Shale Gas is naturally occurring gas trapped within shale (sine grained sedimentary rocks, typically mostly clay) formations. This is harder, and more expensive, to extract than other forms of Natural Gas, but is becoming increasingly attractive to hydrocarbons companies as other sources of gas start to dwindle. Typically Shale Gas is extracted using a technique called Hydraulic Fracturing, or Fracking, which involves blasting water, sand and chemicals into shale beds at high pressure in order to fracture the rocks and release the Gas.
Diagram of a Hydraulic Fractioning operation. geology.com
Shale Gas extraction has expanded rapidly in the US in recent years, and is expected to produce half of all the Natural Gas extracted in the US by the year 2020. It has, however, proved to be extremely unpopular with environmental groups, both within the US and in other countries, to the extent that some countries have altogether banned the practice.
There are four principle objections to Shale Gas extraction. One of these is that Natural Gas is a hydrocarbon, and potentially contributes to Global Warming; this is no different to the objections to the extraction of Natural Gas from other sources, excepting that extracting the gas from shale significantly increases the available reserves. The remaining objections are with the Fracking process, and are therefore specific to Shale Gas extraction.
Firstly the process causes Earthquakes. This is not in dispute, though the scale of the quakes the process can cause is hotly disputed between environmentalists and the industry. An Earthquake is shaking in the ground, regardless of the source; a large truck driving past your house does not merely feel like its causing an Earthquake, it actually is. Blasting water, sand and chemicals into buried sediments with the intention of fracturing the rock will certainly cause Earthquakes (if it did not it would not work).
Industry experts do not expect the process to produce quakes larger than a magnitude of 1 on the Richter Scale, but areas where Fracking occurs in the US have seen an unexpected increase in quake activity, with some quakes exceeding magnitude 3. Since the Richter Scale is logarithmic this represents quakes more than a hundred times as large as predicted, leading the industry to claim that any connection is impossible, but not able to provide an alternative explanation (in some cases this is further confused by the employment of lobbyists who do not understand the process and who will offer blanket denials for even the most minor of quakes). In the UK the process has been linked to two small quakes near an experimental Fracking operation at Preese Hall in Lancashire, leading to a halt in operations.
Secondly the process has been linked to the contamination of aquifers; the chemicals used in the process are potentially toxic, and people do not like the idea of these getting into drinking water. Again industry models do not predict that the chemicals could escape the targeted deposits into other strata, but the chemicals have been found in the aquifers. A report into the industry in the US was unable to confidently say that the process had caused the contamination, but only because the chemical containment at the surface was so poor that contamination from ground-level sources could not be ruled out.
Thirdly the process uses large amounts of water, a matter of some concern in more arid parts of the US, where the industry is suspected of the using water that could be used for other purposes, notably agriculture.
In the UK a report commissioned by the Department of Energy and Climate Change was published last month (April 2012), recommending that the process should be allowed in the UK, subject to very tight environmental regulation, bringing the process back into the public eye.
On 18 June 2012 the Geological Society of London is hosting a public meeting to discuss Shale Gas Extraction, at Burlington House in London. The meeting will not seek to address whether the process should be used in the UK, but will seek to explain the geological science behind the process, and whether it can be undertaken safely. The meeting is not aimed at geologists, but rather at elected representatives (politicians), local and central government officials, regulators, NGOs, representatives of other industries likely to be affected (such as water companies) and other interested parties.
The location of Burlington House.
The meeting will be addressed by Mike Stephenson of the British Geological Survey, who will discuss the nature and distribution of shale gas reserves in the UK, Richard Davies, of Durham University, who will discuss the Hydraulic Fractionation process, Peter Styles of Keele University (one of the authors of the Department of Energy and Climate Change report), who will discuss the safety of the process with regard to induced seismicity (i.e. causing Earthquakes). The meeting will also discuss the potential effects on groundwater, and the uses of water in the industry, as well as the regulatory framework for the industry in the UK, though the speakers on these subjects are yet to be confirmed.
The layout of Burlington House.
See also Report recommends Fracking should be allowed to continue in the UK, Protests against hydraulic fractionation across Bulgaria, Oklahoma shaken by Earthquake on Christmas Day, Earthquake in Texas attributed to fracking and Fracking linked to earthquakes in Lancashire, northeast England.
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