Energy companies in several countries have turned to hydraulic fracturing as a method of extracting natural gas trapped in deep shale rock formations. The t...
Question 1 Report
Energy companies in several countries have turned to hydraulic fracturing as a method of extracting natural gas trapped in deep shale rock formations. The technique has been controversial, with supporters pointing to energy security benefits and opponents raising environmental concerns. Fig. 7.5 shows a cross-section of a fracking operation.
The process involves injecting high-pressure fluid into rock to create fractures that release trapped hydrocarbons. Fracking has generated debate between those who see it as an important energy source and those concerned about its environmental impacts.
Hydraulic fracturing involves drilling deep into shale rock formations and pumping a mixture of water, sand and chemicals at high pressure to fracture the rock and release trapped gas or oil. Supporters of fracking argue that it provides access to previously unreachable energy reserves, creates jobs and reduces dependence on imported fossil fuels.
(a) State what fracking involves. [1]
(b) Describe two environmental concerns associated with fracking. [2]
(c) Suggest why some governments have allowed fracking while others have banned it. [2]
Answer Details
(a) Fracking (hydraulic fracturing) involves pumping a high-pressure mixture of water, sand and chemicals into deep shale rock formations to create fractures that release trapped natural gas or oil. [1]
The well is drilled vertically and then horizontally into the shale layer (typically 1000-3000 m below the surface). The sand props the fractures open so that gas can flow to the surface.
(b) Two environmental concerns associated with fracking: [2]
- Groundwater contamination: The chemicals used in fracking fluid can leak into underground aquifers (water-bearing rock layers) through cracks in the rock or through faulty well casings. If these chemicals reach the water table, they can make drinking water unsafe for human consumption. [1]
- Induced seismicity: The injection of high-pressure fluid into rock, and the subsequent disposal of large volumes of contaminated wastewater into deep injection wells, has been linked to small earthquakes. While most are too small to cause damage, some have been strong enough to be felt and to damage buildings. [1]
Other acceptable answers include: very large volumes of fresh water are required; surface disturbance and habitat loss from well pads and access roads; methane leakage from wells contributes to the greenhouse effect; difficulty of safely disposing of contaminated flowback water.
(c) Why some governments allow fracking while others ban it: [2]
- Governments that allow fracking may prioritise energy security and economic benefits. Fracking creates jobs, generates tax revenue and reduces dependence on imported fossil fuels. In countries with large shale reserves (such as the USA), fracking has significantly boosted domestic energy production. [1]
- Governments that ban fracking may prioritise environmental protection and public health. They may judge the risks of water contamination, seismicity and landscape damage to be unacceptable. Some may also have sufficient energy supply from other sources (renewables, nuclear, imported gas) and therefore see no need to accept the environmental risks. [1]
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