A little more than a month ago, Robert Howarth, a Cornell University professor of ecology and environmental biology, along with two other Cornell professors, Renee Santoro and Tony Ingraffea, published a peer-reviewed study in the journal Climate Change titled, “Methane and the greenhouse-gas footprint of natural gas from shale formations.” The study evaluates natural gas from shale compared with other energy sources with respect to how much “greenhouse gases” are created during the extraction process. The study makes the claim that shale gas extraction is actually worse for the environment than burning coal because of greenhouse gases.
The initial media reaction was a breathless Paul Revere-style recitation of the slug “shale gas worse for global warming than coal.” Howarth’s paper has now been roundly refuted by none other than the U.S. Department of Energy’s National Energy Technology Laboratory. Howarth, Santoro and Ingraffea’s conclusions are based on assumptions rather than hard data, and those assumptions were wrong.
…the Department of Energy’s National Energy Technology Laboratory (NETL) has applied ISO standard methodology, and a substantial understanding of industry operations, to do the calculation itself… Its conclusion? Used to generate electricity, natural gas – conventional or not – results in far less emissions than coal.
Using a 100-year global warming potential and assuming an average power plant, unconventional gas results in 54% less lifecycle greenhouse gas emissions than coal does. Even using a 20-year global warming potential, as Howarth controversially argues one should, the savings from substituting unconventional gas for coal are almost 50%. The NETL study acknowledges – and explores – a range of uncertainties. But it finds nothing close to the problems that Howarth claims.
Howarth found a large fraction of produced gas from unconventional wells never made it to end users, assumed that all of that gas was vented as methane, and thus concluded that the global warming impacts were huge. As the NETL work explains, though, 62% of that gas isn’t lost at all – it’s “used to power equipment”.*
Don’t hold your breath that you’ll now see headlines that say “Sorry, Howarth, Santoro and Ingraffea were wrong, natural gas really is better for reducing greenhouse gas than coal.”
*Council on Foreign Relations/Michael A. Levi (May 20, 2011) – Rebutting the Howarth Shale Gas Study