We recently posted about a new study that concluded natural gas – especially from fracking – might be worse than other fossil fuels, even worse than coal, for climate change.

Calculating the net climate impact of an activity is complex and fraught with uncertainties, requiring tracking many different emissions (not just CO2) and accounting for their (time-varying) impacts. Gavin at RealClimate notes a couple of caveats about the results of the study.

For shale gas extraction (and indeed for most fossil fuel extraction), a big issue is fugitive emissions. The estimates for fugitive emissions are uncertain because they are not being reported, either voluntarily by the industry or through regulation from the states. Fugitive emissions mostly consist of methane, which is relatively more important for a 20 year time frame than it is for a 100 year time frame by a factor of ~3. For lack of anything better, the Howarth study had to rely on admittedly poor observations.

Another problem is that, for other fossil fuels, fugitive emissions weren’t considered.

For an apples-to-apples life cycle comparison, one would need to also update the impacts of coal and oil to include their fugitive emissions, their impact on other short-lived components (black carbon, CO, etc). The Howarth study compared apples to oranges.

Still, the main point of the study remains valid: natural gas, conventional or fracked, isn’t the energy or climate panacea we hoped it was.

A new analysis published in Climatic Change, “Methane and the Greenhouse-Gas Footprint of Natural Gas from Shale Formations,” finds that shale gas fracking is worse than coal for its climate change impacts. In fact, if total methane emissions are factored in, shale gas turns out to have the greatest climate impact of all the fossil fuels – and conventional gas isn’t the salvation we thought it was, either.

Why? Methane leaks out during the fracking process:

Natural gas is composed largely of methane, and 3.6% to 7.9% of the methane from shale-gas production escapes to the atmosphere in venting and leaks over the life-time of a well. These methane emissions are at least 30% more than and perhaps more than twice as great as those from conventional gas. The higher emissions from shale gas occur at the time wells are hydraulically fractured — as methane escapes from flow-back return fluids — and during drill out following the fracturing. Methane is a powerful greenhouse gas, with a global warming potential that is far greater than that of carbon dioxide, particularly over the time horizon of the first few decades following emission. Methane contributes substantially to the greenhouse gas footprint of shale gas on shorter time scales, dominating it on a 20-year time horizon. The footprint for shale gas is greater than that for conventional gas or oil when viewed on any time horizon, but particularly so over 20 years. Compared to coal, the footprint of shale gas is at least 20% greater and perhaps more than twice as great on the 20-year horizon and is comparable when compared over 100 years.

This graph from the paper illustrates the climate impacts of various fossil fuels of 20- and 100-year time frames.

Although the authors concede that the data is far from perfect, natural gas may be just as polluting as coal in the long term – and far worse in the short term due to the higher warming impact from methane when it is first released to the atmosphere during the fracking stage.  Gas is no solution to our energy or climate crises.

Natural gas may not be nearly as “clean” as we thought. Here’s the opening paragraph from a new study by Cornell University Professor Robert W. Howarth titled Preliminary Assessment of the Greenhouse Gas Emissions from Natural Gas obtained by Hydraulic Fracturing.

Natural gas is being widely advertised and promoted as a clean burning fuel that produces less greenhouse gas emissions than coal when burned. While it is true that less carbon dioxide is emitted from burning natural gas than from burning coal per unit of energy generated, the combustion emissions are only part of story and the comparison is quite misleading. A complete consideration of all emissions from using natural gas seems likely to make natural gas far less attractive than oil and not significantly better than coal in terms of the consequences for global warming. [Bold in original.]

Considering the release during combustion alone, greenhouse gas emissions from burning natural gas average 13.7 g C of CO2 per million joules of energy compared to 18.6 for gasoline, 18.9 for diesel fuel, and 24.0 for bituminous coal. Additional emissions of greenhouse gas occur during the development, processing, and transport of natural gas (due to the use of fossil fuels to build pipelines, truck water, drill wells, make the compounds used in drilling and fracturing, and treat wastes, and the loss of carbon-trapping forests). Howarth estimates that such emissions are at least one third of those released during combustion, compared to about 8% for gasoline and diesel. But the leakage of methane gas during production, transport, processing, and use of natural gas is the major culprit. Methane is by the far the major component of natural gas, and it is a powerful greenhouse gas: 72-times more powerful than is CO2 per molecule in the atmosphere.

Hydrofracking (high-volume, slick water hydraulic fracturing) is much worse than conventional methods of extracting natural gas.

A first attempt at comparing the total emissions of greenhouse gas emissions from HVSWHF obtained natural gas suggests that they are 2.4-fold greater than are the emissions just from the combustion of the natural gas. This estimate is highly uncertain, but is likely conservative, with true emissions being even greater. When the total emissions of greenhouse gases are considered, Greenhouse gas emissions from HVSWHF-obtained natural gas are estimated to be 60% more than for diesel fuel and gasoline. HVSWHF-obtained natural gas and coal from mountain-top removal probably have similar releases.

Howarth cautions that society should be wary of claims that natural gas is a desirable fuel in terms of the consequences on global warming. He urges us instead to rapidly move towards an economy based on renewable fuels.

An investigation by ProPublica found that the chemicals used in hydraulic fracturing may be threatening  the nation’s increasingly precious drinking water supply.

ProPublica studied Sublette County, Wyoming and six other contamination sites and found that water contamination in drilling areas around the country is far more prevalent than the EPA asserts. Tests on well water in Sublette County showed it contained benzene, a chemical believed to cause aplastic anemia and leukemia, in a concentration 1,500 times the level safe for people.

Hydraulic fracturing shoots vast amounts of water, sand and chemicals several miles underground to break apart rock and release natural gas. The process has been considered safe since a 2004 study (PDF) by the Environmental Protection Agency found that it posed no risk to drinking water. After that study, Congress even exempted hydraulic fracturing from the Safe Drinking Water Act. Today fracturing is used in nine out of 10 natural gas wells in the United States.

ProPublica’s investigation found that the 2004 EPA study was not as conclusive as it claimed to be. Close review showed that the body of the study contains damaging information that wasn’t mentioned in the conclusion. Rather, the study foreshadowed many of the problems now being reported across the country.

The contamination in Sublette County is significant because it is the first to be documented by a federal agency, the U.S. Bureau of Land Management. But more than 1,000 other cases of contamination have been documented by courts and state and local governments in Colorado, New Mexico, Alabama, Ohio and Pennsylvania.

The precise nature and concentrations of the chemicals used by industry are considered trade secrets. Not even the EPA knows exactly what’s in the drilling fluids. Of the 300-odd compounds that private researchers and the Bureau of Land Management suspect are being used, 65 are listed as hazardous by the federal government. Many of the rest are unstudied and unregulated.