Increasing Business Value With Landfill Gas-to-Energy Projects: Environmental Issues and Implications

Increasing Business Value With Landfill Gas-to-Energy Projects: Environmental Issues and Implications Landfill gas is a renewable energy source. Making use of this resource in wasteto-energy projects at municipal solid waste landfills can reduce air emissions while also providing significant a variety of other methods, such as incineration of solid or hazardous organic waste, pyrolisis, gasification, and biotransformation. However, these methods re- economic benefits. Using landfill gas in energy quire using a different set of approaches and production offers a particularly valuable strategy perspectives; they also involve different environmental control regulations. As such, they are for reducing emissions of methane, which is a powerful greenhouse gas. beyond the scope of this article. In this article, I offer some background on About This Article solid waste, which is primarily disposed in landfills. I discuss the climate-change implications of This article focuses on creating value with landfill gas-to-energy projects at municipal solid methane (a key component of landfill gas) and waste (MSW) landfills. It is the first in a series explain how using LFG for energy production of articles that will present practical concepts can reduce greenhouse gas emissions. I also review some of the pertinent literature on landfill regarding the use of landfill gas (LFG) for energy production, while also discussing pertinent environmental management issues. benefits that can be gained by implementing gas-to-energy projects and outline the many My discussion concentrates specifically on the production of electricity from combustion of landfill gas. It should be noted that wasteto-energy projects can also be developed using Reducing greenhouse gas emissions while creating profits 2008 Wiley Periodicals, Inc. Published online in Wiley InterScience (www.interscience.wiley.com). DOI: 10.1002/tqem.20203 Environmental Quality Management / DOI 10.1002/tqem / Winter 2008 / 17

such projects. I conclude with some key technical information. Future articles in this series will emphasize information related to air-quality permitting and management, emission calculations, general compliance requirements, and other pertinent aspects that must be considered when planning waste-to-energy projects. Proactive Environmental Management and Value Creation This discussion continues a series of articles describing the economic and financial benefits associated with good environmental planning What is important to keep in mind is this: An expenditure that is seen as simply a cost at the present time can also be viewed as an investment that will create value over the long term. and management strategies. It follows up on prior articles for this journal in which I discussed how proactive environmental management can be used as a tool for creating value (Cora, 2007, 2008). As one commentator has noted, Environmental performance and disclosure pressures from the supply chain, finance providers, regulatory agencies, and other stakeholders result in ever-increasing environment-related costs for organizations, but there is also an increasing recognition of the potential monetary benefits of improved environmental performance (Jasch, 2006). In prior articles, I have emphasized the importance of value creation as it relates to environmental management. In this context, creating value means earning a return on capital that exceeds the cost of the investment over time, or earning a positive economic profit from investment (revenue expenses = positive value). What is important to keep in mind is this: An expenditure that is seen as simply a cost at the present time can also be viewed as an investment that will create value over the long term. Background: Solid Waste Generation and Disposal Solid and Hazardous Waste The applicable federal regulation, codified at 40 CFR section 261.2, defines solid waste as discarded material, which is further defined to include material that is abandoned or inherently waste-like. Hazardous waste is a subset of solid waste. Material in this category includes waste with characteristics (such as ignitability, corrosivity, toxicity, or reactivity) that make the waste particularly dangerous or harmful to human health or the environment (40 CFR subpart C). Hazardous waste can take the form of a liquid, solid, contained gas, or sludge. Hazardous wastes often are generated as by-products of manufacturing processes, although they can also simply be discarded commercial products, such as cleaning fluids or pesticides. Many hazardous waste streams are rich in organic content, a factor that could allow them to be used as feedstock in special waste-to-energy projects (U.S. EPA, 2008). Increases in Solid Waste Generation According to the United States Environmental Protection Agency (EPA), both the per-capita rate of solid waste generation and the total amount of solid waste generated have increased substantially in the United States over recent decades. In 1960, the per capita waste generation rate was 2.7 pounds per day, while total waste generation was 88.1 million tons. By 2006, per capita waste generation had increased to 4.6 pounds per day, and total waste generation had grown to 251.3 million tons. These figures have continued to increase even though our society is now recycling more materials from the waste stream (U.S. EPA, 2008). 18 / Winter 2008 / Environmental Quality Management / DOI 10.1002/tqem

