Solar energy (energy got from the sun) is a very useful form of energy like atomic and wind energy. The problems of rising costs of fuels like oil and gas and the pollution (dirtiness of the atmosphere) caused by them have made scientists work on solar energy for man’s future use. About half of the solar energy is light, about half is infrared radiation (heat, energy, etc. in rays) and very little ultraviolet radiation.
In modern times, the first main use of solar energy is to change it into thermal energy (of heat as that of coal or gas). Solar rays hit a flat plate collector which absorbs a lot of heat. This flat plate collector is then used for water heating, house heating, air-conditioning and for getting salt from salt water and pure drinking water from seawater. Solar water heaters are in use in Australia, Japan, and America. In air-conditioning, the flat-plate collector supplies heat to operate an air-conditioner. In solar evaporation, saltish water is made to evaporate from ponds, and thus salt is got. In solar distillation, pure water vapor is collected in storage tanks.
Secondly, scientists are trying to convert (change) solar energy to electrical energy through solar cells. A solar cell is an invention (device) that directly changes solar radiation to electric energy. Spaceships get their electric power through solar cells. Further, they are being used to provide power to radios, telephones, and other wireless equipment. Lighthouses at sea get their power supplies from them. At present, the cost of producing electricity from solar cells is very high.
Thirdly, heat engines are being used to convert solar energy to mechanical energy. This mechanical energy is used directly or again converted to electric energy for operating machines. Heat collectors are used to heat fluids whose steam passes through engines where it is converted to mechanical energy.
Fourthly, we can use the solar energy or heat stored in the sea. Most of the solar energy that comes to the world is taken by the sea. The water at the surface of the sea is warmer than at the depth. Heat flows from the area of higher temperature to that of a lower one. So if we make this heat of the warm water flow through a heat engine, the heat energy can be converted to mechanical or electric energy. Power plants can thus use thermal energy, especially in warm waters.
Fifthly, in Japan and some other countries, small plants grow in the sea by absorbing sunlight. These plants are dried and then used as food.
There have been attempts to make solar cars in Europe and elsewhere. These cars run on electric energy instead of oil. The car batteries charged with solar energy provide the electric energy. However, at present, the batteries are too heavy and are charged over long hours.
Solar energy may be the answer to many of our energy problems.