Study: EPA overlooks large methane sources

Oct. 14, 2014
Methane inventories by the US Environmental Protection Agency, which underlie efforts to regulate emissions from hydraulic fracturing and other oil and gas work, overlook other, potentially larger sources of the greenhouse gas, a study by Los Alamos National Laboratory (LANL) suggests.

Methane inventories by the US Environmental Protection Agency, which underlie efforts to regulate emissions from hydraulic fracturing and other oil and gas work, overlook other, potentially larger sources of the greenhouse gas, a study by Los Alamos National Laboratory (LANL) suggests (OGJ Online, Sept. 22, 2014).

The study suspects methane leaks from coal mines.

Remote, regional-scale ground measurements confirm a large methane “hot spot” has existed over the Four Corners area of the US Southwest for almost a decade, according to LANL.

“A detailed analysis indicates that methane emissions in the region are actually three times larger than reported by EPA,” said LANL scientist Manvendra Dubey. The hot spot covers about 2,500 sq miles in the Four Corners intersection of Arizona, Colorado, New Mexico, and Utah.

“We attribute this hot spot to fugitive leaks from coal-bed methane that actually preceded recent concerns about potential emissions from fracing,” Dubey said in a press release.

The measurement ground site was near Waterflow, NM, close to two coal-fired power plants. The area has extensive coal mining.

LANL remote sensing observations, taken continuously through 2011 and 2012, showed large morning increases of methane. The measurements followed indications of the hot spot by a European satellite, which measured methane in the area daily during 2003-09.

The ground and satellite observations indicated EPA modeling estimates of methane emissions for the regions were too low by a factor of three.

The region had almost no hydraulic fracturing of oil or gas wells during the period of satellite observations of methane. “As the quest to understand emissions continues we must also correct for the missing coal-related methane sources and other biogenic sources that include cattle, landfills, and wetlands,” Dubey said.