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Natural Gas May Benefit Climate Despite Methane Leaks

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Methane leaks are common in the U.S. natural gas production and distribution system, but they do not fully negate the climate benefits of using natural gas to produce electricity over burning coal for electric power, according to a new Stanford University analysis.

The paper, to be published Friday in the journal Science, concludes that U.S. Environmental Protection Agency inventories underestimate methane emissions from natural gas production, but hydraulic fracturing — a process of fracturing underground rock to release natural gas into wells — is not likely the largest source of methane leaks. The study says better science needs to be done to determine where the methane emissions are coming from and how to stop them.

A natural gas drilling rig.
Credit: EPA

Myriad studies have been done showing that natural gas production is a source of excess methane emissions, sparking concern among scientists that natural gas may not be a “bridge fuel” between coal and renewables because the affect natural gas has on climate change may have been underestimated. Methane is about 100 times as potent as carbon dioxide as a greenhouse gas soon after being released into the atmosphere, and about 34 times as potent as CO2 after about 100 years in the atmosphere.

The Stanford-led paper, which reviewed more than 200 studies examining emissions from natural gas production, paints a complicated picture of what we know about methane emissions, and whether it makes sense to replace coal-fired power plants with those running on natural gas.

Atmospheric testing shows that methane emissions are roughly 50 percent higher than EPA estimates, said study lead author Adam Brandt, assistant professor of energy resources engineering at Stanford University.

Brandt and his team reviewed studies that measured methane emissions both on the ground near natural gas production facilities and in the atmosphere, where the studies found methane emissions to be between 25 and 75 percent higher than EPA estimates. But EPA estimates, which the agency reduced by 30 percent last year, exclude natural sources of methane and emissions suspected to be from abandoned oil and gas wells because the amount of methane those sources emit are unknown. The EPA calculates methane emissions by counting the number of cows, oil and gas wells and oil refineries in a region, then estimates total emissions based on how much methane each of those soruces is expected to emit. 

The Stanford-led study was unable to calculate total methane leakage from the energy industry, making it difficult to determine the exact climate benefit of using natural gas over coal for electric power generation, Brandt said. 

Over a 100-year period, the emission estimates from Brandt’s team suggest that the climate impact of burning natural gas is less than that of coal. The team examined previously published  “lifecycle assessments” of coal and natural gas, which analyze the overall climate impacts associated with each fossil fuel. Most lifecycle assessments use EPA greenhouse gas inventories to conclude that natural gas has less of an aggravating effect on climate change than coal.

But the paper concludes that even though official EPA natural gas emissions inventories underestimate methane in the atmosphere, producing and burning natural gas is still better for the climate than coal over a 100-year period.

Other studies have refuted the idea natural gas is a "bridge fuel" that will allow the U.S. to transition from greenhouse gas-rich coal to clean renewable energy sources because leaks associated with producing and burning natural gas may exacerbate climate change too much in the short term to avoid looking for cleaner fuels. 

The paper also concludes that, while switching from coal to natural gas for electic power generation is good for the climate, using natural gas for buses may not be. Brandt said that given the leakage rate in the natural gas production and distribution system, there does not appear to be a climate benefit to switching transportation fuel to natural gas from diesel, which is a highly efficient fuel. 

"You need a stricter leakage standard in order to benefit (from natural gas)," Brandt siad. 

Cornell University civil and environmental engineering professor Anthony Ingraffea, co-author of a 2011 Cornell study showing that leaking emissions from natural gas production are higher than previously thought, said he disagrees with Brandt's conclusion that natural gas is more beneficial for the climate than coal over the span of a century. 

Methane leak rates specified in the paper, "Methane Leaks from North American Natural Gas Systems."
Credit: Stanford University/Science

“Once again, there is a stubborn use of the 100-year impact of methane on global warming, a factor about 30 times that of CO2,” Ingraffea said. “All the current consensus on climate science, summarized in IPCC AR 5 (the Intergovernmental Panel on Climate Change Assessment Report 5), says that we only have about 20-30 years before we reach the warning zone of temperature rise that could lead to climate tipping points. And we can’t wait 20-30 years to start decreasing CO2 equivalent emissions from fossil fuels.”

He said there is no scientific justification to use the 100-year time window.

“That is a policy decision, perhaps based on faulty understanding of the climate change situation in which we find ourselves, perhaps based on wishful thinking,” he said.

Ingraffea said the Brandt team’s paper confirms his and others’ research that EPA inventories underestimate methane emissions from natural gas development.

The Brandt team’s paper finds experiments measuring emissions from specific sources show that most methane leakage comes from a handful of “super-emitters,” the locations of which are generally unknown, but are likely somewhere in the natural gas processing and production system.

Studies that have shown high methane leakage rates are not likely representative of the entire natural gas industry, the study says.

“We don’t know what’s causing excess natural gas leakage,” Brandt said. “We don’t know how much (of the) emissions are from hydraulic fracturing. Hydraulic fracturing is likely to produce only a fraction of the emissions.”

Hydraulic fracturing, or “fracking,” is a controversial method of injecting millions of gallons of water, sand and chemicals underground at high pressure, cracking open crude oil- and natural gas-bearing rock formations and releasing the hydrocarbons to a well at the surface. Advances in fracking technology, along with horizontal and directional drilling techniques, are responsible for current shale oil and gas boom across the U.S., but the technique is widely feared to contaminate surface and groundwater and emit unquantified amounts of greenhouse gases.

Brandt said fracking is unlikely to be the largest source of methane emissions because high methane leakage rates were recorded before the current fracking boom began within the past decade.

