The U.S. Environmental Protection Agency is overestimating the amount of methane emissions from hydraulic fracturing production of natural gas, concludes a new study from an independent energy analysis firm.
EPA’s Estimates ‘Not Credible’
According to the study, conducted by IHS Cambridge Energy Research Associates, EPA’s current methodology for estimating gas field methane emissions “is not based on methane emitted during well completions, but paradoxically is based on a data sample of methane captured during well completions” (emphasis in original).
The report found the assumptions underlying EPA’s methodology do not reflect current industry practices. “As a result, its estimates of methane emissions are dramatically overstated and it would be unwise to use them as a basis for policymaking,” the study explains.
The faulty nature of EPA’s methodology is apparent, according to the study, when examining real-world methane levels at natural gas well sites.
If methane emissions were as high as EPA assumes, the study observes, “extremely hazardous conditions would be created at the well site. Such conditions would not be permitted by industry or regulators. For this reason, if no other, the estimates are not credible.”
The study results are important, the report explains, because EPA has proposed additional regulation of hydraulically fractured gas wells under the Clean Air Act.
Battle over Natural Gas Emissions
Lifecycle greenhouse gas emissions from hydraulic fracturing have become a point of contention for alternative energy advocates. Natural gas power emits approximately 45 percent less carbon dioxide than coal-fired electricity. Solar and wind power advocates, however, argue methane emissions during natural gas production eliminate the greenhouse gas benefits of natural gas versus coal power.
The debate over natural gas’s lifecycle emissions became heated when a group of Cornell researchers published a study earlier this year in Climatic Change suggesting shale gas has the same carbon footprint as coal over a 100 year horizon because of methane released during the extraction process. Methane is estimated to have a global warming potential 25 times that of carbon dioxide.
However, a subsequent study by researchers at Carnegie Mellon University, published in Environmental Research Letters, found a much different result. This study, which was cosponsored by the environmental activist Sierra Club, found Marcellus shale gas produces 20-50 percent fewer lifecycle greenhouse gas emissions than coal.
Air Improvement Advantages
America’s Natural Gas Alliance (ANGA), a trade association representing independent natural gas exploration and production companies, argues the IHS CERA report better reflects real-world conditions than the Cornell study.
Dan Whitten, ANGA vice president for strategic communications, says natural gas reduces many other emissions in addition to greenhouse gases.
“Natural gas produces low emissions of nitrogen oxides, while producing virtually no sulfur dioxide, mercury, and particulate matter, which can help improve air quality in communities across this nation,” said Whitten.
John Monaghan ([email protected]) is the legislative specialist for energy and environment issues at the Heartland Institute.
“Mismeasuring Methane: Estimating Greenhouse Gas Emissions from Upstream Natural Gas Development,” IHS Cambridge Energy Research Associates: http://heartland.org/sites/default/files/Mismeasuring%20Methane.pdf
“Methane and the greenhouse-gas footprint of natural gas from shale formation,” Climatic Change: http://www.sustainablefuture.cornell.edu/news/attachments/Howarth-EtAl-2011.pdf
“Life cycle greenhouse gas emissions of Marcellus shale gas,” Environmental Research Letters, http://iopscience.iop.org/1748-9326/6/3/034014/fulltext