A new study by the University of Texas, Austin, shows that methane emissions from onshore natural gas drilling are much lower than previous estimates, in part because of the effectiveness of techniques required by the U.S. Environmental Protection Agency for completing a well and bringing it into production.
However, the study released Monday also showed higher leakage rates than expected from valves and control devices used in the production of natural gas. Despite that, the overall level of methane leakage from gas production was 0.42 percent of total volume, slightly less than the most recent EPA estimates of 0.47 percent.
The paper, published in the Proceedings of the National Academy of Sciences, is the first of 16 studies measuring methane leakage throughout the natural gas supply chain, a project organized by the Environmental Defense Fund, nine oil and gas companies, and various individuals and foundations. The companies that cooperated with the study represented about half of the 4,000 wells drilled in 2011.
The level of methane leakage from natural gas wells and pipelines has been the focus of debate as the level of shale gas drilling and production surges. Foes of shale gas drilling argue that leaks of methane, which is a greenhouse gas 72 times more potent than carbon dioxide over a 20-year time frame, offset the benefits of substituting gas for coal.