Study finds natural gas releases twice as much greenhouse gas as coal

Published 2 May 2011

A new study shows that natural gas is not as environmentally friendly as previously thought, dealing a major blow to environmentalists who viewed it as a “bridge fuel” to cleaner energy alternatives; researchers found that the greenhouse-gas footprint of shale gas over a twenty year period was at least 20 percent higher than coal and could even be “more than twice as great”; the study was quick to draw criticism from oil and gas companies for its use of shoddy data; the study also outlines multiple ways that the oil and gas companies could reduce methane emissions by up to 90 percent during the drilling process

A new study shows that natural gas is not as environmentally friendly as previously thought, dealing a major blow to environmentalists who viewed it as a “bridge fuel” to cleaner energy alternatives.

Researchers at Cornell University recently found that the process of obtaining natural gas from shale is far worse for the environment than coal or gasoline. Their study, published in the science journal Climatic Change, found that the greenhouse-gas footprint of shale gas over a twenty year period was at least 20 percent higher than coal and could even be “more than twice as great.”

Greenhouse gas emissions from natural gas primarily occur during the drilling process which releases large amounts of methane and other pollutants. To obtain natural gas, energy companies use a drilling process called hydraulic fracturing, or hydrofracking, which involves blasting large amounts of highly pressurized water mixed with sand and chemicals at shale rock formations to break them apart.

Robert Howarth, the study’s author and a professor of earth sciences at Cornell, claims that with hydrofracking large amounts of methane mix with the water and is released when it returns to the surface. In addition, the drilling of well plugs to separate fracking stages also emits large amounts of methane making shale gas’s greenhouse gas footprint “significantly larger” than conventional natural gas.

Natural gas had been viewed by many environmentalists as a bridge fuel to help ease the transition to alternative energy sources as it emits less carbon dioxide. When gas is used to create electricity, it emits approximately half as much carbon dioxide per megawatt as coal. But the recent findings suggest that over its lifespan natural gas could actually result in far greater greenhouse gas emissions through venting, equipment leaks, and hydrofracking.

In addition, natural gas leaks consist of methane which is a more powerful greenhouse gas than carbon dioxide. The Environmental Protection Agency (EPA) recently stated that it had “significantly underestimated” the amount of methane released from shale gas. In some cases, methane emissions were nearly 9,000 times higher than previously thought

Energy companies have sharply increased the use of hydrofracking to obtain natural gas in recent years and the U.S. Energy Information Administration projects that total production will increase by 20 percent over the next twenty-five years with shale gas accounting for almost half of the total.

Howarth’s study was quick to draw criticism from oil and gas companies. Energy in Depth, a coalition of independent U.S. petroleum producers, said Howarth used poor quality data to “jack up” the greenhouse gas footprint of methane.

Howarth admitted that his data was incomplete explaining, “The reason is that all of the data come from industry sources … and industry has not been very forthcoming.”

He went on to say, “Were the industry to comply, then more and better documented data could become available, and one could improve on our study.”

Mark Jaccard, a professor of energy and materials research at Simon Fraser University, does not necessarily disagree with the study’s findings, but says that it should not be construed as an argument against shale gas. Rather than abandon the practice all together, the study should be viewed as a call for stricter regulations because “shale gas could be produced in a way that had very little emissions.”

The study supports Jaccard’s beliefs as it outlines multiple ways that the oil and gas companies could reduce methane emissions by up to 90 percent during the drilling process. The study noted that “these technologies are currently not in wide use.”

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