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It is “extremely unlikely” that groundwater supplies would be polluted by methane as a result of fracking for shale gas, a prominent geologist has said.
The controversial fracking process uses high-pressure liquid pumped deep underground to fracture shale rock and release gas trapped within it. Fracking caused two minor earthquakes in Lancashire last year.
Campaigners called for a moratorium on fracking in the UK following the earthquakes. They fear the process could lead to pollution of drinking water by methane gas or chemicals in the liquid used.
In the US, where shale gas is being exploited on a large scale, footage has been captured of people able to set fire to the water coming out of their taps as a result of gas contamination.
But Professor Mike Stephenson of the British Geological Survey (BGS) said most geologists thought fracking was a pretty safe activity and the risks associated with it were low.
He said the distance between groundwater supplies around 40-50m below the surface and the deep sources of gas in the shale a mile or two underground made it unlikely methane would leak into water as a result of fracking.
“Most geologists are pretty convinced that it is extremely unlikely contamination would occur,” he said. There was no evidence in peer-reviewed literature of pollution of water by methane as a result of fracking, he said. He added that the presence of the gas in US water supplies was likely to be natural.
The BGS has launched a project that will establish the baseline levels of methane found naturally in groundwater in various hydrological settings in the UK. The project will start in the North West of England in areas that have been earmarked for future shale gas exploration.
Stephenson explained: “If you don’t know what the baseline is, you don’t know if people are running a tight ship. There’s natural methane in groundwater and you have to distinguish
between what’s there already and what might have leaked in.”
He added that two cases of methane pollution of water in the US, neither of which were due to fracking for shale gas, were the result of mismanagement.
The UK has one of the strictest regulatory regimes in the world, he added.
Jenny Banks, energy and climate change policy officer at environmental charity WWF-UK, said: “Although it’s good news that these geologists think that the risk of water contamination from fracking is low, the very limited existing peer-reviewed evidence suggests that failure of the well casing itself, not the actual fracking, is more likely to be a cause of contamination.”