Phillippines Landfill Gas Model User Manual
Contents
1. User s Manual 1 1 12 2009 The model employs a first order exponential decay function that assumes that LFG generation is at its peak following a time lag representing the period prior to methane generation The model assumes a six month time lag between placement of waste and LFG generation For each unit of waste after six months the model assumes that LFG generation decreases exponentially as the organic fraction of waste is consumed For sites with known or estimated year to year solid waste disposal rates the model estimates the LFG generation rate in a given year using the following equation which is used by the U S EPA s Landfill Gas Emissions Model LandGEM version 3 02 EPA 2005 n 1 l M kt Qu kL e i gt Com i l a 10 maximum expected LFG generation flow rate m yr 1 year time increment year of the calculation initial year of waste acceptance 0 1 year time increment methane generation rate 1 yr ultimate methane generation potential m Mg mass of solid waste disposed in the i year Mg age of the j section of waste mass disposed in the i year decimal years methane concentration volume fraction The above equation is used to estimate LFG generation for a given year from each increment of waste disposed up through that year Multi year projections are developed by varying the projection year and then re applying the equations The year of maximum LFG genera2. between the opening year and the closure year inclusive remains constant If you want to enter different disposal rates for different years continue to Step 18 otherwise skip to Step 19 Enter the amount of waste disposed in metric tonnes for each year the site is open in Column 2 see Figure 2 The model accommodates up to 100 years of waste disposal history or projection The model defaults to assume that each year s waste disposal amount is the same as that of the previous year therefore values for amount of waste disposed needs to be entered only in the years it changes The disposal estimates should be based on available records of actual disposal rates and be consistent with site specific data on amount of waste in place total site capacity and projected closure year For years without historical data adjust the disposal amounts until the calculated total tonnes in place matches estimated actual tonnes in place as of the most recent year with waste in place data Enter the actual LFG recovery rates in cubic meters per hour for sites with active gas collection systems in Column 5 of the Annual Landfill Activity Data table see Figure 2 This should be the average annual total LFG flow at the flare station and or energy recovery plant NOT the sum of flows at individual wells and is usually based on gas flow measurements If the measured methane content was not entered in Step 5 adjust all flow rates to 50 methane equivalent by
3. dioxide with trace amounts of non methane organic compounds and air pollutants k is a model constant that determines the estimated rate of landfill methane generation The first order decomposition model assumes that k values before and after peak landfill gas generation are the same k is a function of moisture content in the landfill refuse availability of nutrients for methanogens pH and temperature Units 1 year The year in which the landfill begins or is expected to begin accepting waste vi Ultimate Methane Generation Potential Lo Philippines Landfill Gas Model v1 0 User s Manual 12 2009 DEFINITION Lo is a model constant that represents the potential capacity of a landfill to generate methane a primary constituent of landfill gas Lo depends on the amount of degradable organic carbon in the refuse Units cubic meters per megagram m Mg vii 1 0 INTRODUCTION The Philippines Landfill Gas Model Philippines LFG Model provides an automated estimation tool for quantifying landfill gas LFG generation and recovery from existing or future municipal solid waste MSW landfills across Philippines This manual provides an introduction to the model and step by step instructions for using the model The main purpose of the Philippines LFG Model is to provide landfill owners operators and potential developers with a tool to evaluate the feasibility and potential benefits of collecting and using th
4. landfill properly compacted on an ongoing basis 2 Does the landfill have a focused tipping area Are there leachate seeps appearing along the landfill sideslopes Or is there ponding of water leachate on the landfill surface 4 ls the average depth of waste 10m or greater 5 ls any daily or weekly cover material applied to newly deposited waste ls any intermediate final cover applied to areas of the landfill that have reached interim or final grade 7 Does the landfill have a geosynthetic or clay liner 8 in which bracket I to V does the LFG System Area Coverage Percentage fall See user s manual for assistance in answering the above questions or for instructions on how to enter a user specified or default collection efficiency below Step 15 Review the values of k Lo collection efficiency and fire discount factor recommended by the model based on his inputs in Steps 6 through 14 These appear under Model Recommended Value If you wish to change one or more of these values or if you did not complete Steps 6 through 14 and want to enter site specific value s for one or more of these parameters except for the fire discount factor enter the preferred value s under User Recommended Value Specifically enter single values for k Lo and collection efficiency into Cells H43 through H45 respectively This should be done only if you have reliable site specific informat
