Featured Research

from universities, journals, and other organizations

America's natural gas system is leaking methane and in need of a fix

Date:
February 13, 2014
Source:
Stanford University
Summary:
The US natural gas system is letting more methane, a potent greenhouse gas, escape into the air than previously thought, a new study confirms.

Oil and gas processing plants are significant sources of methane, Stanford researchers have found.
Credit: © Budimir Jevtic / Fotolia

The first thorough comparison of evidence for natural gas system leaks confirms that organizations including the Environmental Protection Agency (EPA) have underestimated U.S. methane emissions generally, as well as those from the natural gas industry specifically.

Related Articles


Natural gas consists predominantly of methane. Even small leaks from the natural gas system are important because methane is a potent greenhouse gas -- about 30 times more potent than carbon dioxide. A study, "Methane Leakage from North American Natural Gas Systems," published in the Feb. 14 issue of the journal Science, synthesizes diverse findings from more than 200 studies ranging in scope from local gas processing plants to total emissions from the United States and Canada.

"People who go out and actually measure methane pretty consistently find more emissions than we expect," said the lead author of the new analysis, Adam Brandt, an assistant professor of energy resources engineering at Stanford University. "Atmospheric tests covering the entire country indicate emissions around 50 percent more than EPA estimates," said Brandt. "And that's a moderate estimate."

The standard approach to estimating total methane emissions is to multiply the amount of methane thought to be emitted by a particular kind of source, such as leaks at natural gas processing plants or belching cattle, by the number of that source type in a region or country. The products are then totaled to estimate all emissions. The EPA does not include natural methane sources, like wetlands and geologic seeps.

The national natural gas infrastructure has a combination of intentional leaks, often for safety purposes, and unintentional emissions, like faulty valves and cracks in pipelines. In the United States, the emission rates of particular gas industry components -- from wells to burner tips -- were established by the EPA in the 1990s.

Since then, many studies have tested gas industry components to determine whether the EPA's emission rates are accurate, and a majority of these have found the EPA's rates too low. The new analysis does not try to attribute percentages of the excess emissions to natural gas, oil, coal, agriculture, landfills, etc., because emission rates for most sources are so uncertain.

Several other studies have used airplanes and towers to measure actual methane in the air, so as to test total estimated emissions. The new analysis, which is authored by researchers from seven universities, several national laboratories and federal government bodies, and other organizations, found these atmospheric studies covering very large areas consistently indicate total U.S. methane emissions of about 25 to 75 percent higher than the EPA estimate.

Some of the difference is accounted for by the EPA's focus on emissions caused by human activity. The EPA excludes natural methane sources like geologic seeps and wetlands, which atmospheric samples unavoidably include. The EPA likewise does not include some emissions caused by human activity, such as abandoned oil and gas wells, because the amounts of associated methane are unknown.

However, the analysis also finds that some recent studies showing very high methane emissions in regions with considerable natural gas infrastructure are not representative of the entire gas system. "If these studies were representative of even 25 percent of the natural gas industry, then that would account for almost all the excess methane noted in continental-scale studies," said a co-author of the study, Eric Kort, an atmospheric science professor at the University of Michigan. "Observations have shown this to be unlikely."

Natural gas as a replacement fuel

Even though the gas system is almost certainly leakier than previously thought, generating electricity by burning gas rather than coal still reduces the total greenhouse effect over 100 years, the new analysis shows. Not only does burning coal release an enormous amount of carbon dioxide, mining it releases methane.

Perhaps surprisingly though, the analysis finds that powering trucks and buses with natural gas instead of diesel fuel probably makes the globe warmer, because diesel engines are relatively clean. For natural gas to beat diesel, the gas industry would have to be less leaky than the EPA's current estimate, which the new analysis also finds quite improbable.

"Fueling trucks and buses with natural gas may help local air quality and reduce oil imports, but it is not likely to reduce greenhouse gas emissions. Even running passenger cars on natural gas instead of gasoline is probably on the borderline in terms of climate," Brandt said.

The natural gas industry, the analysis finds, must clean up its leaks to really deliver on its promise of less harm. Fortunately for gas companies, a few leaks in the gas system probably account for much of the problem and could be repaired. One earlier study examined about 75,000 components at processing plants. It found some 1,600 unintentional leaks, but just 50 faulty components were behind 60 percent of the leaked gas.

"Reducing easily avoidable methane leaks from the natural gas system is important for domestic energy security," said Robert Harriss, a methane researcher at the Environmental Defense Fund and a co-author of the analysis. "As Americans, none of us should be content to stand idly by and let this important resource be wasted through fugitive emissions and unnecessary venting."

