Shale and GHG: Cornell v. Cornell

Newly published research by Cornell University scientists challenges the core calculations and conclusions of a paper by other Cornell researchers, led by Robert Howarth.

The publication of "Methane and the greenhouse-gas footprint of natural gas from shale formations,” by Howarth and colleagues Anthony Ingraffea and Renee Santoro in Climatic Change Letters, disputed the wide circulated proposition that shale gas drilling was a positive development, because natural gas emits half the greenhouse gases of coal, and a third less than oil.

Howarth’s “life-cycle evaluation” of shale gas drilling, suggested that shale gas had a larger greenhouse gas (GHG) footprint than coal and that this larger footprint “undercuts the logic of its use as a bridging fuel over the coming decade."

The paper became a lighting rod for opponents of the hydraulic fracturing technique used in shale gas extraction.

An abstract from the new paper by Lawrence M. Cathles, Larry Brown, Milton Taam and Andrew Hunter concludes:

We argue here that their (Howarth et al.) analysis is seriously flawed in that they significantly overestimate the fugitive emissions associated with unconventional gas extraction, undervalue the contribution of “green technologies” to reducing those emissions to a level approaching that of conventional gas, base their comparison between gas and coal on heat rather than electricity generation (almost the sole use of coal), and assume a time interval over which to compute the relative climate impact of gas compared to coal that does not capture the contrast between the long residence time of CO₂ and the short residence time of methane in the atmosphere. High leakage rates, a short methane GWP, and comparison in terms of heat content are the inappropriate bases upon which Howarth et al. ground their claim that gas could be twice as bad as coal in its greenhouse impact. Using more reasonable leakage rates and bases of comparison, shale gas has a GHG footprint that is half and perhaps a third that of coal.

Howarth's conclusions were widely questioned.  The foe of hydraulic fracturing did acknowledge that his conclusions were based on limited data.

Read the new paper, by Lawrence M Cathles, Larry Brown, Milton Taam and Andrew Hunter - A Commentary on “The Greenhouse‐gas footprint of natural gas in shale formations” by R.W. Howarth, R. Santoro, and Anthony Ingraffea 

Related Reading: If Shale Gas Were Dangerous