ABSTRACT
A striking feature of contemporary society is the life-style based on machines and gadgets that consume power. Currently the energy-requirement (consumption) estimate for seven billion people worldwide is about 13 terawatts (TW) and this is expected to go up by another 10 TW in 40 years time. Available fossil fuel resources are limited and depleting rapidly. Hence, there is increased global awareness concerning the urgent need to fi nd alternative energy resources to meet our requirements. Three viable options are being discussed: carbon-fuel-based sources, nuclear power and renewable sources, such as solar. The main criticism against carbon-based energy is its impact on the environment; its use will lead to a substantial increase in atmospheric CO2 levels, provoking catastrophic climate changes. On the nuclear front, power needs would require hundreds of gigawatt (GW)-level nuclear power stations to be built, and yet no viable method has been found to dispose of the dangerous nuclear fuel wastes. The third choice, that of renewable energy based on the sun as the source is therefore very attractive and promising for several reasons. Sunlight is an abundant energy resource freely available, supplied directly to our home. The amount of solar energy reaching the surface of the earth is 120,000 TW. Even if a small fraction of sunlight could be converted to alternative and usable energy forms, there would be no worry about the energy supply line.