Solid Waste Landfills A large percentage of the solid waste generated in the United States is disposed in municipal solid waste landfills. Despite the growth in waste generation, EPA notes that the number of landfills in the United States has steadily decreased (from 8,000 in 1988 to 1,754 in 2006). Overall disposal capacity has remained relatively constant, however, because new landfills are much larger than those used in the past and landfilling methods are more efficient. Composition of Municipal Solid Waste MSW consists primarily of household waste. This waste contains a significant amount of valuable material that can be recovered and transformed into a source of energy. Among the main components of MSW are paper, cardboard, plastics, textiles, rubber, leather, yard waste, and food waste (Tchobanoglous et al., 1993). If these waste components are not recycled, they eventually end up in landfills. Much of the waste still being disposed in landfills contains a sizeable fraction of organic content. The actual fraction of organic content in landfilled material varies from location to location and can be affected by community recycling rates. Creation of Landfill Gas Approximately 50 to 70 percent of municipal solid waste is biodegradable. In other words, the material can be transformed and decomposed (biodegraded) by the action of microbes. Over time, with proper burial (i.e., compaction) of municipal solid waste in a landfill cell, the organic content of the waste biodegrades. This process produces landfill gas, which contains a variety of compounds. The two primary component gases are methane and carbon dioxide, both of which are classified as greenhouse gases because of their ability to trap and retain heat in the atmosphere. Landfill gas also contains trace amounts of toxic substances. Reducing Greenhouse Gas Emissions With Landfill Gas-to-Energy Projects Landfills and Global Warming Landfills contribute a significant amount to greenhouse gas emissions. For example, methane emissions originating at municipal solid waste landfills account for 2.4 percent of all greenhouse gas (GHG) emissions in the European Union (Gugele et al., 2002). reduce But why does burning landfill gas for energy greenhouse gas emissions? I have heard this asked by members of the public at information sessions and hearings held as part of the permitting process for waste-toenergy projects involving the use of landfill gas. It is one of the primary questions that led me to research and write this series of articles. At first glance, one might think that LFGto-energy projects would simply transform one greenhouse gas (methane, or CH 4 ) into another greenhouse gas (carbon dioxide, or CO 2 ). To fully understand the benefit of landfill gas-to-energy projects, it is necessary to understand some more about methane and its properties. Methane Generation Methane is one of the primary components of natural gas. It can also be generated by a wide variety of processes and sources, both anthropogenic (human-made) and nonanthropogenic. Approximately 50 to 70 percent of municipal solid waste is biodegradable. In other words, the material can be transformed and decomposed (biodegraded) by the action of microbes. Methane is produced biologically (in the form of biomethane) by the action of methanogenic bacteria in anaerobic environments through, Increasing Business Value With Landfill Gas-to-Energy Projects Environmental Quality Management / DOI 10.1002/tqem / Winter 2008 / 19

for example, enteric fermentation in animal digestive systems, wetland rice cultivation, and decomposition of animal wastes (U.S. EPA, 2002). Landfills play a major role in methane generation. Methane production at landfills occurs due to the anaerobic decomposition of organic matter by biological agents. Methane emission levels at landfills depend on waste composition, landfill size, and the percent of methane content in the landfill gas stream. Methane in the Atmosphere The concentration of methane in the atmosphere has grown by around 150 percent Many organizations are now exploring the financial and technical feasibility of using landfill gas as a source of fuel for combustion engines and gas turbines in order to produce electricity for their own use. since the middle of the eighteenth century (before the Industrial Revolution). The Intergovernmental Panel on Climate Change estimates that slightly more than half of the current methane flux to the atmosphere results from anthropogenic activities, including waste disposal (Houghton et al., 2001). Methane s