News Brief

Researchers Find Holes in Climate Argument for Natural Gas

Methane leaks make natural gas a poor choice for vehicle fuel but still better than coal for power generation over a 100-year period.

Methane Leakage Rates from the Natural Gas System

EPA estimates of natural gas leakage, developed in the 1990s, are far below what 20 years of actual testing have revealed. But even small leaks make a big difference, given the scale of the infrastructure (see EIA map below).

Source: Stanford University
A new study suggests federal regulators have grossly underestimated the climate impact of natural gas.

The team of researchers, whose findings were published in the journal Science, analyzed 20 years’ worth of studies measuring actual emissions from and near natural gas facilities. The fuel is mostly methane, a powerful greenhouse gas that has a 20-year global warming potential (GWP) 85 times that of CO2 and a 100-year GWP 30 times that of CO2.

Standard estimates by the U.S. Environmental Protection Agency (EPA) of overall U.S. methane emissions are off by about 50%, according to lead researcher Adam Brandt, Ph.D., assistant professor at Stanford University. And the agency’s estimates of the natural gas industry’s emissions are based on assumptions about 1990s technology and infrastructure, leading the research team to suggest leakage rates up to 10% higher than EPA’s estimates from production and processing.

Substituting these higher leakage rates in life-cycle assessments comparing different fuels, the authors suggest that, from a climate perspective, diesel is a better vehicle fuel than natural gas. But over a 100-year period, natural gas likely still wins out as a substitute for coal in power plants.

Map of U.S. Natural Gas Pipelines

With millions of miles of natural gas infrastructure in the U.S., a small amount of leakage from many components leads to massive amounts of excess methane emissions, compromising the climate benefits of this “bridge” fuel.

Source: U.S. Energy Information Administration
Brandt sees a silver lining to the news of the industry’s excess emissions: because the excess comes primarily from unintentional leaks from old wells, corroded pipes, and faulty storage tanks, most of these emissions could be controlled. Since leaks cost money, “hopefully the technology can get cheap enough for the industry to do this on its own,” Brandt said in a video on the Stanford website.

However, the paper concludes, “If natural gas is to be a ‘bridge’ to a more sustainable energy future, it is a bridge that must be traversed carefully: diligence will be required to ensure that leakage rates are low enough to achieve sustainability goals.”

For more information:

Stanford University

Published March 3, 2014

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April 18, 2014 - 3:16 pm

Methane releases from drilling activities have been grossly underestimated by EPA, according to new research. See McClatchy coverage of forthcoming report here: