Presented by David L. Howard Based largely on presentations developed by Brian Guzzone of U.S.EPA LMOP and Alex Stege o

1. Climate Technology Partnership Workshopjointly organized by KEMCO, U.S. EPA and NREL14-15 June 2004, Seoul, KoreaGas 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

2. 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

3. 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

4. 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

5. Site Location • Site acceptance • Landfill gas utilization project is to be accepted by the local government and community • Demonstrates commitment to improving local environment

6. 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

7. 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

8. 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

9. 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

10. Utilization Options for Landfill Gas • Are there uses for the energy recovered? • Direct use • Electricity generation • Gas processing • Emerging technologies

11. 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?

12. 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?

13. 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

14. 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

15. 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

16. 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)

17. 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

18. 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.

19. 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

20. 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.

21. 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

22. Key Model Inputs • Annual waste disposal rates • Methane decay rate (“k”) • Methane generation potential (“Lo”) • Collection efficiency

23. 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

24. 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

25. 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

26. 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

27. 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.

28. 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

29. 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

30. 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%

31. 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

32. Modeled Thailand Sites Central 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

33. Sample Model Output – Bangkok-Kampangsaen Landfill

34. Sample Model Output – Megalo

35. Overview of ResultsThailand 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)

36. Existing Sites

37. Potential Regional Sites

38. 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

39. 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

40. Install Test Wells • Install vertical extraction wells or horizontal collectors in the landfill • Flare recovered gas to control discharge

41. 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

42. Field Testing Issues • Advantages: • Provides site-specific data • Provides information on landfill leachate levels • Disadvantages: • Cost increase • Potential inaccuracies • Limited information on seasonal variations

43. 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

44. 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

45. 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