Only with such comprehensive knowledge can appropriate regulatory frameworks be developed. We call for a moratorium on shale-gas development to allow for better study of the cumulative risks to water quality, air quality and global climate. Only this year have studies begun to appear in peer-reviewed journals, and these give reason for pause. This flowback is collected in open pits or large tanks until treated, recycled or disposed of.īecause shale-gas development is so new, scientific information on the environmental costs is scarce. Fracking also extracts natural salts, heavy metals, hydrocarbons and radioactive materials from the shale, posing risks to ecosystems and public health when these return to the surface. Around one-fifth of the fracking fluid flows back up the well to the surface in the first two weeks, with more continuing to flow out over the lifetime of the well. In a 2-hectare site, up to 16 wells can be drilled, cumulatively servicing an area of up to 1.5 square kilometres, and using 300 million litres or more of water and additives. In the United States, such secrecy has been abetted by the 2005 'Halliburton loophole' (named after an energy company headquartered in Houston, Texas), which exempts fracking from many of the nation's major federal environmental-protection laws, including the Safe Drinking Water Act. Many of the fracking additives are toxic, carcinogenic or mutagenic. The fracking of a conventional well uses at most 1–2% of the volume of water used to extract shale gas 1. An average of 20 million litres of water are forced under pressure into each well, combined with large volumes of sand or other materials to help keep the fissures open, and 200,000 litres of acids, biocides, scale inhibitors, friction reducers and surfactants. This approach is far bigger and riskier than the conventional fracking of earlier years. However, less than 2% of the well fractures since the 1940s have used the high-volume technology necessary to get gas from shale, almost all of these in the past ten years. Industry sources claim that they have used fracking to produce more than 1 million oil and natural gas wells since the late 1940s. Outside North America, only a handful of shale-gas wells have been drilled.Ī drilling operation in Bradford County, Pennsylvania: one of the many places where shale rocks are fractured to release oil and gas. Significant shale-gas production in other states, including Arkansas, Pennsylvania and Louisiana, began only in 2007–09. Industry first experimented with these two technologies in Texas about 15 years ago. Over the past decade or so, two new technologies have combined to allow extraction of shale gas: 'high-volume, slick-water hydraulic fracturing' (also known as 'fracking'), in which high-pressure water with additives is used to increase fissures in the rock and precision drilling of wells that can follow the contour of a shale layer closely for 3 kilometres or more at depths of more than 2 kilometres (see 'Fracking for fuel'). Until quite recently, most of this gas was not economically obtainable, because shale is far less permeable than the rock formations exploited for conventional gas. Shale rock formations can contain vast amounts of natural gas (which is mostly methane). But shale gas isn't clean, and shouldn't be used as a bridge fuel. Natural gas from shale is widely promoted as clean compared with oil and coal, a 'win–win' fuel that can lessen emissions while still supplying abundant fossil energy over coming decades until a switch to renewable energy sources is made.
Natural gas extracted from shale comes at too great a cost to the environment, say Robert W.
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