Energy Collective: Should the Shale Gas Revolution be Feared or Cheered?
The boom in shale gas production currently reshaping North American energy markets has a mixed environmental record. Cheap natural gas is forcing the closure of dozens of America's dirtiest coal plants and driving U.S. carbon dioxide emissions to new lows, giving some environmentalists cause for celebration. At the same time, the controversial hydraulic fracturing method used to unlock shale gas resources consumes vast amounts of water and raises new fears over the potential for water contamination.
A typical hydraulic fracturing operation involves pumping millions of gallons of water, sand, and a cocktail of proprietary chemicals – ranging from the mundane, such as salt and citric acid, to toxic and carcinogenic substances, including benzene, formaldehyde, and lead – all carried at pressures up to 15,000 pounds per square inch through a well drilled horizontally into shale rock formations as deep as 10,000 feet below the surface. The high pressures force open dozens of fissures that then become propped open by sand and other materials carried in the fracking fluid. After the fluid is pumped back to the surface, natural gas once trapped in the shale can flow freely, pumped through the fissures and back up the well by the natural pressure created by the thousands of feet of rock sitting above.
This fracking process raises a number of environmental risks. Improperly drilled wells or faulty well casings can leak fracking fluids, associated chemicals, or methane gas into nearby aquifers and water wells. To date, these kinds of failures have been relatively rare, but the Environmental Protection Agency has investigated at least two cases of probable drinking water contamination near fracked wells in Pavillion, Wyoming and Susquehanna County, Pennsylvania.