New estimates from the EPA indicate that methane leakage from natural gas production is substantially lower than previously believed. Or, translated to English: Natural gas may be a better solution to rampant global warming than anyone believed.
The recent boom in natural gas production — largely a function of improvements in the process of hydrofracturing, or fracking — has been seen as a mixed blessing by environmentalists focused on curbing the atmospheric warming created by greenhouse gases. On one hand, more natural gas extraction has led to lower natural gas prices, which has led to increased use of natural gas in electricity generation, which has led to lower emissions of the greenhouse gas carbon dioxide, since natural gas burns more cleanly than coal. On the other hand, natural gas is comprised mostly of methane, a gas that is 21 times better at trapping atmospheric heat than carbon dioxide. When natural gas is produced, some of it escapes. If the amount that escapes is significant enough, the anti-warming benefit of adding less carbon dioxide to the atmosphere could be offset by adding a smaller amount of methane. That's the argument that was made by 350.org's Bill McKibben, a prominent environmental activist, last year.
For years, environmental groups were torn on the merits of natural gas as what was called a "bridge fuel," a way to ease from heavy-carbon dioxide producing energy systems to clean, renewable ones. At one time, the Sierra Club advocated for increased use of natural gas; the Environmental Defense Fund (with an economic push from Michael Bloomberg) similarly pushes for increased gas use.
By revising its estimate of how much methane leaks at production sites, the EPA has substantially bolstered that middle ground. The AP reports on the change:
In a mid-April report on greenhouse emissions, the agency now says that tighter pollution controls instituted by the industry resulted in an average annual decrease of 41.6 million metric tons of methane emissions from 1990 through 2010, or more than 850 million metric tons overall. That's about a 20 percent reduction from previous estimates. The agency converts the methane emissions into their equivalent in carbon dioxide, following standard scientific practice.
The EPA revisions came even though natural gas production has grown by nearly 40 percent since 1990.
In other words, the EPA thinks the amount of methane leakage is only about 80 percent of what was previously thought, despite the boom in natural gas production.
This drop is significant, but hardly enough to quell all opposition. The EPA's new estimate doesn't come from field testing at production sites, prompting Cornell professor Robert Howarth, author of a 2011 report suggesting that leakage was higher than believed, to say that he thinks "the EPA is wrong."
Howarth wrote that the EPA seems "to be ignoring the published NOAA data in their latest efforts, and the bias on industry only pushing estimates downward — never up — is quite real. EPA badly needs a counter-acting force, such as outside independent review of their process."
It's not only natural gas production that creates methane, as the detailed report articulates, though that is the largest contributor. The second-largest? "Enteric Fermentation" — burps and flatulence from livestock.
Under the EPA's new estimate, methane now comprises nine percent of all of the country's greenhouse gas emissions. Since 2005, emissions have fallen 6.9 percent.
Photo: A worker checks a wellhead at a fracking rig. (AP)