FINAL ASSESSMENT REPORT: LANDFILL BIOGAS RECOVERY AND UTILIZATION AT THE SOLID WASTE TREATMENT CENTER BR-040 BELO HORIZONTE, BRAZIL

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1 FINAL ASSESSMENT REPORT: LANDFILL BIOGAS RECOVERY AND UTILIZATION AT THE SOLID WASTE TREATMENT CENTER BR-040 BELO HORIZONTE, BRAZIL Prepared for: Urban Sanitation Superintendence of Belo Horizonte Prepared under: U.S. Environmental Protection Agency Landfill Methane Outreach Program Contract: EP-W TO 008 and 021 By: Eastern Research Group, Inc. and MGM International Group, LLC September 5, 2008

2 PREFACE This report provides a preliminary assessment of the feasibility of recovering and using landfill biogas from Central de Tratamento de Resíduos Sólidos BR-040 (CTRS BR- 040) (i.e., Solid Waste Treatment Center BR-040; hereinafter called Belo Horizonte Landfill ), in the municipality of Belo Horizonte, Brazil. The report was prepared through the Methane to Markets assistance program of the U.S. Environmental Protection Agency s (EPA) Landfill Methane Outreach Program (LMOP). As part of the Methane to Markets Partnership, EPA is working in conjunction with the Government of Brazil on an international initiative to reduce global methane emissions. Methane to Markets promotes the beneficial use of landfill methane, while also reducing landfill methane emissions to the atmosphere. One of the key activities of this cooperative program includes identifying suitable landfills with sufficient quantities of high quality biogas that can be used to meet local energy needs. To support this activity, EPA has contracted with ERG and MGM International to conduct the assessment presented in this report. MGM International is a subcontractor to ERG. MGM staff visited the Belo Horizonte Landfill on 27 June The staff of Urban Sanitation Superintendence (Superintendência de Limpeza Urbana from Belo Horizonte - SLU) provided information on the landfill. Staff members include Heuder Pascele, landfill manager, Cícero Antonio Antunes Catapreta, landfill engineer and Karla Garcia Tavares, biologist.their assistance is appreciated. Throughout this report, costs are given in 2007 U.S. dollars, unless other units are specified. The currency conversion rate is approximately 1.8 Brazilian Reais per U.S. dollar. DISCLAIMER This report was prepared under Contract No. EP-W between ERG and EPA. Opinions and judgments expressed herein do not necessarily represent the views of EPA. This report is a preliminary assessment intended to introduce potential project developers to the Belo Horizonte Landfill. It is based, to a great extent, on information provided to the authors by others. The information is not guaranteed to be complete or ii

3 accurate. Developers or investors should perform their own due diligence before investing in a landfill biogas recovery project at the landfill. Designs and calculations of costs, landfill biogas production, and other factors in this report are based on mathematical models, experience at other landfills, and assumptions. They are estimates based on a degree of care suitable only for a preliminary assessment. Final designs, costs, and landfill biogas production may differ from those presented in this report. The information and data used in preparing this report were collected in mid Substantial changes might have occurred between that time and the date of the final report. The report has not been modified to reflect those changes. Potential developers and investors should make certain that they base decisions on up-to-date information. iii

4 DEFINITIONS AND ABBREVIATIONS ABNT ABRELPE C EPA EPC ER FEAM GHG GJ GWP h Ha IC Associação Brasileira de Normas Técnicas (Brazilian Association of Technical Standards) Associação Brasileira de Empresas de Limpeza Pública e Resíduos Especiais (Brazilian Association of Public Cleaning and Special Waste Companies) Celsius United States Environmental Protection Agency Engineering, Procurement, and Construction. A project development method in which a single contractor is hired to design, to procure equipment, and to construct the project. It is often referred to as a turnkey project. Emission Reduction Credit. Credit or payment given in exchange for reducing greenhouse gas emissions. Fundação Estadual de Meio Ambiente (State Environmental Foundation). The environmental permitting agency in the state of Minas Gerais. Greenhouse Gas Gigajoule (one billion Joules) (approximately 0.95 million British Thermal Units). In this report, all values of heat are based on the higher heating value calorimeter test method. Global Warming Potential. The strength of a greenhouse gas relative to the strength of an equal mass of carbon dioxide. The GWP of methane is taken to be 21 in Clean Development Mechanism processes. Hour Hectare (10,000 square meters) Internal Combustion (type of engine) iv

5 IPCC IRR kj kw kwh m³/h Mg MSW MW MWh Nm³ NPV OM&M SLU TCO 2 E Tonne UNFCCC Intergovernmental Panel on Climate Change Internal Rate of Return Energy equivalent of one kw for one second. In this report, all values of heat are based on the higher heating value calorimeter test method. Kilowatt Kilowatt-hour. Electric energy equivalent of one KW for one hour. cubic meters per hour Megagram. One Tonne (1,000 kg) Municipal Solid Waste Megawatt (1,000 kw) Megawatt-hour. Electric energy equivalent to one MW of power for one hour. Normal cubic meters. Gas volume when the gas is at a temperature of zero degrees Celsius and a pressure of 1,013 millibars. Net Present Value Operation, Maintenance, and Monitoring Urban Sanitation Superintendence of Belo Horizonte Metric tonnes of carbon dioxide equivalent. A unit of measure used to express a quantity of a greenhouse gas, such as methane, in terms of the metric tonnes of carbon dioxide that would exhibit an equivalent global warming effect. Metric ton (1,000 kilograms; about 2,204 pounds) United Nations Framework Convention on Climate Change v