One possible reason leaks in the gas industry have been underestimated is that emission rates for wells and processing plants were based on operators participating voluntarily. One EPA study asked 30 gas companies to cooperate, but only six allowed the EPA on site.

"It's impossible to take direct measurements of emissions from sources without site access," said Garvin Heath, a senior scientist with the National Renewable Energy Laboratory and a co-author of the new analysis. "But self-selection bias may be contributing to why inventories suggest emission levels that are systematically lower than what we sense in the atmosphere."

The research was funded by the nonprofit organization Novim through a grant from the Cynthia and George Mitchell Foundation. "We asked Novim to examine 20 years of methane studies to explain the wide variation in existing estimates," said Marilu Hastings, sustainability program director at the Cynthia and George Mitchell Foundation. "Hopefully this will help resolve the ongoing methane debate."

Other co-authors of the Science study are Francis O'Sullivan of the MIT Energy Initiative; Gabrielle Pιtron of the National Oceanic and Atmospheric Administration (NOAA) and the University of Colorado; Sarah M. Jordaan of the University of Calgary; Pieter Tans, NOAA; Jennifer Wilcox, Stanford; Avi Gopstein of the U.S. Department of State; Doug Arent of the National Renewable Energy Laboratory and the Joint Institute for Strategic Energy Analysis; Steven Wofsy of Harvard University; Nancy Brown of the Lawrence Berkeley National Laboratory; independent consultant Richard Bradley; and Galen Stucky and Douglas Eardley, both of the University of California-Santa Barbara. The views expressed in the study are those of the authors, and do not necessarily reflect those of the U.S. Department of State or the U.S. government.


Story Source:

The above story is based on materials provided by Stanford University. The original article was written by Mark Golden. Note: Materials may be edited for content and length.


Journal Reference:

  1. A. R. Brandt, G. A. Heath, E. A. Kort, F. O'Sullivan, G. Pιtron, S. M. Jordaan, P. Tans, J. Wilcox, A. M. Gopstein, D. Arent, S. Wofsy, N. J. Brown, R. Bradley, G. D. Stucky, D. Eardley, R. Harriss. Methane Leaks from North American Natural Gas Systems. Science, February 14, 2014 DOI: 10.1126/science.1247045

Cite This Page:

Stanford University. "America's natural gas system is leaking methane and in need of a fix." ScienceDaily. ScienceDaily, 13 February 2014. <www.sciencedaily.com/releases/2014/02/140213142225.htm>.
Stanford University. (2014, February 13). America's natural gas system is leaking methane and in need of a fix. ScienceDaily. Retrieved December 21, 2014 from www.sciencedaily.com/releases/2014/02/140213142225.htm
Stanford University. "America's natural gas system is leaking methane and in need of a fix." ScienceDaily. www.sciencedaily.com/releases/2014/02/140213142225.htm (accessed December 21, 2014).

Share This


More From ScienceDaily



More Matter & Energy News

Sunday, December 21, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Touch-Free Smart Phone Empowers Mobility-Impaired

Touch-Free Smart Phone Empowers Mobility-Impaired

Reuters - Innovations Video Online (Dec. 21, 2014) — A touch-free phone developed in Israel enables the mobility-impaired to operate smart phones with just a movement of the head. Suzannah Butcher reports. Video provided by Reuters
Powered by NewsLook.com
Building Google Into Cars

Building Google Into Cars

Reuters - Business Video Online (Dec. 19, 2014) — Google's next Android version could become the standard that'll power your vehicle's entertainment and navigation features, Reuters has learned. Fred Katayama reports. Video provided by Reuters
Powered by NewsLook.com
AP Review: Nikon D750 and GoPro Hero 4

AP Review: Nikon D750 and GoPro Hero 4

AP (Dec. 19, 2014) — What to buy an experienced photographer or video shooter? There is some strong gear on the market from Nikon and GoPro. The AP's Ron Harris takes a closer look. (Dec. 19) Video provided by AP
Powered by NewsLook.com
Obama: Better Ways to Create Jobs Than Keystone Pipeline

Obama: Better Ways to Create Jobs Than Keystone Pipeline

AFP (Dec. 19, 2014) — US President Barack Obama says that construction of the Keystone pipeline would have 'very little impact' on US gas prices and believes there are 'more direct ways' to create construction jobs. Duration: 00:47 Video provided by AFP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:

Strange & Offbeat Stories

 

Space & Time

Matter & Energy

Computers & Math

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins