Assessment of Landfill Gas Potential: Loja Landfill Loja, Ecuador

Transcription

1 Assessment of Landfill Gas Potential: Loja Landfill Loja, Ecuador Prepared for: Municipalidad de Loja, Ecuador Prepared under: U.S. Environmental Protection Agency Landfill Methane Outreach Program Contract: EP-W TO 006 By: Eastern Research Group, Inc. and Carbon Trade, Ltd June 11, 2007

2 Status: Final Date: June 11, 2007 TABLE OF CONTENTS 1. INTRODUCTION PROJECT LIMITATIONS LANDFILL GAS LANDFILL DATA Site Location and Operation Waste Inputs WASTE COMPOSITION RECYCLING ACTIVITIES SITE CONSTRUCTION General Observations Environmental Data Waste Depth Waste Placement Base Lining Capping Layer GAS AND LEACHATE Leachate Gas Fires GAS MODELING Emission Modeling Model Parameters BASELINE RESULTS OF GAS MODEL ANTICIPATED COLLECTION EFFICIENCY Available Area Oxygen Ingress CALCULATED GAS AVAILABILITY OPTIONS FOR UTILIZATION Thermal Energy Electrical Energy EMISSIONS TRADING OUTLINE SPECIFICATION OF A GAS EXTRACTION SYSTEM FINANCE MODEL CONCLUSIONS...23 REFERENCES...24 i

3 LIST OF TABLES & FIGURES Table 1 Estimated Waste Input (Actual) and (Projected)...4 Table 2 Estimated Waste Composition...5 Table 3 Average Rainfall (mm) (source: Table 4 Model Input Parameters...10 Table 5 Landfill Gas Model Results...12 Table 6 Estimated Available Thermal Energy...14 Table 7 Typical Cost of Electrical Generator Equipment...16 Table 8 Estimated Available Emission Reductions...18 Table 9 Indicative Bill of Quantities for Gas Extraction System...20 Table 10 Indicative Construction Cost Estimate for Gas Extraction and Flaring...21 Table 11 Indicative Capital Cost Estimate for Electrical Energy Production...21 Table 12 Indicative Operation Cost Estimate for Electrical Energy Production...21 Table 13 Financial Model Assumptions...22 Table 14 Financial Model Revenue Assumptions...22 Table 15 Financial Model Results - Electrical Energy Production...22 Table 16 Financial Model Results - Flaring Only...22 Figure 1 Baseline Landfill Gas Emissions...11 Figure 2 General View of the Landfill...34 Figure 3 Passive Vent with Evidence of Recent Fire...35 Figure 4 Fire on the Site...36 Figure 5 Area of Exposed Waste...37 Figure 6 Failing Slopes at the Site...38 Figure 7 Analysis of Gas in Covered Area...39 Figure 8 Capping Material is Cut for Covering the Waste...40 Equation 1 - First Order Decay Model...9 Equation 2 - Baseline GHG Emissions...10 Equation 3 - Available Emission Reductions...17 Equation 4 - Emission Reductions from Fossil Fuel Offset...17 APENDICES Appendix I... Drawings Appendix II...Financial Model Output Example Appendix III... Gas Analysis Record Appendix IV...Photos ii

4 EXECUTIVE SUMMARY The Loja landfill, owned and operated by the Municipality of Loja, Ecuador accepts domestic and commercial waste from the City of Loja and the surrounding area. The site accepts approximately 30,000 tonnes of domestic waste annually. With a planned extension, the site is expected to contain approximately 676,000 cubic meters of waste when it reaches the proposed closure date of However, there is an option to expand the site into new areas in the future. Under contract to the United States Environmental Protection Agency (U.S. EPA), Carbon Trade, Ltd. completed an initial assessment of the Loja landfill s potential to generate methane. Analysis of the data provided by the Municipality of Loja indicates that the site could be currently emitting between 211 m 3 /hr and 350 m 3 /hr of landfill gas, containing approximately 50% methane. This rate could reach a peak of approximately 500 m 3 /hr in 2017, with further gas generation in the event that the site is expanded. However, due to the construction techniques, particularly the compaction of the waste and materials currently used for capping at the site, not all of this landfill gas will be available for collection and utilization. Improvements particularly in the use of lower permeability capping materials will enhance the efficiency with which landfill gas can be collected. In the absence of local industry and with a moderate quantity of energy available from the landfill gas (as is typical of smaller landfill sites), the opportunity for development of landfill gas to energy projects using Loja landfill s gas is limited. However, the location of the recycling center and a local school may offer possibilities for direct heat use. The site does not currently have any landfill gas control system other than passive venting measures. It was noted that some landfill gas is being burnt where the passive vents have been ignited. The site offers the opportunity to install a gas flaring system for environmental control, which may qualify for emission reduction credits. 1. INTRODUCTION The U.S. EPA is working in conjunction with the Ministerio del Ambiente, Republica del Ecuador on a cooperative program to promote the beneficial use of landfill methane, while also reducing landfill methane emissions to the atmosphere. Some of the key activities of this cooperative program include the following: (1) identifying suitable landfills with sufficient quantities of high quality gas that can be used to meet local energy needs, (2) conducting a workshop to train landfill owners, municipal officials, and local organizations on the ways to develop landfill methane projects, (3) conducting a workshop to bring together landfill owners, project developers, and financial institutions to help promote the development of landfill methane projects in Ecuador. To support these activities, the U.S. EPA has contracted with two companies, Eastern Research Group, Inc. (ERG) and Carbon Trade, Ltd. (Carbon Trade). An important part of identifying landfills that are good candidates for energy projects involves conducting site visits to landfills that have been identified by El Ministerio del Ambiente del Ecuador as potential project sites. Several site visits were completed between October 23 and 27, In these visits, ERG and Carbon Trade collected information on landfill design, waste volume, waste 1

