Anthropogenic emissions of methane in the United States

Anthropogenic emissions of methane in the United States


Successful regulation of greenhouse gas emissions requires knowledge of current methane emission sources. Existing state regulations in California and Massachusetts require ∼15% greenhouse gas emissions reductions from current levels by 2020. However, government estimates for total US methane emissions may be biased by 50%, and estimates of individual source sectors are even more uncertain. This study uses atmospheric methane observations to reduce this level of uncertainty. We find greenhouse gas emissions from agriculture and fossil fuel extraction and processing (i.e., oil and/or natural gas) are likely a factor of two or greater than cited in existing studies. Effective national and state greenhouse gas reduction strategies may be difficult to develop without appropriate estimates of methane emissions from these source sectors.

Commentary on the study:

Bridge Out: Bombshell Study Finds Methane Emissions From Natural Gas Production Far Higher Than EPA Estimates | ThinkProgress.

Huffington Post coverage:

NY Times coverage:

Harvard University Press Release:

Link to Study:

Anthropogenic emissions of methane in the United States

▶ Emissions: Images From The Mixing Layer – YouTube

▶ Emissions: Images From The Mixing Layer – YouTube.

Aging US Gas Pipeline Infrastructure Costs Consumers Billions – Forbes

Aging US Gas Pipeline Infrastructure Costs Consumers Billions – Forbes.

Is Natural Gas ‘Clean’? –

Is Natural Gas ‘Clean’? –

Uinta Basin gas leakage far worse than most believe | The Salt Lake Tribune

Uinta Basin gas leakage far worse than most believe | The Salt Lake Tribune.

Another View on Gas Drilling in the Context of Climate Change –

Another View on Gas Drilling in the Context of Climate Change –

Schlumberger Gas Leak Study

Schlumberger Gas Leak Study.

Gangplank to a Warm Future – Dr. Ingraffea.

Gangplank to a Warm Future –


<nyt_headline version=”1.0″ type=” “>Gangplank to a Warm Future


Published: July 28, 2013 149 Comments

ITHACA, N.Y. — MANY concerned about climate change, including President Obama, have embraced hydraulic fracturing for natural gas. In his recent climate speech, the president went so far as to lump gas with renewables as “clean energy.”

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Readers’ Comments

As a longtime oil and gas engineer who helped develop shale fracking techniques for the Energy Department, I can assure you that this gas is not “clean.” Because of leaks of methane, the main component of natural gas, the gas extracted from shale deposits is not a “bridge” to a renewable energy future — it’s a gangplank to more warming and away from clean energy investments.

Methane is a far more powerful greenhouse gas than carbon dioxide, though it doesn’t last nearly as long in the atmosphere. Still, over a 20-year period, one pound of it traps as much heat as at least 72 pounds of carbon dioxide. Its potency declines, but even after a century, it is at least 25 times as powerful as carbon dioxide. When burned, natural gas emits half the carbon dioxide of coal, but methane leakage eviscerates this advantage because of its heat-trapping power.

And methane is leaking, though there is significant uncertainty over the rate. But recent measurements by the National Oceanic and Atmospheric Administration at gas and oil fields in California, Colorado and Utah found leakage rates of 2.3 percent to 17 percent of annual production, in the range my colleagues at Cornell and I predicted some years ago. This is the gas that is released into the atmosphere unburned as part of the hydraulic fracturing process, and also from pipelines, compressors and processing units. Those findings raise questions about what is happening elsewhere. The Environmental Protection Agency has issued new rules to reduce these emissions, but the rules don’t take effect until 2015, and apply only to new wells.

A 2011 study from the National Center for Atmospheric Research concluded that unless leaks can be kept below 2 percent, gas lacks any climate advantage over coal. And astudy released this May by Climate Central, a group of scientists and journalists studying climate change, concluded that the 50 percent climate advantage of natural gas over coal is unlikely to be achieved over the next three to four decades. Unfortunately, we don’t have that long to address climate change — the next two decades are crucial.

To its credit, the president’s plan recognizes that “curbing emissions of methane is critical.” However, the release of unburned gas in the production process is not the only problem. Gas and oil wells that lose their structural integrity also leak methane and other contaminants outside their casings and into the atmosphere and water wells. Multiple industry studies show that about 5 percent of all oil and gas wells leak immediately because of integrity issues, with increasing rates of leakage over time. With hundreds of thousands of new wells expected, this problem is neither negligible nor preventable with current technology.

Why do so many wells leak this way? Pressures under the earth, temperature changes, ground movement from the drilling of nearby wells and shrinkage crack and damage the thin layer of brittle cement that is supposed to seal the wells. And getting the cement perfect as the drilling goes horizontally into shale is extremely challenging. Once the cement is damaged, repairing it thousands of feet underground is expensive and often unsuccessful. The gas and oil industries have been trying to solve this problem for decades.

The scientific community has been waiting for better data from the E.P.A. to assess the extent of the water contamination problem. That is why it is so discouraging that, in the face of industry complaints, the E.P.A. reportedly has closed or backed away from several investigations into the problem. Perhaps a full E.P.A. study of hydraulic fracturing and drinking water, due in 2014, will be more forthcoming. In addition, drafts of an Energy Department study suggest that there are huge problems finding enough water for fracturing future wells. The president should not include this technology in his energy policy until these studies are complete.

We have renewable wind, water, solar and energy-efficiency technology options now. We can scale these quickly and affordably, creating economic growth, jobs and a truly clean energy future to address climate change. Political will is the missing ingredient. Meaningful carbon reduction is impossible so long as the fossil fuel industry is allowed so much influence over our energy policies and regulatory agencies. Policy makers need to listen to the voices of independent scientists while there is still time.


