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Fracking: the science

Published: 20th April, 2012 at 14:00
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Shale gas could solve the fuel crisis. But in parts of Europe and America it's been banned over safety fears, and it was blamed in 2011 for a couple minor earthquakes in the UK.

The countryside around Weeton, a few miles inland from Blackpool in the northwest of England, seems pretty unremarkable. But what lies beneath it could prove revolutionary, transforming Britain’s energy supplies and also our fuel bills. Around 3000 metres beneath this farmland lies a huge band of rock known as the Bowland Shale, and trapped inside it are vast quantities of natural gas. Now, a small British energy company is drilling down into the rock to explore its potential. And already there’s talk of this ‘shale gas’ providing as much as 10 per cent of the nation’s gas needs within a decade.


Gas accounts for 40 per cent of the energy used in the UK and with rocketing energy prices making the headlines, the discovery of a huge new source of it must be good news. More so across the Atlantic, where a report published by the US Energy Information Administration declared that by 2035 shale gas would account for nearly half of the country’s gas production. The report also said that extraction of shale gas around the world would increase global gas resources by up to 40 per cent. Both were conservative estimates that don’t take into account regions and countries – including Russia – that are yet to be inspected.

But not everyone is convinced by shale gas. Climate change experts warn that shale gas is still just a fossil fuel, and thus a source of carbon dioxide – the prime driver of global warming. Environmentalists have also raised concerns about the impact of extracting the gas. They point to incidents of drinking water allegedly becoming contaminated with the chemicals used to extract the gas, and even shale gas itself, leading to tap water becoming flammable. Such fears have already prompted the French government to impose a temporary ban on shale gas extraction. Meanwhile in the UK, a minor earthquake at the site in Weeton led to test drilling being suspended at the end of May 2011.

A new way to get an old fuel

So should we welcome the discovery of this new energy source, which could prove to be the biggest source of natural energy in the UK since North Sea Oil? Or should we fear it as a potentially lethal eco-nightmare?

According to Dr Richard Selley, emeritus professor of petroleum geology at Imperial College, London, there’s a host of misconceptions about shale gas. And one of the biggest is that it’s a new source of energy. Shale gas has been used by householders in parts of the US for centuries. “Production has long carried on throughout the Appalachians as a cottage industry, but profit margins were too small to interest major companies,” he says. Shale gas was first found in the UK in 1875, but again no-one gave much thought to its commercial value.

Similar indifference prevailed as recently as the 1980s, even as experts warned of an impending energy crisis. At the time, Dr Selley tried to draw attention to the opportunities: “Attempts to inform the wider world of the UK’s potential shale gas resource failed miserably,” he recalls.

But all that has changed. Part of the reason has been technological advances in extracting gas. “It’s now possible to drill vertically and horizontally, steering the drill-bit to stay in one bed of shale,” says Dr Selley. Such advances are at the heart of another misconception about shale gas. Any mention of drilling rigs and wells conjures up images of huge derricks towering into the sky. “People need to put aside the conventional idea of what extraction involves,” says Dr Selley. “Advances in drilling technology mean you can now have 20 to 30 wells coming off one small rig.”

Certainly one of the most striking things about the test site near Blackpool is the modest size of the plant. The rig is about the size of a water tower, and surrounded by pumping equipment and a small group of buildings. According to Cuadrilla, the company that runs the site, even that is only temporary, as the rig is only needed to start the release of the gas. The process is called hydraulic fracturing, or ‘fracking’, and involves pumping a mixture of pressurised water and chemicals into the well, creating tiny fissures in the shale that allow the gas within it to percolate out.

After a few months, the fracking is complete and the gas starts flowing up the well. The engineers can then move on, leaving a small collection site behind. “A site of 10 to 12 wells would cover about a hectare,” says Cuadrilla’s CEO Mark Miller, “and if you planted a hedge, you wouldn’t see them”.

But environmentalists insist that fracking can have consequences that are anything but short-term. Aside from the suspension of activity at the Weeton site, bans on fracking have been imposed in parts of the US and Europe, and the Green Party has called for a ban on fracking in the UK.

Critics of the process have focused on incidents highlighted in Gasland, an award-winning documentary released in the US in 2010. The film interviews residents who blame chronic ill-health on the chemicals used in fracking, and claim to have been offered compensation by some energy companies. In one dramatic sequence, a householder succeeds in igniting the water emerging from a tap, because of the amount of natural gas that has seeped into the supply.

Industry experts insist that the incidents are due to contamination by methane from much shallower sources of natural gas than those now being exploited. At the Weeton site, Cuadrilla points out that the shale being drilled is thousands of metres deeper than the aquifers supplying local water, with solid rock between the two.

Even so, Miller doesn’t dismiss the concerns out of hand. “It’s about doing the job right,” he says. “There have been cases in the US, but they’re rare – 40,000 new wells are drilled each year, around 8 to 10 go wrong and someone gets gas in the water table. But it’s avoidable if you adopt best industry practice, and it’s easily repairable.”

Energy crisis vs climate crisis

Not all environmentalists are opposed to the idea of using shale gas, in any case. Earlier this year, the US-based Worldwatch Institute announced that while industry must work harder to tackle the environmental risks, shale gas could help nations move towards a low-carbon economy. The same point was highlighted in a recent report by the independent UK-based Global Warming Policy Foundation. It argued that natural gas is the most efficient fuel for generating electricity, and produces less than half the carbon dioxide produced by burning coal.

Yet according to Professor Kevin Anderson of the University of Manchester’s Tyndall Centre for Climate Change, there’s a huge flaw with this argument for shale gas. “I find worrying the naivety in the assumption that we’ll all use shale gas instead of coal,” he says. In a report commissioned by The Co-operative, Prof Anderson and his colleagues warn that the world’s demand for cheap energy is likely to lead to shale gas being used as well as, rather than instead of, other sources. “All the climate cares about is the total amount of carbon being released, not the relative amounts from different sources,” explains Prof Anderson.

Such arguments may have less potency now that public concern about global warming trails more immediate fears about soaring gas prices. At the same time, politicians are increasingly focusing on energy security – there have been predictions that by the end of the decade 80 per cent of UK gas will come from foreign sources.

In the face of such problems, the case for exploiting shale gas can seem compelling. Prof Anderson agrees. “It will help in the short term,” he says. “But if it affects climate change and issues like food supplies, that could prove to be far too narrow a view of energy security.”

Note: since this article was first published in Summer 2011, a government-named panel of experts has given the green light for shale gas extraction near Blackpool, as long as the fracking companies follow procedures outlined in the panel's report.


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Robert is a science writer and visiting professor of science at Aston University.


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