Shale gas: what’s its greenhouse footprint?

Someone asked us the other day what information we had on the lifecycle emissions of natural gas, and I recalled seeing a report a few months ago suggesting that greenhouse gas (GHG) emissions from the production and use of natural gas from shale could be roughly comparable to GHG emissions from coal. If true, this would be a big deal, since we are being told daily that the answer to all of America’s energy needs is right in front of us, in the gas contained within the vast geological formation known as the Marcellus Shale (sample language spotted today in the Washington, D.C., publication Politico: “One solution for more abundant domestic energy is staring us in the face. Natural gas is the natural choice–now and in the future. We know we need to use cleaner, American energy. And, we have it. Today, the U.S. has more natural gas than Saudi Arabia has oil, giving us generations of this clean, domestic energy source.”)

What, I thought, has happened to that report I remembered? Has it been discredited? Confirmed? The answer: no answer yet. Here’s some Daily Kos coverage from September on the issue. It includes a short video of the report’s author, Prof. Robert Howarth, who is the David R. Atkinson Professor of Ecology and Environmental Biology at Cornell University. Prof. Howarth’s basic premise is that during the process of shale gas production, processing, and use, some methane leaks into the atmosphere. Methane is a potent greenhouse gas, much more so than carbon dioxide, and so even a relatively small amount of leakage adds up. Prof. Howarth is currently leading a followup to his preliminary analysis, a full-bore, to-be-peer-reviewed life-cycle analysis of greenhouse-gas emissions from shale gas development relative to existing fossil fuel and renewable energy sources. In the video, he says that he expects the analysis to be published soon and that his team’s tentative conclusion is that shale gas is as “dirty,” in terms of greenhouse emissions, as coal–”It might be marginally better, it could be substantially worse, that’s sort of the error bounds we have on it.” Prof. Howarth also says his analysis, when published, will be the first detailed look at emissions from shale gas in the scientific literature.

If Prof. Howarth’s conclusions are correct, it’s not good news. The combination of a lagging economy (=low energy demand) and the potential new availability of huge shale gas resources has driven natural gas prices to rock-bottom levels, and a host of folks ranging from environmentalists (for example, the Worldwatch Institute) to the oil and gas industry are planning on heavy reliance on shale gas for the foreseeable future. Less hype and more caution may be advisable.

Further reading:

Natural gas is as dirty as coal, Cornell researcher says, undated article by Robert Howarth
Natural Gas May Be Worse for the Planet than Coal, Technology Review blog entry, 4/16/10
Mythbusting Fact: Yes, Wind Does Reduce Emissions, 8/27/10

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