Energy From The Sea

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

What are the limitations of energy that can be harnessed from the sea ?

Name any three forms of energy which could be harnessed from the sea.

Common salt can be separated from the sea water by the method of ___

Name the fossil fuel formed from the dead organisms present in the sea :

Why can a ship not use the internal energy of sea water to operate its engine?