What are the limitations of extracting energy from—
(a) the wind? (b) waves? (c) tides?
(i) high speed winds are required to obtain wind energy, most places do not experience high speed winds.
(ii) the initial cost of setting up wind mills is very high.
(iii) large amount of area is required to set up windmill farms.
Sea wave energy can only be harnessed at places where sea-waves are very strong.
Such places are very limited.
There are very few sites around the world which are suitable for building tidal dams.
The rise and fall of sea-water during high and low tides is not enough to generate electricity on a large scale.