Agriculture and Forestry
Bioenergy
Climate Change
Renewable Energy

Issue Brief | Biogas Capture and Utilization: An Effective, Affordable Way to Reduce GHGs

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June 16, 2009

Table of Contents

    According to the U.S. Environmental Protection Agency (EPA), methane is over 20 times more effective at trapping heat in the atmosphere than carbon dioxide over a 100 year period. Methane’s role as a potent greenhouse gas, coupled with the fact that its average lifespan in the atmosphere is 12 years, means that activities to reduce methane emissions efforts have great potential for reducing human impact on climate change in the near term.

    Methane is commonly produced through anaerobic digestion of organic material. In this process, bacteria in an oxygen-deprived environment break down organic material into a mixture of gases, water, and a solid effluent. The gaseous mixture, called biogas, can contain 50 to 95 percent methane depending on the source. According to the most recent data from the Energy Information Administration (EIA), the United States emitted 699.9 million metric tons carbon dioxide equivalent (MMTCO 2 E) of methane in 2007, which accounted for 9.9% of the country’s total GHG emissions. Of this total, landfills accounted for 169.0 MMTCO 2 E, solid waste from animals for 65.0 MMTCO 2 E, and wastewater management for 26.7 MMTCO 2 E.

    At many of these sources, biogas can be captured and burned on site (a process called “flaring”), thereby reducing climate change impacts substantially as the methane in the gas is converted to carbon dioxide. Even greater effects can be realized by using the energy-rich biogas as a substitute for carbon-intensive fossil fuels. A number of technologies exist that allow biogas to be collected and used on site or transported to a central location, where it can be refined to pipeline-quality gas (comparable to natural gas, which is 97% methane) or combusted for electrical generation or heating. Biogas capture at many facilities can be an effective, affordable way to reduce greenhouse gas emissions by reducing methane emissions and displacing fossil fuels for energy production.

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