On January 25, ProPublica published a story disclosing that the EPA had more than doubled its estimates of the amount of greenhouse gases believed to be leaked into the atmosphere from the natural gas drilling and extraction processes. The article used these new EPA estimates, combined with peer-reviewed research methodologies, to compare the total lifecycle emissions from natural gas use to the total lifecycle emissions from coal. We found that in a worst-case -- but very common -- scenario, the advantage of using natural gas was substantially diminished from the advantage held by conventional wisdom. To be clear, our article did not say that the EPA had conducted the lifecycle analysis of the fuels, or that the EPA had concluded gas was disadvantageous.

Last week the industry-funded pro-drilling group Energy in Depth – which has not contacted ProPublica directly to express concerns about the article’s accuracy – issued a statement challenging the facts of our story. The EID release states that the EPA data cited in the article is not new, that the agency never undertook a lifecycle assessment of natural gas, that ProPublica ignored other EPA documents, and that ProPublica’s conclusions are based on a “pamphlet” by a university researcher.

These assertions amount to a misunderstanding of the article and a distortion and mischaracterization of the facts.

For one, EID inexplicably claims that ProPublica’s characterizations are made “absent any data.” ProPublica’s finding is based on several interviews with agency officials and the recent publication by the EPA of a working document that clearly outlines the EPA’s revision of its older figures. Page 10 of that document states that greenhouse gas emissions from the production stage of oil and gas alone are now believed to be 198 MMtCo2e, an upward revision from 90 MMtCo2e under the agency’s old analysis. Broken down, that same page states that total methane leaked and vented from all natural gas systems -- not just production, but also including processing and transmission – was about 261 MMtCo2e, far more than double the comparable amount the EPA had last reported on page 3-45 of its annual published greenhouse gas inventory. EPA officials told ProPublica that their research was on this topic was evolving quickly, that the figures published in the working document represented the latest and most accurate understanding held by the agency, and that they supersede the comparable data published in the EPA’s April, 2010 Greenhouse Gas Inventory. They advised that because the figures seemed to be changing frequently, we generalize our conclusions to say that emissions estimates had “at least doubled.”

The EID statement argues that no new EPA research exists concerning the lifecycle of natural gas, and states that ProPublica’s report is based on “a six-page pamphlet.” ProPublica’s original story is clear in explaining that EPA provided revised estimates for gas field emissions, not the lifecycle assessment. The lifecycle analysis itself is based on a peer-reviewed article published in the highly-regarded scientific journal Environmental Science and Technology. That journal article explains in detail the methodology used to calculate the lifecycle emissions from natural gas compared to the lifecycle emissions from coal, depending on multiple variables including the various efficiencies and heat rates of the power plants where the fuel is ultimately burned. The author of that paper worked with ProPublica to provide a formula, which ProPublica then used to calculate a new lifecycle estimate based on the updated emissions figures set by the EPA.

The EID response points to a chart contained on page 3-45 of the EPA’s 2010 Greenhouse Gas Inventory that shows declining annual emissions from natural gas drilling and alleges that ProPublica ignored this data. In fact, ProPublica’s article not only linked to this document and referenced this exact chart as one measure of the government and industry’s success in working to cut emissions, but factored an estimate for the EPA’s emission-reduction program, called GasSTAR, into its calculations.

EID suggests that this older EPA document reflects the best known data for emissions. It does not. The new EPA estimates are more recent and more accurate, according to the EPA, and when the Greenhouse Gas Inventory is updated in April 2011 it will reflect the revisions.

The EID statement, referencing the chart on p. 3-45 of the old 2010 inventory, states that “methane that escapes into the air pursuant to natural gas operations in the United States continues to go down. By a lot.” In fact, when these numbers are updated to reflect the EPA’s latest figures, the chart is expected to change and the net amount of emissions will have gone up, not down, according to an explanation given by the EPA to ProPublica.

The EID response criticizes the EPA technical paper itself, stating incorrectly that on p. 84 the EPA based all of its findings “on a single data point.” In fact, the reference in question is on p. 86 and it clearly states that the EPA’s estimates were based on “several” factors, including data from the GasSTAR program itself. The document goes on to describe one example, but states repeatedly that its estimates are still considered to be conservative, and likely underestimated.

The EID response suggests that the EPA’s own conclusions are based on thin research. But the fact is that there is a long, deep record of peer-reviewed scientific research and government-sponsored reports that have also said that gas field emissions are underestimated and should be sharply revised upward. Here is a sampling of documents explaining how emissions estimates have been underestimated: A Texas study by the EPA’s current regional administrator when he was a professor at Southern Methodist University; a climate evaluation completed by the state of New Mexico, and a paper published by researchers at the University of California, Irvine. One especially good resource is this document containing an industry estimate from the gas drilling company Williams.

Finally, EID attacks the methodology of a Cornell University researcher, Robert Howarth, and alleges that ProPublica’s article was incorrectly based on Howarth’s estimates. In fact Howarth’s research was not the basis for any of the emissions figures or calculations reported by ProPublica, and ProPublica’s article was completed before Howarth’s latest letter, cited by EID, was released.

ProPublica repeatedly sought comment and input on its reporting from the natural gas industry over the past several months, including Energy in Depth. EID was shown the specific findings of our article, and was pointed to the documentation that supported it, before ProPublica’s article was published, yet repeatedly declined to comment.

Separately, the EPA has also sent a statement regarding ProPublica’s reporting to Energy in Depth. In it, press officer Erin Birgfeld references the same technical paper discussed above and emphasizes that it “does not estimate emissions from the gas industry and the emissions estimates in the article were not developed by EPA.” When we contacted the EPA for an explanation, we were told that the EPA did not find any factual discrepancies with what ProPublica had reported and was not disputing any of the emissions figures contained in the documents referenced here. The agency’s statement was only meant to clarify that the lifecycle analysis was calculated by ProPublica and was separate from the emissions figures the agency has reported.