5. migration both on site and off site thus mitigating the risks of explosions or fires 1 2 1 Estimating Collection Efficiency Collection efficiency is a measure of the ability of the gas collection system to capture generated LFG It is a percentage value that is applied to the LFG generation projection produced by the model to estimate the amount of LFG that is or can be captured for flaring or beneficial use Although rates of LFG capture can be measured rates of generation in a landfill cannot be measured hence the need for a model to estimate generation therefore there is considerable uncertainty regarding actual collection efficiencies achieved at landfills In response to the uncertainty regarding collection efficiencies the U S EPA EPA 1998 has published what it believes are reasonable collection efficiencies for landfills in the United States U S that meet U S design standards and have comprehensive gas collection systems According to the U S EPA collection efficiencies at such landfills typically range from 60 to 85 with an average of 75 A comprehensive LFG collection system is defined as a system of vertical wells and or horizontal collectors providing 100 collection system coverage of all areas with waste within one year after the waste is deposited Most landfills particularly those that are still receiving wastes have less than 100 collection system coverage and require a coverage factor adjustment
6. multiplying the measured flow by the measured methane content of the LFG and then dividing the result by 50 as indicated in the table below This is not necessary if the measured methane content was entered in Step 5 The numbers placed in these cells will be displayed as data points in the graph output sheet so do not input zeros for years with no flow data leave blank instead The actual measured values entered will not change the gas generation and recovery curves Comparing the gas recovery projected by the model to actual data points provides an indication of how well the model is predicting gas recovery at the landfill Equation for adjusting methane content to 50 Measured yx Measured methane Flow rate Flow Rate 50 methane at 50 methane FIGURE 2 MODEL INPUTS continued Modeling Parameters Based on your inputs the model will use the model recommended values below to estimate the gas potential of the landfill If you have reliable data that suggest a different value should be used you may enter it under the user recommended value and it will be used to generate the gas estimates Model User Recommended Recommended Value Value k 1 yr 0 18 Lo m fmetric tonne 60 Collection Efficiency 81 Fire Discount Factor None Cannot Be Changed Annual Landfill Activity Data Input into column 2 the landfills annual waste acceptance rate The model recommended or user recommended collection efficiencies have been entered
7. seca ia 2 6 Zio Model Ouiput Gracia ip 2 8 E REFERENCES cec EC ets 3 1 Philippines Landfill Gas Model v1 0 User s Manual iv 12 2009 LIST OF FIGURES Figure 1 Model Inputs Figure 2 Model Inputs Continued Figure 3 Sample Model Output Table Figure 4 Sample Model Output Graph LIST OF TABLES Table 1 Landfill Collection Efficiency Philippines Landfill Gas Model v1 0 User s Manual Vv 12 2009 GLOSSARY OF TERMS Closure Year DEFINITION The year in vvhich the landfill ceased or is expected to cease accepting vvaste Collection Efficiency The estimated percentage of generated landfill gas that is or can be collected by a gas collection system Collection System Area Coverage The percentage of the landfilled area that has or vvill have a comprehensive and operating landfill gas collection system Landfill Fire Uncontrolled combustion of waste placed in a landfill Landfill fires can be above ground or underground subsurface Signs of landfill fires include smoke especially from cracks and fissures in the waste mass elevated gas temperature and carbon monoxide levels smoke stained gas vents smoldering wastes excessive settlement etc Landfill Gas Methane Generation Rate Constant k Opening Year Philippines Landfill Gas Model v1 0 User s Manual 12 2009 Landfill gas is a product of biodegradation of refuse in landfills and consists of primarily methane and carbon
8. two parameters 1 Lo is the ultimate methane generation potential of the refuse and 2 k is the methane generation rate constant For a unit of waste LFG generation is assumed to be at its peak the first year following placement in the landfill The model provides recommended default values of Ly and k based on values calculated using IPCC methodology and waste composition data from a number of landfills in different locations of Philippines adjusted through experience however the model also allows the user to enter Ly and k values derived using site specific data collected at the landfill 1 1 1 Methane Generation Rate Constant k The methane generation rate constant k determines the rate of generation of methane from refuse in the landfill Its unit is 1 year and describes the rate at which refuse placed in a landfill decays and produces biogas The higher the value of k the faster total methane generation at a landfill increases as long as the landfill is still receiving waste and then declines after the landfill closes over time The value of k is a function of the following factors 1 refuse moisture content 2 availability of nutrients for methane generating bacteria 3 pH and 4 temperature Different waste types can have significantly different k values as a result of differences in decay rates Food waste for example decays faster than paper or wood The k value also varies with climate especially temperature