Global Warming Potential Once released into the atmosphere, methane molecules absorb terrestrial infrared radiation that otherwise would escape into space. Methane is a major factor in climate change because of its global warming potential (GWP). The GWP concept was developed to compare the capacity of various greenhouse gases to trap heat in the atmosphere. The GWP for a given gas is the ratio of heat trapped by one unit (in mass) of that particular greenhouse gas compared to one unit of carbon dioxide over a specified period of time. As part of its scientific assessment related to climate change, the Intergovernmental Panel on Climate Change has published GWP reference values for a number of greenhouse gases. There is consensus in the relevant literature that methane has a GWP of about 21 to 25 that is, methane is at least 21 times more efficient at trapping heat (and thus warming the atmosphere) than the same of amount of carbon dioxide by weight (Forster et al., 2007). This makes methane a very powerful greenhouse gas. Curbing Greenhouse Gas Emissions While Creating an Energy Source With interest in climate change growing, organizations are seeking to reduce GHG emissions from a variety of sources. These wide-ranging emission reduction efforts are beginning to affect not only the industrial and energy sectors, but also related fields, such as the financial industry. Many organizations are now exploring the financial and technical feasibility of using landfill gas as a source of fuel for combustion engines and gas turbines in order to produce electricity for their own use. Lombardi et al. (2006) studied how feasible it would be to reduce GHG emissions through innovative landfill gas-to-energy approaches. The study looked at several methods, all of which involved feeding landfill gas to a stationary or vehicle fuel cell (either directly or after steam reforming and CO 2 capture). The researchers compared these approaches to the more conventional practice of using reciprocating internal combustion engines for energy recovery. CDM Projects Barton et al. (2008) noted that the clean development mechanism (CDM) established under the Kyoto Protocol offers a way to attract investment in projects that control landfill gas emissions. The CDM allows developed countries to earn credit toward meeting their greenhouse gas reduction obligations under the Kyoto Protocol by creating 20 / Winter 2008 / Environmental Quality Management / DOI 10.1002/tqem

or financing projects that reduce greenhouse gas emissions in developing countries. Waste-to-energy projects developed under the CDM can help to reduce greenhouse gas emissions from landfills. As the authors note, however, in developing countries, such projects have been discounted for a range of reasons related primarily to the lack of technical and other support services required for these more sophisticated process trains. The authors of this article evaluated six options for managing solid waste in developing countries. The options included: open dumping of waste (which the researchers considered the base case ), landfilling with passive venting of landfill gas, landfilling with LFG capture and flaring, landfilling with LFG capture and energy production, composting and anaerobic digestion of waste with electricity production, and composting of the waste digestate. The researchers found that the highest levels of greenhouse gas emissions resulted from landfilling without either gas flaring or electricity production. Landfills with LFG flaring or energy production from collected LFG also produced greenhouse gas emissions. However, emission levels from these facilities were substantially lower than those produced by open dumping and by landfills that did not use either flaring or energy production. Growth of Landfill Gas-to-Energy Projects I have worked on a wide variety of permitting review projects. Recently, I have noticed a net increase in the number of organizations that intend to implement landfill solid waste-to-energy conversion projects. As of December 2006, approximately 425 landfill gas-to-energy projects were operating in the United States. Collectively, they generate about 10 billion kilowatt-hours of electricity per year and deliver 230 million cubic feet per day of landfill gas to direct-use applications. EPA estimates that approximately 560 additional landfills could potentially develop landfill gas-to-energy projects. Converting Landfill Gas Into Electrical Energy: Literature Review As part of my research for this article series, I reviewed relevant books and technical articles discussing the conversion of landfill gas into electrical energy in order to obtain a The researchers found that the broad overview of the highest levels of greenhouse gas subject matter. The emissions resulted from landfilling topic is discussed in without either gas flaring or a significant number electricity production. of writings and within the context of a variety of projects and programs. I summarize several recent articles in the following sections. Impact