Sources of Energy
Harnessing renewable energy such as wind and solar is an appropriate first consideration in sustainable development, because apart from constructing the plant, there is no depletion of mineral resources and no direct air or water pollution. In contrast to the situation even a few decades ago, we now have the technology to access wind on a significant scale, for electricity.
But harnessing these "free" sources cannot be the only option. Renewable sources other than hydro - notably wind and solar, are diffuse, intermittent, and unreliable by nature of their occurrence. The very fact that we seek the sun for our summer holidays testifies to its low intensity. Similarly, bad weather and night-time underline its short-term unreliability. These two aspects offer a technological challenge of some magnitude. It requires collecting energy at a peak density of about 1 kilowatt (kW) per square metre when the sun is shining to satisfy a quite different kind of electricity demand, - one which requires a relatively continuous supply.
Wind is the fastest-growing source of electricity in many countries, albeit from a low base, and there is a lot of scope for further expansion. While it has been exciting to see the rapid expansion of wind turbines in many countries, capacity is seldom more than 30% utilised over the course of a year, which testifies to the unreliability of the source and the fact that it does not and cannot match the pattern of demand. The rapid expansion of wind farms is helped considerably by generous government grants and subsidies. But there is often a strong groundswell of opposition on aesthetic grounds from the countryside where the turbines are located.
Apart from renewables, it is a question of what is most abundant and least polluting. Today, to a degree almost unimaginable even 25 years ago, there is an abundance of many energy sources in the ground. Coal and uranium (not to mention thorium) are available and unlikely to be depleted this century. Uranium is even available from sea water at costs which would have little impact on electricity prices. In any case the resource can be multiplied 60- to one hundred-fold by adopting the kind of technology which our postwar forebears thought would be necessary by now - fast neutron reactors used as breeders.
The criteria for any acceptable energy supply will continue to be cost and safety, as well as environmental considerations. Addressing environmental effects usually has cost implications, as the current greenhouse debate makes clear. Supplying low cost electricity with acceptable safety and low environmental impact will depend substantially on harnessing and deploying reasonably sophisticated technology. This includes both large-scale and small-scale nuclear energy plants, which can be harnessed directly to industrial processes such as hydrogen production or desalination, as well as their traditional role in generating electricity.
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