6 TABLE OF CONTENTS PREFACE... ii DISCLAIMER... ii DEFINITIONS AND ABBREVIATIONS... iv 1. LANDFILL BACKGROUND Location Waste Quantity and Composition Landfill Owner and Operator Landfill Design and Filling Practices Permits and Environmental Compliance LANDFILL BIOGAS GENERATION AND POTENTIAL GREENHOUSE GAS EMISSION REDUCTIONS Landfill Biogas Recovery Modeling Energy Recovery Greenhouse Gas Emission Reductions CONCEPTUAL DESIGN Design Overview Well Field Design Flare Station Design Electric Power Plant Design ECONOMIC ANALYSIS Initial Investment Annual Costs Project Income Net Present Value (NPV) and Internal Rate of Return (IRR) CONCLUSIONS AND RECOMMENDATIONS vi

7 TABLES Table ES-1. Emission Reductions and Economic Results 2 Table 1. Annual Municipal Solid Waste Disposal... 5 Table 2. Municipal Solid Waste Composition at Belo Horizonte Landfill... 6 Table 3. Estimated Methane and Energy Recovery Table 4. Estimated Emission Reductions (TCO E) 2...Error! Bookmark not defined. Table 5. Economic Analysis Table 6. Emission Reductions and Economic Results FIGURES Figure 1. Location of Belo Horizonte City... 4 PHOTOS Photo 1. Scale at Landfill Entrance... 5 Photo 2. Filling Area of Belo Horizonte Landfill... 7 vii

8 EXECUTIVE SUMMARY This report provides a preliminary assessment of the feasibility of collecting and burning landfill biogas generated by the Belo Horizonte Landfill to generate electricity. The Belo Horizonte landfill receives about 670,000 tonnes of municipal solid waste per year from the municipality of Belo Horizonte. Belo Horizonte is about 586 kilometers north of São Paulo in the state of Minas Gerais, Brazil. The Belo Horizonte Landfill complies with the commonly-accepted standards for sanitary landfills in Brazil. It operates under a permit granted by the environmental regulatory agency of the State of Minas Gerais. Waste is moved into place in an organized manner, compacted, and covered daily. The landfill has gas vents, leachate drains and an impermeable bottom liner. Leachate is stored prior to treatment off site at the Estate Waste Waster Treatment Plant operated by COPASA, Companhia de Saneamento de Minas Gerais (i.e., Minas Gerais Sanitation Company). The landfill opened in It is expected to close by the end of 2007 because it will reach its design capacity. After 2007, the waste from Belo Horizonte will likely be disposed at a privately-owned landfill that is several kilometers from the current disposal site. The municipality has tentative plans to open another publicly-owned landfill, but this will likely take at least two years. The Belo Horizonte landfill is controlled and owned by the Municipality of Belo Horizonte. Any project at the site would likely be developed through a contract or concession agreement with the Municipality of Belo Horizonte. Municipal staff reported that a request for proposals may be issued soon. The LandGEM landfill biogas generation model developed by the EPA was used to estimate methane generation in the landfill. Landfill biogas was assumed to be captured at an efficiency of 65 percent if clay were used to cover the landfill. Greater collection efficiency might be achieved if certain designs and operating procedures were adopted, such as the use of a geomembrane landfill cover. Sufficient landfill biogas could be recovered to generate 9 MW of power in However, power that could be generated would decrease rapidly after the first few years 1

9 of operation as the supply of decomposable waste is depleted. In this report, a power plant capacity of 5 MW is found to yield the greatest net present value. Table ES-1 shows estimated emission reductions for a variety of scenarios. A 14-year landfill biogas energy project extending from the beginning of 2009 through the end of 2022 is estimated to generate emission reductions exceeding 1.8 million tonnes of carbon dioxide equivalent (TCO 2 E). About 75 percent of the emission reductions are estimated to occur by the end of Table ES-1. Emission Reductions and Economic Results Project Duration (years) Emission Reductions (TCO 2 E) MW Power Generation 1,448,831 1,892, MW Power Generation 1,412,590 1,855, MW Power Generation 1,337,363 1,779,452 Flare Only (1) 1,244,426 1,623,007 Internal Rate of Return 7.5 MW Power Generation 22.1% 24.5% 5.0 MW Power Generation 29.2% 31.3% 2.5 MW Power Generation 36.5% 38.7% Flare Only (1) 58.8% 59.3% 5%/year (2)($000) 7.5 MW Power Generation 7,417 10, MW Power Generation 8,493 12, MW Power Generation 7,298 10,813 Flare Only (1) 5,148 5,838 10%/year (2)($000) 7.5 MW Power Generation 4,633 6, MW Power Generation 5,914 8, MW Power Generation 5,371 7,595 Flare Only (1) 4,118 4,577 Notes: 1. All scenarios include a flare. If power generation is included, then the gas not used to generate power is assumed to be flared. 2. In calculating internal rate of return and net present value, inflation is assumed to be zero. The NPV is expressed in thousands of US dollars. The internal rate of return (IRR) exceeds 25 percent per year for all of the scenarios presented in Table ES-1, except for the 7.5 MW generator options. Numerous assumptions and estimates were used in calculating the IRR. For example, electricity was taken to have a value of $65 per MWh at the point of delivery to the electricity transmission grid. 2

