UtilizationThe sun, a source of unlimited energy, can potentially provide the equivalent of about 25,000 times the total amount of energy presently used from all other sources. However, only a very small fraction of this freely available energy is exploited through direct means for human use. At the world's current consumption of fossil fuels (petroleum and natural gas), depletion of the reserves of these energy resources is now a predictable matter of universal concern.
Alternative energy resources other than coal are inadequate to meet the total future needs on a global scale. In order to diminish the dependence on the rapidly depleting oil resources, special consideration is being given to the feasibility of expanding the exploitation of coal reserves in a manner that would ensure the reduction of the associated environmental impacts.
In view of these rapidly growing concerns, it would be reasonable to assume that solar energy is bound to play an important role in the future supply of energy, particularly in the developing world. Although the use of solar energy is still limited at present, the development of appropriate technology is underway to harness solar power, as well as other renewable energy sources, for various industrial and household applications. The areas of solar usage include drying of food and crops, desalination, generation of electricity, heating and cooling of houses, water heating, and cooking and refrigeration.
Fuelwood: An environmental issueIn many developing countries, particularly in rural and remote population centres, the energy consumed for household use is largely from local resources such as fuelwood, charcoal, cow dung, and agricultural wastes.
According to well informed UN sources (UNEP, Global Environmental Issues. Edit., E. El-Hinnawi and M. Hashmi. Tycooly International Publishing Ltd., Dublin, 1982) well over two billion people, mostly in rural areas, use fuelwood as the principal source of energy for cooking and other domestic purposes. This has been a traditional practice for centuries among rural populations in Africa, Asia, and Latin America, where nearly 95% of the households depend upon fuelwood as their major source of energy at an annual consumption rate of 1.3 m3 to 2.3 m3 per capita. Kenya, Zambia, Tanzania, Upper Volta, Nigeria, China, India, Bangladesh, Sri Lanka, Thailand, and Nepal are typical examples of the countries involved.
Through over-exploitation of forest trees, shrubberies, and other woody vegetation, partly to make room for new farmlands and partly for use as fuel, situations of acute fuelwood scarcity are currently prevailing in many parts of the developing world. About one billion people are believed to have been faced with such critical situations in 1980. Some of the salient ecological consequences include deforestation, lack of woody vegetation, and destructive soil erosion. In some of the semi-arid regions like the sub-Saharan parts of Africa from Senegal to Ethiopia, there are indications that fuelwood consumption has already contributed to the process of desertification.
The Meritable AspectsBesides its availability in abundance in most parts of the developing world, solar radiation possesses a number of advantages over other energy sources which are now rapidly dwindling. The prominent ones include the following: