A new study measures methane leaks in the natural gas industry

Mark Brownstein

Earlier this week, a prestigious scientific journal, the Proceedings of the National Academy of Sciences (PNAS) published “Measurements of methane emissions at natural gas production sites in the United States.”  This study is the first in a comprehensive research initiative that Environmental Defense Fund is helping to produce with more than 90 partner universities, scientists, research facilities and natural gas industry companies. This effort, the largest scientific undertaking in EDF’s history, is an unprecedented attempt to measure where and how much methane is being released across the entire natural gas supply chain.

By the time the work is finished, around the end of 2014, scientists working with EDF will have completed sixteen studies characterizing methane emissions in five key areas of the natural gas system: production, gathering and processing, transmission and storage, local distribution and use in operating and fueling heavy and medium weight trucks.

The study that published Monday was led by Dr. David Allen of the University of Texas at Austin (UT) and is based on some of the first-ever direct measurements of methane emissions from shale gas wells that use hydraulic fracturing, or “fracking.”

Getting the facts

You’ve probably heard or seen advertisements sponsored by the natural gas industry talking about how natural gas is a low-carbon alternative to coal and oil, and this is true, but it’s not the whole story.  Natural gas has roughly half the carbon content of coal and one-third the carbon content of oil.  This means that natural gas creates less carbon dioxide than coal or oil when burned.

But the fact the natural gas industry likes to ignore is that natural gas is methane, and when methane is vented or escapes into the atmosphere its short-term impact on global warming is 72 times more powerful than the carbon dioxide created when it is burned.  Even a small amount of methane emitted to the atmosphere, as little as 1% or less of all the natural gas produced, can work to undo some or all of the benefits we think we are getting when we substitute natural gas for coal or oil.

The problem is that while folks in the natural gas industry know that some amount of the methane they produce and distribute is lost along the way, they don’t know exactly how much is lost, or where exactly those loses are the greatest.  All anyone has had until now are estimates based on research that the U.S. Environmental Protection Agency did nearly 20 years ago. 

It is much more difficult to solve a problem when you don’t know its size or source.  And that’s why EDF believes it is critically important to go out into the field and get real data on methane emission pollution from gas production, and then put that information to work in formulating regulations and practices that reduce or eliminate this pollution.

Shedding light on total leakage rates

Dr. Allen found that overall emission rates at the wells studied are in line with current EPA estimates for the production segment. The study also contains three other notable findings:

First, methane emissions  during  ‘well completion’ – the process of getting the well ready to produce gas after it is drilled and fractured - are lower than current EPA estimates.  This is because the majority of wells tested were using “green completion” technology or flares which were shown to be highly effective in reducing methane emissions at this point in the production process. 

The use of these technologies is a direct consequence of federal New Source Performance Standards (NSPS) for natural gas producers, enacted in the summer of 2012.  By January of 2015, this requirement in EPA’s rule tightens and all natural gas producers will have to green complete to control wellhead emissions. Clearly, the study shows that some have adopted green completions already and that it works really well.  What we don’t know is how common this technology is across the industry in advance of the mandatory compliance date. 

Second, the UT study showed that emissions from pneumatic valves, which control routine operations at the well pad, are higher than EPA estimates.  These valves are designed to vent a certain amount of methane during normal operation, and the fact that these emissions are higher than EPA estimates indicates that there is an opportunity to further reduce emissions through the use of available low- and no-emissions valves.

Third, the study found “fugitive emissions” – leaks from equipment at the production site – are also much higher than EPA estimates.  This too suggests an opportunity for lowering production sector emissions through leak detection and repair requirements.  This means an emphasis on better field performance and maintenance.

Are these results representative?

There are over 2000 natural gas producers in the United States, and so it is fair to wonder whether the nine who participated in this study are representative of the industry as a whole.  No one can say for sure, but what we do know is that the nine companies participating in this study account for roughly 12% of all onshore gas wells in the U.S., and 16% of gross gas production and almost half of all new well completions in 2012.

As to whether participating companies provided only their “best” sites, the answer is no.  The University of Texas study team decided where and when they wanted to test based on their study criteria.  Companies then made available all of the sites that satisfied UT’s request.  Companies did not cherry pick the sites.

Finally, skeptics may wonder whether these companies made cosmetic improvements to their sites before testers came to take measurements.  The answer is no.

First, companies usually only had limited advance notice of when UT was coming to region to test. 

Second, the air emission control equipment that was tested is typically designed into a drilling project from the start and cannot simply be rolled out at a moment’s notice.  And further, once the capital is spent to develop the site using emission-controlling technologies and techniques - such as “green completions,” which reduce emissions at the end of the hydraulic fracturing process, when frack fluids and sands are drawn back up the well to make way for gas production – companies have every incentive to run it.  Otherwise, they would not reap a return on their investment. 

Third, and finally, there is the simple fact that if companies were modifying their behavior in anticipation of the UT researchers’ arrival, it is doubtful fugitive emissions – leaks due to inattentive maintenance and operations - would have been so high.  If companies were trying to game the results, they certainly did not succeed. 

One headline from the study is that green completions are an effective way to control emissions at the end of the hydraulic fracturing process, and that’s good news, because the Environmental Protection Agency is requiring unconventional natural gas wells to use green completions beginning in January 2015. (Today, operators can either use green completion or flare off the methane). No one knows how many operators today are using green completions. For that reason, this study does not claim to offer a snapshot of current industry wide production practices. However, the data suggests that once this practice is required broadly in Jan. 2015, emissions from this phase of the production process will decline.  

Where do we go from here?

While EDF will continue to sponsor and participate in research to better understand methane emissions across the natural gas supply chain, this first study provides enough information to suggest where regulatory reforms are required.  

First, green completion technology, which this study demonstrates is so effective, should be required for all unconventional oil and gas development, and not just gas development, as is currently the case.  The rule needs to be extended to shale oil and hybrid oil-and-gas wells, which are not covered by the EPA regulation. 

Second, clearly there is a need to reduce emissions from pneumatic valves, and there is technology that can do this, and it should be required.  

Third, there is no excuse for us to allow natural gas to be lost through leaks.  This is bad for the environment and a waste of a natural resource.  A requirement that natural gas producers engage in regular and effective leak detection and repair program is in order.  Both the states and the federal government have the authority and the obligation to act and EDF will be campaigning hard to make sure that they do.