What are the limitations of extracting enegry from :
(a) the wind
(b) waves
( c) tides ?

Explanation

(a) Limitations of extracting energy from wind :
(i) Wind generators to produce electricity can be established only at those places where wind blows for the greater part of the year.
(ii) The wind speed should be higher than 15 km/h to maintain the required speed of wind turbines for generating electricity.
(iii) There should be some back-up facilities like storage cells to take care of energy needs during the period there is no wind.
(iv) A large area of land is required for establishing wind energy farms
(v) The initial cost of establishing wind energy farms is quite high.
(b) Limitations of extracting energy from waves (or sea-waves) :
(i) The wave energy can be harnessed at only those places where the sea-waves are very strong.
(ii) The efficiency of power plants based on wave energy is very low.
(iii) The power plants built in oceans or at sea-shores have high cost of installation. corrode easily and need a lot of maintenance.
(c ) Limitations of extracting energy from tides :
(i) There are very few sites around the world which are suitable for building tidal barrages (or tidal dams).
(ii) The rise and fall of sea-water during high and low tides is not enough to generate electricity on a large scale.