New study: natural gas worse than coal for climate change
April 12th, 2011A new analysis published in Climatic Change, “Methane and the Greenhouse-Gas Footprint of Natural Gas from Shale Formations,” finds that shale gas fracking is worse than coal for its climate change impacts. In fact, if total methane emissions are factored in, shale gas turns out to have the greatest climate impact of all the fossil fuels – and conventional gas isn’t the salvation we thought it was, either.
Why? Methane leaks out during the fracking process:
Natural gas is composed largely of methane, and 3.6% to 7.9% of the methane from shale-gas production escapes to the atmosphere in venting and leaks over the life-time of a well. These methane emissions are at least 30% more than and perhaps more than twice as great as those from conventional gas. The higher emissions from shale gas occur at the time wells are hydraulically fractured — as methane escapes from flow-back return fluids — and during drill out following the fracturing. Methane is a powerful greenhouse gas, with a global warming potential that is far greater than that of carbon dioxide, particularly over the time horizon of the first few decades following emission. Methane contributes substantially to the greenhouse gas footprint of shale gas on shorter time scales, dominating it on a 20-year time horizon. The footprint for shale gas is greater than that for conventional gas or oil when viewed on any time horizon, but particularly so over 20 years. Compared to coal, the footprint of shale gas is at least 20% greater and perhaps more than twice as great on the 20-year horizon and is comparable when compared over 100 years.
This graph from the paper illustrates the climate impacts of various fossil fuels of 20- and 100-year time frames.
Although the authors concede that the data is far from perfect, natural gas may be just as polluting as coal in the long term – and far worse in the short term due to the higher warming impact from methane when it is first released to the atmosphere during the fracking stage. Gas is no solution to our energy or climate crises.