Map of Shale Formations in the United States

Natural Gas Fractionator

Pictured here is a fractionator that separates processed natural gas into distinct hydrocarbons, including ethane, propane, and butane.

References

http://www.npr.org/blogs/money/2013/10/10/231475085/the-u-s-is-the-worlds-biggest-producer-of-natural-gas-heres-what-that-means

http://www.naturalgas.org/index.asp

http://www.eia.gov/

http://www.aga.org/our-issues/issuesummaries/Pages/EnvironmentalBenefitsofNaturalGas.aspx

http://www.epa.gov/cleanenergy/energy-and-you/affect/natural-gas.html

http://www2.epa.gov/hydraulicfracturing

http://www.eia.gov/coal/

http://www.eia.gov/naturalgas/

http://science.howstuffworks.com/environmental/energy/pros-cons-shale-gas.htm

http://www.forbes.com/sites/jeffmcmahon/2013/04/23/4-reasons-coal-declines-even-as-natural-gas-prices-rise-eia/