Mixed messages on methane
There was a time when environmentalists were all googly-eyed about natural gas, primarily because the cleaner-burning fossil fuel was far more climate-friendly than coal – or so it seemed. The Sierra Club and Chesapeake Energy even became allies in the fight to phase out coal. But as tales of tainted water and polluted air emerged from worried gas patch residents, big environmental groups grew more distant. Soon, natural gas seemed to entirely lose its luster. It’s true that natural gas is cleaner than coal when burned, but it’s mostly made of methane – a greenhouse gas much more potent than CO2. And a series of recent studies all seemed to conclude that a lot of methane was leaking into the atmosphere throughout the the natural gas supply chain – too much, it seemed, for it to be crowned the cleanest of fossil fuels.
Then, this week, the Environmental Protection Agency further complicated the narrative. It lowered its estimate of how much methane leaked out along the supply chain by about 20 percent. The revision, according to the Associated Press has “major implications for a debate that has divided environmentalists: Does the recent boom in hydraulic fracturing help or hurt the fight against climate change?”
How much methane is actually leaking out as natural gas is produced and consumed does, indeed, have big implications for that debate. Troubling measurements taken in two Utah and Colorado gas fields last year show that nine and four percent of methane produced there, respectively, was escaping -- a lot more than expected and more than the 3.2 percent or less rate needed for gas to be better for the climate than coal. But despite this study, and the EPA's softer assessment of leakage, we still don’t have a firm grasp on how much of the gas is being lost to the atmosphere in all of our major gas fields, or from well-to-consumer.
And that’s what we need to know to really have that debate – and to figure out to what extent those losses can be stemmed with emissions control technology. Here are some of the reasons the information we have so far is incomplete: The EPA’s estimates are not based on field measurements. When field measurements aren’t available, emissions rates for pollutants can be calculated using typical leakage rates for equipment or valves measured in factories or labs. But in the field, as equipment weathers and ages, actual emissions can be quite higher. So, EPA’s estimates are just that: estimates. The Utah and Colorado studies, while based on field measurements, aren't a scientific indictment of every gas field everywhere. That is, those rates aren’t necessarily representative of other gas fields’ emissions, partly because control requirements and production methods are inconsistent.
In a few weeks, the first results of the most comprehensive attempt to measure the gas industry's methane emissions in the U.S. are expected to be made public. That study, a collaboration between the University of Texas-Austin, the Environmental Defense Fund, Duke, Harvard and Boston universities, and a number of industry partners, will directly measure fugitive emissions across the supply chain to “determine the true parameters of the problem,” according to EDF. The first phase will quantify emissions during production in the country's major gas fields. Even when the whole thing is complete, there will, inevitably, still be questions to answer, but we should be able to have a much more informed debate about the proper role of natural gas in our energy and climate future. Until then, it’d be wise to heed this cautionary note from Environmental Defense Fund scientist Steven Hamburg, on drawing broad conclusions from the info we have so far:
Great care should be taken to avoid drawing conclusions based on the partial data these studies provide. This will be a particular challenge given that advocates for natural gas production are likely to call attention to the low-leakage results, while opponents of natural gas production are likely to call attention to the high-leakage results, with each side claiming that the latest study “proves” its argument. Neither claim will be reliably accurate.
In other words, anyone who wants to get this important story right will need to be patient and wait for the more comprehensive results to come in later this year. Until then, no accurate conclusion can be drawn about the full scope of this critical issue. Please proceed with caution.
Cally Carswell is High Country News' assistant editor.
Photo courtesy Flickr user Andy Revkin.