Question

list two limitations each of extracting energy from (i) waves (ii)tides

Answer 1

(1)WAVE:

*Very strong ocean waves are required in order to extract energy from waves. But these are not available all time.

*waves energy is commercially viable at the places where waves are strong

(2)TIDES:

* strong tides are not available everywhere 

  *Very high tides are required in order to extract energy from tides. But tides depends on the relative positions of the Sun, moon, and the Earth

Answer 2

i..the waves are generated by strong winds blowing across the sea
limitations...
wave energy would be a viable preposition only where waves are very strong

ii.. tidal waves and energy possessed by rising and falling water tiles is known as tidal energy.
limitations..
the tidal waves in sea Build up and recede only twice a day (due to attraction of moon on sea water which comes at night)