Fracking debate heats up
By Ron Hester, emeritus professor of chemistry at the University of York
It is only in the last few years that an awareness of hydraulic fracturing – or 'fracking' – has become commonplace in the UK, though it has been a controversial issue in the USA for at least 20 years.
Concern for energy security has led the UK government to favour the development of fracking, but public opinion appears to be largely opposed to it.
The recent decision by the Lancashire County Council to reject a second application by Cuadrilla for fracking at a site near Blackpool has been met with delight by some and dismay by others. Democracy itself is under examination.
So what is fracking and why is it so controversial?
Geopolitical considerations, coupled with the depletion of conventional natural gas reserves in the US, led to the development of a new technology involving deep horizontal drilling and the injection of high pressure water (containing various chemicals and sand) in order to release unconventional gas from underground shale deposits. Hydraulic fracturing of shales to release the trapped gas – mainly methane – became known as 'fracking'.
Commercial exploitation in the US is credited with many benefits, including lowered energy costs and increased national security associated with reduced dependence on imports of oil and gas. However, a number of environmental problems, including contamination of water supplies, air pollution, creating minor earthquakes and contributing to climate change, have been identified and have led to the banning of commercial fracking in several countries (including Germany and France) and even within the US (most notably in New York state).
On the local scale, the recent Lancashire council decision to reject the Cuadrilla application was made on the grounds of visual impact and unacceptable noise. Objectors also point to heavy traffic movement on small local roads, involving transportation of large quantities of water and toxic chemicals to and from the site. Some of the chemicals may be carcinogenic.
Advocates of fracking point to the high demand for energy, which far exceeds the current capacity of renewable sources such as wind and solar farms. The intermittent nature of wind and solar energy also militates against them. Furthermore, coal-fuelled power stations remain an important component of the electricity generating industry and it is argued that gas from fracking represents a much cleaner fuel than coal. The US experience shows how using shale gas as a fuel can reduce energy costs.
Opponents of fracking point to the fact that shale gas, as with conventional gas, is a fossil fuel that generates carbon dioxide when burned and thus contributes to climate change. The internationally agreed target for restricting greenhouse gas emissions (mainly carbon dioxide) if dangerous climate change is to be avoided dictates that shale gas should at best be viewed as a ‘transition fuel’ and may well be a ‘stranded asset’ if agreed carbon budgets are to be protected. Moreover, the US experience on energy costs is unlikely to be relevant to the UK where world rather than internal market pricing would apply.
Environmental impact
The risk of groundwater contamination due to leakage of fracking fluids is a subject of much debate. The cocktail of chemicals used in fracking varies greatly with the company involved but typically includes substances to modify pH, surface tension and viscosity, as well as sand to prop open the fissures in the shale rock caused by injection of fluid at high pressure.
Wells are drilled vertically through the rock strata, including the water table, to reach shale deposits at depths of several kilometres. Multiple horizontal channels that can extend a further 1 – 1.5 km are then drilled into the shale.
Failure of the well containment casings, perhaps due to earth movement or incorrect installation, could allow leakage of toxic fluid into underground aquifers. Careful regulation and monitoring are required to assess and minimise such risks. Large quantities of water are needed for fracking and most of the (contaminated) water returns to the surface as ‘flowback’. This imposes requirements for a plentiful water supply and for storage, treatment and disposal facilities at the site. These requirements all carry cost implications as well as environmental risk.
The Royal Society of Chemistry has recently published Fracking – Volume 39 in the book series Issues in Environmental Science and Technology. This multi-authored book is edited by Professor Roy Harrison OBE and myself. The issues outlined above are all covered in the book in much greater detail by an international group of experts, providing a well-balanced and authoritative treatment of the issues.