBangkok- Kampangsaen Landfill

0

5,000

10,000

15,000

20,000

1990 1995 2000 2005 2010 2015 2020 2025 2030

Gas

Flo

w a

t 50

% M

eth

ane

(m3/

hr)

0

5

10

15

20

25

30

Pro

ject

Gen

erat

ion

Pot

enti

al (

MW

)

Generation, k=0.08 Recovery, k=0.08

Generation, k=0.15 Recovery, k=0.15


Sample Model Output – MegaloExhibit 4-1

Landfill Gas Generation and Recovery Projection (Flow)Megalo Landfill, Cheongju, South Korea

0

300

600

900

1,200

2001 2006 2011 2016 2021 2026 2031 2036 2041

Year

LF

G (

m3/h

r) Generated

Recovered

Passive


Overview of ResultsThailand

Size of Potential Landfill Gas Facilities

0.5-1 MW2 sites

4-10 MW2 sites

0.2-0.5 MW

13 sites

<0.2 MW39 sites

Existing 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)

Suitability of Landfill Conditions for LFG Development

not assessed

3 siteslow

5 sites

high 24 sites

medium 24 sites


Existing Sites

Bangkok-Kampangsean 10 15 (2004-2018) mediumBangkok- Ratchathewa 4 16 (2004-2019) high

0.5 23 (2004-2026)0.7 10 (2013-2022)

Nakorn Ratchasima 0.5 12 (2004-2015) highNakorn Pathom 0.4 23 (2004-2026) highPathum Thani 0.4 10 (2004-2013) highHat Yai 0.4 16 (2004-2019) -

0.2 35 (2004-2038)0.5 14 (2013-2026)0.2 42 (2004-2045)0.3 31 (2012-2042)

Songkhla 0.2 50 (2004-2053) high*Includes sites with capacities > 1,000,000 tons

Kampang Phetlow

Project Capacity

(MW)

Project Duration (Years)

Phitsanulokmedium

Potential Projects at Large Disposal Sites*

Site Name

Landfill Suitability for Project

Nonthaburilow


Potential Regional Sites

2 - 5 20 (2008-2013)5 - 8 14 (2014-2027)2 - 5 14 (2028-2041)1 - 2 14 (2008-2012)2 - 3 11 (2013-2023)1 - 2 14 (2024-2032)

Potential Projects at Potential Regional Sites*

Site Name

Project Capacity

(MW)

Project Duration (Years)

Landfill Suitability for Project

*Assumes disposal site will receive all waste from the home province and neighboring provinces.

Chiang Maihigh

Ubon Ratchathanilow


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


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


Install Test Wells

• Install vertical extraction wells or horizontal collectors in the landfill

• Flare recovered gas to control discharge


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


Field Testing Issues

• Advantages:– Provides site-specific data– Provides information on

landfill leachate levels

• Disadvantages:– Cost increase– Potential inaccuracies– Limited information on

seasonal variations


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


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


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 climate technology partnership workshop jointly organized by...

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