UK ministers have been advised to allow the controversial practice of fracking for shale gas to be extended in Britain, despite it causing two earthquakes and the emergence of serious doubts over the safety of the wells that have already been drilled. Fuel companies say drilling for shale gas is safe, clean and could meet UK energy needs for 100 years.
The experts say hydraulic fracturing, whereby a well is drilled hundreds of metres deep and pumped full of water, sand and chemicals in order to release methane gas, should be allowed on a wide scale, although they accept that two small earthquakes at Poulton-le-Fylde, Blackpool last spring were caused by the first stages of fracking activities in the only British plants operating. According to seismologists, the UK experiences about 20 earthquakes a year of a similar magnitude, the majority of which occur along the west coast. The largest recorded earthquake experienced in the UK occurred in 1931 and measured 6.1. The epicentre was Dogger Bank in the North Sea.
Campaigners called for the practice to be banned outright after the report confirmed that an operation by Cuadrilla, an energy company, was responsible for two tremors last spring. The report, titled Preese Hall Shale Gas Fracturing: Review and Recommendations for Induced Seismic Mitigation, concluded that both earthquakes were related to the drilling. The report also revealed another concern – instruments showed the second tremor had caused "deformation" to the structure of the well. A study by Cornell University last year predicted its impact on climate change would be worse than coal. Cuadrilla continued to inject liquid into the shale bed following a 2.3 magnitude earthquake well above the new 0.5 magnitude recommended limit. A decision on whether to allow Cuadrilla to continue fracking is due by the government in six weeks' time, with ministers expected to green light it.
In new report, experts said fracking could resume with stronger controls after it was halted last year following two earthquakes near Blackpool after the drilling of two sites in Lancashire by Cuadrilla Resources. The "fracking" process, hydraulic fracturing, involves a well-being drilled hundreds of metres deep and pumped full of water, sand and chemicals in order to release methane gas.
An independent panel commissioned by the government said the controversial method of obtaining natural gas should no longer be permitted unless a strict new system is set up to detect warning tremors in the rock. Fracking involves injecting water, sand and chemicals at very high pressures into beds of shale to release the reserves of natural gas which are stored within. It has been extensively linked to the contamination of groundwater supplies, air pollution and an increased risk of earthquakes. A report earlier this year for Ofgem by management consultants Poyry suggested shale gas from techniques such as fracking was likely to only provide 1-4% of UK gas by 2020. It also said local objections could hamper its uptake.
UK shale gas deposits
Great Britain holds significant reserves of the in-demand gas. Britain has sizeable reserves of shale gas in a band running under the Pennines from Lancashire to Humberside, with further deposits in Hampshire, Sussex, Kent, south Wales, central Scotland and Northern Ireland.
Cuadrilla puts the potential resources in Lancashire alone at a 200 trillion cubic feet – an amount that could supply the whole of the UK's gas needs for more than five decades. British Geological Survey put the likely resources at 4.7 trillion cubic feet. Even then, only about 5% to 10% of that figure is likely to be recoverable. In order to wring the maximum from the UK's resources, there will need to be six to eight wells per square mile around each of the tens of sites to be explored, including as many as 800 in Lancashire and more in areas such as Sussex.
Shale gas is now one of the major sources of energy in the US, following years of intensive fracking operations, but critics point to ravaged landscapes, contaminated water supplies and potentially damaging pipeline installations left by industrial-scale operations, as well as concerns over the long-term safety of the wells. Although natural gas is supposed to be a "cleaner" fuel than coal, releasing less carbon when burned, evidence also suggests fracking produces more carbon than exploring for conventional gas supplies, making the fuel less attractive from an environmental point of view.
Many shale deposits are buried under aquifers, and if the cement casing around the wellhole is not adequate, then the process of drilling and fracking can release the chemicals into the aquifer. Leaks of methane can occur, leading potentially to fires or explosions.
The water-chemical mixture pumped in gradually returns to the surface, where it can contaminate land and water. It can also be highly saline and contain solids, such as flakes of rock. Some companies have been accused of poor disposal of the sludge waste that results from fracking. In addition, the vast quantities of water used can lead to problems by depleting local ecosystems. There is also concern about the seismic activity involved in fracking.
More about fracking and disposal wells in US and about it connection with earthquakes read in our earlier post The startling increase in earthquakes across US is “almost certainly man-made”.
Sources: TheGuardian, BBC, Telegraph, British Geological Survey
Featured image: Protesters scale a shale gas rig near Southport, Merseyside. An insurance broker has downplayed the risks of fracking. Photograph: Peter Byrne/PA
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