of LFG Electricity Generation Shin et al. (2005) analyzed how generating electricity from landfill gas affected energy markets, electricity-generating costs, and emissions of greenhouse gases in Korea. They compared the LFG-to-energy approach to other existing technologies. The study used a software modeling tool known as the long-range energy alternative planning (LEAP) system. LEAP was developed by the Stockholm Environment Institute as a tool for evaluating the impacts (including economic and environmental effects) of alternative energy initiatives. The researchers concluded that a number of technological, economic, and regulatory uncertainties must be addressed before landfill Increasing Business Value With Landfill Gas-to-Energy Projects Environmental Quality Management / DOI 10.1002/tqem / Winter 2008 / 21

gas-to-energy projects can be implemented on a widespread scale in Korea. Technologies for Producing Electricity from Landfill Gas Bove and Lunghi (2006) researched several possible technological options for producing electricity from landfill gas. Their study also considered energy, environmental, and economic issues. The researchers evaluated the following technologies: reciprocating internal combustion engines, gas turbines, power plants with an organic Rankine cycle, Stirling cycle engines, molten carbonate fuel cells, and solid oxide fuel cells. The study found that internal combustion engines offer the poorest performance in environmental terms. They are the most widely used technology, however, because of the economic advantages they offer. Environmental Feasibility of Landfill Gas-to- Energy Projects Desideri et al. (2003) published a case study that considered the environmental effects of using landfill gas for generating energy. The study focused on biogas from a landfill located in central Italy. The authors analyzed the amount of gas produced, as well as its composition and energy potential. Exhibit 1 summarizes key sitespecific and experimental data from their study. The researchers analyzed biogas samples manually, using equipment that could detect five gases: methane, carbon dioxide, oxygen, hydrogen sulfide, and carbon monoxide. They used infrared techniques to determine how much methane and carbon dioxide was contained in their samples. In addition, they used a galvanic cell with acid electrolyte to determine the quantity of oxygen, hydrogen sulfide, and carbon monoxide. The authors concluded that exploiting landfill biogas for energy purposes would be environmentally sound. They noted that this approach increases the use of a renewable energy source while reducing atmospheric emissions of methane and carbon dioxide, both of which have global warming impacts. Leachate Recirculation Procedures Now that landfills are increasingly being viewed as bioreactors, it is becoming more important to implement recirculation procedures for the landfill leachate. An example of these ef- Exhibit 1. Data from a Landfill Gas-to-Energy Evaluation Project* Study Parameter Data and Findings Total landfill capacity 2,000,000 cubic meters Average collected/landfilled waste 160,000 tons per year Number of biogas collection wells 72 Diameters of collection wells 75, 90, and 100 millimeters Average distance between collection wells 30 meters Biogas composition (by volume) Methane (60%) Carbon dioxide (40%) Biogas heating value 19,000 kilojoules per normal cubic meter * Project operated in 1984 at a landfill in central Italy that served an area with a population of around 400,000. Adapted from Desideri et al. (2003). 22 / Winter 2008 / Environmental Quality Management / DOI 10.1002/tqem

forts was highlighted by Jiang et al. (2007). These researchers described a study investigating how leachate recirculation affected several aspects of landfill operation, including waste stabilization and generation of landfill gas. The results suggested that leachate recirculation approaches should be modified over time as the waste stabilization process advanced through its various stages. The study also found that certain leachate management approaches could increase production of biogas. Site-Specific Topographical Issues Certain site-specific topographical features of landfills (such as the potential for waste-mass slumps and slides) can make it difficult to implement a landfill gas-to-energy project, especially in developing countries. In response to this problem, Gharabaghi et al. (2008) assessed the effectiveness of simple tools that can be used to analyze the stability of landfills. The study involved two landfill sites in Brazil one that had never been known to experience slope failure and one where several slope failures had occurred. The study results indicated that the tools being evaluated could offer a realistic screening mechanism for assessing landfill stability, and thus could be useful in determining the feasibility of LFG-to-energy projects. Life-Cycle Assessment Other authors have discussed life-cycle assessment concepts and techniques, including how these concepts can help planners and