"Fracking is a process to unlock vast reserves of shale gas. In fracking, large volumes of water and sand, along with chemical additives, are injected under high pressure into a well bore to create small cracks (fissures) in hard shale formations that allow the gas to flow to the surface. Fracking goes back about 60 years."

"Fracking made extraction of natural gas from shale layers commercially viable. Natural gas is tightly bound in the dense shale layers, and therefore, hard to release. Fracking both creates fissures in the rock and keeps them open for a sustained outflow of the gas. When used in conjunction with horizontal drilling, more surface area of the gas containing shale layer is exposed to the fracking fluid. This dramatically increases the yield of natural gas and shifts the economics to a much more favorable position."

Natural gas production in the Barnett Shale region of Texas has increased rapidly since 1999, and as of June 2008, over 7700 oil and gas wells had been installed and another 4700 wells were pending. Gas production in 2007 was approximately 923 Bcf from wells in 21 counties. Natural gas is a critical feedstock to many chemical production processes, and it has many environmental benefits over coal as a fuel for electricity generation, including lower emissions of sulfur, metal compounds, and carbon dioxide. Nevertheless, oil and gas production from the Barnett Shale area can impact local air quality and release greenhouse gases into the atmosphere. The objectives of this study were to develop an emissions inventory of air pollutants from oil and gas production in the Barnett Shale area, and to identify costeffective emissions control options.

We pay a lot of attention to revolutions when they emerge suddenly and violently, but when a transformation arrives gradually and peacefully it's easy to miss.