5 composition and gas composition to be used to assess the gas potential of the landfill. Information was also collected on the local energy users that could potentially be interested in using the energy produced by the landfill. This assessment report summarizes the findings of the site visit to Loja Landfill in Loja, Ecuador. This report includes a brief assessment of the gas potential of the landfill and examines the opportunities that may exist for using the landfill gas to meet the energy needs of local utilities or industries. This report also includes technical information that will be helpful to potential project developers as they assess the potential of a landfill methane energy project on the site. The site visit included non-invasive analysis of the landfill gas, as well as a walk over inspection of the leachate control measures, containment technology, topography and general operation of the landfill. Physical work on the site was limited to collection of gas samples and measuring leachate depths (where possible). 2. PROJECT LIMITATIONS The information and predictions contained within this assessment report are based on the data provided by the site owners and operators. Neither the U.S. EPA nor its contractors can take responsibility for the accuracy of this data. Measurements, assessments, and predictions presented in this report are based on the data and physical conditions of the landfill observed at the time of the site visit. Note that landfill conditions will vary with changes in waste input, management practices, engineering practices, and environmental conditions (particularly rainfall and temperature). Therefore, the quantity and quality of landfill gas extracted from the landfill site in the future may vary from the values predicted in this report, which are based on conditions observed during the site visit. The Loja landfill site does not have a current gas collection, flaring or utilization system. The estimated capital, operational costs, and return on investment resulting from installing such a system at the Loja site are based on current, typical, costs in Latin America, but no warranty is given or implied on the accuracy of these data. While all due care and attention has been given to development of this report, potential investors in landfill gas utilization projects at Loja landfill are advised to satisfy themselves as to the accuracy of the data and predictions contained in this report. This report has been prepared for the U.S. EPA Methane to Markets Partnership and is public information. 3. LANDFILL GAS Landfills produce biogas (normally called landfill gas) as organic materials decompose under anaerobic (without oxygen) conditions. Landfill gas is composed of approximately equal parts methane and carbon dioxide, with a smaller percentage of oxygen, nitrogen, and water vapour, as well as trace concentrations of volatile organic compounds (VOCs) and hazardous air pollutants (HAPs). Both of the two primary constituents of landfill gas (methane and carbon dioxide) are considered to be greenhouse gases (GHG), which contribute to global warming. However, the Intergovernmental Panel on Climate 2

6 Change (IPCC) does not consider the carbon dioxide specifically present in raw landfill gas to be a GHG. IPCC considers landfill carbon dioxide to be biogenic and thus, part of the natural carbon cycle. Because IPCC does not consider landfill carbon dioxide to be a GHG, only the methane content of the gas is included in calculations of atmospheric emissions. Methane is a more potent GHG than carbon dioxide (CO 2 ), with a global warming potential over 20 times that of CO 2. Therefore, the capture and combustion of methane (transforming it to carbon dioxide and water) in a flare, an engine generator or other device, results in a substantial net reduction of GHG emissions. Additional benefits of landfill gas combustion beyond GHG emission reductions include the potential for improvement in local air quality through the destruction of HAPs and VOCs. There are two natural pathways by which landfill gas can leave a landfill: by migration into the adjacent subsurface and by venting through the landfill cover system. In both cases, without capture and control, the landfill gas (containing methane) will ultimately reach the atmosphere. The volume and rate of methane emissions from a landfill are a function of the total quantity of organic material buried in the landfill, the material s age and moisture content, compaction techniques, temperature, and waste type and particle size. While the methane emission rate will decrease after a landfill is closed (as the organic fraction is depleted), a landfill will typically continue to emit methane for many (20 or more) years after its closure. A common method for controlling landfill gas emissions is to install a landfill gas collection system that extracts landfill gas under the influence of a small vacuum. Landfill gas control systems are typically equipped with a combustion (or other treatment) device designed to destroy methane, VOCs, and HAPs prior to their emission to the atmosphere. Good quality landfill gas (high methane content with low oxygen and nitrogen levels) can be utilized as a fuel to offset the use of conventional fossil fuels. The heating value typically ranges from 15 Megajoules (MJ) to 18 MJ per cubic meter, which is approximately one half the heating value of natural gas. Potential uses of landfill gas generally fall into one of the following categories: electrical generation, direct use for heating/boiler fuel (medium-btu), upgrade to high Btu gas, and other uses such as vehicle fuel. This study focuses on evaluation of a potential electrical generation, direct heating or flaring project at the Loja landfill. 4. LANDFILL DATA Prior to the site visits, the landfill site operator, the Municipality of Loja, was requested to provide information on the waste inputs, engineering details, and environmental conditions of the landfill site. Data provided by the operator has been edited into a standard format. The following data were obtained for the Loja landfill. Data were updated during the site visits Site Location and Operation The Loja landfill is located to the west of the City of Loja. The area is generally rural and has little industrial development. 3

7 The site occupies an area of hectares (Ha), which is bounded on all sides by agricultural land. The site is owned and operated by the Municipality of Loja Waste Inputs The site started to accept waste in 1997 with the first phase of the landfilling due for completion during A second phase of operation will provide capacity for additional waste and a land area of Ha is available for expansion. Data provided by the site indicate that there are approximately 450,735 cubic meters of waste in place as of August While there is no waste density information available the methods of compaction would indicate that a figure of 0.65 T/m 3 would be a reasonable assumption. This implies that the current waste mass is 292,978 tonnes, which agrees with the operator s estimate of an average of 30,000 tonnes per annum. No weighbridge is installed on the site and therefore the amount of waste in place and the rate of waste input must be assumed to be an estimate. The Municipality has not provided information on the composition of the waste. Visual examination indicates that the waste being deposited in the site is entirely domestic and commercial in origin and is high in organic components. As annual waste input data has not been provided by the Municipality, an estimate based on 5.3% growth rate of waste input has been used to develop the schedule of waste inputs shown in Table 1. This growth rate is similar to other landfill sites in the Andean region of Ecuador studied under the Methane to Markets program. Table 1 Estimated Waste Input (Actual) and (Projected) Year Annual Input (tonnes) TOTAL Current Phase 292,978 1 Tonnes

