Physical Resources / 127It has been found in continental permafrost regions and in the oceans at all latitudes. Methane has
been recovered from several sites. It is estimated that the total amount of natural gas hydrate may be
more than double that of all other fossil fuels combined (KVENVOLDEN, 1994).
Natural gas is burned in stationary installations in power stations, factories, and homes, its principal
rivals for power generation being nuclear power, coal, and hydroelectric power. Solar heat and light
make a minor contribution, as does wind power, the difficulty with such ‘renewables’ arising from
their extremely dispersed nature. It would require more than 3000 of the present generation of 450
kW wind generators, for example, occupying not less than 6000 ha, to produce as much power as one
modern, 1.5 GW, conventional power station, and when conditions were calm and during storms the
wind generators would not function at all. In Europe, fast-growing trees, such as willows, are being
grown experimentally for fuel. After harvest, the material is dried and chopped for use in power
generation.
Vehicles require a liquid fuel, although they can use gas. Biomass fuels, derived from crops grown
for the purpose, have the advantage of making no contribution to atmospheric carbon dioxide, because
the carbon dioxide their combustion releases precisely equals the amount absorbed by the crop
plants during their growth. Ethyl alcohol has been used in this way, most notably in Brazil and the
United States, although it is more costly to produce than petrol. Oilseed crops are now being developed
from which ‘biodiesel’ fuel can be obtained, one of the most promising being rape, with seeds that
are 40 per cent oil. Again, production costs are high, but may be reduced through a combination of
economy of scale as output increases, and genetic engineering to increase the oil content.
Electrically powered vehicles have also been the subject of much research, but they, too, present
difficulties, mainly arising from the speed and range limitations imposed by the weight and power of
their batteries. Nor may they be so clean as many people suppose. It has been calculated that an
electric car may release into the air 60 times more lead than a car running on leaded petrol (LAVE
ET AL., 1995).
Fuel cells are also under development. These are devices comprising two electrodes separated by an
electrolyte, which is a substance that permits the passage of ions (charged atoms or molecules) but
not of electrons. A fuel containing hydrogen flows to the anode (positive electrode), where electrons
are stripped from the hydrogen atoms. This leaves positively-charged hydrogen ions that diffuse
through the electrolyte, while the electrons travel through an external circuit as an electric current.
As the hydrogen ions arrive at the cathode (negative electrode) they are rejoined by the electrons and
combine with oxygen to produce water, which is the only exhaust product. Unfortunately, fuel cells
are extremely costly. The British physicist William R.Grove discovered their underlying principle in
1839 and NASA uses them to power spacecraft, but it will be several more years before they drive
production cars (APPLEBY, 1999).
Energy conservation is often proposed as a partial alternative to increased exploitation of reserves or
the search for new sources. If appliances and vehicles used energy more efficiently, it is argued, our
demand for fuel would be correspondingly reduced. Unfortunately, the equation may not be so simple.
If energy is used more efficiently, effectively it will be made cheaper and this could encourage an
increase in the use of appliances to restore the balance. People would be able to obtain more use for
the same price and energy consumption would not decrease. When US cars became more economical
in their fuel use, during the 1970s and 1980s, consumption remained fairly constant; people drove
their cars more for the same cost (INHABER AND SAUNDERS, 1994).
Nuclear power provides about 27 per cent of the electricity used in Britain and in some countries it
provides much more. In Belgium, for example, it supplies 55 per cent of all electricity, in France 30
per cent, and in Lithuania 85 per cent.