Submitted to: Book Chapter
Publication Type: Book / chapter
Publication Acceptance Date: 9/18/2009
Publication Date: 6/1/2010
Citation: Bogner, J., Spokas, K.A. 2009. Landfill Methane. In: Reay, D., Smith, P., and van Amstel, A. Methane and Climate Change. Earthscan Ltd., London, UK. pp. 175-200. Interpretive Summary:
Technical Abstract: Landfill methane (CH4) accounts for approximately 1.3% (0.6 Gt) of global anthropogenic greenhouse gas emissions relative to total emissions from all sectors of about 49 Gt CO2-eq yr-1. For countries with a history of controlled landfilling, landfills can be one of the larger national sources of anthropogenic CH4; U.S. landfills, for example, are currently the second largest source of anthropogenic CH4 after ruminant animals. Because CH4 has a relatively high GWP and a relatively short atmospheric lifetime of about 12 years, many countries have targeted reductions in landfill CH4 emissions as part of a strategy to stabilize and reduce atmospheric CH4 concentrations as well as utilizing a renewable energy source. In many developed and developing countries, landfilling and other waste management activities are highly regulated; thus, their associated GHG emissions have also come under public scrutiny with many existing and evolving regulatory, planning, energy-related, and financial mechanisms. The single most important strategy to reduce landfill CH4 emissions is the installation of engineered gas extraction systems using vertical wells or horizontal collectors. The collected landfill gas (40-60% CH4) can be an important local source of renewable energy for industrial or commercial boilers to provide process heating, for on-site electrical generation using internal combustion engines or gas turbines, or for upgrading (by removal of CO2 and trace components) to a substitute natural gas. In developing countries, where landfills may have been developed without engineered cells, daily and final cover materials, and engineered control systems for liquids and gases, it can be a substantial challenge to construct efficient landfill gas recovery systems—in many cases, re-grading and additional cover material will be required. This review will update and complement previous reviews with emphasis on field measurement of landfill CH4 emissions and oxidation, modeling of emissions and oxidation, and current trends.