Anti-fracking posters dot towns where exploration companies have leased land to drill for natural gas. (Image by arimoore via Flickr)

A special series from Fortune

Natural gas has quickly and quietly grown to become a major source of energy for the United States, thanks to a controversial technique called fracking. As Fortune writes:

The number of horizontal drilling [or fracking] rigs skyrocketed from 40 in the 1990s to over 500 in 2008. The country currently consumes just under 23 trillion cubic feet of gas per year and half of that amount is produced from wells drilled within the last 3.5 years, using the combination of horizontal drilling and hydraulic fracking.

Doug Morris, a reserves and production expert with the Energy Information Administration's Office of Oil and Gas, says, "you go back ten years and nobody predicted this boom in shale gas." Yet the boom has brought with it an unprecedented chance to investigate and regulate the potential environmental damage fracking can cause, thanks in part to New York State's de facto moratorium on fracking, about which the EPA held public  hearings in Binghamton, New York in September. More