Natural gas is cleaner than coal, but only if the industry can control its methane releases. A new report says it's doing OK, but methane releases are underestimated.
Natural gas may be the bridge to America’s energy future – unless the industry can’t control its methane releases, which could burn that conduit.
The primary methane threat – which might come as a surprise to some – does not stem from the most obvious source of new natural gas: controversial shale gas drilling. Instead, it stems from abandoned oil and gas wells, according to the latest in a series of studies that have looked at such potent heat-trapping emissions. Published this week in the journal Science by the Joint Institute for Strategic Energy Analysis, the report concludes that while official numbers tied to methane releases are underestimated, they are still not large enough to undermine the ongoing switch from coal to natural gas power generation.
“Recent life cycle assessments generally agree that replacing coal with natural gas has climate benefits,” said Garvin Heath, a senior scientist at the National Renewable Energy Laboratory and a lead author of the report, in a release. “Current evidence suggests leakages may be larger than official estimates, so diligence will be required to ensure that leakage rates are actually low enough to achieve sustainability goals.”
Why the focus on methane? According to scientists, it is 72 times as powerful as carbon dioxide when it comes to trapping heat, although the methane dissipates after 20 years whereas the carbon dioxide stays active for a 100 years. Just how such methane releases are calculated could have a profound outcome on whether natural gas remains a go-to energy source for companies and nations worried about climate change.
Compared with coal, natural gas releases about half the carbon emissions, which is a big reason natural gas is displacing coal in utility markets. Its share of the power generation market has risen from 20 percent to 30 percent in recent years. The Energy Information Administration expects that share of the electric generation pie to reach 50 percent by 2035, mostly because of the boom in production from horizontal drilling and hydraulic fracturing (or fracking) of shale gas deposits.
Here’s the industry’s challenge: If those fracking and other operations allow more than 3.2 percent of the methane they produce to escape, then the benefits of switching from coal to natural gas are lost. according to Princeton University.
So how much methane do they actually emit? Anywhere from less than 1 percent to more than 8 percent, depending on how it is calculated and who is doing the calculating.
A University of Texas study released this past fall says that natural gas developers are doing a good job of minimizing the escaping methane and limiting it to 0.42 percent of all methane produced. That report was funded by several interests that include nine oil and gas companies as well as the Environmental Defense Fund – and it only looked at 489 sites and didn’t review potential leaks from the pipeline system.
“We know that immediate methane reductions are critical to slow climate change," says Fred Krupp, president of the EDF, in a release. “But we don't yet have a handle on how much is being emitted. We need better data, and that's what this series of studies will deliver.”
That analysis, which will be broadened and updated, follows one by the US Environmental Protection Agency that found that the amount of methane that is leaked into atmosphere during the production and piping of shale gas fell by 20 percent from 1990 to 2010 because of tougher regulations and better equipment. Those escapes are now at 1.5 percent, the EPA says.
Environmental groups are leery. They point to a 2012 exam by the National Oceanic and Atmospheric Administration and the University of Colorado, which found that air samples near fracking wells in Colorado and Utah had a 4 percent methane leakage rate. That report said the leakage could be much as 9 percent.
That evaluation is in line with one by Cornell University a few years ago that said that total greenhouse gases over 20 years associated with drilling for shale gas are at least 20 percent greater when compared with coal. It also said that pipeline leaks are core to the overall problem.
“Natural gas can be part of the climate solution,” says Carl Pope, former executive director of the Sierra Club, in an interview. “It is not so risky that it should be demonized. But it is not so intrinsically clean” that it should be relied upon to solve the problem of global warming.
All the relevant studies involve variables and assumptions – ones that are favorable to the groups bankrolling the reviews. The bottom line is that, absent some big, unexpected revelation, natural gas will continue to expand its share of the power markets and that drilling technologies will improve along with those advances. With proper regulatory oversight, methane releases will fall and help reduce the effects of climate change.