The need to be seen to be clean

摘要

Drill rigs tower over the silos on farms in Pennsylvania. Once-empty mesas in western Colorado, where mule deer and sage grouse ranged freely, now look like a neural network from a bird's-eye view, with well-pads connected by dirt roads scattered across the landscape.rnThese are the signs of America's natural-gas boom. Thanks to new drilling technology, and in particular a controversial process called hydraulic fracturing or "tracking," the size of the proven reserves is growing.