Fracking

Shale gas is natural gas stored deep underground in fine-grained sedimentary rocks. It can be extracted using a process known as hydraulic fracturing – or “fracking” – which involves drilling long horizontal wells in shale rocks more than a kilometre below the surface. Massive quantities of water, sand and chemicals are pumped into the wells at high pressure. This opens up fissures in the shale, which are held open by the sand, enabling the trapped gas to escape to the surface for collection.

Advocates argue that exploiting the world’s potentially vast shale gas deposits will help keep energy affordable and cut consumption of dirtier coal. But sceptics claim fracking is dangerous and polluting, and that tapping into extra natural gas supplies will boost rather than reduce planet-warming carbon emissions.

“Fracking is a nightmare! Toxic and radioactive water pollution. Tap water you can set on fire. Earthquakes. Runaway climate change. To produce expensive gas that will soon run out.”Frack Off campaign group

“Shale has changed the equation. Abundant, relatively low-priced supplies now make natural gas a highly competitive alternative to both nuclear and wind power and even to coal generation. It has the added advantage of being relatively low-carbon.”Energy commentator Daniel Yergin

In the US, shale gas has scaled up rapidly to account for around a quarter of the country’s natural gas extraction. Fracking is also now underway in many other countries, including China, Poland and the UK, where drilling company Cuadrilla Resources claims to have found vast reserves at its site near Blackpool.

But as fracking sites have multiplied so have the controversies. A 2010 film showed people near one US site setting tap water on fire and in 2012 a whistleblower claimed fracking could poison New York’s drinking water. Meanwhile, Cuadrilla’s UK operation was put on hold after causing tremors (tiny earthquakes). Due to these kinds of concerns, France and Bulgaria have banned fracking and campaigners are calling for other countries and US states to follow suit. But Australia recently gave fracking the go-ahead.

Shale gas was formed hundreds of millions of years ago from decomposing plants trapped by clay and silt. Like coal-bed methane and oil from tar sands, it’s considered an ‘unconventional’ fossil fuel. A small amount of easily accessible shale gas was extracted in the 19th century, but it wasn’t until the 1970s that shale gas technology started to develop in earnest, supported by US government R&D funding.

Breakthroughs in horizontal drilling techniques combined with developments in fracking technology (which is also used for some other energy sources) gradually increased the economic feasibility of shale gas and American production started soaring in around 2005. This – combined with rising energy prices and increasingly vast estimates of global reserves – lead to growing interest in the energy source around the world.

The most high-profile controversy surrounding shale gas is the potential for fracking to contaminate drinking water with methane or drilling chemicals. This link has been acknowledged by the US Environmental Protection Agency in the case of one Wyoming community, though recent reports from the University of Texas report and a UK Select Committee concluded that that fracking for shale gas wasn’t inherently worse for groundwater than conventional oil and gas drilling, and that risks could be mitigated by better drilling practices.

However, both reports highlighted other issues, such as the huge quantities of water and chemicals (many of them toxic) used in shale gas extraction and amount of wastewater generated. Other concerns include tremors; emissions of explosive and climate-warming methane; and the impact of clearing forests for fracking sites. The industry claims the risks are small but campaigners are calling for a moratorium on fracking.

"Let me be clear: hydraulic fracturing as it’s practised today will contaminate our aquifers. Not might contaminate our aquifers. Hydraulic fracturing will contaminate New York’s aquifers.”Paul Hetzler, an ex-staffer at an agency responsible for regulating fracking

“In the US, it is possible that bad practice by a very small number of operators may have led to some isolated and short-term incidents of natural gas contaminating water. However, these practices are the exception out of the hundreds of thousands of producing wells.”Cuadrilla Resources

Creating heat or electricity by burning natural gas produces less CO2 and other pollutants than using coal or oil. Hence the gas industry argues that shale gas is good news for the climate, as it could limit coal consumption while renewables and nuclear are scaling up. Indeed, insiders say the US government’s plan for reducing carbon emissions relies heavily on switching from coal to fracked natural gas.

However, some studies – though not others – have suggested that shale gas may be no better than coal due to large-scale leaks of the powerful greenhouse gas methane at fracking sites. The Select Committee enquiry claimed these leaks could be avoided but green groups point out that even if this turns out to be true, there’s no guarantee that extra gas supplies will reduce global coal use. A recent Tyndall Centre report concluded that, without a global carbon cap, additional gas may simply add to overall fossil fuel use, driving emissions higher and making climate change harder to solve.

“At the global level … where there is currently no carbon constraint, the exploitation of shale gas will most likely lead to increased energy use and increased emissions.” The Tyndall Centre for Climate Change Research

“Increased reliance on gas in the near term saves money and jobs, delivers on climate targets and allows new technologies to be improved before large scale deployment.” David Rimmer, Shell’s general managed for global gas

Estimates of shale gas reserves vary widely. A US government assessment of 32 countries claimed they had 169 trillion cubic metres of technically recoverable shale gas – around the same as the world’s economically recoverable reserves of conventional natural gas. The survey put the largest reserves in China, the US, Argentina and Mexico. But the estimates keep changing. The official figure for the US was almost halved in early 2012, while Cuadrilla claims that its Blackpool site alone has 5 trillion cubic meters – ten times more than the US estimate for the whole UK. Similarly, China’s own survey put its reserves nearly twice as high as the figure given in the US survey.

Whatever the size of the reserves, actual rates of extraction in each region will depend on economics and politics as well as technology. The US government expects shale gas to account for 46% of its natural gas extraction by 2035 and according to BP shale gas – along with tar sands and other unconventional fuels – will make the Americas largely self-sufficient in energy by 2030. By contrast, a Deutsche Bank report looking at the potential for shale in Europe concluded that there would be no ‘shale gas revolution’ there, due to factors such as higher population density and stronger environmental regulation.

“There is now so much potential gas that for policy purposes it is better to assume that supplies have the potential to exceed demand … for the rest of the century.” Dieter Helm, Oxford energy academic

“Those waiting for a shale gas ‘revolution’ outside the US will likely be disappointed, in terms of both price and the speed at which high-volume production can be achieved.” Deustche Bank