While shale gas reserves could change energy geopolitics, opinion is split on the environmental risks
Mention the film Gasland to anyone involved in shale gas exploration and they’ll shake their head. “It’s fairytales,” they’ll tell you. “Especially the part where the guy ignites water from the kitchen tap.”
The Oscar-nominated film, documenting the environmental and social impacts of hydraulic fracturing for shale gas in North America, has created a public backlash both within and beyond US borders. As featured in last month’s Ethical Corporation, shale gas has the potential to drastically increase gas reserves in countries currently running out of “traditional” supplies. But who is involved and what are the environmental risks?
According to BP’s latest Energy Outlook, shale gas will account for 57% of North American production by 2030, switching the US from being an importer to an exporter of liquefied natural gas (LNG).
In Europe, significant shale gas discoveries in Poland, France, Germany and the UK have brought energy speculators flocking in the hopes of replicating the US experience. However, concerns over environmental and health impacts have stalled progress.
In March last year, the US Environmental Protection Agency launched a study into the impacts of hydraulic fracturing. Since then US and French regulators have put the brakes on shale gas exploration until the results of various studies are published. In the UK, where UK independent group Cuadrilla has already begun drilling, the Tyndall Centre for Climate Change has called for a moratorium on further exploration on the basis of its own study.
In order to be produced commercially, gas-rich shale must be fractured. This involves horizontal drilling to access the hydrocarbon-bearing rock seam, followed by hydraulic fracturing, known as “fracking”, to allow the gas to flow into the well bore.
Millions of litres of fracking fluid (a mixture of salt water, proppants and chemicals such as biocides, surfactants, hydrochloric acid and gelling agents, which account for about 2% of the fluid) must be pumped down a perforated well bore at high pressure in order to fracture the shale rock.
Roughly two-thirds of the fracking fluid remains “down hole”, presenting a risk of subsurface migration of contaminants. The remaining third flows back up as “brine” laced with a cocktail of heavy metals, volatile organic compounds such as benzene, toluene, ethylbenzene and xylenes, and radioactive material.
A common concern is that the fracking fluids and potential well blow-outs – as happened in June 2010 in the Marcellus Shale, New York state in the US – could contaminate groundwater reserves. But the oil and gas industry says such concerns are unfounded.
“Groundwater contamination from fracking isn’t possible,” says George Eynon, at Calgary’s Energy Resources Conservation Board. “You’re injecting fracking fluids at a 2km depth, whereas groundwater reserves sit 100 metres or so below surface.”
The industry insists the concentration of fracking fluids is too small to have a significant impact. But Prof Brian Horsfield, GFZ German Research Centre for Geosciences, argues that given the sheer volume of fracking fluids used, groundwater contamination is a potential risk.
As for leaking wells, a long-documented history of compromised well casings in the North Sea and Gulf of Mexico implies that the case for environmentally sound shale gas exploration is far from watertight.
For more on how shale gas is changing energy geopolitics and confusing the environmental arguments, see Jon Entine the March edition of Ethical Corporation.