Methane is the second most prevalent anthropogenic greenhouse gas emitted in the United States and has a global warming potential 28–34 times higher than carbon dioxide over a
100-year time horizon (IPCC 2013). Municipal solid waste landfills are the third-largest source of human-made methane emissions in the United States, responsible for 18 percent of methane emissions in 2012 (US EPA 2014). Landfill gas (LFG) produced through the anaerobic decomposition of the organic content of municipal solid waste consists of 50–55 percent
methane and 40–45 percent carbon dioxide. Methane is a primary constituent of natural gas and an important energy source. As a result, landfill gas energy (LFGE) projects—which capture methane emissions from landfills and use it as an energy source for electricity or heat generation—provide both energy and environmental benefits.