9. December 2009 User s Manual Philippines Landfill Gas Model Version 1 0 Prepared on behalf of ED ST 4 o NZ f A AL PROTES anotan O V AGENCY L Rachel Goldstein Landfill Methane Outreach Program U S Environmental Protection Agency VVashington D C Prepared by Clint Burklin P E Eastern Research Group Inc Morrisville NC 27560 and Bryce Lloyd Organic Waste Technologies Hong Kong Limited Hong Kong SAR China EPA Contract EP W 06 022 Task Order 36 DISCLAIMER This user s manual has been prepared specifically for Philippines on behalf of the U S EPA s Landfill Methane Outreach Program U S Environmental Protection Agency The methods contained within are based on engineering judgment and represent the standard of care that would be exercised by a professional experienced in the field of landfill gas projections The U S EPA and its contractors ERG and OWT do not guarantee the quantity of available landfill gas and no other warranty is expressed or implied No other party is intended as a beneficiary of this work product its content or information embedded therein Third parties use this report at their own risk The U S EPA and its contractors ERG and OWT assume no responsibility for the accuracy of information obtained from compiled or provided by other parties ABSTRACT This document is a user s manual for a computer model Version 1 0 of a landfill gas LFG generation model for estim
10. an then be classified as belonging to one of the following two climatic zones or regions Region 1 Hot and Wet Region 2 Hot and Dry Based on available information most locations in Philippines would be classified as Hot and Wet although there could be isolated locations that might qualify as Hot and Dry It should be noted that there are no Cold and Wet or Cold and Dry locations in Philippines Unless a user specified k value is entered into the Philippines LFG Model the model uses a recommended default value of k based on the assumption that the landfill location is Hot and Wet The recommended value of k was developed based on a value calculated using IPCC methodology and average waste composition from a number of landfills in different locations of estimated based on climate and waste composition using IPCC methodologies IPCC 2006 Philippines Landfill Gas Model v1 0 User s Manual 1 5 12 2009 Philippines adjusted through experience The recommended default k value for Philippines assuming a Hot and Wet location is 0 18 If the user has reliable data that indicate the mean annual precipitation MAP at the landfill location is less than 1000 mm and or the average water content of the waste in the landfill is relatively low e g less than 30 it would be more appropriate to use a k value that corresponds to Hot and Dry conditions Using the average waste composition data f
11. andfill side slopes and whether there are ponds of water leachate on the landfill surface The response should be No only if there are neither leachate seeps nor ponds of water leachate The absence of leachate seeps and surficial ponds of water leachate is indicative of a relatively well drained waste mass with low leachate levels which is beneficial to LFG collection Question 4 asks whether the average depth of waste is 10 m or greater The response should be Yes only if the depth of waste averaged over the entire landfill exceeds 10 m Since the waste close to the top of the landfill tends to decompose aerobically and does not contribute to LFG generation a shallower landfill would have a lower apparent collection efficiency since it has a larger proportion of such waste Philippines Landfill Gas Model v1 0 User s Manual 1 10 12 2009 e Question 5 asks whether any daily or weekly cover material is applied to newly deposited waste The response should be Yes only if newly deposited waste is covered with an appropriate material such as soil plastic tarp or geosynthetics on a regular basis preferably daily but at least weekly material with large voids such as gravels construction and demolition debris or leaves and branches are not considered appropriate cover material The timely application of appropriate cover material to newly deposited waste is essential to minimize the amount of rapidly decomposing waste such as f
12. ating LFG generation and recovery from existing or future municipal solid waste MSW landfills in Philippines Philippines Landfill Gas Model v 1 0 referred to as Philippines LFG Model hereafter The model was developed by ERG and OWT under contract to the U S EPA s Landfill Methane Outreach Program LMOP The Philippines LFG Model can be used to estimate LFG generation rates from landfills and potential LFG recovery rates for landfills that have or plan to have gas collection and control systems in Philippines The Philippines LFG Model is an Excel spreadsheet model based on a first order decay equation The model requires the user to input site specific data for landfill opening and closing years refuse disposal rates history of landfill fires and a number of landfill characteristics that determine LFG collection efficiency Based on the site specific data supplied by the user the model selects recommended values for input variables including methane generation rate constant k potential methane generation capacity Lo collection efficiency and fire discount factor and estimates generation and recovery rates Users can also specify their own values for these input variables provided the information is reliable The recommended values for input Philippines Landfill Gas Model v1 0 User s Manual ii 12 2009 variables were developed using data on climate waste characteristics and disposal practices in Philippines and the e
13. ch projection year LFG generation rates for each projection year in cubic meters per minute and cubic meters per hour Collection system efficiency for each projection year LFG recovery rates for each projection year in cubic meters per minute and cubic meters per hour Carbon dioxide equivalent of recoverable methane gas in metric tonnes per year MTCOze year Potentially available energy output from a direct use project in megajoules per hour MJ hr assuming the gas is combusted in a boiler with 85 efficiency to produce steam Potentially available energy output from a electric generation project in megawatts MW assuming the gas is combusted in an engine with 30 efficiency to produce electricity Philippines Landfill Gas Model v1 0 User s Manual 2 6 12 2009 Beneath the table the following information is provided e The methane content assumed for the model projection 50 unless changed by the user in the Inputs worksheet e The k value used for the model run e The Lo value used for the model run To print the table select File Print OK FIGURE 3 SAMPLE MODEL OUTPUT TABLE Return to Inputs Page XYZ Landfill The Philippines Collection LFG Recovery from Energy Output Energy Output Disposal Waste LFG System Existing and From Direct From Electric Rate In Place Generation Rate Efficiency Planned System Use Project Generation Project Year metric tonnes yr_ m
