Khilendra Basnyat

Energy, which has been considered the fuel of overall development, is also the prime mover of economic growth. Actually, major advances in civilisation have been accompanied by an increased consumption of energy. In fact, there is a direct correlation between the degree of economic growth, the size of per capita income and per capita consumption of energy. This is why countries that have had abundant supply of energy available to them have high rates of industrial growth and a corresponding increase in the gross national product.

Sun as source of energy
Most energy we use comes from the sun, and we live in an atmosphere warmed by solar energy. We eat food produced by photosynthetic conversion of solar energy and obtain benefit from a system of wind, rain and rivers driven by solar energy. Though most energy in the universe is gravitational, human is most concerned with solar radiation. This is proved in many countries, specifically in the developed ones. Experiments have shown that most life processes at or near the earth is surface use the sun as the source of energy. Actually, the earth intercepts a huge quantity of energy from the sun, which is very high than annual human consumption.
The flow of energy from the sun to the earth and the many transformations of that energy represent a complex system. Such energy is transformed, stored and transported because it moves through the system and is in a state of long-term equilibrium. The sun's energy spectrum has been found to range from the shortest wave length (gamma, X-ray and ultraviolet) through the visible and infrared wavelengths, with infrared accounting 50 per cent of the total radiation received.
On a clear day, 10 to 50 per cent of the solar radiation can be reflected from the top of cloud and another 2 to 20 per cent can be absorbed by cloud. The planet average for cloud reflection and absorption has been found to be 23 per cent, with reflection representing 20 per cent of the total. Actually, human is a part of a dynamic system that includes the physical and chemical living and inert component of his environment. The system is constantly adjusting and changing, and the greatest quantity of its energy enters the system as solar radiation.
Researchers have made clear that part of the solar radiation is captured by green plants, which through photosynthesis converts it to chemical or food energy. The chemical energy of plants is available to be converted to heat by burning or to be buried and stored as a fossil fuel. Food energy may pass through animals and plants and through herbivores to meat-eating animals along a series known as food chain, which is a channel of energy flow and dissipation.
Energy enters the global ecosystem as solar radiation as heat flowing from within the earth and as tidal energy. About 30 per cent of the solar radiation intercepted by the earth is directly reflected back into space by cloud and land. About 47 per cent is absorbed by atmosphere, land and water. It has been discovered from research that a small percentage of the incoming solar radiation is absorbed by the leaves of plants used in photosynthesis, which converts carbon dioxide and water into organic carbohydrates and oxygen. This small portion of the solar radiation intercepted by the earth provides the energy for the basic biological requirements of the earth's plants and animals. However, most people are ignorant of this fact still now.

Enormous potential
Solar radiation can be controlled to produce useful heat and to produce electric power while controlled solar radiation has long been used to heat water and provide warmth for sprouting seeds and raising flower and certain vegetables. It has also been collected to heat small and large houses in many urban areas, especially in developed countries. Though the development of solar energy is in its early stage in Nepal, the number of solar heaters installed here is increasing every year. Actually, there are various potential applications of solar energy here, of which heaters, driers, pumps, cookers and furnaces are worth mentioning. Likewise, photovoltaic cells and other direct energy conversion devices can be used for water pumping, lighting and telecommunication purpose, especially in remote areas.
In Nepal, the potential of solar energy is enormous. A study, conducted by the Water and Energy Commission in 29 sites some years ago, estimated that the total solar energy available in the country here would be approximately 25X106 Mw. However, the availability of the resource only does not fulfill our needs. What is essential is its maximum utilisation to meet the growing power needs. For this purpose, both the governmental and non-governmental agencies should work hand in hand.

(Basnyat is a freelance writer)