Hydraulic fracturing (aka “fracking”), the controversial process to extract shale gas, has raised some significant concerns. Here is an overview of shale gas and fracking and their roles in meeting energy needs.

Unconventional gas promises to help the United States reach its decades-old goal of energy independence. Oil and gas giant BP forecasts that North America can actually turn its energy deficit into a surplus by 2030.

“The U.S. is on a path that will greatly reduce its demand for oil imports,” BP’s chief economist, Christoff Ruehl, recently told the Financial Times.

The U.S. Energy Information Agency (EIA) says that natural gas is the world’s fastest-growing fossil fuel, and forecasts consumption to increase at an average rate of 1.6 percent per year from 2008 to 2035. In its International Energy Outlook 2011, the EIA projects natural gas to increase moderately in importance for the world’s energy needs, growing from 22.1 percent of supply in 2012 to 22.7 percent in 2035.

Shale, a common sedimentary rock, contains natural gas formed by organic materials. Up until the late 1990s, the energy industry viewed shale gas as too difficult to extract economically. But since the energy crises of the 1970s, the U.S. Department of Energy (DOE) had been funding research into methods for making shale gas a feasible alternative to help the country achieve energy independence. Finally, a partnership between the DOE and Mitchell Energy, a gas company in Texas, developed the necessary technologies, including horizontal drilling, hydraulic fracturing (aka “fracking”), three-dimensional mapping and seismic imaging. (See Alex Trembath’s History of the Shale Gas Revolution, The Breakthrough Institute.)

Shale Gas: Clean Energy?

One of the more promising aspects of gas is that it provides a less environmentally harmful alternative to coal for electrical generation and represents a logical bridge from coal to cleaner energy sources such as wind, solar and nuclear power.

A study by the U.S. National Academy of Sciences (NAS) compares the environmental effects of various energy sources for electrical generation. Considering sulfur dioxide (SO2), nitrogen oxides (NOx), fine particulates (PM2.5) and coarse particulates (PM10), the NAS estimates the damage from natural gas at $.0016 per kilowatt hour (kWh), compared with $.032 for coal power. A recent study in the journal Energy Policy estimates the lifecycle carbon footprint for natural gas at 443 carbon dioxide equivalents, compared with 960-1,050 for coal. (See The Damage Done, Part 4 — Natural Gas, Green or Dirty? on ThomasNet’s Green & Clean blog.)

However, not all observers are so sanguine about the environmental benefits of natural gas, especially shale gas and the fracking technique used to extract it.

Environmental advocates have raised concerns about the chemical composition of the fluids used in fracking, the “flammable water” phenomenon observed in some shale-gas extraction areas and even the possibility that fracking can cause earthquakes. (See What’s The Big Fracking Deal? on Green & Clean.) Overall, though, the environmental effects of natural gas energy production appear less harmful than those from coal. However, gas still is more problematic than nuclear and renewables. (See The Damage Done, Part 10 — Are Renewables Really Better for the Environment Than Fossil Fuels? on Green & Clean.)

Scientists from the Energy Institute at the University of Texas at Austin recently released preliminary results of a study about the real and perceived environmental problems of shale gas development. Their study finds “no evidence of aquifer contamination from hydraulic fracturing chemicals in the subsurface by fracturing operations” and “no leakage from hydraulic fracturing at depth.” Groundwater contamination, they note, can occur in conventional oil and gas operations and is “not unique to hydraulic fracturing.”

The Energy Institute researchers believe that surface spills of fracking fluids pose a greater risk to groundwater than fracking itself, and that blowouts (“uncontrolled fluid releases during construction or operation”) are an under-reported risk. Moreover, they find that regulation regimes have not yet caught up sufficiently with shale gas production.

“As long as environmental concerns are dealt with satisfactorily, further expansion in shale gas could have significant economic benefits for economies involved in its production through potentially lower energy prices and the feedstock benefits that would accrue to other industries,” consultancy McKinsey & Company concluded in a November 2011 study.