New Barnett Shale Study Further Confirms Low Methane Leakage Rates

Researchers from the Environmental Defense Fund (EDF) and a number of other universities have just released a new report looking at methane emissions in the Barnett Shale in Texas. The report analyzes data from 12 previous EDF papers and determines that the methane leakage rate during natural gas development is very low, far below what is required for natural gas to have significant benefits when it comes to climate change.

Despite this, EDF has focused its analysis of the study almost entirely on how its data compares to previous estimates, namely those of the Environmental Protection Agency (EPA), rather than looking at what actually matters for climate change: the overall leakage rate.  EDF has long maintained that natural gas is advantageous for the climate “as long as leakage remains under 3.2%.”  With an average leakage rate of 1.5 percent in the Barnett Shale, the climate advantages are pretty clear. After all, natural gas’ impact on climate change is the reason methane emissions are under the spotlight in the first place.

Here are the top three things to know about the report:

#1: Finds very low methane leakage rates – well below the threshold for natural gas to have significant climate advantages

The report finds,

“Measured oil and gas methane emissions are 90% larger than estimates based on the US Environmental Protection Agency’s Greenhouse Gas Inventory and correspond to 1.5% of natural gas production. This rate of methane loss increases the 20-y climate impacts of natural gas consumed in the region by roughly 50%.”

The researchers go on to note that leakage rates need to be under the roughly 3 percent mark in order for natural gas to have environmental benefits:

“Although natural gas emits less carbon dioxide (CO2) per unit of energy than coal or oil when burned, CH4 losses during the production, processing, transportation, and use of natural gas reduce its climate advantage compared with other fossil fuels. For example, if CH4 losses are large enough (e.g.,∼3% of production), new natural gas power plants can cause greater climate damage than new coal plants for decades or longer (∼1% when comparing natural gas to diesel freight trucks).” (emphasis added)

The report continues,

“The measured Barnett methane leakage is low enough that gas fired electricity in this region causes less climate forcing than coal-fired electricity…” (emphasis added)

But instead of noting the low leakage rate and its significant benefits for the climate, EDF put out a blog post with the headline proclaiming, “New Study Finds Oil & Gas Methane Emissions in the Barnett Shale Almost Twice What Official Estimates Suggest” and proceeded to go into a full endorsement of EPA’s methane rules, arguing:

“But most importantly, the research shows the increasing confidence we now have in dealing with a methane problem bigger than previously recognized, and that means EPA’s work is not yet over. Once a strong set of rules is created for mitigating methane emissions from new and modified sources, EPA needs to address emissions from existing sources that will still be contributing the overwhelming majority of emissions in the coming years. And, as seen in the Barnett Shale region of Texas, where the true scale of the existing problem is now well defined, that will be a significant amount.”

To characterize a very low leakage rate as “a methane problem bigger than previously recognized” is not to focus on what is actually important for conversations about methane emissions. Energy In Depth’s recent infographic puts the low leakage rates from the latest methane studies into perspective:

Final Methane_Chart

#2: Even though researchers specifically sought out “super-emitters” they still found very low leakage rates

As the report puts it, the researchers’ work was “biased toward high-emitters”:

“To obtain the relatively large sample of high-emitters in dataset 6, two teams drove around the Barnett region and estimated the emission rate of the source of each plume encountered (31, 32). Because high emission sources produce plumes that remain above an instrument’s detection limit over longer distances than low-emission sources, this method tends to favor identifying high-emitters.”

It’s important to note these “super-emitters” were the exception rather than the rule, only making up about 2 percent of all the facilities:

“The estimated emission distributions imply that, at any one time, 2% of facilities in the Barnett region are responsible for half of the emissions, and 10% are responsible for 90% of emissions.”

In other words, even with making a point of seeking out “higher” emitting sources, the researchers still found a very low leakage rate overall.

#3: EDF’s report is the latest in a long string of studies finding low methane leakage rates

This latest study is a compilation of EDF’s previous studies, which all found very low methane leakage rates (between 1.2 and 1.9 percent).  Before EDF released that package of studies, it teamed up with researchers from the University of Texas (UT) in 2013 to produce a study that looked at 190 onshore natural gas production sites in the United States.  The researchers found a leakage rate of 1.5 percent and noted that emissions were “nearly 50 times lower than previously estimated by the Environmental Protection Agency.” 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.

In addition, researchers from the University of Colorado at Boulder and the National Oceanic and Atmospheric Administration (NOAA) recently released a report, which found a methane leakage rate of 1.1 percent in areas that collectively represent over half of the United States’ total shale gas production.

Perhaps most importantly, the Intergovernmental Panel on Climate Change’s (IPCC) latest climate assessment noted 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:

“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.”

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.” (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.


The fact is that most if not all of the recent studies on methane emissions have confirmed that leakage is simply not negating the climate benefits of natural gas. This latest EDF study is no exception.

It’s also important to note that EDF’s data doesn’t necessarily mean that EPA is underestimating emissions.  EPA’s data are designed to give us a picture of what the overall impact is, rather than zeroing in on what EDF has admitted is only about two percent of facilities that are considered to be high-emitters – the exception, not the rule.

Instead of focusing on these distractions, what’s important is that the data show real – and very positive – environmental impacts of natural gas.


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