10 The electricity market in Brazil may change substantially in the next several years and changes in government incentive programs for renewable energy might affect prices. Potential developers should evaluate independently the price for which they would be able to sell electricity. If the price were $45 per MWh instead of $65 per MWh, the IRR for a 5 MW project, would be only about 18 percent instead of 31 percent as shown in Table ES-1. The IRR for all other power generation scenarios in Table ES-1 would also be decreased substantially. Generally, the IRRs for projects with greater power capacities are less than the IRRs for projects of lower capacity. The decrease in IRR occurs because, after the first few years of operation, the supply of landfill biogas is not sufficient to keep the larger plants operating at or near their full capacity. The investment in underutilized capacity adversely affects the rate of return on the investment in the larger projects. The values of IRR and NPV are based on an emission reduction credit price of $10 per TCO 2 E. That price could increase or decrease substantially, depending on the source of the credits. Overall, a landfill biogas recovery project with electric power generation at the Belo Horizonte Landfill appears to be very attractive. However, the economic feasibility of a project will decrease rapidly if the initiation of a project is delayed. Landfill biogas generation will begin decreasing soon because the landfill will stop receiving new waste late in As the rate of landfill biogas generation decreases, the economic return on underutilized equipment will decline. 3

11 1. LANDFILL BACKGROUND 1.1. Location The Belo Horizonte landfill is located in the municipality of Belo Horizonte in the state of Minas Gerais in southeastern Brazil. Belo Horizonte is located in the Southeastern region, approximately 444 kilometers northwest of the city of Rio de Janeiro. Belo Horizonte is a major industrial center with a good transportation infrastructure providing access to major cities and ports. Figure 1. Location of Belo Horizonte City The landfill lies about 850 meters above sea level. The climate in Belo Horizonte is tropical. About 1,500 millimeters of rain falls per year. The average annual temperature is about 20 C. 4

12 1.2. Waste Quantity and Composition Virtually all of the municipal solid waste (MSW) disposed at Belo Horizonte Landfill is from the municipality of Belo Horizonte, which has a population of about 2,400,000 people. Currently, about 670,000 tonnes of MSW is disposed per year. Table 1 shows annual MSW disposal data. Waste quantities are measured by an on-site scale, as shown in Photo 1. Table 1. Annual Municipal Solid Waste Disposal Year Mass of Waste (tonne) Year Mass of Waste (tonne) , , , , , , , , , , , , , , , , , ,000 (1) Source: Superintendência de Limpeza Urbana Belo Horizonte Municipality (1) Landfill is expected to close late in 2007 Photo 1. Scale at Landfill Entrance 5

13 The landfill was opened in 1975, but did not operate as a sanitary landfill until From 1990 to million tonnes of MSW was disposed in the landfill. The landfill is expected to close by the end of 2007, at which time it will have received about 11 million tonnes of MSW since In addition to MSW, about 1,200 tonnes per day of mostly inert construction and demolition waste is delivered to the landfill site. This waste is recycled and not disposed in the landfill. About 50 tonnes per day of hospital waste is disposed in a speciallydesignated area on the landfill site. The composition of the MSW is approximately as shown in Table 2. Food, paper, and other material that readily decomposes to form landfill biogas compose about 76 percent of the total mass of waste on a wet basis. Table 2. Municipal Solid Waste Composition at Belo Horizonte Landfill Waste Component Fraction by Mass (%) Food Waste 41 Paper/cardboard 10 Plastics 11 Metal 2 Glass 3 Garden and Park Waste 9 Nappies/Diapers 12 Rubber and Leather 4 Other Inert Waste 9 Source: Superintendência de Limpeza Urbana Belo Horizonte Municipality 1.3. Landfill Owner and Operator The Belo Horizonte Landfill is under the legal control of the Municipality of Belo Horizonte, through Superintendência de Limpeza Urbana (SLU), which is a municipally-owned sanitation services company. SLU has legal ownership of the MSW and of the land. It is in charge of daily landfill operations Landfill Design and Filling Practices The Belo Horizonte Landfill covers an area of about 70 hectares. The deepest sections of the landfill have a depth of about 65 meters. The sanitary landfill consists of three cells, the last of which will be completed by the end of

14 The Belo Horizonte Landfill is a sanitary landfill. That is, the landfill complies with the Brazilian Association of Technical Standards (ABNT) standards for sanitary landfills. It is surrounded by residential and industrial areas, so controlling odors through regular cover and combustion of vented biogas is important. Photo 2. Filling Area of Belo Horizonte Landfill Part of the landfill, which was filled prior to 1990, is landscaped and used for environmental education programs and activities for the public and for schools. In the remaining areas, the waste is covered daily with soil. The waste is moved into place and compacted by heavy mechanical equipment to minimize the area of uncovered waste, to minimize the volume, and to promote structural stability. In accordance with sanitary landfilling practices in Brazil, leachate is collected via horizontal and vertical drains within the landfill. Initially, the bottom of the sanitary landfill was lined with compacted clay. However the more-recently filled areas are lined with impermeable plastic. Leachate is treated offsite at the Estate Waste Water Treatment, COPASA (Companhia de Saneamento de Minas Gerais). Vents for removing gas from the landfill are constructed from vertical columns of rocks extending from the bottom of the landfill to the surface. Metal pipes are placed into the rock columns near the surface of the landfill to carry the gas one to two meters above 7

