Estimate of methane emissions from the U.S. natural gas industry.

Global methane emissions from the fossil fuel industries have been poorly quantified and, in many cases, emissions are not well-known even at the country level. Historically, methane emissions from the U.S. gas industry have been based on sparse data, incorrect assumptions, or both. As a result, the estimate of the contribution these emissions make to the global methane inventory could be inaccurate. For this reason the assertion that global warming could be reduced by replacing coal and oil fuels with natural gas could not be defended. A recently completed, multi year study conducted by the U.S. Environmental Protection Agency's Office of Research and Development and the Gas Research Institute had the objective of determining methane emissions from the U.S. gas industry with an accuracy of +/-0.5% of production. The study concluded that, in the 1992 base year, methane emissions from the industry were 314 +/- 105 Bscf or 6.04 +/- 2.01 Tg (all conversions to international units are made at 15.56 degrees C and 101.325 kPa).