Hydraulic fracturing and the extraction of shale gas are of growing interest worldwide due to potential political and economic benefits. However, this form of energy is fraught with environmental and political uncertainties. Its application in the UK requires further research and development. It is essential that a global view is taken on both the political and environmental impacts of shale gas extraction.
- What is shale gas?
Shale is a type of sedimentary rock, comprising of many thin layers of fine clay particles, and also layers of organic matter. These rocks have a very low permeability and so trap shale gas which is produced from shale’s rich in organic matter. The impermeable nature of this rock makes extraction difficult and so shale’s are termed unconventional gas reservoirs. The natural gas found within shale is not a new discovery; however the technology i.e. hydraulic fracturing and horizontal drilling, was developed in the early 2000s. The process of hydraulic fracturing can be seen in Figure 1; it begins with drilling a well horizontally into shale formations. Horizontal drilling allows access to a larger area of gas in comparison to vertical drilling; facilitating the economic extraction of gas. Explosives are then used to make holes in the rock, fracturing fluid, consisting of water, sand and several additives is then pumped into the formation at a pressure intended to crack the rock, creating fractures throughout the formation hence the name ‘fracking’. The fracturing fluid is then displaced by gas flowing into the well.
|Figure 1: The process of extracting shale gas; water, sand and other chemicals are pumped into cement sealed horizontal well. High pressure fractures the rock allowing the gas to flow back into the well and be collected.|
- Shale gas in the UK
Shale gas has been of increasing interest in recent years since the US shale gas revolution where production of shale gas increased from <1% in 2000 to more than 20% in 2010. This has had a dramatic effect on the global market, driving gas prices down. This development has been accompanied by an inadvertent reduction in US CO2 emissions as coal power plants have been converted to cheap gas. With the UKs growing dependency on natural gas imports the prospect of this ‘cheap’ energy coupled with emission reductions, interest in UK shale gas exploitation has grown. Licences for the exploration of UK shale gas reserves have been granted since 2008. Subsequently there have been several small scale test wells drilled, the first in Lancashire in 2010 by Cuadrilla Resources. There are numerous arguments associated with the rise of fracking in the UK concerning environmental impacts, climate change, investment shifts and economic and political feedbacks. It is estimated that the UK holds 20 trillion cubic feet of technically recoverable shale gas however, huge uncertainties are associated with this estimate.
The advent of shale gas and hydraulic fracking in the UK has been met with mixed feelings owing to the potential opportunities and impacts of a shift in the UKs energy source.
- Political Opportunities
The UK has a 34% emissions reduction target by 2020 and a longer term 80% reduction by 2050, with 15% of energy coming from renewables. The UK’s CO2 emissions decreased by 8% last year, a trend thought to be accounted for by the displacement of coal and oil by natural gas.
The UK is increasingly reliant on gas imports from countries such as Norway and the Netherlands, therefore expanding domestic gas production may create a more self-sufficient and secure energy source. This domestic energy would remaining unaffected by the fluctuating global energy market and cut out expensive gas transport costs.
It is argued that natural gas could be beneficial as a transition fuel, displacing more carbon intensive fuels and allowing a short term reduction in emissions while renewables are further developed. It is also said that a more long term place may develop for natural gas as a flexible complement to renewable technology which require energy back up during demand fluctuations[7, 11].
Socioeconomic opportunities may include employment in an expanding industry and low fuel pricespossibly leading to wider public acceptance.
- Environmental Opportunities
Natural gas releases half as much CO2 as coal, per unit burnt, and does not release sulphur dioxide, particulate matter, ash or mercury which is emitted from coal[6, 9]. It is therefore a cleaner energy source compared to coal at point of use, however lifecycle analyses may not reflect this. It is widely accepted that US emissions reductions are the result of large scale conversion from coal to natural gas however there is evidence that increasing renewable energy contributed to this reduction. Environmental risks such as contamination, overexploitation of water, leakage and waste treatments can be minimised through best practices, and monitoring. Tight UK regulations may reduce the risks of environmental damage. However, huge uncertainty surrounds the emissions and environmental effects of shale gas extraction and so environmental opportunities in terms of climate change should be scrutinised.
Gas competes with other fuels and the development of new technologies; for example carbon capture and storage (CCS) and improvements in gas use equipment may increase gas efficiency while reducing consumption levels. These advances could decrease the emissions from shale gas and potentially increase global temperature 2°C rather than the 3.5°C predicted without these advances .
- Political Impacts
The calculation of UK GHG emissions only take into account CO2 production not total CO2 consumption; emissions in the country of extraction are therefore ignored[12, 13]. If the UK starts to extract all the gas it consumes, methane leaks associated with extraction may offset this assumed trend.
There are several complex political impacts relating to the expansion of shale gas in the UK. Public perception of this environmentally invasive industry is fraught with concerns over health impacts and contamination. Methane is damaging to health, toxic if inhaled or exposed to skin[6, 14] and shale gas extraction also results in emissions of neurotoxin carbon disulphide.
Although the gas revolution in the US in many ways appeals, there are many issues which decouple the UK shale gas potential from that seen in the US. US legislation excludes fracking fluid from clean water protection and so creates a loop hole for fracking, many extractions done without an environmental impact assessment or monitoring system. In contrast the UK has strict regulations protecting water and its safe treatment. This tighter legislation will result in higher expenses to the industry. This among other differences, makes it highly unlikely that the UK will share the experience of the US gas industry boom leaving British exploitation unlikely to significantly affect energy prices.