8 Table 1 Estimated Waste Input (Actual) and (Projected) (Continued) Year Annual Input (tonnes) TOTAL 749,994 Tonnes 1 Total as estimated by the Municipality of Loja The area provided for the second phase of development of the Loja landfill indicates that there will be sufficient space for many more years of waste disposal. While the site may continue to operate for a longer period, for the purposes of this study an additional 10 years of operation has been assumed. 5. WASTE COMPOSITION The Municipality did not provide waste composition data. Therefore, the average waste composition observed in the other Methane to Markets studies for Ecuador has been assumed for the Loja Site. This composition is presented in Table 2. Table 2 Estimated Waste Composition Composition (%) Waste Category Food 61.2% Paper and Cardboard 12.0% Plastics 9.2% Metal 1.8% Glass 2.5% Grass clippings, manure Garden and yard waste Wood (lumber and tree trunks) Rubber, tires, textiles Organic waste, including nontoxic sludges, septic tank wastes, diapers and dead animals Appliances and furniture 9.6% Construction debris Inerts 8.7% Consistent with other published information on the composition of waste in Ecuador 5, the percentage of organic waste is relatively high and more than 60% of the waste can be categorized as rapidly decaying. 5

9 6. RECYCLING ACTIVITIES Recycling operations on the site are removing a proportion of the plastic and paper waste products. A recycling facility at the entrance to the site includes a waste picking line in which plastics and paper are manually separated and the remaining waste returned to the landfill. The fraction of the inert or slowly degradable waste including plastic (in particular P.E.T.), glass, metal, paper and cardboard that is sorted from the waste on site and recovered for recycling is considered to be limited. Because the majority is inert in nature, this waste will not have a noticeable effect on the site s overall methane generation. In addition, a relatively large lombriculture project is currently composting green and food waste, which is collected from markets and commercial operations. This process is aerobic and therefore does not generate any methane. It is assumed that the lombriculture project has been in operation since the inception of the site. It should be noted that although this project is already fairly large, if it were expanded there would be a corresponding reduction in the amount of methane generated by the site. 7. SITE CONSTRUCTION A site visit was completed on October 24, 2006 to examine the engineering of the landfill site and obtain monitoring data where available. The following items describe the pertinent features of the landfill site General Observations The Loja landfill site is constructed on the hillsides of the main valley containing the City of Loja. The site is bounded by agricultural land to the south and east and by relatively steep hills to the west and north. There is little local industry and the surrounding area is agricultural. No housing adjoins the site. However, there are a number of buildings associated with the composting plant and recycling plant, which are located within a short distance from the landfill site. In addition, a group of school buildings exists close to the entrance and within the boundaries of the site. The school is currently active Environmental Data The site is at approximately the same altitude as the City of Loja at 2040 m. Barometric pressure readings on the site noted 777 mb, equivalent to 2186 m under standard atmospheric conditions. Average rainfall data for the City of Loja is shown in Table 3. 6

10 Table 3 Average Rainfall (mm) (source: Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Total mm The site is therefore categorized as moderately dry, however the available rainfall is fairly evenly spread throughout the year and therefore moisture content in the waste is likely to be maintained at a level that does not restrict anaerobic decomposition. Further discussion of the effect of moisture content on the generation of landfill gas is given in Section 10, Gas Modeling Waste Depth No original drawings of the site area prior to waste placement are available. The site operators indicate that the current waste is an average of 20 m deep. Waste is deposited in a single platform that has a gradual slope generally to the south of the site Waste Placement Waste is deposited directly from the delivery vehicles into the site. There is no compaction equipment, although an excavator and bulldozer are used to distribute the waste as well as place daily cover and capping materials. There are several locations on the upper surface of the site where slippage fractures are evident in the waste. The lower sections of the site have a retaining wall constructed from timber posts that prevents a waste slide onto the leachate plant access road. This arrangement is currently failing and works are underway to improve the stability of the lower slopes of the waste. While there are no very steep slopes on the site, the instability of the waste mass is likely to be a result of the limited compaction Base Lining The site has a plastic lining that is installed on natural soils. There was no areas of lining material visible during the site visit and observation of the strata excavated near the site indicated that these are likely to have high permeability Capping Layer The current waste covering is constructed from materials that have been obtained from the site excavations. Daily cover is placed on the waste by the site machinery. However as the site is still active, there are no (apparent) areas that have a permanent capping layer. Visual examination of the current capping layer, which could be considered to be temporary pending the development of the new area of the site, indicates that the consistency is variable. The material collected from the perimeter of the site could be considered to be gravels rather than clays with particle 7

11 size of the order of millimeters. Loose materials were being collected from excavations in the hillside to the north of the landfill. Due to both the depth and granular nature of the capping layer, there appears to be limited resistance to either the escape of landfill gas from the waste or the entrance of surface water to the waste. There are a number of areas, particularly in the lower slopes of the site, where waste is exposed. Generally the capping layer can be characterized as variable and offers limited resistance to the ingress of surface water or escape of landfill gas. 8. GAS AND LEACHATE 8.1. Leachate Leachate is the liquor produced by contamination of water within the landfill site by a wide range of solutes resulting from the disposal and decomposition of waste (including organic and in-organic components) in landfills. The water in landfills results from drainage of moisture from the original waste, water resulting from biodegradation, and surface water (rainfall) entering the site. Leachate is highly contaminative and usually has a very low concentration of dissolved oxygen. A leachate collection system, consisting of gravel filled trenches (a French drain ) was installed at the site prior to the deposit of waste. These trenches are interconnected with passive vents for allowing landfill gas to escape from the leachate system. The leachate drains discharge into a concrete chamber at the base of the site and then are directed to a number of interconnected lagoons. No mechanical aeration of leachate takes place, however the arrangement of the lagoons will allow a certain amount of oxygenation. No facilities exist for the measurement of leachate depth in the waste. There is evidence of leachate breakout on the lower slopes of the site, particularly in areas where waste has broken through the capping layer Gas Landfill gas is currently vented from the site through a number of passive vent columns. The passive vents are constructed from boulder-filled steel drums that have been perforated. These columns are constructed from the base of the site where they intersect with the leachate collection system. Measurements of gas concentration were taken at a number of locations. While only one of the measured vents had gas concentrations considered to be typical of landfill gas, there is some evidence that landfill gas is escaping through cracks in the landfill cap. The maximum recorded methane concentration was 24.3% v/v, which was measured at one of the passive vents in the center of the site. The majority of other samples analyzed had methane concentrations of less than 5% v/v. However, strong smells of landfill gas, and the evidence of fires at some of the passive vents, indicates that the site is producing landfill gas with higher methane concentrations than measured. The gas samples were 8

