Tens of thousands of pounds of methane leak per hour from equipment in three major natural gas basins that span Texas, Louisiana, Arkansas and Pennsylvania, according to airborne measurements published today by a NOAA-led team of scientists. But the overall leak rate from those basins is only about one percent of gas production there—lower than leak rates measured in other gas fields, and in line with federal estimates.

“We are beginning to get a sense of regional variation in methane emissions from natural gas production,” said lead author Jeff Peischl, a scientist with the Cooperative Institute for Research in Environmental Sciences (CIRES) in Boulder, Colorado. “The gas fields we studied for this paper produced about 20 percent of the natural gas in the United States, and more than half the shale gas, so this moves us closer to understanding methane leaks from U.S. natural gas production.”

Peischl works at NOAA’s Earth System Research Laboratories in Boulder, Colorado. His team’s analysis appears online today in the Journal of Geophysical Research: Atmospheres, published by the American Geophysical Union.

In the new paper, he and his colleagues used sophisticated measurements taken from a NOAA research aircraft to determine methane emissions from the Haynesville, Fayetteville, and Marcellus regions during five flights in the summer of 2013.

Overall, they found that methane leaking from gas equipment totaled about 1.1 percent of gas produced in those regions; estimates from the Environmental Protection Agency, based on average equipment leak rates, put that figure at about 1 percent.  

“It is good news that our atmospheric measurements are close to the EPA estimates,” said co-author Joost de Gouw, a CIRES scientist who also works at NOAA. “If leak rates are too high, natural gas does not compare favorably with one alternative, coal, in terms of climate impact. Where leak rates are low, the comparison favors natural gas.”

In the new study, the researchers also reported their findings by region:

• Methane emissions in the Marcellus region of northeastern Pennsylvania were about 16.5 tons (33,000 lbs) per hour, or 0.18-0.41 percent of production.
• Methane emissions in the Haynesville shale of eastern Texas/northwestern Louisiana of about 88 tons (176,000 lbs) per hour, or 1.0-2.1 percent of production.
• Methane emissions in the Fayetteville shale region of Arkansas were roughly 43 tons (86,000 lbs) per hour, or 1.0-2.8 percent of produced gas.

In other published papers, CIRES, NOAA and other researchers have found methane losses of:

• about 4 percent of natural gas production in the Denver-Julesberg Basin
• 6-12 percent of natural gas production in Utah’s Uinta Basin (also called Uintah)
• about 17 percent of natural gas production in the Los Angeles Basin

The Colorado, Utah and California basins combined produce less than 3 percent of all U.S. natural gas, much less than the eastern basins.

The variable methane leak rates in the different studies suggests that other chemicals emitted during gas production, including compounds that contribute to episodes of poor air quality, are also variable, de Gouw said. There could be many reasons for significant regional differences in leak rates, he added.  The composition of gas can vary across different regions, with slightly more or less methane, for example. And equipment, techniques and regulations vary, as well.

The CIRES and NOAA team is planning another aircraft mission this spring, to expand emissions measurements from gas-producing regions stretching from Texas to North Dakota. The researchers hope that, taken together, the studies will help industry identify the conditions and techniques that minimize the leaks during gas production, benefitting both the atmosphere and the industry’s bottom line.

CIRES is a partnership of NOAA and the University of Colorado Boulder.

Authors of "Quantifying atmospheric methane emissions from the Haynesville, Fayetteville, and northeastern Marcellus shale gas production regions," are J. Peischl (CIRES/NOAA), T. B. Ryerson (NOAA),  K. C. Aikin (CIRES/NOAA), J. A. de Gouw (CIRES/NOAA), J. B. Gilman (CIRES/NOAA), J. S. Holloway (CIRES/NOAA), B. M. Lerner (CIRES/NOAA), R. Nadkarni (Texas Commission on Environmental Quality), J. A. Neuman (CIRES/NOAA), J. B. Nowak (Aerodyne Research, Inc), M. Trainer (NOAA),  C. Warneke (CIRES/NOAA), and D. D. Parrish (CIRES/NOAA).

On the web:

• Read the paper.
• More about the Southeast Nexus mission in the summer 2013, which explored the nexus of climate change and air quality in the U.S. Southeast. Data for this paper came from Southeast Nexus.
• More about an upcoming mission SONGNEX, the Shale Oil and Natural Gas Nexus mission, which will expand measurements of the atmospheric impacts of oil and natural gas development, with research flights from Texas to North Dakota this spring and summer.

Download high-resolution images:

• Two scientists check out an instrument pre-flight.
• Shale plays in the United States, a map by the U.S. Energy Information Administration.
• The NOAA research aircraft on the tarmac during the 2013 mission.
• Natural gas drilling in Tioga County, Pennsylvania, in the Marcellus Shale.

CIRES Contacts:

• Jeff Peischl, CIRES scientist, Jeff.Peischl@noaa.gov, 303-497-4849
• Joost de Gouw, CIRES scientist, joost.degouw@noaa.gov, 303-497-3878
• Katy Human, CIRES communications, kathleen.human@colorado.edu, 303-735-0196

AGU Contact:

• Peter Weiss, AGU public information, pweiss@agu.org, 202-777-7507