Magnetohydrodynamic power generation

The basic principle employed here is the Faraday’s law of electromagnetic induction which involves direct conversion of kinetic energy of a flowing fluid into electricity by passing the conventional multiple conversion process. In the design of the generator, a pipe whose diameter increases from beginning to end is taken. A gas is allowed to flow through this pipe at very high temperature from left to right. A field coil is used to generate a magnetic field in a direction perpendicular to the direction of the motion of the gas. This results in the development of EMF. Gas conductivity can be increased by the addition of small amount of potassium. A two-stage cyclone furnace is used as a combustor. The electrodes used here are made of tungsten cooled with iridium and are separated from one another by beryllia insulating material. The field coil is made of a superconducting material either niobium-zirconium or niobium-tin.

Renewable sources of energy

Photovoltaic cells are renewable sources of energy. Main principle involved here is ‘photovoltaic effect’ where a photovoltaic cell converts sunlight into electricity. Electron-hole pairs are created when light strikes the photovoltaic cell. Since no materials are being wasted, it is known as a renewable process. Solar cells are composed of various semiconducting materials. Silicon is the most popular candidate since it is the second most abundant element in the earth’s crust. The other advantages of silicon are silicon wafers are thin, non-toxic etc. A large area p-n junction diode can be used as a photovoltaic cell. When sunlight strikes a photovoltaic cell, photon knocks an electron from a silicon atom. Thus electron is emitted and a hole is created in silicon.