(i) They are the energy resources in use since ages.
(ii) They make use of non-renewable sources of energy.
(iii) They are expensive.
(iv) They can cause pollution; e.g., Coal
(iv) They can cause pollution; e.g., Coal petroleum, natural gas, electricity, etc.
(i) They are in use recently only.
(ii) They make
(iii) They are cheaper.
(iv) No pollution is caused by them; e.g., Solar, wind, tidal, geothermal, biogas, etc.