G azərbaycan respublikasi təHSİl naziRLİYİ azərbaycan texniKİ universiteti M. M. QƏNDİLova e. Q. İsmayilova

UNIT VIII

It is always in season for men

to learn Addison, Joseph.

DIRECT CONVERSION OF ENERGY TO ELECTRICITY

Our life is revolving around electricity and its many uses. Much has been written on the progress achieved in producing electricity. Most cases have dealt with direct conversion of energy to electricity. What are such processes? Are they new? Will one of the methods be used in place of the present ones for generating electricity? Will the cost of electricity be less? These and other questions will be answered and answers will depend on whether one is considering electricity from the standpoint of the few watts for a satellite in space or the millions of watts for even a small city.

First let us be sure we all understand what electricity is and the common means by which it is produced. We now define electricity or electric current using the atomic theory according to which all matter is made up of tiny particles or atoms. Atoms contain electrons which are negatively charged and neutrons which have no charge. The electrons are in the outer part of the atom and are free to move from one atom to another. When these electrons move in one direction an electric current occurs. A good conductor of electricity is a material in which the electrons readily move from atom to atom. An insulator or poor conductor on the other hand is a material in which the electrons are more strongly bound to the atom and, therefore, do not move freely. Although the electrons pass from one atom to another, the conductor is not charged directly by the process. For example, a 60 watt lamp requires the “passing” of 3.10x18 electrons per second. Although this is a tremendously large number it is small in comparison to the number of electrons an inch of even the thinnest wire.

Common sources of electricity are batteries and power plants. Energy is converted into electricity, and the chief energy source is heat from fuel. But the heat is not directly converted into electricity; it is first used to generate steam which turns the turbine operating an electrical generator. Electricity flows through transmission lines to houses, factories, etc.

Now the generation of electricity by this process is very uneconomic. Actually only about 40 per cent of the heat in the fuel including nuclear energy is converted into electricity, while the remaining part is generally lost in the cooling process. There has been a lot of effort and thought given to other means for generating electricity and experiments are being carried out at present in order to raise the efficiency of energy conversion. There are some processes which are more efficient as high as 80%. These are generally connected with direct conversion of energy into electricity in thermo-ionic, magneto-hydrodynamic, thermo-electric and thermo-photovoltaic energy converters. We have pointed out that matter is electronic in nature: “line-up” the electrons so they will pass from one atom to another and an electric current will flow.