For National Geographic News
May 9, 2011
This story is part of a special series that explores energy issues. For more, visit The Great Energy Challenge.
A team of researchers has produced the first systematic evidence that methane has escaped into drinking water in areas where shale gas drilling is under way, finding explosive concentrations at distances far greater than were previously thought possible.
The Duke University scientists sampled 60 private water wells from homes across northeastern Pennsylvania, where rich underground deposits of natural gas are being extracted from shale rock through a process called hydraulic fracturing, or "fracking."
In a paper published Monday in the Proceedings of the National Academy of Science, the team reported that in active gas drilling areas, the concentration of methane increased with proximity to wells.
And as far away as 3,200 feet (1 kilometer) of an active drilling site, they found water that contained enough methane that it could, in some cases, be lit on fire....continued...