Methane Capture
As solid waste decomposes in a landfill, methane gas, a potent greenhouse gas, is released (along with other gases such as carbon dioxide). According to the EPA, municipal solid waste landfills account for about 25% of the human-related methane emissions in the U.S. Instead of contributing to climate change, methane gas can be captured and used to create energy. This not only keeps methane from entering the atmosphere, but offsets other potential greenhouse gas emitting energy sources from being used (such as coal or oil).
As of May 2008, there were 450 landfills that captured methane. In Massachusetts, 20 landfills have methane capture programs and 3 more have been identified as candidate landfills by the EPA (see map).
Harvard's trash is brought to a landfill in South Carolina that captures its methane.
Landfill gas system (Source: EPA)
More Information/Sources
EPA Landfill Methane Outreach Program
Mass DEP: Massachusetts Leading the Way in Landfill Gas to Energy Generation
Boston Globe article: Tapping into Trash to Find a New Energy Source