by Sarah Keller
Burning coal belches about twice as much carbon dioxide as burning natural gas, but the question of whether natural gas is a bridge to renewable energy or just a bridge to nowhere hinges on how much greenhouse gas escapes before it is used. Methane, the main component of natural gas, is 21 times more potent at warming than carbon dioxide, over a 100-year period. And according to research by the Environmental Defense Fund, if a little over three percent of the methane produced escapes during production, natural gas plants no longer beat coal plants at the climate game.
As part of a larger study on air quality in Utah’s oil and gas fields, researchers flew a sensor-laden airplane over the Uintah Basin and found that the amount of methane released there is 6 to 12 percent of total production, on average. Since the team from the National Oceanic and Atmospheric Administration and the Cooperative Institute for Research in Environmental Sciences (CIRES) needed consistent wind speeds to test the new technique, the measurement is only a snapshot from a single day in February 2012, and doesn’t provide the big picture for the whole state, much less the whole industry.
Still, the current observations from Utah are much higher than the U.S. Environmental Protection Agency’s recent report of 0.88 percent escaping from U.S. gas production on average. Some saw the EPA’s numbers from earlier this year—a downward revision from earlier reports—as a win for the green cred of gas. But that figure is based on estimates from typical leakage rates, not independent field monitoring. To get a more complete picture, we’ll have to wait for results from wider-ranging studies.
The current study was also a proof-of-concept for one way to track rogue methane, something that will help researchers and could be useful if the feds regulate it more tightly in the future. Currently, the EPA’s oil and gas emissions rules, adopted last April, require producers to burn methane off wells in gas flares (which is still wasteful and emits carbon dioxide), or use “green completion” technologies that capture methane and other air pollutants during production. By 2015, the rule phases out flaring and requires emissions capture technology.
However, the rule focuses on limiting volatile organic compounds (VOC) emissions—precursors to ozone, which is a health risk at ground level. Capturing methane is a virtuous side effect of the new Clean Air Act standards for VOCs. It’s not clear if the EPA will also seek strict standards for methane, as it did for VOCs. But the issue has northeastern states, which want methane standards, squaring off with heartland and western states.
In 2011, the attorneys general from New York, Connecticut, Delaware, Maryland, Rhode Island, Vermont, and Massachusetts notified the EPA of their intent to sue for not regulating oil and gas methane emissions under the Clean Air Act. This May, Oklahoma, Alabama, Indiana, Kansas, Montana, Nebraska, North Dakota, Ohio, South Dakota, Texas, West Virginia and Wyoming sent the EPA a letter warning the agency not to negotiate a friendly settlement with the eastern states, without at least including energy producing states in the discussion.
Meanwhile, climatologists are still debating the issue of how much we should worry about leaked methane negating the greenhouse gas benefits of moving away from coal in the first place.