Why is there a need to harness non-conventional sources of energy ? How can energy be harnessed from the sea in different ways ?

Explanation

The population of world is increasing at a very rapid rate due to which demands for energy is increasing day by day. Following are the main reasons because of which there is a need to harness non-conventional sources of energy:
(i) Limited non-renewable fuels : Today, fossil fuels are the main energy sources for us. But it takes millions of years for the formation. The rate at which we are using them means they are not going to last many years from now. They would be definitely exhausted sooner rather than later.
(ii) Polluting fuels : Burning of fossil fuels releases greenhouse gas. Carbon monoxide can be poisonous even in low concentration. Oxides of sulphur and nitrogen cause acid rain. Air pollution also results in increased cases of respiratory problems.
The energy from the sea energy can be harnessed from the sea in different ways:
(a) Tidal energy : Tidal energy or tidal power can be defined as the energy that is the result of the Moon and the Sun.s gravitational influence on the ocean. Height differences between high and low tides create tidal currents in coastal areas, and these currents can be strong enough to drive turbines. The turbine fixed at the opening of the dam converts tidal energy to electricity.
(b) Ocean thermal energy: OTEC uses the principle of a heat engine. It works by converting a temperature difference into energy. This means the difference in temperature between the warmer water on the surface and the cooler water in the depths of the ocean can be converted into electricity.
(c) Wave energy: The kinetic energy possessed by huge waves near the seashore can be trapped to generate electricity. The waves are generated by strong winds blowing across the sea. Wave energy would be a viable proposition only where waves are very strong. A wide variety of devices has been developed to trap wave energy for rotation of turbine and production of electricity.