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Shale gas is natural gas that is found trapped within shale formations. Shale gas has become an increasingly important source of natural gas in the United States since the start of this century, and interest has spread to potential gas shales in the rest of the world. In 2000 shale gas provided only 1% of U.S. natural gas production; by 2010 it was over 20% and the U.S. government's Energy Information Administration predicts that by 2035, 46% of the United States' natural gas supply will come from shale gas. Some analysts expect that shale gas will greatly expand worldwide energy supply. China is estimated to have the world's largest shale gas reserves.〔Staff (5 April 2011) (World Shale Gas Resources: An Initial Assessment of 14 Regions Outside the United States ) US Energy Information Administration, Analysis and Projections, Retrieved 26 August 2012〕 A study by the Baker Institute of Public Policy at Rice University concluded that increased shale gas production in the US and Canada could help prevent Russia and Persian Gulf countries from dictating higher prices for the gas they export to European countries.〔Rice University, News and Media Relations (21 July 2011): (''Shale Gas and U. S. National Security'' ), accessed 12 November 2012.〕 The Obama administration believes that increased shale gas development will help reduce greenhouse gas emissions. In 2012, US carbon dioxide emissions dropped to a 20-year low.〔Carey, Julie M. (7 December 2012) (Surprise Side Effect Of Shale Gas Boom: A Plunge In U.S. Greenhouse Gas Emissions ) Forbes magazine, Retrieved 21 February 2013〕 Human and public health will both benefit from shale gas displacing coal burning. A 2013 review by the United Kingdom Department of Energy and Climate Change noted that most studies of the subject have estimated that life-cycle greenhouse gas (GHG) emissions from shale gas are similar to those of conventional natural gas, and are much less than those from coal, usually about half the greenhouse gas emissions of coal; the noted exception was a 2011 study by Howarth and others of Cornell University, which concluded that shale GHG emissions were as high as those of coal.〔David J. C. MacKay and Timothy J. Stone, (Potential Greenhouse Gas Emissions Associated with Shale Gas Extraction and Use ), 9 Sept. 2013. MacKay and Stone wrote (p.3): "The Howarth estimate may be unrealistically high, as discussed in Appendix A, and should be treated with caution."〕 More recent studies have also concluded that life-cycle shale gas GHG emissions are much less than those of coal,〔Burnham and others, ("Life-cycle greenhouse gas emissions of shale gas, natural gas, coal, and petroleum" ), Environmental Science and Technology, 17 Jan. 2012, v.46 n.2 p.619-627.〕〔James Conca, (Fugitive Fracking Gets Bum Rap ), Forbes, 18 February 2013.〕〔(Why Every Serious Environmentalist Should Favour Fracking ), 2013 report by Richard A. Muller and Elizabeth A. Muller of Berkeley Earth〕 among them, studies by Natural Resources Canada (2012),〔Natural Resources Canada, (Shale gas ), 14 Dec. 2012.〕 and a consortium formed by the US National Renewable Energy Laboratory with a number of universities (2012).〔Jeffrey Logan, Garvin Heath, and Jordan Macknick, Elizabeth Paranhos, William Boyd, and Ken Carlson, ( Natural Gas and the Transformation of the U.S. Energy Sector: Electricity ), Technical Report NREL/TP-6A50-55538, Nov. 2012.〕 Some 2011 studies pointed to high rates of decline of some shale gas wells as an indication that shale gas production may ultimately be much lower than is currently projected.〔David Hughes (May 2011). "Will Natural Gas Fuel America in the 21st Century?" Post Carbon Institute, ()〕 But shale-gas discoveries are also opening up substantial new resources of tight oil / "shale oil".〔Syed Rashid Husain. "Shale Gas Revolution Changes Geopolitics." Saudi Gazette. 24 Feb 2013. ()〕 ==History== 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Shale gas」の詳細全文を読む スポンサード リンク
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