Study: Climate pollution from gas drilling overstated

Natural gas emits far less carbon dioxide than oil and coal when burned for electricity or as a transportation fuel.

But a key question is how much methane — a potent greenhouse gas — is escaping amid development of gas wells from shale formations in many states where production is booming.

The new IHS report alleges EPA made a significant mistake in 2010, when it increased its estimates of methane emissions from natural gas wells. EPA found in particular that so-called unconventional wells at the heart of the current boom emit vastly more methane.

The EPA methodology suffers from several flaws, IHS states, arguing that the EPA’s assumptions don’t reflect current industry well practices — therefore, the EPA “dramatically” overstated methane emissions.

IHS also takes aim at a paper by Cornell University Professor Robert Howarth and colleagues earlier this year that attacked the conventional wisdom that gas is a more climate-friendly alternative to other fossil fuels.

The Cornell paper used the 2010 EPA data and other sources to reach the eye-catching conclusion that natural gas produced from unconventional wells contributes to global warming as much as coal, or even more.

But the IHS study counters:

“If methane emissions were as high as EPA and Howarth assume, extremely hazardous conditions would be created at the well site. Such conditions would not be permitted by industry or regulators. For this reason, if no other, the estimates are not credible.”

An Energy Department advisory panel, in a major report this month on the environmental footprint of unconventional gas production, noted that the Cornell conclusion is “not widely accepted.”

But the panel nonetheless said more data on the greenhouse gas impact of the gas development are needed, noting there have been “relatively few analyses done of the question of the greenhouse gas footprint over the entire fuel-cycle of natural gas production, delivery and use, and little data are available that bear on the question.”

“These data will help answer key policy questions such as the time scale on which natural gas fuel-switching strategies would produce real climate benefits through the full fuel cycle and the level of methane emission reductions that may be necessary to ensure such climate benefits are meaningful,” the Energy Department advisers stated.