decision makers evaluate waste-to-energy approaches. A paper published by Obersteiner et al. (2007) discussed a number of issues regarding life-cycle assessment (LCA) of landfill impacts. The discussion noted that such assessment can be complicated by a range of factors. In particular, because landfill emissions may continue for a period of many years, it can be difficult to choose an appropriate time frame for LCA. In addition, LCA relies on the use of lifecycle inventory data; the quality and quantity of these data can affect the validity of LCA results. Kirkeby et al. (2007) discussed a computerbased model called EASEWASTE, which can be used to assess the life-cycle environmental impacts of various solid waste management technologies and systems. The study focused on the portion of the model dealing with landfills. The model calculates LFG generation rates based on the amount of organic matter contained in the landfill s waste. In another article, Barlaz (2006) reviewed research dealing with cellulosic wastes and their decomposition in landfills. The author noted that cellulosic components can be found in paper and wood products, which make up a significant portion of the biodegradable material in municipal solid waste. The study highlights the lack of information currently available on how individual waste components decompose in landfills. Benefits of Landfill Gas-to-Energy Projects Landfill gas-to-energy projects offer a number of significant environmental and economic benefits, as discussed below. More information on these benefits can be found on EPA s Landfill Methane Outreach Program Web site (http:// www.epa.gov/lmop/benefits.htm). Exhibit 2 shows a simplified process flow diagram for a landfill gas-to-energy project. Reducing Methane GHG Emissions From Municipal Solid Waste Landfills Certain site-specific topographical features of landfills (such as the potential for waste-mass slumps and slides) can make it difficult to implement a landfill gas-to-energy project, especially in developing countries. Landfill gas-to-energy projects can capture a large proportion of the gas produced by MSW Increasing Business Value With Landfill Gas-to-Energy Projects Environmental Quality Management / DOI 10.1002/tqem / Winter 2008 / 23

Exhibit 2. Simplified Process Flow Diagram for Landfill Gas-to-Energy Project landfills including around 60 to 90 percent of biomethane, by some estimates. (Actual performance depends on system design and operation.) The captured gas is combusted for energy production, leaving behind water and carbon dioxide (which has substantially lower global warming potential). Offsetting Fossil Fuel Use Generating electricity from landfill gas-to-energy projects can reduce the need to burn fossil fuels (such as coal and natural gas) that otherwise would be used to produce the equivalent amount of energy. Improving Local Air Quality LFG-to-energy projects reduce odors emitted by landfills, thus creating a net improvement to the air quality of surrounding communities. Reducing Explosion Hazards When landfill gas accumulates, it can create a danger of explosion. LFG-to-energy projects, which capture gas and prevent it from accumulating, can reduce this hazard and improve safety. Reducing Health Risks Landfill gas generally contains small amounts of nonmethane organic compounds that can create health issues if they are emitted into the atmosphere. LFG-to-energy processes, which destroy such compounds, can reduce these health risks. Creating Economic Value LFG-to-energy projects offer a range of economic benefits to both landfill owners and surrounding communities. Such a project can: turn landfill gas into a revenue-producing resource; create additional revenue through generation of electrical power; create jobs in construction, operations, and maintenance; allow for the creation and sale of renewable energy credits; and reduce the cost of complying with environmental requirements, especially air regulations. Landfill Gas: Some Technical Basics In the sections that follow, I summarize some technical information on landfill gas, including how it is formed and how its rate of generation can be calculated. Generation of Landfill Gas Solid waste buried at a landfill undergoes microbial degradation, which eventually creates 24 / Winter 2008 / Environmental Quality Management / DOI 10.1002/tqem