12 taken from a number of the passive gas vents and cracks in the capping layer. Therefore, the low concentrations found in the gas samples are likely to be a result of dilution of the samples with air. Slightly elevated levels of carbon monoxide were also found in the gas samples. This is indicative of landfill fires. Complete gas analysis data is attached to this report Fires Several passive gas vents were on fire during the time of the visit. Generally these were burning at ground level, but in one location this had created a significant underground fire within the waste mass and had created a depression in the landfill surface. The presence of fire within the waste mass is a significant hazard to health and precludes the installation and operation of a landfill biogas extraction system. The existing techniques for extinguishing landfill fires should be investigated. The elimination of fires would allow the installation and operation of a landfill gas collection system and would improve the environmental conditions at the landfill site. 9. GAS MODELING 9.1. Emission Modeling The estimation of landfill gas emissions indicates the potential total landfill gas emissions from the site. This calculation should not be confused with the estimation of recoverable landfill gas that may be available for utilization. Recoverable landfill gas is estimated in Section 12 on page 13 of this report. The baseline for the estimated amount of methane generated by the site has been calculated with the use of two gas models that are based on first order decay mathematics. The Carbon Trade model and the U.S. EPA Mexico LFG Model landfill gas model. Both the proprietary Carbon Trade model and the U.S. EPA Mexico LFG Model are based on the following equation (Eqn.1); Equation 1 - First Order Decay Model n 1 k ( t tlag ) Q = kml 0 % 0e Where: vol Q total quantity of landfill gas generated (Normal cubic meters) n total number of years modeled t time in years since the waste was deposited t lag estimated lag time between deposition of waste and generation of methane % vol estimated volumetric percentage of methane in landfill gas L 0 estimated volume of methane generated per tonne of solid waste k estimated rate of decay of organic waste M mass of waste in place at year t (tonnes) 9

13 When the amount of landfill gas being generated by the site has been theoretically determined, the following equation (Eqn. 2) can be used to estimate the effective number of tonnes of carbon dioxide equivalent being emitted by the site. This factor of 21 1 is used to estimate the greenhouse gas potential, in tonnes of carbon dioxide equivalent, resulting from the emission of methane. Equation 2 - Baseline GHG Emissions TCO eq = % vol Q ρch Where: T CO2eq. Total tonnes of carbon dioxide equivalent generated % vol Estimated volumetric percentage of methane in landfill gas. Q Total quantity of landfill gas from Eqn. 1 (Normal cubic meters) Density of methane = tonnes / cubic meter ρ CH Model Parameters 4 The value of the model parameters L o and k depend on the available organic fraction, the temperature, and the moisture content of the waste. For this analysis, three potential sets of values were developed for these variables based on three references. One set of values for these variables was developed from the recommendations of SCS Engineers, Inc. through the development of the U.S. EPA Mexico LFG Model 3. A second set of values for these variables comes from the recommendations of the current IPCC Guidelines for National Greenhouse Gas Inventories 4 based on the waste composition data provided by the Municipality of Loja and available meteorological information for Loja. The third set of values for these variables comes from the Carbon Trade model. Table 4 shows the three sets of model parameters used in the gas models to develop three sets of comparative emission estimates. It should be noted that the U.S. EPA Mexico recommendation and IPCC Guideline recommendations have been used in the EPA Mexico model. The Carbon Trade model includes a gas production smoothing function as well as classifying four different k values for Domestic, Industrial, Commercial and Inert wastes. Table 4 Model Input Parameters Parameter Source Value Rationale CTL 90 m 3 High Organics with Moderate Rainfall U.S. EPA Mexico 84 m 3 Moderate Rainfall L o (Ultimate methane generation potential) K (Methane generation rate IPCC Guidelines 71 m 3 Calculated from available carbon content, averaged to other sites in Ecuador CTL Average Calibrated to similar sites constant) U.S. EPA Mexico 0.08 Moderate rainfall 10

14 Table 4 - Model Input Parameters (Continued) Parameter Source Value Rationale IPCC Guidelines 0.05 Moderate rainfall CTL 50% v/v % vol (Methane percentage volume) U.S. EPA Mexico IPCC Guidelines 50% v/v 50% v/v Accepted norm for average methane concentration in landfill gas under extraction conditions. 10. BASELINE RESULTS OF GAS MODEL Comparison of landfill gas emission estimates by the Carbon Trade model and U.S. EPA Mexico LFG Model (run with both the Mexico model and IPCC values for k and Lo) are given in the following graph (Figure 1) and in Table 5. The different gas models have a reasonable agreement for the current rate of landfill gas generation at the Loja landfill although the U.S. EPA Mexico model is more optimistic than the others. The models estimate that the site should currently be producing between 211 m 3 /hr and 350 m 3 /hr of landfill gas at 50% methane and that this emission rate will rise to an average peak of approximately 500 m 3 /hr in It should be noted that the site may operate beyond this date and that, in this case, the amount of landfill gas will continue to rise. 700 Loja Landfill, Loja Including site extension to Gas Production Rate m3/hr Time CTL Model LMOP Mexico Model IPCC Model Figure 1 Baseline Landfill Gas Emissions 11

15 Year Table 5 Landfill Gas Model Results CTL Model m 3 /hr LMOP Mexico Model m 3 /hr IPCC Model m 3 /hr Average m 3 50% CH ANTICIPATED COLLECTION EFFICIENCY The estimate of landfill gas generation by the site does not imply that all the gas can be collected for combustion or flaring. Many engineering issues and the continued waste management operations on the Loja landfill site must be taken into account to assess the actual amount of gas that could be collected from the site Available Area The municipality of Loja has estimated that most of the landfill area is currently available for the installation of gas extraction systems. Given the relatively slow input of waste, it should be possible to install a surface laid gas collection system at the existing level and extend this as necessary following disposal of additional waste. Completion of the capping layer will be necessary in some areas of the site prior to installation of the gas collection system. In addition, issues of slope stability will require consideration prior to drilling of the gas wells. Those areas of the site that appear to be unstable should not be used for permanent, 12