15 the surface. Vents are spaced at irregular distances from each other, but are as close as 30 meters apart in some places. A small burner and a blower are connected by pipe to a few gas vents. The blower and burner are not operated currently. The system was used several years ago as to perform pump tests to estimate landfill biogas emissions Permits and Environmental Compliance In Brazil, the permitting of landfills is the responsibility of the state governments. The applicable agency in the State of Minas Gerais is FEAM (Fundação Estadual de Meio Ambiente; State Environmental Foundation ). Three types of permits exist. They apply to many types of projects including, but not limited to, landfills. a) Preliminary License is issued in the preliminary phase of planning. It approves the location and conceptual design. It certifies the environmental viability and establishes the basic design requirements. b) License of Installation authorizes the installation of the project. It specifies environmental controls and monitoring to be implemented. c) Operation License authorizes the operation of the project. The Belo Horizonte Landfill has all required permits, including the Operation License, which is valid until the end of The municipality plans to site a new publicly-owned landfill several kilometers from the existing site. Opening a new landfill is expected to take at least two years. Until that time, MSW from Belo Horizonte will be sent to one or two privately-owned landfills that are already operating. Those landfills are several kilometers from the current site, so combining gas collection systems at Belo Horizonte and either of the other landfills is not a realistic option. 8

16 2. LANDFILL BIOGAS GENERATION AND POTENTIAL GREENHOUSE GAS EMISSION REDUCTIONS 2.1. Landfill Biogas Recovery Modeling The LandGEM landfill gas generation model developed by EPA is used in this report to estimate methane generation from the Belo Horizonte Landfill. LandGEM uses a first-order decay model to estimate the quantity of methane generated in a landfill. Its basic form follows. Q CH 4 n kl0 ( M /10) e i 1 1 j 0.1 i k t i j Where Q CH4 = methane generation in the year of the calculation (m³/yr); i = one-year time increment; n = (year of the calculation) (initial year of waste acceptance) j = one-tenth-year time increment k = methane generation rate constant (year -1 ) L 0 M i t ij = potential methane generation capacity (m³ methane per tonne MSW) = mass of waste acceptance in the i th year (tonnes); = age of j th section of waste mass M i accepted in the i th year (decimal years; e.g., 3.2 years). For use in this study, the LandGEM model was specifically tailored to model the conditions at the Belo Horizonte Landfill. The methane generation rate constant (k) is taken to be 0.17/year, in accordance with guidelines of the Intergovernmental Panel on Climate Change (IPCC) for tropical areas. In Belo Horizonte, annual rainfall is 1,500 millimeters per year and the mean temperature is 20 C. The estimated potential methane generation capacity of the MSW at Belo Horizonte landfill (L 0 ) is 75 normal cubic meters (Nm³) of methane per tonne of solid waste. The value of L 0 was derived by applying the waste composition shown in Table 2 to a calculation procedure developed by the IPCC. The procedure accounts for the typical moisture content and degradability of various organic components of typical municipal solid waste. 9

17 The mass of waste accepted in each year (M i ) was reported by SLU and is shown, for , in Table 1. Waste disposed prior to 1990 was also included in the LandGEM model. The waste deposited prior to 1990 contributes very little to the current and future methane generation. The estimated quantity of methane generated during each year from 2007 through 2022 is shown in Table 3. The quantities are those calculated by the LandGEM model when applying the site specific factors discussed above. According to the LandGEM model, the methane generation rate increases to a maximum value in 2007, which is the year of landfill closure. After the landfill closes, the methane generation rate decreases exponentially as the amount of decomposable matter in the landfill decreases. Year Methane Generation (tonnes) Table 3. Estimated Methane and Energy Recovery Methane Landfill Biogas Thermal Recovery Flow Rate Energy (tonnes) (Nm³/h) (GJ/h) Electric Power Potential (MW) ,922 22,699 7, ,722 21,920 6, ,450 18,493 5, ,003 15,602 4, ,250 13,163 4, ,084 11,105 3, ,413 9,369 2, ,160 7,904 2, ,259 6,668 2, ,655 5,626 1, ,302 4,746 1, ,161 4,004 1, ,197 3,378 1, ,385 2, ,699 2, ,121 2, Note: See text for procedures and assumptions used in calculating values in this table. It is very difficult or impossible to recover all of the biogas generated in a landfill because the landfill cover is not impermeable and biogas can escape through the cover and through the bottom of the landfill. To estimate the quantity of methane that can be recovered, an assumed value of collection efficiency is multiplied by the quantity of methane generated. The net collection efficiency depends on the quality of the landfill cover, the fraction of the landfill affected by gas collection wells, the design of the wells, the suction applied to the wells, and other factors. 10