14. e Therefore given the same waste composition waste in a dry location with a lower water content would have a higher value of Lo than waste in a wet location with a higher water content Philippines Landfill Gas Model v1 0 User s Manual 1 6 12 2009 Therefore if the user has reliable data that indicate the mean annual precipitation MAP at the landfill location is less than 1000 mm and or the average water content of the waste in the landfill is relatively low e g less than 30 it would be more appropriate to use a Lo value that corresponds to dry conditions Using the average waste composition data for Philippines the value of Lo would be approximately 70m Mg The user can enter the selected value in the model as a user specified value to override the recommended default value 1 1 3 Landfill Fires Landfill fires have been reported or observed at a number of landfills in Philippines Landfill fires can be above ground or underground subsurface Once fires are started especially subsurface landfill fires they are very difficult to extinguish or control Signs of landfill fires include smoke especially from cracks and fissures in the waste mass elevated LFG temperatures or carbon monoxide levels smoke stained gas vents smoldering wastes and accelerated settlement Landfill fires can consume a significant amount of the organic matter and thus drastically reduce the LFG generation rate Landfill fires can also damag
15. e generated LFG for energy recovery or other uses To accomplish this purpose this computer model provides estimates of potential LFG recovery rates and available emission reductions This is accomplished using the LFG generation rates estimated by the model and estimates of the efficiency of the collection system in capturing generated gas known as the collection efficiency The model provides LFG recovery estimates by multiplying the LFG generation by the estimated collection efficiency potentially available emission reductions estimates are obtained by multiplying the LFG recovery estimates by the methane content the density of methane and the global warming potential of methane 21 The model also estimates energy output from either a direct use project or an electricity generation project Landfill gas is generated by the decomposition of refuse in the landfill and can be recovered through the operation of gas collection facilities installed at the landfill The following information is needed to estimate LFG generation and recovery from a landfill see the Glossary of Terms e The annual refuse disposal rate for the landfill e The methane generation rate k constant e The ultimate methane generation potential Lo e The collection efficiency of the gas collection system e Whether there are and or have been landfill fires at the site and e The opening and closure years of the landfill Philippines Landfill Gas Model v1 0
16. e the LFG collection system poison the methanogenic bacteria and reduce the collection efficiency For landfills where current or past landfill fires have been observed or are likely present a reduction of 20 to 40 in the methane estimate might occur as the combined result of loss of organics and damaged collection system If the user indicates that signs of current or past landfill fires were observed the model applies a default fire discount factor 30 percent reduction to the methane estimate 1 2 Landfill Gas Recovery Landfill gas generated in landfills can be captured by gas collection and control systems that typically burn the gas in flares or alternatively the collected gas can be used beneficially Beneficial uses of LFG include use as fuel in energy recovery facilities such as internal combustion engines gas turbines microturbines steam boilers furnaces kilns or other equipment that uses the gas as fuel to generate electricity or useable heat Philippines Landfill Gas Model v1 0 User s Manual 1 7 12 2009 In addition to the energy benefits from the use of LFG collection and control of generated LFG helps to reduce emissions that are harmful to the environment Control of LFG destroys methane which is a greenhouse gas that contributes to global climate change Control of LFG also destroys organic compounds that could adversely affect human health The collection and control of LFG also reduces the potential for methane
17. el output worksheet in a table format and e A model output worksheet in a graph format Only the inputs worksheet is accessible initially The output table and output graph worksheets will become accessible once all necessary information has been entered by clicking on the View Output Table and View Output Graph buttons When using the model all of the editing by the user should take place in the model inputs worksheet Philippines Landfill Gas Model v1 0 User s Manual 1 12 12 2009 2 0 ESTIMATING LANDFILL GAS GENERATION AND RECOVERY 2 1 Model Inputs All model inputs are entered into the model inputs worksheet Cells highlighted in yellow require user inputs See Figure 1 for model inputs The following inputs are required to run the model properly and produce acceptable outputs tables and graphs If the landfill is an existing landfill the inputs should be based on recorded data and actual conditions where available although inputs based on anticipated or planned conditions can be entered in some steps to obtain hypothetical estimates for evaluation purposes For future landfills by definition inputs can only be based on anticipated or planned conditions Step 1 Enter the landfill name and title of the case study project Cell E10 The information entered here will automatically appear in the first heading of the output table and the output graph Step 2 Enter the location city and province of the la