16 drilled, landfill gas wells because there is a high likelihood that these will be destroyed by movement in the waste. In this circumstance, temporary gas well installations will allow extraction of a percentage of the landfill gas at lower capital cost Oxygen Ingress Landfill gas that is generated within the waste mass results in a positive pressure within the waste. If the landfill gas is uncontrolled, this pressure drives the gas out of the waste mass by the route of least resistance. Commonly, this results in landfill gas escaping from the surface of the site. But the pressure can also cause the gas to move laterally. For example, gas can move through porous geology or disturbed soils caused by excavations if the capping layer offers a higher resistance. In extreme cases, landfill gas has been known to travel many hundreds of meters along pipes or ducts laid close to the waste. The difference between the site pressure and atmospheric pressure is the driving force of gas migration by this means. Landfill gas collection systems operate by exerting a small vacuum on the waste mass (typically between 5 mb and 50 mb) and thus inducing a pressure gradient. The pressure gradient causes the landfill gas to flow toward the gas wells in preference to its normal migration routes. However, the presence of the vacuum within the waste can also cause air (containing oxygen) to migrate into the site particularly if the sealing of the base or capping layer is poor. Ingress of oxygen into the waste mass alters the anaerobic conditions in the waste to aerobic, thereby reducing the amount of methane generated. To avoid pulling oxygen into the landfill, landfill gas is extracted from some distance below the surface of the site. Higher quality sealing of the capping layer will allow extraction from nearer the surface of the site. On the Loja site, the observed properties and the reported thickness of the capping layer indicate that permeability is moderately high. This permeability limits the vacuum that can be exerted on the waste and the methane collection efficiency. The amount of methane collected could be increased by using a capping clay with lower porosity and by increasing the thickness of the capping layer. Application of a vacuum, with the potential for ingress of oxygen, is extremely hazardous on landfills in which fires exist. Any additional oxygen will increase the rate of combustion of the waste and create very dangerous and potentially uncontrollable fires. It will be a prerequisite that the existing fires are extinguished and procedures are implemented to prevent future fires before any gas extraction can commence on the site. 12. CALCULATED GAS AVAILABILITY The Municipality of Loja has estimated, in the site data provided for this study, that most of the area of the landfill site would be available for installation of a gas collection system. Depending on the management of waste placement at the Loja site, it is estimated that 85% of the site surface could have permanent or temporary gas extraction systems installed. An adjustment factor based on the available extraction area and sealing conditions of the current landfill cap can be calculated as follows: 13

17 Availability Factor = 85% (Available Area) x 60% (Collection Efficiency) The Collection Efficiency is estimated based on the normal assumption of between 70% and 80% efficiency for sites with low permeability clay or synthetic capping layers. The capping layer at Loja appears to be variable in quality; therefore, a lower efficiency should be used. For the purpose of this study, 60% has been selected. The available gas is therefore 51% of the baseline estimated gas generation from the site. Applying this to the data in Table 5 gives an estimated available gas flow shown in Table 6. Methane has a calorific value of approximately 35.5 MJ/m 3, however, because the landfill gas contains approximately 50% methane, the resultant thermal energy contained in landfill gas is MJ/m 3. Table 6 also shows the estimated available thermal energy. Year Table 6 Estimated Available Thermal Energy Average m 3 /hr 50% CH 4 Thermal Energy MJ/hr Thermal Energy mmbtu/hr Thermal Energy kw

18 13. OPTIONS FOR UTILIZATION A number of options exist for the utilization of landfill gas for industrial and agricultural processes, as well as the generation of electrical energy. The methane content of landfill gas can also be separated from the other components and used to supplement natural gas supplies or, in certain circumstance, compressed for use as vehicle fuel. In addition, because methane from solid disposal on land is one of the major sources of greenhouse gas emissions, its capture and oxidation to carbon dioxide results in an environmental benefit. This benefit may be measured and traded under a number of different emission reduction trading schemes worldwide Thermal Energy Landfill gas has been used in a number of industrial or agricultural processes that require thermal energy input. In circumstances where there is a direct use for heat within a reasonable distance from the landfill site, a potential exists for low cost utilization of the landfill gas. Landfill gas has been used for projects including the firing of brick kilns or other ceramic manufacture, heating of greenhouses and other industrial space heat. It should be noted that the combustion products of landfill gas, without pretreatment, may contain compounds that are hazardous to health including dioxins and furans. Therefore, direct use of landfill gas in agricultural processes must be carefully controlled. The current estimated thermal energy available from the Loja landfill indicates that transporting the landfill gas significant distances from the landfill is not likely to be economical. However, it was noted that the Loja Municipality operates a separate collection scheme for clinical waste. In circumstances where a centralization of waste disposal is made at the Loja landfill, the current estimated flow of landfill gas the site would be a significant source of energy to fuel an autoclave. The current recycling center, located on the landfill, has equipment for washing of plastic containers recovered from the waste stream. This is process currently operates with a cold water supply. The landfill gas resource could easily be utilized to provide large amounts of hot water for use in the recycling center and workers premises as well as the neighboring school for space heating and hygiene purposes Electrical Energy Electrical energy can be produced with a variety of technologies. The majority of landfill gas energy projects use spark ignition engines of typically 1.0 megawatt (MW) capacity, while very large projects have used conventional gas turbines producing upwards of 10 MW. Recently developed microturbine technology, typically in the 50 kilowatt (kw) to 250 kw range, has been used on a number of smaller landfill gas projects because the new technology offers low emissions and low maintenance costs. However, microturbines also have lower thermal efficiency than spark ignition engines. Table 7 shows a typical cost comparison for microturbines and spark ignition engines. 15

