There are many conflicting messages out there about natural gas.  Commercials from interests in the natural gas industry claim it's the clean abundant way to "power America's future" by creating jobs and providing a cleaner and more climate-friendly alternative to coal.  However, anyone who has seen the documentary Gasland and remembers the neighbor of a fracking operation setting fire to his tap water may raise an eyebrow at the use of the word "clean" to describe natural gas. 

Fracking, or hydraulic fracturing, is the method used to extract natural gas from shale rock.  Part of the confusion about fracking and its environmental impacts is due to differing definitions of fracking.  Defenders of the practice tend to define it narrowly, to only include the injection of chemicals, sand and water into the rock, whereas critics define it more broadly to also include the drilling that precedes the injection.  This distinction is important since the drilling part of the extraction process is to blame for several cases of water pollution, such as the methane contamination of surface and ground water in parts of Pennsylvania in recent years. 

Natural gas vs. coal

Part of the appeal of natural gas comes from the comparison between its air emissions to those from coal at power plants.  According to the U.S. EPA "compared to the average air emissions from coal-fired generation, natural gas produces half as much carbon dioxide, less than a third as much nitrogen oxides, and one percent as much sulfur oxides" and mercury emissions from natural gas are negligible.  However, this does not include the full lifecycle emissions that come from the extraction and treatment of the natural gas, and they note that methane can be emitted from incomplete combustion or leaks before combustion occurs.

When it comes to water pollution, natural gas looks like a less appealing option.  Aside from methane leaks from improper drilling, fracking fluid itself contains chemicals that are harmful to human health.  What's in fracking fluid?  It's difficult to say conclusively, because for several years the companies doing the fracking have refused to say what chemicals they use, claiming it is a proprietary trade secret and varies from location to location.  Some states require companies operating within their boundaries to disclose the compounds used in fracking fluid.  Based on the disclosure to states as well as testing by scientists, kerosene and diesel fuel are believed to be used frequently in fracking fluid.  Both diesel and kerosene contain toxic and carcinogenic compounds, such as benzene and formaldehyde.  Under President Bush, the 2005 energy bill exempted hydraulic fracturing from the Safe Drinking Water Act.

But natural gas is better for the climate, right?

Another argument used in favor of natural gas is that it is friendlier for the climate than coal.  A commonly cited estimate is that the greenhouse gas impact of natural gas is about half that of coal.  This argument was challenged last year in a study by Robert Howarth, published in the Climatic Change journal.  The study predicts that natural gas may actually have greater warming potential from its greenhouse gas emissions than coal, since the methane leaked at the well and along aging pipelines is over 20 times more potent of a greenhouse gas than carbon dioxide.  In January, colleagues of Howarth from Cornell published their own study disputing his work.  You can read more about the battle of the scientists here.   

Fracking news

Federal regulations for natural gas and oil extraction from shale are set to come out any day now from the Obama administration.  The rules will require disclosure of fracking fluid chemicals and set standards for well construction on public land.  Some congressional Democrats do not believe that the regulations are adequate, and are calling on the President to support the Fracturing Responsibility and Awareness of Chemicals Act, which would repeal the Safe Drinking Water Act exemption and require disclosure of fracking chemicals used on all land in the U.S. rather than only public land.

Bonus: earthquakes!

The injection of fracking fluids and disposal of wastewater by injection are believed to be responsible for several earthquakes in recent years, including the 4.0 magnitude quake in Youngtown, Ohio on New Year's Eve.  The fluids can cause strike-slip earthquakes by lubricating the rock close to deep-injection wells, allowing slippage along rock boundaries.  Research by a team of geologists found that the magnitude of a fracking-induced earthquake is proportional to the volume of fluid injected, and that the probability of an earthquake depends on the strength and permeability of the rock.

Written by :

Elizabeth Klusinske