Seite - 80 - in Water, Energy, and Environment - A Primer

its nuclear power plants has further increased its dependence on imported LNGwhich is costly in the Asianmarket (several times higher than in theUSmarket). The US program was jump-started by the passage of The National Methane Hydrates R&DAct of 2000, which requires ‘the development of a national methane hydrate R&D program that utilizes the talents of federal, private, and academic organizations.’ The result is a joint public–private effort supported in part by several US government departments and agencies. 6.3.2 Fracking Hydraulic fracturing is the fracturing of rock by a pressurized liquid. Some hydraulic fractures form naturally. Induced hydraulic fracturing or hydrofracturing, commonly known as fracking, is a technique inwhichwater is mixedwith sand and chemicals, and the mixture is injected at high pressure into a wellbore to create small fractures (typically less than 1mm in length), along which fluids such as previously trapped oil and natural gas may migrate to the well. When hydraulic pressure is removed from the well, small grains of sand or aluminium oxide hold these fractures open once the rock achieves equilibrium. The technique is very common in wells for shale gas, tight gas, tight oil, and coal seam gas and hard rockwells. It is now also being considered for use in revitalizing existing hydrogeothermalwells. It was first used commercially in 1998 in the Barnett Shale formation in Texas. Today it is being widely used in several shale regions in theUS and its use is being explored actively in many other countries. It is also a large fossil fuel resource, and according to the IEA technically recoverable resources are estimated to be 7.3 quadrillion cubic feet for shale gas, 2.7 quadrillion cubic feet for tight gas, and1.7 quadrillion cubic Water,Energy, andEnvironment–APrimer80