18 In this report, the net collection efficiency is assumed to be 65 percent. That value is considered reasonably achievable for a moderately well-designed well field. Actual collection efficiency could be greater or less than 65 percent. A plastic geomembrane cover over the landfill, combined with diligent maintenance, could increase the collection efficiency substantially. A geomembrane cover would also decrease rainwater intrusion into the landfill and, thereby, decrease leachate generation. The combined benefits of improved landfill biogas collection efficiency and decreased leachate generation might justify the cost of installing a geomembrane cover at the Belo Horizonte Landfill. This option should be considered by potential project developers. However, in this report, a geomembrane cover is assumed to not be installed. Cost estimates and landfill biogas recovery estimates are based on the assumption that the landfill is covered only with clay and topsoil. The estimated quantity methane recovered when the collection efficiency is 65 percent is shown in the third column of Table 3. The average flow rate of landfill biogas is shown in the fourth column of Table 3. The flow rate is calculated as follows. The Methane Recovery (tonnes) is multiplied by 1,000 kg/tonne; divided by the density of methane ( kg/nm³) to yield normal cubic meters of methane recovered during a year; divided by 8,760 hours per year to calculate an hourly flow; and multiplied by 2 to estimate total landfill biogas flow assuming the concentration of methane is 50 percent. The maximum flow rate of 5,890 Nm³/h in 2009, the assumed project start-up year project, would be used to select the size of pipes and other equipment in a landfill biogas recovery system Energy Recovery In Table 3, the amount of thermal energy that could be produced by burning the recovered landfill biogas is shown in the fifth column. Methane has a higher heating value of about 39,800 kilojoules per normal cubic meter. The maximum flow of energy is estimated to occur in 2007 and to amount to 144 gigajoules (GJ) per hour. By 2012, the energy recovery rate decreases to about half of its maximum value. The electric power that could be generated by the recovered landfill biogas is shown in the sixth column of Table 3. Electric power, in megawatts (MW), is calculated by 11

19 dividing the thermal energy (in the fifth column) by an estimated heat rate of 13.0 GJ/MWh. This heat rate is intended to conservatively estimate the net power generated by a landfill biogas-fueled power plant. Assuming a project start date of 2009, the peak gas flow from the Belo Horizonte landfill is estimated to be sufficient to generate 9.0 MW of power. By 2013, the power that could be generated is estimated to decrease by about 50 percent of the maximum value. If a power plant began operation in 2009, it would be 14 years old in 2022, a common project lifespan that will be used in the analysis of this assessment. By that time, the recovered landfill biogas flow is estimated to be sufficient to generate only 0.99 MW Greenhouse Gas Emission Reductions Landfill biogas recovery projects can decrease emissions of greenhouse gases in two ways. First, the methane in the landfill biogas is destroyed through combustion. One tonne of methane is estimated to have a global warming effect equivalent to 21 tonnes of carbon dioxide (Climate Change 1995: The Science of Climate Change. Intergovernmental Panel on Climate Change, J.T. Houghton, L.G. Meira Filho, B.A. Callander, N. Harris, A. Kattenberg, and K. Maskell, eds. Cambridge University Press. Cambridge, U.K.). Thus, the global warming potential (GWP) of methane is 21. Second, landfill biogas can be used as a fuel to generate electricity or to produce useful thermal energy. If the landfill biogas displaces the use of fossil fuel such as coal, oil, or natural gas; then carbon dioxide emissions from fossil fuel would be avoided. Emission reductions achievable from a landfill biogas recovery project at Belo Horizonte landfill are shown in Table 4. Emission reduction quantities are expressed as the mass of carbon dioxide, in tonnes, equivalent to the emission reductions from methane destruction and from the displacement of fossil fuel in electricity production (i.e., tonnes of carbon dioxide equivalent or TCO 2 E). Emission reductions from 100 percent methane destruction are shown in the second column of Table 4. They are calculated by multiplying the mass of recovered methane (third column of Table 3) by 21 (the GWP of methane), by applying an adjustment for baseline emission reductions, as described in the following paragraph, and by assuming 12

20 the destruction efficiency of the project is 100 percent. Many energy recovery technologies are assumed to achieve close to 100 percent methane destruction. Table 4. Estimated Emission Reductions (TCO 2 E) Methane Destruction Fossil Fuel Displacement Cumulative Year 100% 90% Full Potential 5.0 MW Reduction , ,212 24,415 11, , ,425 23,577 11, , ,611 19,891 11, , , ,898 16,781 11, , , ,019 14,158 11, , , ,905 11,944 11, , , ,656 10,077 10,077 1,154, , ,510 8,502 8,502 1,294, , ,826 7,173 7,173 1,412, ,515 85,064 6,051 6,051 1,512, ,739 71,765 5,105 5,105 1,596, ,273 60,546 4,307 4,307 1,667, ,756 51,080 3,634 3,634 1,726, ,883 43,095 3,066 3,066 1,777, ,397 36,357 2,586 2,586 1,820, ,082 30,674 2,182 2,182 1,855,960 Note: See text for procedures and assumptions used in calculating values in this table. Emission reduction credits from methane combustion can be claimed only to the extent that more methane is burned in the emission reduction project than would be burned in the absence of the project (i.e., the baseline ). Many landfills in Brazil include passive vents that allow gas to escape from porous rock columns that are installed as the landfill is constructed. If landfill biogas emitted from those vents were burned as a normal practice at the landfill, a project developed for the purpose of decreasing GHG emissions would have to account for the methane that would be destroyed in the absence of the project. The common practice at such landfills in Brazil is to assume that 20 percent of the methane destroyed in a landfill biogas recovery project would have been burned in the absence of the project due to the presence of the passive vents. The Belo Horizonte Landfill normally burns landfill biogas emanating from vents. So, a 20 percent decrease in emission reductions is included in the calculations in Table 4. In the third column of Table 4, emission reductions are shown for the destruction of 90 percent of the recovered methane. A methane destruction efficiency of 90 percent is often the default value assumed for enclosed flares. 13

