In the U.S., where fracking has reversed declines in oil and gas production, the Environmental Protection Agency recorded only one case of water contamination from fracking operations since 2009, and then dropped the case when its data was challenged.

Although Cuadrilla hasn’t yet produced any oil or gas and says it has no plans to frack at the site, Balcombe, which may sit on top of oil-bearing shale rock, has become the focus of the national debate on shale drilling as explorers look at areas throughout the country.

The British Geological Survey estimates a single area --the Bowland basin stretching from the east Midlands into England’s northwest -- may hold as much 1,300 trillion cubic feet of gas. Even if only 10 percent of the gas is extracted, a typical rate in the U.S., that’s enough to meet 47 years of U.K. demand.

Generous Taxes

Chancellor of the Exchequer George Osborne has proposed the world’s most generous tax system to encourage drilling of U.K. shale deposits. Exploiting so-called unconventional resources can replace largely depleted North Sea fields that are starting to run dry and cut energy costs for consumers, he said.

The government will license more areas for exploration in 2014, estimating that as many 40 wells will be drilled over the next two years, Energy Minister Michael Fallon said last month.

Even before shale wells produce any commercial oil and gas in the U.K., fracking has been used to keep production going at Wytch Farm, which pumps about 20,000 barrels of oil a day now. The field, which peaked at 110,000 barrels a day in 1997, has horizontal wells stretching more than 10 kilometers under Sandbanks and into the English Channel.

Drillers have fracked more than 200 wells at sites through the U.K., including Wytch Farm, according to James Verdon, a geophysicist at the University of Bristol. Although the process, which employs a mixture of pressurized water, sand and chemicals, has come to prominence because of results at U.S. shale fields, the technique has also been used to coax more from conventional fields.

While the fracking at Wytch Farm is on a smaller scale than what would be needed for a shale field, “the risk profile of what is proposed isn’t very different from the risk profile of what has been done before,” Verdon said in an interview.

Royal Society