The Resources of the Earth - Thanatia: The Destiny of the Earth's Mineral Resources - page 154

methane reserves may be larger than 190.5 Gtoe, albeit that the lack of basic infor-
mation on the gas content of coal resources makes this number highly speculative
(IPCC, 2007b). A similar quantity is estimated to be in the form of tight sands.
In short, there is a great quantity and variety of non-conventional fossil fuel
resources that could be exploited, although not without environmental and techni-
cal challenges. To demonstrate the growth in its use, the United States shale-gas
industry has increased annually by 45% from 2005 to 2010 and in 2011 it provided
24% of the nation's total gas production (Nye, 2012). As for Europe, the Euro-
pean Centre for Energy and Resource Security (Eucers) estimates that shale gas
resources should cover the whole continent's energy demand for at least 60 years
(Kuhn and Umbach, 2011). Yet it also warns of the risk of local opposition due
to the higher population density experienced in Europe compared to the US and
the lack of experience in this type of technology. Together these factors make the
future of unconventional gas in Europe uncertain.
The technique used for the recovery of oil and natural gas from very dense
and deep shale rocks (2000-3000 m deep) is called hydraulic fracturing (fracking).
The technology consists of injecting water and sand with some chemicals acting
as proppants, surfactants and lubricants, at high pressure. This pressure cracks
open the rock liberating gas that then migrates up the well. Groundwater and
wastewater contamination due to flammable tap waters (a mixture of methane and
various other chemicals) and low magnitude earthquakes, not to mention the release
into the atmosphere of important volumes of methane 14 , are just a few issues that
have been reported (Manning, 2013).
Generally speaking, the greatest drawback of these kinds of unconventional fuels
is the elevated quantity of energy required for their extraction. The refinement of
oil shale for instance, needs two or three times more energy than the production of
conventional fuel oil. Furthermore, the associated environmental footprint is huge,
since vast forest areas often need to be destroyed as the significant amount of water
used and emissions produced threatens local biodiversity.
Despite such problems, unconventional fuels, including coalbed methane, tight
gas and shale gas, are expected to be supplied in greater quantities into the future
due to their wide dispersal and the fact that the number of reserves are considerably
larger than those of conventional sources. Reserves are estimated by the USGS
(2004) to be greater than 1,400 Gtoe whilst others such as Kvenvolden (1999) and
Beauchamp (2004) report methane clathrate reserves of over 18,000 Gtoe.
Table 6.7 shows a global data compilation of conventional and non-conventional
fossil fuel reserves.
large amounts within its crystal structure. It is usually found in vast quantities under sediments
on the ocean floor.
14 The global warming potential of methane is 21 times larger than CO 2 .