21 The fourth column of Table 4 shows the maximum carbon dioxide emission reductions attributable to displacing fossil fuels for electricity generation. When operating at full capacity, the landfill biogas-fueled power plant is assumed to use all of the available landfill biogas. The electric power capacities shown in the sixth column of Table 3 were used to calculate these emission reductions. However, a capacity factor of 90 percent is applied in calculating total electricity generated in a year because the plant is expected to operate at part-load some of the time and to be completely shut down some of the time, primarily for maintenance and repair. On an annual basis, the power plant is assumed to generate only 90 percent of the electricity it would generate if it used all of the available landfill biogas. Emission reduction credits from electricity generation depend substantially on how electricity on the electric grid is normally produced in a given region. If all of the electricity distributed on the grid were generated by hydroelectric projects, which do not produce carbon dioxide emissions, then using landfill biogas to displace some of that electricity would not decrease carbon dioxide emissions. On the other hand, if the power were generated by coal-fired power plants, about 0.9 tonne of carbon dioxide would be avoided for each megawatt-hour of coal-fired power displaced by landfill biogasgenerated power. Belo Horizonte lies in the southeast region of Brazil, where the carbon emission factor is about 0.28 tonne of carbon dioxide per MWh. The factor is low compared to many other areas because much of the electricity in the region is derived from hydroelectric projects. The method for calculating the carbon emission factor is under review and it is possible that a new value of about 0.1 tonne per MWh will be designated for calculating displaced emissions credits. In this report, the value of 0.28 tonne of carbon dioxide per MWh is used to estimate the emission reductions from fossil fuel displacement. A major shortcoming of many landfill biogas-fueled power plants is that the supply of landfill biogas varies as a landfill ages. Often, landfill biogas power projects are not designed to use the maximum landfill biogas flow rate. A project that includes equipment sized to handle the maximum landfill biogas flow would be underutilized much of the time. The cost of equipment needed to fully utilize the landfill biogas is often not justified. 14

22 The fifth column of Table 4 shows the emission reductions attributable to a 5 MW landfill biogas power plant. The plant would generate 5 MW when there is sufficient gas to generate at least 5 MW (i.e., to 2012). At other times, the plant would use all of the collected landfill biogas and would generate less than 5 MW. The 90 percent engine capacity factor discussed above is also applied in calculating the values in the fifth column. The sixth column of Table 4 shows the cumulative emission reductions for a landfill biogas power project of 5 MW capacity. The cumulative emission reductions include the following: - All emission reductions from previous years. The landfill biogas project is assumed to begin operation at the beginning of Emission reductions attributable to the displacement of electricity from the regional grid (values from the fifth column) - Emission reductions from the destruction of 100 percent of the methane used in power generation and 90 percent of the methane used in an enclosed flare. Recovered landfill biogas not utilized in generating power is assumed to be burned in the flare. Because the combustion efficiency is taken to be 90 percent for gas burned in a flare and 100 percent for gas burned in an engine, the cumulative emission reductions shown in the sixth column are not exactly equal to the sum of emission reductions shown in the other columns. The estimated emission reductions during the 14-year period 2009 through 2022 amount to 1.86 million TCO 2 E. While the estimates in this section were derived using commonly-accepted methods and assumptions, they are not guaranteed. Project developers and investors should do their own analyses of the project before undertaking a landfill biogas recovery project at Belo Horizonte Landfill. 15

23 3. CONCEPTUAL DESIGN This section addresses the major design features of a possible landfill biogas-to-energy project that may be feasible at the Belo Horizonte Landfill. Designs and design criteria are addressed only to the extent necessary to provide a basis for the preliminary economic evaluation in Section 4 of this report Design Overview A landfill biogas recovery and utilization project at the Belo Horizonte landfill would include the following components. a) A well field consisting of vertical or horizontal wells, pipe connecting the wells to the flare station, improvement of the landfill cover, monitoring and control equipment, and a condensate management system. Generally, pipes should be sized to avoid gas velocities exceeding 15 meters per second. b) A flare station consisting of an enclosed flare, blowers to move the landfill biogas, and ancillary equipment for safety, process control, and monitoring. The flare station would be designed to handle the expected maximum landfill biogas flow rate. The estimated rate of 5,890 Nm³/h, as shown in Table 3 for the estimated start-up year of 2009, are used in the economic analysis in this report. Developers should perform their own analyses to estimate flow and to design the project. c) An electric power plant consisting of landfill biogas-fueled engines, generators, and ancillary equipment. The power plant capacity is taken to be 5.0 MW. A power plant of this capacity would use almost all of the hourly landfill biogas flow in the early years of the project. In later years, the landfill biogas flow would be sufficient to fuel the engines at only a small fraction of their full capacity. Final designs should include a careful analysis of the trade-offs between sizing the power project to utilize all of the available landfill biogas versus investing in capacity that will be underutilized during much of the project life. 16