18. etric tonnes m min m hn 0 Lla min m hr MTCOze MJ hr 365 365 00 0 8196 0 8196 11 318 2 104 81 1 a 112 dl 28 669 2588 8194 2 090 137813 35 265 2992 81 401 246 159344 40 774 3 330 81 46 2689 177 327 45376 3612 81 49 29171 192348 49219 3847 8194 521 3107 204 895 52 430 4 044 8196 54 3266 215 374 55 112 4 203 8196 571 3398 204128 57 351 4345 81 sel 3509 281430 59 222 4461 81 60 3602 287546 50 785 4558 611 3679 242647 52 090 4636 62 3744 246 905 63 181 53 3798 250 Ei 54 091 54 852 5 187 4 805 Es 3881 255 ey 55 487 4 845 65 3912 257 997 66 018 4877 66 3938 259729 66 461 66 3960 66 832 55 3308 2184152 55822 46 2763 182216 46 627 38 2308 152200 38946 32 198 32530 21 1345 1g 1128 338 61800 Philippines Landfill Gas Model v1 0 User s Manual 2 7 12 2009 2 3 Model Output Graph Model results are also displayed in graphical form in the model Output Graph worksheet See Figure 4 for a sample graph layout Data displayed in the graph includes the following e A curve of LFG generation rates during the projection years in cubic meters per hour e A curve of LFG recovery rates during the projection years in cubic meters per hour e Actual historical LFG recovery rates in cubic meters per hour shown as individual data points The t
19. he following table LFG System Area Bracket Coverage Percentage 80 100 I 60 80 II 40 60 II 20 40 IV lt 20 V The estimation of collection efficiency has been partly automated in the model the adjustment of the collection efficiency below 85 will be performed automatically if a Yes or No response is provided to each of the seven questions The model will also select the appropriate ACF if the bracket I to V in which the LFG System Coverage Percentage falls is identified The model will then reduce the adjusted collection efficiency by the ACF to calculate Philippines Landfill Gas Model v1 0 User s Manual 1 11 12 2009 the final collection efficiency Users can also specify their ovvn value for the collection efficiency if the information is reliable 1 3 The Model The Philippines LFG Model can be operated in a Windows 20005 Windows XP or Vista environment The program is a Microsoft Excel spreadsheet Open the model file LMOP Philippines Model v1 0 xis by choosing file open and then open when the correct file is highlighted To enable the model to run correctly the user will need to enable macros when prompted since high security settings may automatically disable macros it may be necessary to change the computer s security settings to enable macros The model has three worksheets as follows e A model inputs worksheet e A mod
20. into column 4 You may change these if you have better data for any given year If the landfill has a gas collection system in place and has measured actual gas recovery for ae years these data ee be entered into column 5 ee not enter zeros ars Disposal Rate Us Collection Actual ie View Output Table Year etric tonne le tonn em Efficien Recove 365 000 81 81 FS 0 460 900 Pam ae E owo fa IEA 2007 5 2555000 Pam 208 Se _ 2009 365000 A El View Output Graph En 65 saso p eo SSCS 206 I 540 90 TR E 2017 CEI CS 8 IC Pf 000 657 00 P s _______ Philippines Landfill Gas Model v1 0 User s Manual 2 5 12 2009 2 2 Model Output Table Model results are displayed in a table located in the model Output Table worksheet see Figure 3 for a sample table layout The model output table worksheet and the model output graph worksheet is accessible only after all required information has been entered in the model input worksheet The titles of the table have been set by user inputs in the model inputs worksheet The table provides the following information which was either copied from the model inputs worksheet or calculated by the model Projection years starting with the landfill opening year and continues for 100 years in total Annual disposal rates Cumulative amount of waste in place at the end of ea
21. ion on these parameters or if you do not have sufficient information to answer the questions in Steps 7 through 14 and would like to enter an assumed nominal value for the collection efficiency If you enter a value for collection efficiency into cell H45 then the model will feed it into the annual landfill activity data table below and use it to estimate the LFG recovery rates Philippines Landfill Gas Model v1 0 User s Manual 2 3 12 2009 Step 16 Step 17 Step 18 Step 19 Philippines 12 2009 For collection efficiency if you vvant to enter different values for different years enter them into the corresponding cells in Column 4 of the Annual Landfill Activity Data table see Figure 2 If not skip to Step 17 The model defaults to assume that each year s collection efficiency is the same as the previous year therefore values for collection efficiency need to be entered only in the years it changes For example if the landfill improves or plans to improve the gas collection system or puts a final cap in place during a given year you might want to enter a higher collection efficiency in Column 4 for that year The model will automatically apply that collection efficiency to the subsequent years Enter the average or actual annual waste disposal rate for the landfill in the opening year in Column 2 of the Annual Landfill Activity Data table Cell ES6 The model defaults to assume that the annual disposal rate for the years