landfill gas. The amount of gas generated can vary depending on waste composition and landfill size. Gas generation typically begins a few years after waste is disposed and may continue for 20 to 30 years after closure of the landfill. A number of site-specific conditions influence potential landfill gas generation rates. At an individual site, however, waste composition plays the most important role. The potential for landfill gas generation depends largely on the quantity of organic content in the waste, the nature of that content, and the decomposition rates associated with the material. The waste decomposition process (and hence the rate of gas production) depends on site-specific variables such as moisture content, nutrient content, bacterial content, ph level, temperature, and the design and operational plan of the landfill. Variations in gas production levels occur from site to site, largely because of differences in management programs and waste composition. For example, a World Bank report notes, Waste produced in Latin America and the Caribbean typically has a higher organic and moisture content than most North American or European waste and therefore would be expected to generate LFG at equivalent or higher rates (Terraza & Grajales, 2006). Stages of Waste Stabilization Research studies have shown that stabilization of waste buried in a landfill occurs in several stages. Shearer (2001) described the waste stabilization process as having five phases, each of which is characterized by production of specific gas and leachate types: lag period, transition, acid formation, methane fermentation, and maturation. Determining the Amount of Landfill Gas Available for Use The amount of gas available for energy recovery depends on the quantity being produced by the landfill. EPA has developed methods for determining how much gas landfills are generating. These methods are discussed in detail in EPA s compilation of emission factors, known as AP-42. The composition of landfill gas changes during the waste stabilization process. As AP-42 notes, however, once the landfill reaches a steady state, the gas it produces contains fairly predictable concentrations of methane (55 percent by volume), carbon dioxide (40 percent), and nitrogen (5 percent), along with trace amounts of nonmethane organic The amount of gas available compounds. Thus, if for energy recovery depends the methane generation rate can be deter- on the quantity being produced by the landfill. mined, it is simple to calculate the overall amount of landfill gas being produced. EPA has developed a theoretical model for estimating landfill gas generation rates based on methane production. This tool, known as the Landfill Gas Emissions Model (LandGEM), is available on the Agency Web site; it has been revised and updated several times. In AP-42, a version of the LandGEM equation is shown, as follows: Q CH4 = L o R (e kc e kt ) where: Q CH4 = methane generation rate at time t (in cubic meters per year); L o = methane generation potential (in cubic meters of methane per million grams of refuse); R = average annual refuse acceptance rate during the landfill s active life (in million grams per year); Increasing Business Value With Landfill Gas-to-Energy Projects Environmental Quality Management / DOI 10.1002/tqem / Winter 2008 / 25

e = base log (unitless); k = methane generation rate constant (year 1 ); c = time since landfill closure, in years (c = 0 for active landfills); and years. t = time since initial refuse placement, in The LandGEM model estimates how much landfill gas is generated, not how much is actually emitted to the atmosphere. As the AP-42 discussion notes, however, It is generally accepted For safety reasons, EPA advises that only experienced personnel should perform this testing procedure since the methane in LFG can lead to explosions. the following observations: that the bulk of the gas generated will be emitted through cracks or other openings in the landfill surface. AP-42 offers detailed guidance on using the LandGEM equation, including Site-specific landfill information is generally available for variables R, c, and t. When refuse acceptance rate information is scant or unknown, R can be determined by dividing the refuse in place by the age of the landfill. If a facility has documentation that a certain segment (cell) of a landfill received only nondegradable refuse, then the waste from this segment of the landfill can be excluded from the calculation of R. Nondegradable refuse includes concrete, brick, stone, glass, plaster, wallboard, piping, plastics, and metal objects. The average annual acceptance rate should only be estimated by this method when there is inadequate information available on the actual average acceptance rate. The time variable, t, includes the total number of years that the refuse has been in place (including the number of years that the landfill has accepted waste and, if applicable, has been closed). Values for variables L o and k must be estimated. Estimation of the potential CH 4 generation capacity of refuse (L o ) is generally treated as a function of the moisture and organic content of the refuse. Estimation of the CH 4 generation constant (k) is a function of a variety of factors, including moisture, ph, temperature, and other environmental factors, and landfill operating conditions. EPA Method 2E (described in 40 CFR, Part 60, Appendix A) can be used to measure the LFG production flow rate from municipal solid waste landfills. This method can also be used to support determination of the site-specific methane generation rate constant (k) that is required in the LandGEM equation. The method requires installing extraction wells (the extraction well configuration is organized in