Top Methane Studies Confirm Low and Dramatically Declining Emissions

There have been a number of landmark methane studies published recently that have made a significant contribution to our understanding of emissions during the production of oil and natural gas.  Each one of these studies has found that as natural gas production has skyrocketed, methane emissions have plummeted, a trend that is helping our economy and environment.

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Here are the top methane studies to know about:

Intergovernmental Panel on Climate Change (IPCC) Climate Assessment  

In its latest climate assessment, the Intergovernmental Panel on Climate Change (IPCC) found that it’s largely thanks to hydraulic fracturing and natural gas that the United States has been able to reduce its greenhouse gas emissions dramatically.  From the report:

“A key development since AR4 is the rapid deployment of hydraulic fracturing and horizontal drilling technologies, which has increased and diversified the gas supply…is an important reason for a reduction of GHG emissions in the United States.” (Ch. 7, p. 18)

On methane emissions specifically, the IPCC states,

“While some studies estimate that around 5% of the produced gas escapes in the supply chain, other analyses estimate emissions as low as 1% (Stephenson et al., 2011; Howarth et al.,2011; Cathles et al., 2012). Central emission estimates of recent analyses are 2%─3% (+/‐1%) of the gas produced, where the emissions from conventional and unconventional gas are comparable.” (p. 19; emphasis added)

The IPCC also clarifies that even “[t]aking into account revised estimates for fugitive emissions, recent lifecycle assessment indicate that specific GHG emission are reduced by one half” as more power plants are powered by natural gas (p. 19).

Environmental Protection Agency Greenhouse Gas Inventory

Earlier this year, the U.S. Environmental Protection Agency (EPA) released its latest Greenhouse Gas Inventory, which found a dramatic decline in methane emissions from natural gas production in recent years.  According to the EPA, methane emissions from natural gas production have fallen 38 percent since 2005.   Over the same period, U.S. natural gas production has increased by 26 percent.

University of Colorado at Boulder and the National Oceanic and Atmospheric Administration (NOAA)

Researchers from the University of Colorado at Boulder and the National Oceanic and Atmospheric Administration (NOAA) recently released a report, which found that methane leakage rates from three major shale developing regions are in line with EPA’s leakage estimate of 1.1 percent of production.

Specifically, the researchers found emissions in the Haynesville Shale in Louisiana and Texas to be 1.0 to 2.1 percent; in the Fayetteville Shale in Arkansas the rate was 1.0 to 2.8 percent; and the Marcellus Shale it was 0.18 to 0.41 percent.

Importantly, the areas of study collectively represent over half of the United States’ total shale gas production.  From the report:

“The climate impact of CH4 loss from shale gas production depends upon the total leakage from all production regions. The regions investigated in this work represented over half of the U.S. shale gas production in 2013, and we find generally lower loss rates than those reported in earlier studies of regions that made smaller contributions to total production. Hence, the national average CH4 loss rate from shale gas production may be lower than values extrapolated from the earlier studies.” (emphasis added)

Environmental Defense Fund Reports

Just last week, researchers from a number of universities partnered with the Environmental Defense Fund (EDF) to publish eleven new studies in the journal Environmental Science and Technology.  These studies found that methane leakage rates from natural gas systems in the Barnett Shale area were extremely low.  As the Lyon et al study explains,

“Barnett Shale O&G wells produced 5.6 Bcf day-1 natural gas and 54.5mbl oil and condensate day-1 in October 2013.  Assuming a constant production rate and weighted average gas composition of 88.5% methane by volume, our O&G emission estimate is equivalent to 1.2% (1.0-1.4%) of gas production. If oil production site emissions (4% of O&G total) are excluded then the natural gas leak rate decreases to 1.1% (1.0% – 1.3%).  (p. 8153; emphasis added)

Many scientists have observed that, for natural gas to maintain its climate advantages, methane leaks need to be kept between 2 to 3 percent. EDF has long maintained that natural gas is beneficial for the climate “as long as leakage remains under 3.2%.”  With an average leakage rate of 1.2 percent, the data clearly show a leakage rate well below that threshold.

These studies follow a number of other reports spearheaded by EDF.  In 2013 the University of Texas (UT) and the Environmental Defense Fund (EDF) released a study that looked at 190 onshore natural gas production sites in the United States and found that emissions were “nearly 50 times lower than previously estimated by the Environmental Protection Agency.” The study found a leakage rate of only about 1.5 percent, which is comfortably below the threshold required for shale to maintain its obvious and significant climate benefits

UT and EDF followed up with two more studies, which also found very low methane leakage rates.  These studies concluded that methane emissions from the upstream portion of the supply chain are only 0.38 percent of production. That’s about 10 percent lower than what they found in their 2013 study.

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