Environmental Engineering Reference
In-Depth Information
drilling level of around 1000 wells per year.
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At the European level, analysis
for the European Commission shows that, even under the most optimistic
scenario for the development of shale gas in the EU, production only offsets
the decline in conventional production and import dependence will stay at
around 60% in 2040.
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However, this analysis looks at energy security purely from the perspective
of security of supply. Friends of the Earth believes energy security should be
defined more broadly than just about supply and geopolitics, and should
also include price security (providing energy at reasonable prices) and en-
vironmental security (achieving emissions targets and minimising other
impacts). In a report for Friends of the Earth, energy security expert, Pro-
fessor Michael Bradshaw, concluded that ''the best way to reduce the energy
security risks associated with the UK's growing gas import dependence is to
hold the course, promote renewable power generation, improve energy ef-
ficiency and reduce overall energy demand''.
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5 Other Forms of Unconventional Gas
Much of the attention in the UK and elsewhere in Europe in recent years has
focused on fracking for shale gas. But this is not the only form of un-
conventional fossil fuel that is arousing interest in the UK and Europe today.
Companies are also investigating the potential for shale oil, coal bed me-
thane and underground coal gasification.
Coal bed methane (CBM) is gas which is trapped in coal seams. To extract
CBM, companies must 'de-water' the coal seam by drilling vertically and
then horizontally (for up to 1 kilometre) and pumping out vast quantities of
water. This releases the pressure in the coal seams and allows the gas to flow.
CBM extraction does not always involve fracking - at least not in the early
years of an operation. But if seams are not porous, or when gas flow starts to
decline after a few years, wells are often fracked to increase productivity. In
Australia, where CBM (known there as coal seam gas) is more developed, the
industry estimates that up to 40% of wells end up being fracked
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(see also
Chapter 6 by Prof Alan Randall in this topic).
Coal bed methane extraction brings many of the same problems as shale
gas. Although CBM extraction does not always involve fracking, the chem-
icals used in CBM drilling muds can be just as toxic as those used in
fracking, and there are the same risks of spills and leakages. And because
CBM is typically found at much shallower depths than shale gas (up to 1200
m underground for CBM, compared to 2000-3000 m for shale gas), risks
such as groundwater contamination are increased.
CBM waste water is extremely salty and has been found to contain not only
harmful chemicals from the drilling fluids used, but also highly toxic BTEX
(benzene, toluene, ethylbenzene and xylenes) chemicals, including known
carcinogens, and naturally-occurring radioactive materials.
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Spills and
leaks of drilling fluids can also contaminate agricultural land and harm
livestock. Vast quantities of contaminated water must be treated and