either a cluster of three wells, or else five wells distributed at specific locations throughout the entire landfill). The system also requires a blower to extract LFG. The Method 2E testing procedure involves measuring LFG composition, landfill pressure, and other elements necessary to calculate the LFG flow rate. For safety reasons, EPA advises that only experienced personnel should perform this testing procedure since the methane in LFG can lead to explosions. The list of equipment and supplies required for Method 2E ranges from a 24-inch well drilling rig to gravel and backfill material. Method 2E contains specific guidance on designing the test and performing measurements, calibrations, and calculations. Closing Thoughts This article series aims to promote a more proactive approach to dealing with municipal solid waste landfills and the gases they produce. Using 26 / Winter 2008 / Environmental Quality Management / DOI 10.1002/tqem

the inherent energy contained within material buried at landfills can create profit while reducing environmental impacts from greenhouse gas emissions and air pollutants. The discussion in this article (the first of the series) offers background on solid waste and landfilling, along with information on the greenhouse gas properties of methane, a key component of landfill gas. It summarizes the benefits that can be gained from utilizing landfill gas for energy production rather than emitting it to the atmosphere, where it contributes significantly to global warming. The article also offers some technical information on landfill gas. It describes how LFG is produced and highlights the LandGEM equation and Method 2E, which can be used to calculate production rates for landfill gas. Landfill gas-to-energy projects clearly can create financial value for the business units that operate them. But they also generate sustainable value to the communities surrounding them, ultimately benefiting both the environment and the economy. For More Information Readers who are interested in learning more about the topics discussed here can find a wide variety of informational resources, ranging from governmental agencies to private organizations (both nonprofit and for-profit). The sources cited in this article provide a useful starting point. Several of them provide data about methane gas concentrations in the atmosphere, as well as information about the behavior of methane, its fate-and-transport mechanisms, and its properties as a greenhouse gas. Sources Barlaz, M. A. (2006). Forest products decomposition in municipal solid waste landfills. Waste Management, 26(4), 321 333. Barton, J. R., Issaias, I., & Stentiford, E. I. (2008). Carbon Making the right choice for waste management in developing countries. Waste Management, 28, 690 698. Blake, D. R., & Rowland, F. S. (1988). Continuing worldwide increase in tropospheric methane, 1978 to 1987. Science, 239(4844), 1129 1131. Bove, R., & Lunghi, P. (2006). Electric power generation from landfill gas using traditional and innovative technologies. Energy Conversion and Management, 47(11 12), 1391 1401. Carbon Dioxide Information Analysis Center Web site, http:// cdiac.ornl.gov/aboutcdiac.html Cora, M. G. (2007). Environmental management as a tool for value creation. Environmental Quality Management, 17(2), 59 70. Cora, M. G. (2008). Increasing business value through proactive environmental management and compliance. Environmental Quality Management, 17(3), 45 54. Desideri, U., Di Maria, F., Leonardi, D., & Proietti, S. (2003). Sanitary landfill energetic potential analysis: A real case study. Energy Conversion and Management, 44(12), 1969 1981. Forster, P., Ramaswamy, V., Artaxo, P., Berntsen, T., Betts, R., Fahey, D. W., et al. (2007). Changes in atmospheric constituents and in radiative forcing. In S. Solomon, D. Qin, M. Manning, Z. Chen, M. Marquis, K. B. Averyt, M. Tignor, et al. (Eds.), Climate change 2007: The physical science basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge and New York: Cambridge University Press. Available online at http://www.ipcc.ch/pdf/assessment-report/ar4/ wg1/ar4-wg1-chapter2.pdf Gharabaghi, B., Singh, M. K., Inkratas, C., Fleming, I. R., & McBean, E. (2008). Comparison of slope stability in two Brazilian municipal landfills. Waste Management, 28(9), 1509 1517. Gugele, B., Ritter, M., & Mareckova, K. (2002). Greenhouse gas emission trends in Europe, 1990 2000. Topic Report 7/2002. Copenhagen: European Environment Agency. Available online at http://reports.eea.europa.eu/topic_report_2002_7/en/ Topic_7.pdf Houghton, J. T., Ding, Y., Griggs, D. J., Noguer, M., van der Linden, P. J., Dai, X., et al. (2001). Climate change 2001: The scientific basis. Cambridge: Cambridge University Press (published for the Intergovernmental Panel on Climate Change). Available online at http://www.ipcc.ch/ipccreports/tar/wg1/ index.htm Intergovernmental Panel on Climate Change Web site, http:// www.ipcc.ch Jasch, C. (2006). Environmental management accounting (EMA) as the next step in the evolution of management accounting. Journal of Cleaner Production, 14(14), 1190 1193. Jiang, J., Yang, G., Deng, Z., Huang, Y., Huang, Z., Feng, X., et al. (2007). Pilot-scale experiment on anaerobic bioreactor landfills in China. Waste Management, 27(7), 893-901. Kirkeby, J. T., Birgisdottir, H., Bhander, G. S., Hauschild, M., & Christensen, T. H. (2007). Modeling of environmental impacts of solid waste landfilling within the life-cycle analysis program EASEWASTE. Waste Management, 27(7), 961 970. Increasing Business Value With Landfill Gas-to-Energy Projects Environmental Quality Management / DOI 10.1002/tqem / Winter 2008 / 27