24 The landfill is several kilometers from any industry that could use the landfill biogas in its processes, so piping the gas to an off-site user is probably not practical. Upgrading the landfill biogas to pipeline quality requires a heavy investment in equipment and would probably not be practical at the Belo Horizonte landfill. There are no major potential uses of the landfill biogas on the site, except for leachate evaporation. Leachate evaporation requires a very large investment in equipment and is generally justified only when leachate management costs are very high. Currently, leachate is treated off-site. Leachate treatment costs were not available in preparing this assessment, but it is assumed that the costs would not be high enough to justify installing leachate evaporators. Electric power lines extend to the landfill and, although they may need to be upgraded to support an electric power project, they demonstrate that rights of way and basic electric infrastructure are in place. Consequently, generating electricity is the most likely beneficial use of the landfill biogas. When the landfill biogas is used to generate electric power, a flare is not necessary for burning the landfill biogas. However, it is generally beneficial to include a flare. The power plant is not likely to use all of the available landfill biogas. The value of emission reduction credits that would be lost when methane is vented to the atmosphere rather than burned is likely to exceed the cost of a flare. For example, a 5 megawatt power plant burns about 1.2 tonnes of methane per hour when operating. If the power plant failed to function 10 percent of the time, landfill biogas vented to the atmosphere would amount to about 22,000 TtCO 2 E per year of lost emission reduction credits. At a price of $10 per TCO 2 E, the value of the lost emission reduction credits would be $220,000 per year. That revenue would pay for a flare in about one or two years. Consequently, this report includes a flare, as well as a power plant, in the conceptual design Well Field Design Either vertical or horizontal wells may be used to collect gas. The Belo Horizonte landfill already has biogas vents placed in the landfill that could be modified to make vertical collection wells. If they were not converted to collection wells, the vents would 17

25 be sealed to prevent air intrusion into the landfill. To achieve good collection efficiency, the landfill biogas collection system might include both converted vents and new wells installed in spots that do not have vents now. Typically, vertical wells consist of a cylindrical bore hole of at least 60 centimeters diameter that is drilled or excavated in the waste. The bore hole extends to within a few meters of the bottom of the waste or to a depth where leachate is found. A perforated plastic pipe of 110 to 160 millimeters diameter is placed into the borehole. The perforations allow landfill biogas to flow into the pipe. Gravel or stones are packed around the pipe to provide a highly porous pathway for landfill biogas to flow to the pipe. Near the surface of the landfill, clay or bentonite, rather than gravel, is packed around the pipe to provide a low-permeability layer that impedes the flow of air into the pipe. From the clay layer upward, the pipe is not perforated. It extends to about one meter above the surface of the landfill. An existing landfill biogas vent can be converted to a vertical well by removing and then rebuilding the top few meters of the vent. First, rock and soil are removed to a depth of four or more meters. Perforated pipe is embedded in newly-placed stones or gravel. As in typical vertical wells, the pipe near the surface of the landfill is not perforated. It is embedded in clay instead of in stones. The pipe from each individual modified vent, which has been converted to a vertical well, extends above the surface of the landfill and is connected to the rest of the collection system. In North American landfills, vertical wells are often installed at a density of about two or three wells per hectare. Because the MSW in South America tends to be wetter and denser than North American MSW, and because the landfill cover is often relatively porous, a greater density of wells is likely to be needed. The current gas vent spacing of about 30 meters provides a density of about ten wells per hectare, which might be sufficient. Further investigation of the condition of the landfill is needed to ascertain the best well density. Use of a geomembrane cover can decrease the number of wells needed to obtain good collection efficiency. Horizontal wells are typically installed in trenches of about two meters in depth and one meter wide. The trenches are typically tens of meters in length. Perforated pipe is placed in the trench and packed in stones or gravel. At selected locations, the horizontal 18

26 perforated pipe is connected to non-perforated vertical pipe that extends to above the surface of the landfill. The trenches are covered with low-permeability clay and/or geomembrane sheets. Horizontal wells are often spaced at a horizontal distance of about 30 meters in North American landfills. In South American landfills, a distance of about 20 meters is likely to be more appropriate because of the wetter waste. At or near the surface of the landfill, a control valve and a monitoring port are installed for each well. Each well is connected to a pipe network that carries the landfill biogas to the flare station. The pipe network may be buried or it may be installed on the surface of the landfill. Pipes are generally sized to avoid velocities exceeding 15 meters per second. Generally, pipes leading from individual wells and from groups of a few wells would be 63 millimeters to 110 millimeters (about 2 to 4 inches) in diameter. Pipe carrying the full flow of landfill biogas would be about one-half meter (18 to 20 inches) in diameter. Alternatively, two 350-millimeter (12-inch) pipes would be sufficient. At low points in the pipe network, condensate traps are installed to drain condensed water that would otherwise plug the pipes. The traps are designed to allow water to drain out of the network while preventing air from being drawn into the network Flare Station Design The flare station envisioned for this project includes components and processes typical of many existing flare stations, as described below. - Landfill biogas from the well field enters a moisture separator where droplets of condensate are removed. - The landfill biogas passes through a main shut-off valve that automatically closes when the system shuts down and is opened by the control system only after a pilot flame is burning in the flare. - One or more blowers apply suction of about 100 millibars to the pipe that extends to the well field. This suction promotes the flow of landfill biogas out of the 19