Paper co-author and Massachusetts Institute of Technology lecturer Francis O’Sullivan said that methane emissions from fracking are still significant — about 1 teragram per year in the U.S. — but those emissions account for only a small portion of overall natural gas methane emissions.

Echoing the concerns of scientists speaking at the American Geophysical Union Fall Meeting in December in San Francisco, Brandt said there are numerous unknowns about how and where the natural gas production and distribution system is leaking methane. The Stanford study calls for better research to be conducted so that policymakers can gain a greater understanding of how producing and burning natural gas affects climate change.

“One of the main hurdles right now is a general lack of investment and infrastructure, and lack of investment in science and lack of attention to the problem,” Brandt said, adding that researchers lack of access to natural gas production facilities stands in the way of better emissions testing.

“Fundamentally, you can’t access these sites without permission,” he said.

The paper, "Methane Leaks from North American Natural Gas Systems," will be published Friday in the journal Science. 

Comments

By Patty Stephens (austin, tx 78746)
on February 13th, 2014

The title, while eye catching, and the article don’t match, and of benefit to the climate seems misleading. 

No research cited showed natural gas benefits the climate. Rather it shows it is may be better than coal, not that it is better than renewables. 

And the info on the harm of gas is inadequate due to blocked data..” researchers lack of access to natural gas production facilities stands in the way of better emissions testing”.

Please explain.

Reply to this comment

By Michael Gilfillan (Thrums, BC, Canada V1N4M7)
on April 20th, 2014

I suspect you already know at least some of the answer to your question;  the decision has already been made by the power brokers and their political lap-dogs:  Any “take” on the discussion of energy sources and climate that confuses, obfuscates, hijacks or casts doubt on dissenting science is a tool to be used to support decisions already made.

The idea that knowledge backed by solid science will educate the deniers who wield the power is pie-in-the-sky.  Life that does not serve the personal interests of the elites has no value to them, and is the real justification behind the status qou decisions made by our governments (such as mine, Canada).

We have to become active in opposing insanities like fracking and insist on switching to renewable sources that are now widely believed to be capable of replacing carbon sources (and nuclear) to produce our electricity.  We know that something like 80% of carbon-source reserves have to stay in the ground;  we are now tasked with making this happen.

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By Sue Spencer (NY)
on February 14th, 2014

While it is important to learn as much as possible about the volume of methane emissions from all phases of natural gas production, storage and distribution there is NO way any sane individual could ever consider fracking a viable energy source.  The devastating, catastrophic effects the fracking industry wreaks on human health and fresh water supplies are absolutely unconscionable.  Fracking is a path to destruction as sure as the burning of coal.

As Anthony Ingraffea points out in the article, time is fast running out.  Safe, sustainable energy sources and technology are available and we need to make the shift without further delay.

Reply to this comment

By Terry Cook (Findlay)
on March 12th, 2014

We don’t need one more bucket of coal or drop of oil for anything,  We will have hemp growing soon in this country and the use of hydrogen produced in a green manner will easily supply all our energy needs.  Thetopcatplan is the only idea that makes it possible to reduce fossil fuel use at least 20% a year for the next 5.  Go to the category ENERGY to get 17 divisions of green products produced, transported, and used in a green way.  I say,  fracking is many times more destructive than coal.  Hemp char-coal is the total replacement for fossil coal, and hemp fuel & hydrogen will be our main source of energy along with wind, hydro, and the sun for heat, electricity, and transportation. Any questions? Top Cat II

Reply to this comment

By Louise Stonington (Seattle WA 98112)
on February 15th, 2014

‘Natural gas may benefit climate despite methane leaks.’  This title does not fairly represent the article or the study.
There are some people who claim that using natural gas might be slightly better for the climate than using coal, however it is widely agreed that there are not enough studies of amount of methane leakage in natural gas transport, storage and development to be certain.. Since they don’t know, you would think that our government, would protect us and discourage increasing development of natural gas. The study is clear that using LNG, liquified natural gas for fuel is worse for the climate than using diesel.
Why are there not adequate studies?  The EPA has depended on industry estimates and industry funded studies .  The MIT Report on the the Future of Natural Gas in 2011, co-chaired Ernest J. Moniz,n concluded that the US should continue develop natural gas more, but the study was paid for by the American Clean Skies Foundation which apparently gets its funding from petroleum industries. And Moniz? what is he doing now? Heading up the US Department of Energy.

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By Greg Nullet (Ojai, CA 93023)
on February 28th, 2014

“Methane is about 100 times as potent as carbon dioxide as a greenhouse gas soon after being released into the atmosphere, and about 34 times as potent as CO2 after about 100 years in the atmosphere.”

Do you have any data for this? Most references suggest 20 to 25 times as potent and that it persists in the atmosphere for 11 or 12 years.

Reply to this comment

By Ryan Provonsha (98087)
on March 18th, 2014

The bottom line is that societies around the globe need to be reducing their emissions by 6% per year or more, in order for us to avoid the worst effects of climate change; and the situation has every potential to be even more serious than that, if anything.

And while natural gas is cleaner and less CO2-producing than coal when burned, any CO2 emissions or methane leakages take us farther away from that target. The production and burning of natural gas represent the emissions of greenhouse gasses that were formerly trapped in the ground, period.

The relevant question here is not just whether natural gas is relatively better for the climate than coal, but whether natural gas is good *enough* for the climate on the trajectory we’re on.

And when we worry about the climate, we’re fundamentally worried about the human species’ ability to grow enough food, have enough water, and survive in it.

So just because natural gas is better for the climate than coal does not mean its use as an alternative is adequate for our survival.

It’s an opportunity cost to use natural gas and entrench the infrastructure, instead of going fossil free and engineering our way to sustainability with innovative new wind and solar technologies. And the cost may be our lives, legacy and future.

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