Shale Fracking, Methane Gas, and Climate Change

Shale Fracking, Methane Gas,  and Climate Change

Review by S. Tom Bond, Retired Chemistry Professor & Resident Farmer, Lewis County, WV

This month, Science (February 14, 2014) carried an article titled “Methane Leaks from North American Natural Gas Systems” which will be of interest to both professionals and the public. It has sixteen authors from institutions ranging from top universities to government agencies of the United States and Canada, to a single one from an environmental group. It is a survey and analysis of twenty years of previous research on the source of natural gas in the atmosphere.

The principal findings are “(i) measurement at all scales show that official inventories consistently underestimate actual CH₄ emissions, with the NG and oil sectors as important contributors: (ii) many independent experiments suggest that a small number of “superemitters” could be responsible for a large fraction of leakage; (iii) recent regional atmospheric studies with very high emission rates are unlikely to be representative of typical NG system leakage rates ; and (iv) assessments using 100-year impact indicators show system-wide leakage is unlikely to be large enough to negate climate benefits of coal-to-NG substitution.”

There are two ways to measure natural gas emissions. The first is by using sampling from the ground. This can done for each individual well, pumping station, frack pond, and points on the distribution system, manufacturing plant where used, electrical generating facility where used, etc.; and for areas such as storage fields, production fields, cities, etc. These kinds of measurement are called “bottom up.”

In contrast, measurement can be taken of the atmosphere from towers or an airplane at some altitude, of production fields, cities, and larger areas. There are several sources of the methane in the atmosphere, some human caused and some not. In all sampling, the different sources of gas must be distinguished by use of isotopes, based on the fact so called “thermogenic” methane from deep underground has a different isotope composition from “biogenic” methane, produced by fermentation of carbon at or near the surface of the earth. Presence of non-methane hydrocarbons are also used to some extent. Some regional source samples show more than expected fossil fuel methane.

One of the group’s observations is that bottom-up sampling, which has been going on for a longer time, consistently produces lower results than top-down sampling. This leads to the conclusion that there are “superemitters,” very large sources that are not being found by ground based sampling.

The authors estimate the emission of fossil fuel methane emission in the United States to be 7 to 21 tetragrams (7.7 to 23 million U. S. short tons). This is from national scale top-down studies. This figure is 1.25 to 1.75 times the EPA Greenhouse Gas Inventory constructed by bottom-up sampling. The frequency and magnitude of the super emitters is unknown. They suggest improved science is highly desirable.

The authors have a kind word for hydraulic fracturing, saying (on the basis of one study they find convincing) it is unlikely to prove a major source of the excess. What happens to it subsequently is important, as is unplugged wells and possible geologic leaks.

The authors believe substitution of gas for coal will offer climate benefits, but substitution for vehicle fuel (gasoline and diesel) are “uncertain or improbable” due to the tremendous additional handling procedures. Co-produced gas, gas from wells producing oil or primarily gas wells also producing some oil are “problematic.”

A great deal of scientific work is needed to find effective ways to minimize escape. The research to detail fugitive natural gas amounts and ways to avoid it would be very cost-effective, they say. “Diligence will be required to ensure that leakage rates are low enough to achieve sustainability goals.”

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NOTE: “Colorado First State to Clamp Down on Fracking Methane Pollution” — This week, the State of Colorado has established new strong regulations on methane leakage.  A few of the natural gas production companies have cooperated while others have opposed the new regulations.  The number of shale gas wells in the US is increasing at such a rapid rate that none of the states can keep up with the record keeping, inspections and infrastructure demands, to say nothing about the environmental damages and human health impacts.

Clearly, a moratorium on drilling and fracking is now needed, not just in West Virginia, Pennsylvania, Colorado and Texas, but across the United States.  Our federal government, i.e. our US Department of Energy and US Environmental Protection, are failing in protecting our states and our country.