27 - The landfill biogas passes to the flare and biogas utilization project along a length of pipe that contains instrumentation for measuring the flow rate, composition, pressure, and temperature of the landfill biogas. - Immediately before reaching the flare and biogas utilization project, the landfill biogas passes through a flame arrestor, which is designed to prevent flames from passing back toward the blowers and gas collection system. - Whenever the electric power plant is not operating, the landfill biogas enters the flare where it is burned. An enclosed flare is envisioned for this project because enclosed flares are assumed to have greater combustion efficiency than open flares, and this greater efficiency results in a greater number of marketable emission reduction credits. - The flare, blowers, and other equipment are controlled by a control system that starts, stops, and adjusts the system to maintain safety and to optimize the operation. - An automatic monitoring system records operating data such as the volume of landfill biogas that flows to the flare, the landfill biogas composition, the flare temperature, etc. The flare station would include a control room, electricity supply, concrete foundations for the major equipment, and a small shop for storing spare parts and performing repairs Electric Power Plant Design An electric power project at Belo Horizonte landfill would be reasonably designed to produce 5.0 MW of power. 20

28 Usually, landfill biogas-fueled power plants use spark-ignited reciprocating internal combustion (IC) engines to generate mechanical power to drive an electric generator. Power plants that use gas turbines, diesel engines, steam turbines, and fuel cells can also be fueled wholly or partially by landfill biogas. The designs and economic analysis in this report are based on the use of IC engines because of their proven reliability and widespread use. Several major engine manufacturers provide packaged, skid-mounted, engine-generator systems ( gensets ) that use landfill biogas and produce electric power. In addition to a genset, the power plant design considered in this report includes the following ancillary equipment. - Downstream of the blowers discussed above as part of the flare station, a valve diverts biogas from the flare to a pipe leading to the power plant. - Gas conditioning system. Some engines require gas to be supplied at a pressure of about 3,000 millibars (45 pounds per square inch). Regardless of whether the engine needs compressed gas, a compressor is useful in cleaning and drying the biogas. Cleaning and drying helps to maintain good engine performance, minimizes engine maintenance, and prolongs the life of the engine. A simple biogas conditioning system includes a gas compressor and a cooler that uses circulating water as the cooling medium. It removes condensable water and other contaminants from the landfill biogas. After being cooled, the landfill biogas is heated slightly, using waste heat from the engine, to prevent further condensation in the downstream pipes and in the engine. More extensive biogas conditioning systems, which are not included in this design, include glycol-base moisture removal systems, mechanical refrigeration of the landfill biogas to promote removal of condensable compounds, and systems based on chemical adsorption or selective membranes to scrub carbon dioxide and other gases from the landfill biogas. - Lubricant, cooling, and exhaust systems for the gensets. Packaged gensets may include these systems on the same skid as the engine and generator. However, there are often advantages in having an externally-mounted radiator to improve cooling efficiency, an extension of the exhaust system to move exhaust away from 21

29 - Monitoring system. The biogas flowing to the engine must be monitored for flow rate and composition in order to quantify GHG emission reductions. Electric power output must also be measured. - Power conditioning equipment. Electricity generated by the genset must be adjusted to the proper voltage, by a transformer, before being sent to the local distribution grid. Switches and other protective equipment are required to protect the distribution grid. - Civil works. The gensets would be located in a building that provides shelter and security for equipment and for operations and maintenance staff. The gensets would be mounted on concrete foundations. 4. ECONOMIC ANALYSIS Estimated cash flow is shown in Table 5 for a landfill biogas electricity project designed to generate 5.0 MW. The methods of calculating most of the values are explained in the table Initial Investment The estimated investment in a landfill biogas collection and flaring system is shown in Tables 5. It includes all costs of Engineering, Procurement, and Construction (EPC). That is, a turnkey project is assumed to be installed. The estimated EPC costs include the following: - Engineering, legal, commercial, accounting, and other professional services at a cost of $200, Well field installation costing $30,000 per hectare of waste included in the project. Belo Horizonte Landfill site is 70 hectares in area. However, a well field extending 22

30 - Flare station installation including the costs of purchasing, delivering, installing, and starting-up equipment. Allowances are made for civil works, spare parts, instrumentation, and other ancillary equipment. The cost is estimated as: estimated biogas flow 650,000 1, That is, a flare station designed for 1,800 Nm³/h is estimated to cost $650,000. The ratio of the actual estimated landfill biogas flow to 1,800 Nm³/h is raised to the power of 0.7 and multiplied by $650,000 to estimate the cost of the flare station. A flare station designed for a landfill biogas flow of 5,890 Nm³/h is estimated to cost $1.49 million. The estimated turnkey project cost of the collection and flaring system is $2.89 million. A landfill biogas-fueled power plant is estimated to cost $1.4 million per megawatt of installed capacity. This cost estimate includes engineering, power grid interconnection, and other professional service costs as well as the cost of purchasing, delivering, and installing the equipment. The power plant cost would be $7.0 million for the 5.0 MW plant envisioned in this report. The typical cost of registering the project with an emissions trading system to obtain emission reduction credits is shown as a separate cost item in Table 5 and is estimated to be $100,000, would be for registration of the project Annual Costs Estimated annual costs of operating, maintaining, and monitoring a collection and flaring project are as follows. The approximate annual costs for the envisioned system are shown. - Well field maintenance: 3 percent of well field cost: $36,000; 23