Anthony R. Ingraffea is a professor of civil and environmental engineering at Cornell University and the president of Physicians, Scientists and Engineers for Healthy Energy, a nonprofit group.

Shale Gas Review: Efforts to test Marcellus in upstate NY produces leaky well Carrizo crews on site to fix casing problem in Owego

Shale Gas Review: Efforts to test Marcellus in upstate NY produces leaky well Carrizo crews on site to fix casing problem in Owego.

Methane leaks erode green credentials of natural gas : Nature News & Comment

Methane leaks erode green credentials of natural gas : Nature News & Comment.

Methane leaks erode green credentials of natural gas

Losses of up to 9% show need for broader data on US gas industry’s environmental impact.

02 January 2013
Natural-gas wells such as this one in Colorado are increasingly important to the US energy supply.


Scientists are once again reporting alarmingly high methane emissions from an oil and gas field, underscoring questions about the environmental benefits of the boom in natural-gas production that is transforming the US energy system.

The researchers, who hold joint appointments with the National Oceanic and Atmospheric Administration (NOAA) and the University of Colorado in Boulder, first sparked concern in February 2012 with a study1 suggesting that up to 4% of the methane produced at a field near Denver was escaping into the atmosphere. If methane — a potent greenhouse gas — is leaking from fields across the country at similar rates, it could be offsetting much of the climate benefit of the ongoing shift from coal- to gas-fired plants for electricity generation.

Industry officials and some scientists contested the claim, but at an American Geophysical Union (AGU) meeting in San Francisco, California, last month, the research team reported new Colorado data that support the earlier work, as well as preliminary results from a field study in the Uinta Basin of Utah suggesting even higher rates of methane leakage — an eye-popping 9% of the total production. That figure is nearly double the cumulative loss rates estimated from industry data — which are already higher in Utah than in Colorado.

“We were expecting to see high methane levels, but I don’t think anybody really comprehended the true magnitude of what we would see,” says Colm Sweeney, who led the aerial component of the study as head of the aircraft programme at NOAA’s Earth System Research Laboratory in Boulder.

Whether the high leakage rates claimed in Colorado and Utah are typical across the US natural-gas industry remains unclear. The NOAA data represent a “small snapshot” of a much larger picture that the broader scientific community is now assembling, says Steven Hamburg, chief scientist at the Environmental Defense Fund (EDF) in Boston, Massachusetts.

The NOAA researchers collected their data in February as part of a broader analysis of air pollution in the Uinta Basin, using ground-based equipment and an aircraft to make detailed measurements of various pollutants, including methane concentrations. The researchers used atmospheric modelling to calculate the level of methane emissions required to reach those concentrations, and then compared that with industry data on gas production to obtain the percentage escaping into the atmosphere through venting and leaks.

The results build on those of the earlier Colorado study1 in the Denver–Julesburg Basin, led by NOAA scientist Gabrielle Pétron (see Nature 482, 139–140; 2012). That study relied on pollution measurements taken in 2008 on the ground and from a nearby tower, and estimated a leakage rate that was about twice as high as official figures suggested. But the team’s methodology for calculating leakage — based on chemical analysis of the pollutants — remains in dispute. Michael Levi, an energy analyst at the Council on Foreign Relations in New York, published a peer-reviewed comment2 questioning the findings and presenting an alternative interpretation of the data that would align overall leakage rates with previous estimates.

Pétron and her colleagues have a defence of the Colorado study in press3, and at the AGU meeting she discussed a new study of the Denver–Julesburg Basin conducted with scientists at Picarro, a gas-analyser manufacturer based in Santa Clara, California. That study relies on carbon isotopes to differentiate between industrial emissions and methane from cows and feedlots, and the preliminary results line up with their earlier findings.

A great deal rides on getting the number right. A study4 published in April by scientists at the EDF and Princeton University in New Jersey suggests that shifting to natural gas from coal-fired generators has immediate climatic benefits as long as the cumulative leakage rate from natural-gas production is below 3.2%; the benefits accumulate over time and are even larger if the gas plants replace older coal plants. By comparison, the authors note that the latest estimates from the US Environmental Protection Agency (EPA) suggest that 2.4% of total natural-gas production was lost to leakage in 2009.

To see if that number holds up, the NOAA scientists are also taking part in a comprehensive assessment of US natural-gas emissions, conducted by the University of Texas at Austin and the EDF, with various industry partners. The initiative will analyse emissions from the production, gathering, processing, long-distance transmission and local distribution of natural gas, and will gather data on the use of natural gas in the transportation sector. In addition to scouring through industry data, the scientists are collecting field measurements at facilities across the country. The researchers expect to submit the first of these studies for publication by February, and say that the others will be complete within a year.

In April, the EPA issued standards intended to reduce air pollution from hydraulic-fracturing operations — now standard within the oil and gas industry — and advocates say that more can be done, at the state and national levels, to reduce methane emissions. “There are clearly opportunities to reduce leakage,” says Hamburg.




03 January 2013





  1. Pétron, G. et al. J. Geophys. Res. 117, D04304 (2012).

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  2. Levi, M. A. J. Geophys. Res. 117, D21203 (2012).

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  3. Pétron, G. et al. J. Geophys. Res. (in the press).

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  4. Alvarez, R. A., Pacala, S. W. Winebrake, J. J., Chameides, W. L. & Hamburg, S. P. Proc. Natl Acad. Sci. USA 109, 6435–6440 (2012).

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