22. itles of the graph have been set by user inputs in the model inputs worksheet To print the graph click anywhere on the graph and select File Print OK FIGURE 4 SAMPLE MODEL OUTPUT GRAPH XYZ Landfill Return to Inputs Page The Philippines 6 000 5 000 4 000 E 2 3 3 000 2 o pa 2 000 1 000 0 2001 2006 2011 2016 2021 2026 2031 2036 2041 2046 2051 2056 2061 2066 2071 2076 2081 2086 2091 2096 Estimated Recovery LFG Generation Actual Recovery Philippines Landfill Gas Model v1 0 User s Manual 2 8 12 2009 3 0 REFERENCES EPA 1991 Regulatory Package for New Source Performance Standards and III d Guidelines for Municipal Solid Waste Air Emissions Public Docket No A 88 09 proposed May 1991 Research Triangle Park NC U S Environmental Protection Agency EPA 1998 Compilation of Air Pollutant Emission Factors AP 42 Volume 1 Stationary Point and Area Sources Sth ed Chapter 2 4 Office of Air Quality Planning and Standards Research Triangle Park NC U S Environmental Protection Agency EPA 2005 Landfill Gas Emissions Model LandGEM Version 3 02 User s Guide EPA 600 R 05 047 May 2005 Research Triangle Park NC U S Environmental Protection Agency EPA 2007 Central America Landfill Gas Model Version 1 0 User s Manual March 2007 EPA 2009 China Landfill Gas Model Version 1 1 User s Manual May 2009 IPCC 2006 2006 IPCC Guide
23. lection efficiency In such case Philippines Landfill Gas Model v1 0 User s Manual 2 2 12 2009 you can skip to Step 15 to enter an assumed nominal value for collection efficiency For a typical landfill constructed and operated in accordance with the state of practice in Philippines it is reasonable to use 25 to 40 as the collection efficiency before landfill closure completion of the gas collection system and 50 to 65 subsequently FIGURE 1 MODEL INPUTS Philippines Landfill Gas Model v1 0 Instructions Please complete the information in the yellow highlighted cells This information is the minimum input required for proper model operation General Information Name Title XYZ Landfill Edittitlteatleft which feeds into the output ocation The Philippin table and graph Year Opened 2001 Inmputyear landfill began receiving waste Year Closed Projected to Close Input closure year i e the final year in which landfill will receive waste lExpected Methane Content of LFG Please enter the expected methane content of the landfill gas A value of 50 is recommended unless specific information is available from the site that warrants a different value This value will be used to calculate the net flow of recovered gas Landfill Characteristics Are there signs of current or past subsurface fires at the landfill Criteria Determining Collection Efficiency 1 jis the waste placed in the
24. lines for National Greenhouse Gas Inventories Intergovernmental Panel on Climate Change IPCC Volume 5 Waste Chapter 3 Solid Waste Disposal Philippines Landfill Gas Model v1 0 User s Manual 3 1 12 2009
25. ndfill Cell E11 The information entered here will automatically appear in the second heading of the output table and the output graph Step 3 Enter the year the landfill opened and began receiving waste Cell E12 This value will feed into the annual landfill activity data table below and into the output table Step 4 Enter the year the landfill closed or is projected to close Cell E13 This value will feed into the annual landfill activity data table below and into the output table Step 5 Enter the expected methane content of the LFG Cell E14 This value will be used to calculate the net flow of the recovered gas It is recommended that this value be left at 50 unless specific information is available from the site that warrants a different value Steps 6 through 14 are required if you want the model to recommend values for k Lo collection efficiency and fire discount factor You can skip to Step 15 if you have reliable information on these parameters and would like to enter site specific values for these parameters except the fire discount factor instead Philippines Landfill Gas Model v1 0 User s Manual 2 1 12 2009 Step 6 Indicate vvhether there are signs of current or past subsurface fires at the landfill This vvill impact the Lo value The follovving eight steps require the user to provide information on the construction and operation of the landfill that determines the collection efficiency of the gas collection
26. nt for No to Question 1 a 5 discount for No to Question 2 a 10 discount for Yes to Question 3 a 10 discount each for No to Questions 4 and 5 and a 5 discount each for No to Questions 6 and 7 i e a maximum of 48 discount to the collection efficiency for the seven questions Question 1 asks whether the waste placed in the landfill is properly compacted on an ongoing basis The response should be Yes only if the incoming waste is compacted thoroughly as the waste is placed or if the waste arrives at the landfill already compacted and baled Thorough and timely compaction of the waste placed in the landfill reduces the amount of air thus oxygen in the waste mass promoting anaerobic decomposition that generates LFG Proper compaction of the waste would also minimize differential settlement thus reducing potential problems with the collection piping and decrease the amount of surface water infiltration thus lowering the amount of leachate Question 2 asks whether the landfill has a focused tipping area The response should be Yes only if the tipping area is smaller than approximately 30 m by 30 m A focused tipping area minimizes the area through which air and surface water can infiltrate into the waste mass It is also a good landfill practice as there would be less exposed waste thereby minimizing odor and pest nuisances Question 3 asks whether there are leachate seeps appearing along the l
27. on efficiency assumption or a site specific collection efficiency EPA recognizes that modeling LFG generation and recovery accurately is difficult due to limitations in available information for inputs to the model However as new landfills are constructed and operated and better information is collected the present modeling approach can be improved In addition as more landfills in Philippines develop gas collection and control systems additional data on LFG generation and recovery will become available for model calibration and the development of improved model recommended values Questions and comments concerning the Philippines LFG model should be directed to Rachel Goldstein of EPA s LMOP at 202 343 9291 or e mail to Goldstein Rachel epamail epa gov 1 1 Landfill Gas Generation The Philippines LFG Model estimates LFG generation resulting from the biodegradation of refuse in landfills The anaerobic decomposition of refuse in solid waste landfills generates LFG The composition of MSW LFG is assumed by the model to be approximately 50 percent methane CH4 and 50 percent other gases primarily carbon dioxide CO2 with trace amounts of other compounds Philippines Landfill Gas Model v1 0 User s Manual 1 3 12 2009 This computer model uses a first order decomposition rate equation and estimates volumes of LFG generation in cubic meters per minute m min and cubic meters per hour m hr Methane generation is estimated using
