Oil sands require monstrous amounts of water and natural gas to recover and process.

FORBES: Reserves

Unlike the normal gas extraction, chemically treated water is forced upon the rock underground to fracture it releasing the gas in the process.

FORBES: Chesapeake Stock Drilling Its Way To $35

The books were then freeze-dried, a process that evaporates the ice into gas to stop further water damage or mildew.

ECONOMIST: The Duchess Anna Amalia library

The process involves extracting gas from rocks by pumping in sand, water and chemicals.

BBC: Gas-fired power stations to be encouraged by government

The process involves drilling a bore hole and using explosives or water to force gas to the surface.

BBC: Keynsham residents against natural gas extraction plans

Fracking is the process of blasting water at high pressure into shale rock to release oil or gas held within it.

BBC: US oil production 'to jump by a quarter by 2014'

Fracking is a controversial process that involves pumping water and chemicals into shale rock at high pressure to extract gas.

BBC: Cuadrilla bids to resume Westby and Banks fracking

Fracking is a drilling process that frees gas from deep rock deposits by injecting wells with chemical-laced water at high pressure.

WSJ: Record: Libous ended stake in firm eyeing fracking

About 25, 000 wells a year are being fracked, a process in which water, chemicals and sand are injected at high pressure underground to release trapped natural gas.

NPR: Report: Flaws In EPA Drilling Pollution Data