Karen Frantz
GHG Monitor
2/21/2014
Total methane emissions in the United States may be about 25 to 75 percent higher than estimates from the Environmental Protection Agency, according to a recent analysis from scientists at the University of Stanford, the National Renewable Energy Laboratory, the University of Michigan, MIT and others. The analysis, published in the Feb. 14 issue of Science, looked at the findings of studies on methane emissions in the U.S. and Canada spanning over 20 years. “People who go out and actually measure methane pretty consistently find more emissions than we expect,” said Dr. Adam Brandt, an Assistant Professor of Energy Resources Engineering at Stanford University and the lead author of the study, in Stanford News. “Atmospheric tests covering the entire country indicate emissions around 50 percent more than EPA estimates. And that’s a moderate estimate.” However, the analysis also found that, despite the fact that methane emissions are likely higher than official estimates, burning natural gas for electricity generation rather than coal still has climate benefits over 100 years (although the climate benefits of the substitution of natural gas for diesel for vehicle fuels is “improbable”), and that many studies suggest that a small number of “super-emitters” might be suspect for a large percentage of methane leaks.
The analysis suggests that the EPA’s estimates may be low because the Agency uses a “bottom-up” approach to calculating methane emissions, in which it multiplies the amount of methane believed to be emitted from various devises by the number of those devises, rather than measuring the actual methane in the air—so-called atmospheric studies. “Across years, scales and methods, atmospheric studies systematically find larger [methane] emissions than predicted by inventories,” the analysis said. It also said that some studies that focus on regions that are major natural gas producers find larger methane emissions than studies that focus on the nation as a whole.
More Data Needed
Secretary of Energy Ernest Moniz appeared to downplay the significance of the analysis at an event at the National Press Club in Washington this week, saying “more data” is needed on the country’s methane emissions. He also said that the estimates from the analysis were still “certainly in the ballpark” of the EPA’s. “More than likely the production wells are not the major focus of that,” he said. “But this is where we need more data and then respond in a variety of ways.” He said the Department of Energy will be convening several environmental groups and labor unions to look at an action plan on methane emissions. “I would also say that when it comes to production wells and unconventional shale or oil production that certainly the technologies for capturing the methane are there, they are being increasingly used: so-called green completions. Recently in North Dakota the state government made a commitment to 95 percent capture of methane, much of which is being flared at the moment because of lack of infrastructure. So I think there’s a lot of progress, and over the next few years I’m certainly hoping we’ll see significantly reduced emissions.”
The Obama Administration has long been touting the rise of natural gas over coal as a “bridge to a lower carbon future.” Although several environmental groups say that the technology to reduce methane leaks exists, and they have been calling on the federal government to do more to limit the release of methane in the production and distribution of natural gas, many industry sources say regulation is not needed because it is in their best interest to capture and sell as much gas as possible.
CO2 Also a Concern
Methane released from the natural gas sector is a concern because it is a potent greenhouse gas, with a 100-year warming influence 28 times greater than carbon dioxide ton-per-ton—although carbon emissions still far outweigh methane emissions. But methane is not the only greenhouse gas that is released from the natural gas sector—CO2 emissions are also released when waste gas is burned in a process through flaring, which is a concern to groups such as the Environmental Defense Fund (EDF). “Sometimes you hear a debate as to whether or not natural gas really does have a benefit when burned for things like electric generation compared to coal,” said Andrew Williams, State Regulatory and Legislative Affairs Manager at EDF, at the winter meeting of the National Association of Regulatory Utility Commissioners in Washington last week. “If you allow CO2 to leak out from the natural gas production chain, there’s a potential that the benefits associated with burning natural gas in the short term will be outweighed and degraded as a result, and then natural gas will then not have a benefit over coal.”
He said that the implementation of leading practices could help reduce the volume of gas reduced from flares, including “using engineered flare technology, high efficiency flares continuously with ignition systems on flaring devices or systems that automatically reignite flares when they do go out. … We’d like to see the number of wells actually flaring gas reduced, and that will come, I think, with infrastructure development and better understanding of the technologies, which leads into a shorter connection time between when a producer actually finishes drilling a well and that well is connected to a gathering system or a pipeline system.” But he also said that ultimately what is needed is greater collaboration among governments and stakeholders to work out policies to reduce emissions from the natural gas sector. “Really, fundamentally, this is a national energy policy issue,” he said.