28. ood waste that undergoes aerobic decomposition it is also necessary for the reduction of air and surface water infiltration and thus promote anaerobic decomposition Furthermore it allows the collection system to operate under the necessary vacuum without drawing excessive air oxygen into the system e Question 6 asks whether any intermediate final cover is applied to areas of the landfill that have reached interim or final grade The response should be Yes only if areas of the landfill that have reached interim or final grade receive an intermediate or final cover in a timely manner i e preferably within one year of reaching such grades Similar to daily or weekly cover it is also necessary for the reduction of air and surface water infiltration and allows the collection system to operate under the necessary vacuum e Question 7 asks whether the landfill has a geosynthetic or clay liner The response should be Yes only if most if not all of the landfill has a properly designed bottom liner made of geosynthetics clay or other appropriate material e Question 8 is related to the LFG System Area Coverage Percentage namely in which bracket I to V does it fall The LFG System Area Coverage Percentage is defined as the percentage of the landfill area that has a comprehensive and operating LFG collection system The response to Question 8 should be selected based on the value of the LFG System Area Coverage Percentage according to t
29. or Philippines the value of k calculated using IPCC methodologies would be approximately 0 10 The user can enter the selected value in the model as a user specified value to override the recommended default value 1 1 2 Ultimate Methane Generation Potential Lo Except in dry climates where a lack of moisture limits methane generation the value for the ultimate methane generation potential of refuse Lo depends almost exclusively on the type of refuse present in the landfill The higher the biodegradable organic carbon content of the refuse the higher the value of Lo The units of Lo are in cubic meters of methane per metric tonne of refuse which means that the Lo value describes the total amount of methane gas potentially produced by a metric tonne of refuse as it decays over its lifetime The values of theoretical and obtainable Ly range from 6 2 to 270m Mg refuse EPA 1991 Unless a user specified Lo value is entered into the Philippines LFG Model the model uses a recommended default value of Lo The recommended default value of Lo is based on a value calculated using IPCC methodology and average waste composition from a number of landfills in different locations of Philippines adjusted through experience The recommended Lo value for Philippines is 60m Mg Although the value of Lo does not depend on the climate zone per se it does depend on the water content of the waste as it is defined in terms of the total weight of the wast
30. precipitation and evapotranspiration To calculate the k value using IPCC methodologies a landfill location has to be categorized as cold or hot and dry or wet based on the following two criteria in accordance with Table 3 4 in the IPCC 2006 Guidelines Cold vs Hot e A location is cold if the mean annual temperature MAT is 20 C or lower Site specific Lo and k values may be developed for landfills with operating gas collection and control systems by calibrating the Philippines LFG Model using known landfill gas recovery data alternatively Lo and k values can be Philippines Landfill Gas Model v1 0 User s Manual 1 4 12 2009 e A location is hot if the MAT is higher than 20 C Based on available information practically all locations in Philippines have a MAT value that is higher than 20 C and thus should be categorized as hot Dry vs VVet For hot locations e It is dry if the mean annual precipitation MAP is less than 1000 millimeters mm e Itis wet if the MAP is 1000 mm or more Based on available information most locations in Philippines have a MAP value that is more than 1000 mm and thus should be categorized as wet For cold locations e It is dry if the ratio of mean annual precipitation MAP to potential evapotranspiration PET is less than 1 e It is wet if the ratio of MAP to PET is greater than 1 Using the above two criteria each location in Philippines c
31. stimated effect of these conditions on the amounts and rates of LFG generation The Philippines LFG Model was developed with the goal of providing general estimation of LFG generation and recovery potential Other models evaluated during the model development process included the U S EPA Central America Landfill Gas Model Version 1 EPA 2007 the U S EPA China Landfill Gas Model Version 1 1 EPA 2009 and the Intergovernmental Panel on Climate Change IPCC 2006 Waste Model The Philippines LFG Model incorporates components of each of these models that help it to reflect conditions at disposal sites in Philippines Philippines Landfill Gas Model v1 0 User s Manual ii 12 2009 TABLE OF CONTENTS Section Page DISCLAIMER gas aa let A NO 11 BS RNE a IE 11 TISTOFEIGUR ES et alat A te id me V LISTOF TABLES retocar A teues ele dte ela V GLOSSARY OE TERMS A vi LO INTRODUCTION mts ue ns id 1 1 1 1 Landfill Gas Generation a iii 1 3 1 1 1 Methane Generation Rate Constant k oooooonnnocccconoccnoncnonoonncoonnncnnnnnos 1 4 1 1 2 Ultimate Methane Generation Potential LO oooonoccnnnncccnonccinonccinnnnnos 1 6 T3 End ES tous ge aa 1 7 1 2 Landtill Gas Recovery estes tl item ta a ie matat 1 7 1 241 Estimating Collection Efficiency citada 1 8 LT CIM dE Le OS 1 12 2 0 ESTIMATING LANDFILL GAS GENERATION AND RECOVERY 2 1 24 Model Tnp ts im tit me et ead ate 2 1 225 Modelouiputsiablemce esteses
