Researchers using satellite data have pinpointed New Mexico's San Juan Basin as a major source of leaking methane in the United States.

The region was responsible for 10 percent of all the methane emissions from the natural gas sector in the country, according to a study published yesterday in Geophysical Research Letters. If gas, coal mining and petroleum sectors are included, the San Juan Basin was responsible for 5 percent of the emissions.

The region emitted 0.59 million metric tons of methane every year between 2003 and 2009, the study found. That rate is three times the amount reported in the European Union's greenhouse gas inventory, called EDGAR. It is 1.8 times the reported value in U.S. EPA's Greenhouse Gas Reporting Program.

The high emissions were recorded in 2003, prior to the advent of hydraulic fracturing, or fracking, a technique used to extract oil and gas from shale reservoirs. But parts of the oil and gas system were leaking even before fracking, said Eric Kort, an assistant professor at the University of Michigan and lead author of the study.

"There is a lot of fixation on high-volume hydraulic fracturing," he said. "The point here is we see this [methane leaks] from an earlier time period in the San Juan, and it is indicative that we can't just be fixated on one part; we have to focus on the industry as a whole."

The results are similar to a ClimateWire analysis of EPA's Greenhouse Gas Reporting Program data that found the San Juan Basin is the leakiest when only the biggest companies emitting more than 25,000 metric tons of greenhouse gases are considered. The analysis tied much of the San Juan's emissions to coalbed methane wells owned by the largest operator in the basin, ConocoPhillips (ClimateWire, Oct. 6).

The study was based on both space and ground observations. Kort and his colleagues used a satellite that produced images of methane and could see that the region at the intersection of four states, Arizona, New Mexico, Colorado and Utah, had high concentrations of the gas.

Results validated by ground observations
They verified their observations on the ground using a device that looks up at the sun and measures the total greenhouse gas in the atmosphere. The ground observations helped validate the observations from space.

Kort hypothesizes that the emissions are coming from coalbed methane extraction. The San Juan Basin is the largest producer of natural gas from coal beds, and it is currently unclear if coalbed methane wells emit more than conventional or unconventional natural gas wells.

Kort said that the San Juan may be showing up as a hot spot in satellite images because of its geography and wind patterns; other basins, like the Barnett Shale, which produce a lot more natural gas from unconventional and conventional reservoirs, may just not show up because the wind diffuses the emitted methane, he said.

But overall, his study warrants a closer look at emissions from the San Juan Basin, he said.

This is the first time scientists have used satellites to image greenhouse gas emissions on the ground. The study demonstrates the power of space-based observations, said Christian Frankenberg, a research scientist at NASA's Jet Propulsion Laboratory and co-author of the study, in a statement.

"Satellite data cannot be as accurate as ground-based estimates, but from space, there are no hiding places," he said.

Reprinted from Climatewire with permission from Environment & Energy Publishing, LLC., 202-628-6500