Lombardi, L., Carnevale, E., & Corti, A. (2006). Greenhouse effect reduction and energy recovery from waste landfill. Energy, 31(15), 3208 3219. National Oceanic and Atmospheric Administration. (2008). Carbon cycle greenhouse gases. Climate Monitoring and Diagnostics Laboratory. Available online at http://www.research.noaa.gov/climate/climate_cmdl.html Obersteiner, G., Binner, E., Mostbauer, P., & Salhofer, S. (2007). Landfill modeling in LCA A contribution based on empirical data. Waste Management, 27(8), S58 S74. Shearer, B. (2001). Enhanced biodegradation in landfills (thesis submitted to the faculty of Virginia Polytechnic Institute and State University in partial fulfillment of the requirements for the degree of master of science in environmental engineering). Shin, H.-C., Park, J.-W., Kim, H.-S. & Shin, E.-S. (2005). Environmental and economic assessment of landfill gas electricity generation in Korea using LEAP model. Energy Policy, 33(10), 1261 1270. Tchobanoglous, G., Theisen, H., & Vigil, S. A. (1993). Integrated solid waste management: Engineering principles and management issues (Chapter 4). New York: McGraw-Hill. Terraza, H., & Grajales, F. (2006). The landfill gas-to-energy initiative for Latin America and the Caribbean. Report 318/06. Washington, DC: World Bank. Available online at http:// www-wds.worldbank.org/external/default/wdscontent- Server/WDSP/IB/2006/04/21/000160016_20060421170416/ Rendered/PDF/esm3180PAPER001gastoenergy01PUBLIC1.pdf U.S. EPA. Office of Air and Radiation, Clearinghouse for Inventories and Emissions Factors (CHIEF) technical area Web site, http://www.epa.gov/ttn/chief U.S. EPA. Office of Air and Radiation, Office of Atmospheric Programs, Climate Change Division Web site, http://www. epa.gov/climatechange/emissions/index.html U.S. EPA. Wastes Web site, http://www.epa.gov/epawaste/ index.htm U.S. EPA (1998). Compilation of air pollutant emission factors (AP-42), Volume II, 6th ed., 2.0-1 to 2.4-18. Washington, DC: U.S. Environmental Protection Agency. U.S. EPA (2002). Greenhouse gases and global warming potential values. Excerpt from the inventory of U.S. greenhouse emissions and sinks: 1990 2000. U.S. Greenhouse Gas Inventory Program, Office of Atmospheric Programs. Washington, DC: U.S. Environmental Protection Agency. U.S. EPA. (2005). Guidance for evaluating landfill gas emissions from closed or abandoned facilities, EPA/600/R-05/123a. Air Pollution Prevention and Control Division, National Risk Management Research Laboratory, Office of Research and Development. Washington, DC: U.S. Environmental Protection Agency. U.S. EPA. (2008). Benefits of LFG energy. Landfill Methane Outreach Program Web site, http://www.epa.gov/lmop/benefits.htm U.S. Global Change Research Program Web site, http://www. usgcrp.gov/usgcrp/default.php, D. Eng, PE, BCEE, REM, received a doctorate from the Department of Civil and Environmental Engineering at Cleveland State University. He holds a master of science degree in engineering management from the University of Akron and a bachelor of science in chemical engineering from the University of Puerto Rico Mayaguez Campus. For the past 12 years, he has worked in a variety of capacities at environmental regulatory agencies in Puerto Rico, Ohio, and Maryland, including the United States Air Force Reserves. He also teaches basic engineering and environmental management courses at local universities in the greater Washington, DC, area. Dr. Cora has published over 15 papers and delivered presentations within his diverse areas of expertise, including air pollution control, air quality management, dispersion modeling, industrial wastewater treatment, water abatement technologies, and environmental management and regulation. He holds professional engineering licenses in the State of Maryland and the Commonwealth of Puerto Rico. He is also a Board Certified Environmental Engineer Air Pollution Control Specialist (Diplomate), American Academy of Environmental Engineers, and a registered environmental manager (REM) with the National Registry of Environmental Professionals. He can be reached by e-mail at mariocora@hotmail.com or mariocora2000@yahoo.com, or by going to www.hernantech.com. The opinions contained in this article are solely those of the author and do not represent the viewpoints of any private and/ or public organization with which the author is associated. 28 / Winter 2008 / Environmental Quality Management / DOI 10.1002/tqem