32. system For Steps 7 through 13 select Yes or No as appropriate in response to each question for Step 14 select the appropriate bracket I to V based on the value of the LFG System Area Coverage Percentage Detailed discussions on how to select the appropriate responses to these eight questions were presented in Section 1 2 1 Step 7 Is the waste placed in the landfill properly compacted on an ongoing basis Step Does the landfill have a focused tipping area Step 9 Are there leachate seeps appearing along the landfill side slopes Or are there ponds of water leachate on the landfill surface Step 10 Is the average depth of waste 10 m or greater Step 11 Is any daily or weekly cover material applied to newly deposited waste Step 12 Is any intermediate final cover applied to areas of the landfill that have reached interim or final grade Step 13 Does the landfill have a geosynthetic or clay liner Step 14 Which bracket I to V applies to the LFG System Area Coverage The LFG System Area Coverage Percentage is defined as the percentage of the landfill area that has a comprehensive and operating LFG collection system LFG System Area Bracket Coverage Percentage 80 100 I 60 8020 II 40 60 II 20 40 IV lt 20 V If you do not have sufficient information to answer all of the questions in Steps 7 through 14 the model will not provide a recommended value for the col
33. terial applied to 0 10 newly deposited waste 6 Is any intermediate final cover applied to areas of 0 5 the landfill that have reached interim or final grade 7 Does the landfill have a geosynthetic or clay 0 5 liner 8 In which bracket I to V does the LFG System Multiply by Area Coverage Area Coverage Percentage fall Factor see below The LFG System Area Coverage Percentage is defined as the percentage of the landfilled area that has a comprehensive and operating LFG collection system brackets I to V are defined in the table below The collection efficiency would be reduced by the ACF which is estimated in accordance with the following table LFG System Area Bracket Area Coverage Factor Coverage Percentage ACF Philippines Landfill Gas Model v1 0 User s Manual 1 9 12 2009 80 10020 I 9590 60 80 I 75 40 60 IH 55 20 40 IV 35 lt 20 V 1520 Note that the recommended method for estimating collection efficiency assumes that some portion at least 15 of generated LFG will escape collection no matter how well designed the landfill or how comprehensive the gas collection system is The following steps are recommended to adjust the efficiency below 85 To evaluate collection efficiency start at 85 and then apply a discount based on the responses to each of seven questions as described in Table 1 and below We suggest a 3 discou
34. tion normally occurs in the closure year or the year following closure depending on the disposal rate in the final years and the value of the methane generation rate constant The Philippines LFG Model requires site specific data for all the information needed to produce generation estimates except for the k and Lo values The model uses recommended default values for k and Ly based on calculations using waste composition data gathered from representative landfills in different cities in Philippines in accordance with the methodology presented in the IPCC 2006 guidelines IPCC 2006 The recommended default k and Lo values Philippines Landfill Gas Model v1 0 User s Manual 1 2 12 2009 are used to produce typical LFG generation estimates for landfills in Philippines Users can also specify their own values for k and Lo provided that the information is reliable The Philippines LFG Model also requires the user to provide information either actual or anticipated planned on certain landfill construction and operation characteristics that determine the collection efficiency of the existing or potential future gas collection system Based on the information provided by the user the model would recommend a value for the collection efficiency The recommended collection efficiency would then be used in combination with the LFG generation estimates to arrive at LFG recovery estimates The user also has the option to input an alternative collecti
35. to the estimated collection efficiency Sites with security issues or large numbers of uncontrolled waste pickers will not be able to install equipment in unsecured areas and cannot achieve comprehensive collection system coverage Table 1 Landfill Collection Efficiency shows an example of how to estimate the collection efficiency using responses to several questions related to landfill construction and Philippines Landfill Gas Model v1 0 User s Manual 1 8 12 2009 operation to determine discounts to the collection efficiency For example if the responses are Yes to questions 1 to 2 and 4 to 7 and No to question 3 then there is no discount beyond the collection efficiency value of 85 related to questions 1 to 7 Furthermore if the LFG System Area Coverage Percentage falls in bracket I then the final estimated collection efficiency is 85 times the Area Coverage Factor ACF 0 95 in this case or approximately 81 TABLE 1 LANDFILL COLLECTION EFFICIENCY Collection Efficiency Discount below 85 No Question Yes No 1 Is the waste placed in the landfill properly 0 3 compacted on an ongoing basis 2 Does the landfill have a focused tipping area 0 5 Are there leachate seeps appearing along the 10 0 3 landfill side slopes Or is there ponding of water leachate on the landfill surface 4 Is the average depth of waste 10 m or greater 0 10 5 Is any daily or weekly cover ma
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