19 Table 7 Typical Cost of Electrical Generator Equipment Spark Ignition Engine Microturbine Typical electrical capacity 1000 kw 100 kw Minimum electrical capacity 300 kw 30 kw Typical efficiency 38% net electrical 30% net electrical Minimum fuel gas quality 35% v/v at 100 mb 45% v/v at 7 Bar Capital cost per Kw From $520 USD / kw (@minimum 500kW) 1 From $7,200 kw (@30kW) to $2,500 USD / kw (@400kW) 1 Operating Cost per kwh $0.013 USD / kwh 2 $0.014 USD / kwh 2 NOx emissions <500ppm <15ppm 1 Capital cost of the engines / turbine only. Not including fuel supply equipment. 2 Operating cost of the engines / turbine only. Not including fuel supply system. From the predicted gas availability at the Loja landfill site, it is possible that there will be sufficient gas to economically operate a spark ignition engine. This could be used either to supply power to the grid or to supply local energy for site consumption at the recycling center and school. The capital cost of installation of engines is very dependant on the capacity of the project. The estimated amount of gas available from the Loja site is barely sufficient for the smallest commercially available landfill gas spark ignition engine. Therefore, an accurate gas yield must be determined before equipment selection. An option also exists to use microturbines at the Loja site. While microturbines provide a lower electrical efficiency than spark ignition engines, they will produce additional heat as a result. They can be equipped with exhaust heat recovery that provides hot water (co-generation). With lower exhaust emissions, microturbines can also be used to provide carbon dioxide gas to agricultural production. Due to contaminants within landfill gas, it is inadvisable to use landfill gas for agricultural production of food. However, other non-food products such as cut flowers or tree seedlings can benefit from the increased carbon dioxide levels provided. The Loja landfill provides a good opportunity for a small heat or co-generation project with an initial electrical output of 200kW rising to nearly 450kW in the next 10 years. 14. EMISSIONS TRADING It is now possible to account for, and transfer, the reduction in greenhouse gas emissions resulting from activities that reduce or capture any of the six main greenhouse gases. Because methane from solid waste disposal on land is one of the major sources of greenhouse gas emissions, its capture and oxidation to carbon dioxide results in an environmental benefit. This benefit may be measured and traded under a number of different emission reduction trading schemes worldwide. In order to qualify for trading of emission reductions, normally a project must be able to prove that there is no requirement under law, or mandated by waste disposal licenses or other regulations, to 16

20 control the emission of the particular greenhouse gas relating to the project. This appears to be the case at the Loja landfill site. The calculation of emission reductions is defined by methodologies relating to the particular trading mechanisms. As part of all methodologies, it must be proven that normal business practice does not alter the emissions of greenhouse gases. Examination of the Loja landfill site indicates that some of the methane generated by the site has been (periodically) combusted in passive landfill gas flares, although this may have been accidental or informal. In assessing the amount of emission reductions available from the site, a small adjustment factor could reasonably be applied. In the absence of evidence of the effectiveness of the passive flaring of landfill gas, an adjustment factor of 10% is reasonable. The following Equation 3 estimates the number of emission reductions available in each year from the Loja landfill as a result of flaring the landfill gas only (without recovery of energy). Equation 3 - Available Emission Reductions T 2eq. = (1 AF) % 21 Q ρ Avail. CO vol Avail CH Where: T AvailCO2eq. Total emission reductions available in Tonnes of Carbon Dioxide Equivalent. % vol Volumetric percentage of methane in landfill gas. Q Avail Total quantity of landfill gas available. AF Adjustment Factor (10% in this case) Density of Methane = Tonnes / cubic meter ρ CH4 While flaring is the normal method for thermal oxidation of landfill gas, any process which prevents the emission of methane to the atmosphere would also qualify for tradable emission reductions. The carbon dioxide created by the thermal oxidation of methane is considered to be "short cycle" and the product of the normal carbon cycle; and therefore, does not need to be accounted for under the current methodologies. If electrical energy production is also included, and that power is either exported to the local distribution network or used to displace other usage of electricity, it is possible to gain additional emission reductions as a result of the displacement of fossil fuel use. To calculate the number of emission reductions available in each year from the export of electricity, the following equation is used: Equation 4 - Emission Reductions from Fossil Fuel Offset TCO eq = EFgrid MWhexported

21 Where: T CO2eq. Total emission reduction in Tonnes of Carbon Dioxide Equivalent EF grid The grid emission factor for Ecuador = tco 2 /MWh 2. MWh exported Total number of mega-watt hours exported to the grid. On the basis of the calculated availability of landfill gas at the Loja landfill, and assuming that all the methane is used for energy generation and/or flaring, the possible number of emission reductions generated is shown in Table 8. The estimates shown in the first column of Table 8 are the credits that would be available if the gas is flared and are based on the assumption that an enclosed flare is used to ensure a high combustion efficiency. If the gas were combusted in an engine to produce electricity, the project would receive the same credits shown in column one for flaring in addition to the credits shown in column two for displacing fossil fuel-fired electricity generation. Emission reductions produced by the generation of electricity result from the displacement of the use of fossil fuels and are therefore additional to flaring activities. Year Table 8 Estimated Available Emission Reductions CO 2 Equivalent Tonnes Flaring Activities Additional CO 2 Equivalent Tonnes from Electricity Generation in Place of Flaring * * Provided that the installed capacity of electricity generating equipment exceeds gas availability at all times. 18

22 15. OUTLINE SPECIFICATION OF A GAS EXTRACTION SYSTEM In order to collect the landfill gas from the Loja landfill, a gas collection system must be installed. The following general description outlines the equipment and operations required for this purpose. Existing passive gas vents must be removed and the surface must be sealed to prevent oxygen from being drawn into the site. Some of the passive vents may be converted into gas wells provided that they have not been disturbed by movement of the waste. Landfill gas will be collected from the site through a number of vertical and/or horizontal gas wells that are either drilled into the waste mass or installed during waste placement. The technology used for the gas wells will vary depending on the locations. However permanent gas wells are normally drilled, using heavy duty drilling equipment, into the waste mass to within 2 m of the base of the site. The gas wells are lined with MDPE well tube, which is perforated below the surface. The top section of the well tube is solid (non-perforated) and is sealed with hydrated sodium bentonite. In locations that are not suitable for permanent installation, for example in areas where further waste deposits are planned, temporary gas wells will be installed. The temporary gas wells consist of either steel perforated tubes that are driven into the site to a depth of approximately 10 m or in some circumstances a horizontal perforated MDPE tube laid within the waste. It is important that all wells have a solid (non-perforated) section from the surface to a depth of several meters and that this is sealed to prevent air ingress. Horizontal collection pipes can be placed under the advancing waste front. These consist of heavy duty perforated pipe that will emerge from the waste at the sides of the site. The gas wells will be connected to a non-perforated MDPE pipe network through facilities that will allow the operator to control the flow of landfill gas and record primary constituents of the gas as well as pressure and temperature at each location. Dewatering facilities are located in the pipe network to allow liquid condensates to be returned to the waste mass through a liquid seal, or via pumps arranged such that no oxygen can enter the collection system even in the event of failure. Final dewatering of the landfill gas will be located prior to entry to the flare or utilization equipment. Landfill gas will be drawn out of the collection pipe network by the vacuum created by a centrifugal gas pump. The same gas pump is used to pressurize the landfill gas prior to injection into the flare stack or delivery to power generation equipment. Two different types of flare stacks exist for thermal oxidation of landfill gas. Larger installation will normally utilize an enclosed flare, in which the landfill gas is combusted in a temperature controlled chamber. These flares have very high efficiency of oxidation of methane and also destruction of the hazardous air pollutants found in landfill gas. Simpler, "elevated" or "candle stick" flares burn gas in an open flame and do not achieve such high combustion efficiency, but offer considerably lower capital costs. In order to maximize the destruction of methane, it is necessary to use an enclosed flare, which will offer around 99% efficiency compared to candle stick flare efficiency of around 50%. However, with the predicted gas availability at the Loja landfill, it may be preferable to use lower cost equipment, particularly in cases where most of the landfill gas is delivered to power generation or other utilization equipment. 19

