The energy needs of the world are constantly increasing, while the energy sources are decreasing. As a result, it is necessary to look for new sources of energy. At present most of the power is obtained mainly from two sources. They are fossil fuels (coal, gas and oil) and the power of water. It should be noted, however, that the generation of electricity by these Conventional means is highly uneconomical and the resources of fossil fuels are limited.Therefore much effort is given to other energy sources. There are alternative energy sources such as .solar energy, the energy of wind, ocean tides and subterranean hot water. The sun is an unlimited energy source, but only a little part of its energy is used directly.
The most promising way of producing electrical energy today is by means of nuclear fission.Nuclearar power plants produce more than 16% of the total electricity generates in the world. The first NPP was built in Russia in the town of Obninsk in 1954.
Nowadays scientists try to make thermonuclear reaction controllable. Theyi-Gonsider hydrogen to be the most promising energy source for fusion. There are some advantages of fusion over fission:
a) it roduces several times more energy than fission;
b) it does not produce radioactive waste;
c) it is not dangerous in case of an accident;
d) it uses materials that are abundant and less harmful to the environment.