It is essential when considering the expansion of shale gas that wider policy and target contexts are analysed. Huge uncertainties remain in the effect of shale gas on the investment in renewable energy. Some arguing that expansion of shale gas may displace coal rather than offer a short term transition fuel. This could potentially diminishing incentives to invest in more expensive renewable energy therefore trapping the UK in a carbon intensive, fossil fuel economy[7, 10] and undermining the government’s targets to decarbonising the economy.
- Environmental Impacts
Natural gas is in no way a clean fuel, when burnt it releases less GHG than coal, but if a full lifecycle assessment is considered, including all emissions from extraction, infrastructure, transportation and leakages of methane it is estimated to release 60% more GHGs than diesel and petrol and equal that of coal. On a 20 year time scale a methane molecule has 72 times the warming potential of a CO2 molecule, this could mean that lower CO2 emissions associated with shale gas could be offset by even small methane leaks[7, 16]. If this is the case, what is assumed to be a less carbon intensive fuel may actually result in greater global warming and a catastrophic temperature rise. Uncertainty of methane emissions remains high as accurate and extensive data from all parts of the fracking process is needed [10, 16, 17].
Waste fracking fluid is of huge environmental concern; these waters contain chemical additives, saline waters, methane, organic and inorganic compounds and naturally occurring radioactive materials[2, 4, 7]. The volume of water used ranges from 7,500 to 20,000 cubic meters per well between 25% and 75% of this fluid make it back to the surface, its composition dependant on the properties of the shale. Despite the recycling potential of waste water if this fluid is leaked into the environment; on site or in waste transport, it has the potential to contaminate surface and ground water resources as well as soil[2, 3].
Images of flaming North American tap water, contaminated with methane as well as property price drops arouse deep public concern for the potential breach of water integrity. Well-casing failure and cement breach can lead to methane and fracking fluids flowing into groundwater. After testing 60 water wells in Pennsylvania, those near fracking sites had an average methane level 17 times higher than others. Although design features aim to reduce this threat there remains a significant risk of groundwater contamination which due to the high population densities in the UK could be substantial[3, 10].
Induced seismicity, a well-known result of hydraulic fracking is another environmental impact of huge public concern. In 2011 a test fracking site in Lancashire was shut down after two earthquakes of magnitude 2.3 and 1.5 were experienced as a result of hydraulic fracking. The subsequent reopening of the site has been met with major public concern
- Where to go from here?
Shale gas is surrounded by uncertainties, in both environmental and political contexts. Huge investment in the research and development of shale reserves, emissions and the political implications of a UK fracking industry would be required to fully understand the impacts of shale gas. Its development in the UK can be justified through several contentious means however ultimately investment in shale gas is an investment in another damaging fossil fuel. The full effect of shale gas extraction and other energy sources can only be fully analysed if a wider energy context, including lifecycle analysis of fuel, is used to calculate emissions. The UK government aims to decarbonise its economy, shale gas exploitation would derail this goal, further putting off a sustainable and diverse low carbon energy economy.
Written by Tabi Ewing
1. DECC, Shale Gas Background Note.
2. Kramer, D., Shale-gas extraction faces growing public and regulatory challeneges. Physics Today, 2011. 64(7): p. 23-25.
3. EPA, Plan to Study the Potential Impacts of Hydraulic Fracturing on Drinking Water Resources, EPA/600/R-11/122, Editor. 2011, US Environmental Protection Agency.
4. Friends of the Earth, Shale gas: energy solution or fracking hell? 2012.
5. Stevens, P., The ‘Shale Gas Revolution’: Developments and Changes, E.a.R. Energy, Editor. 2012, Chatham House.
6. Lavelle, M., Good Gas Bad Gas, in National Geographic. 2012.
7. Bickle, M., et al., Shale gas extraction in the UK: a review of hydraulic fracturing. 2012.
8. EIA, World Shale Gas Resources: An Initial Assessment of 14 Regions Outside the United States, U.S.D.o. Energy, Editor. 2011, U.S. Energy Information Administration: Washington.
9. DECC, 2011 UK Greenhouse gas emissions, provisional figures and 2010 UK greenhouse gas emissions, final figures by fuel type and end-user, D.o.E.a.C. Change, Editor. 2012, National Statistics.
10. HoC, Shale Gas- Fifth Report of Session 2010-2012, H.o.C.E.a.C.C. Committee, Editor. 2011.
11. International Energy Agency, Are We Entering a Golden Age of Gas? World Energy Outlook, S. Report, Editor. 2011.
12. DEFRA, UK’s Carbon Footprint 1990-2009, D.f.E.F.a.R. Affairs, Editor. 2012.
13. Donald, R., The UK’s outsorced emissions almost double its carbon footprint, in The Carbon Brief. 2012.
14. Bull, S., Methane- General Information. 2010, Health Protection Agency.
15. Carrington, D., UK shale gas is more lead balloon than silver bullet. 2012, Guardian.
16. Weber, C.L. and C. Clavin, Life Cycle Carbon Footprint of Shale Gas: Review of Evidence and Implications. Environmental Science and Technology, 2012. 46: p. 5688-5695.
17. Howarth, R.w., R. Santoro, and A. Ingraffea, Venting and leaking of methane from shale gas development: response to Cathles et al. Climate Change, 2012. 113: p. 537-549.
18. Black, R. Fracking ‘should continue with checks’. 2012 29/11/2012]; Available from: http://www.bbc.co.uk/news/science-environment-17726538.