23 In order to maximize gas collection efficiency from the proposed extension of the landfill, gas collection systems should be installed during the waste placement operation. Due to the high cost of drilling (relative to the amount of landfill gas available), the option to use horizontal gas collectors should be considered. Horizontal gas collection pipes, which should consist of heavy duty MDPE perforated pipe, could be installed when the waste depth reaches approximately 5.0 m. A second layer of collectors could be installed when an additional 10.0 m of waste is placed in the area. Table 9 shows an indicative bill of quantities for installing a collection system in the existing waste disposal area. Further pipe work would be required in the future in proportion to the additional areas of the site. Table 9 Indicative Bill of Quantities for Gas Extraction System Description Unit Qty Mobilization of Drill Rig Ea 1 Setup at location Ea 15 Drill 300 mm Diameter holes 0-10 m M 150 Drill 300 mm Diameter holes m M mm plain well screen M mm slotted well screen M 225 Gravel M 300 Bentonite Seals Ea 15 Wellheads Ea 15 Small Diameter Surface laid pipe line M 420 Large Diameter Surface laid Pipe M 340 Based on the equipment in Table 9, an indicative capital cost for the construction of a gas collection system is given in Table 10. These numbers represent the average costs of similar systems in Latin America and must be confirmed by obtaining quotations from specialized contractors and equipment suppliers. 20

24 Table 10 Indicative Construction Cost Estimate for Gas Extraction and Flaring Item Indicative Cost Drilling of 18 gas wells $46,375 Installation of Pipe Network $79,874 High Temperature 300 m 3 /hr Flare Stack $233,000 1 (Alternative) Candle Stick 300 m 3 /hr Flare Stack $156,000 2 General Civil Engineering $11,700 Spares and Tools $10,700 General Installation Costs $10,000 Engineering Design and Management $115,000 Contingency $40,000 Total indicative Construction Cost (with High $546,725 Temperature Flare) Total indicative Construction Cost (with $460,100 Candle Stick Flare) 1. Including provision of portable gas analysis, flow rate and data logging. 2. Use of a candlestick flare will result in a reduction in the number of emission credits available. 16. FINANCE MODEL An initial finance model has been developed for the Municipality of Loja using the following inputs: Table 11 Indicative Capital Cost Estimate for Electrical Energy Production Capital Costs Gas Collection System (Table 10) $546, kw Spark Ignition Engine system (average cost $156,000 Table 7) Total Capital Cost $702,725 Table 12 Indicative Operation Cost Estimate for Electrical Energy Production Operating Costs Labor $20,000 Insurance $10,000 Gas System Maintenance 5% of Initial cost per Annum Imported Electricity $0.12 kwh imported Generating Equipment $0.013 / kwh exported Operating Cost Miscellaneous Costs $2 per Operating Hour Annual Inflation 3% 21

25 Table 13 Financial Model Assumptions Tax, Depreciation and Duration and General Assumptions Equipment Depreciation 10% per year Emission Reduction Contract 10 Years Energy Contract 20 Year Tax Before Tax Flare System Availability 95% Engine / Turbine System 85% Availability Table 14 Financial Model Revenue Assumptions Revenue Electricity Tariff $0.095 / kwh Emission Reduction Credits $5 USD, $10 USD and $15 USD Installed Capacity (Flare) 300 m 3 /hr Installed Capacity (Generation) 300 kw from 2008 to 2015, Waste Heat Nil EconomicValue Two financial model scenarios have been run, both with and without power generation. An example of the output of the financial model can be seen in Appendix II and a summary in Tables 15 and 16. In both cases, the Internal Rate of Return (IRR) and Net Present Value (NPV) have been modeled. The NPV is for the cash flow and based on a 15% discount rate. The NPV does not include the return of initial investment. Table 15 Financial Model Results - Electrical Energy Production Capital Cost: $702,725 Including Microturbine Emission Reduction Value $5 / Tonne Emission Reduction Value $10/Tonne Emission Reduction Value $15/Tonne IRR 23.8% 30.5% 37.5% NPV (@15%) $1,097,856 $1,386,459 $1,675,063 Table 16 Financial Model Results - Flaring Only Capital Cost: $546,725 Flaring Only Emission Reduction Value : $5 / Tonne Emission Reduction Value: $10/Tonne Emission Reduction Value $15/Tonne IRR Negative Negative 2.7% NPV (@15%) Negative $126,889 $385,745 The initial financial model therefore indicates that a landfill gas energy project is of more interest at the Loja landfill site than a flaring only project. However, it should be noted that this calculation is based 22

