Shale gas cannot provide a low carbon “interim” fuel for the transition to a clean energy future, according to David Hughes, fellow at the Post Carbon Institute (PCI). Gas advocates have long advertized unconventional gas as a clean alternative to coal and other polluting fossil fuels. But the cleanliness of unconventional gas is challenged by others who claim that lifecycle greenhouse gas (GHG) emissions from shale gas are in fact higher than coal.
One such claim, maintained by a group of scientists from Cornell University led by Dr. Robert Howarth, puts shale gas GHG emissions 20 to 100 percent higher than coal on a 20-year timeframe. Their study, published in the peer-reviewed Climactic Change Letters, has received enormous criticism from the gas industry and its supporters. Several reviews have challenged the integrity of the Cornell study, including a presentation given by scientist Timothy Skone from the National Energy Technology Laboratory (NETL). According to Skone, GHG emissions from gas are 48 percent lower on a 20-year timeframe.
In an analysis entitled “Lifecycle Greenhouse Gas Emissions From Shale Gas Compared to Coal,” Hughes compares the two conflicting conclusions to get to the source of the disparity. With a little number crunching, he discovers that there may be less of a disagreement than meets the eye.