26 on the relatively high tariff available under Ecuador s renewable energy legislation and potential investors should confirm that this will apply to landfill gas projects in this location. 17. CONCLUSIONS The analysis documented in this assessment report indicates that it is possible that a landfill gas utilization project is financially feasible on the Loja landfill. The site is producing moderate quantities of methane that could be utilized for on-site power generation using a spark ignition engine. This would also allow heat recovery, which may be of value to the recycling center and the local school. An option also exists for the use of landfill gas as a fuel for clinical waste incineration. Note that for this purpose a secondary combustion process, using conventional fuels, may be required for compliance with environmental emission standards. The number of emission reductions available at the Loja landfill is relatively small, however there is a possibility that these can be traded internationally. With the growth in climate change investment programs, options may develop that are more financially attractive for the development of smaller methane sources. In summary, the Loja landfill could provide a good opportunity for a small landfill gas to energy project, however, urgent action is required to control the fires on the site. In addition, an improvement in the capping layer would enhance gas collection efficiency. 23

27 REFERENCES 1. Revised 1996 IPCC Guidelines for National Greenhouse Gas Inventories. Paris: Intergovernmental Panel on Climate Change, United Nations Environment Programme, Organization for Economic Co-Operation and Development, International Energy Agency. 2. Emission Factor - Ecuadorian Electricity Grid, ( ), Cordelim, Ministry of Environment, Ecuador. 3. U.S. EPA Mexico Landfill Gas Model Users Manual IPCC Guidelines for National Greenhouse Gas Inventories, Volume 5, Chapter 3. Paris: Intergovernmental Panel on Climate Change, United Nations Environment Programme, Organization for Economic Co-Operation and Development, International Energy Agency. 5. ANÁLISIS SECTORIAL DE RESIDUOS SÓLIDOS ECUADOR, Organización Panamericana de la Salud, Organización Mundial de Salud,

28 APPENDIX I DRAWINGS

29

30 APPENDIX II FINANCIAL MODEL OUTPUT EXAMPLE

31 Carbon Trade Ltd Initial Finance Model Operating Income 14/05/2007 Loja (in U.S. dollars) Year Ending 31-Dec Dec Dec Dec Dec Dec Dec Dec Dec Dec Dec Dec Dec Dec Dec Dec Dec Dec Dec Dec-27 Total General Information Contracted Tonnes CO2e Flaring 117,608 8,248 8,960 9,672 10,444 11,274 12,105 12,936 13,826 14,716 15, Contracted Tonnes CO2e Offset 1,189 1,294 1,402 1,486 1,486 1,486 1,486 1,486 1,486 1, Contracted kwh Flare System Availability 95.0% 95.0% 95.0% 95.0% 95.0% 95.0% 95.0% 95.0% 95.0% 95.0% 95.0% 95.0% 95.0% 95.0% 95.0% 95.0% 95.0% 95.0% 95.0% 95.0% Engine System Availability 85.0% 85.0% 85.0% 85.0% 85.0% 85.0% 85.0% 85.0% 85.0% 85.0% 85.0% 85.0% 85.0% 85.0% 85.0% 85.0% 85.0% 85.0% 85.0% 85.0% Flare Equipment Operating Hours 8,322 8,322 8,322 8,322 8,322 8,322 8,322 8,322 8,322 8,322 8,322 8,322 8,322 8,322 8,322 8,322 8,322 8,322 8,322 8,322 Engine Equipment Operating Hours 7,446 7,446 7,446 7,446 7,446 7,446 7,446 7,446 7,446 7,446 7,446 7,446 7,446 7,446 7,446 7,446 7,446 7,446 7,446 7,446 Prices: Emission Reduction Price (US$/Tonne) kwh Price (US$/MWh) Revenues Sale of CERs - Contract 1,238,725 88,463 96, , , , , , , , , Sale of kwh's 169, , , , , , , , , , , , , , , , , , , ,089 Total Revenues 1,238, , , , , , , , , , , , , , , , , , , , ,089 Costs Gas System Maintenance 734,535 27,336 28,156 29,001 29,871 30,767 31,690 32,641 33,620 34,629 35,668 36,738 37,840 38,975 40,144 41,349 42,589 43,867 45,183 46,538 47,934 Engine System Maintenance 23,233 25,284 27,389 29,039 29,039 29,039 29,039 29,039 29,039 29,039 29,039 29,039 29,039 29,039 29,039 28,557 26,649 24,893 23,274 21,780 Labour 268,704 10,000 10,300 10,609 10,927 11,255 11,593 11,941 12,299 12,668 13,048 13,439 13,842 14,258 14,685 15,126 15,580 16,047 16,528 17,024 17,535 Electricity 134,169 4,993 5,143 5,297 5,456 5,620 5,788 5,962 6,141 6,325 6,515 6,710 6,912 7,119 7,333 7,553 7,779 8,013 8,253 8,501 8,756 Insurance 254,444 10,000 10,300 10,000 10,300 10,609 10,927 11,255 11,593 11,941 12,299 12,668 13,048 13,439 13,842 14,258 14,685 15,126 15,580 16,047 16,528 Miscellaneous 447,231 16,644 17,143 17,658 18,187 18,733 19,295 19,874 20,470 21,084 21,717 22,368 23,039 23,730 24,442 25,176 25,931 26,709 27,510 28,335 29,185 Total Operating Cost 1,839,083 92,207 96,327 99, , , , , , , , , , , , , , , , , ,719 Operating Income before Depreciation, Interest & Tax -702, , , , , , , , , , , , , , , , , , , , ,370 Initial Capital Cost -702,725 IRR 30.5%

32 APPENDIX III GAS ANALYSIS RECORD

33 Site Monitoring Record Site Name: Loja, Ecuador Record Date: Weather: Sunny Atmos. Pressure mb: 777 ID CH 4 (%) CO 2 (%) O 2 (%) H 2 S (ppm) CO (ppm) mb Depth Flow Rate Note No Note No Note 1 Measurements in Passive vents 2 Large variation in readings, strong gas smell, unable to locate emission, measurement in passive vents 3 Measurement in failure crack 4 Measurement in passive vent, note high CO 5 Measurement in Passive Vent, depth 1 5m estimated waste 20m 6 Measurement in surface crack 7 Measurement in leachate discharge tube. Recorded By: AL & CS

34

35 APPENDIX IV PHOTOS

36 Figure 2 General view of the landfill

37 Figure 3 Passive vent with evidence of recent fire

38 Figure 4 Fire on the site

39 Figure 5 Área of exposed waste

40 Figure 6 Failing slopes at the site

41 Figure 7 Analysis of gas from covered area

42 Figure 8 Capping material is excavated for covering the waste