I think we have 3 primary sources on the Earth. 1st – Sun (nuclear fusion) Coal, oil, water dam – it would not exist without the Sun 2nd – Earth (nuclear fission) Hot geysers 3rd – Moon (gravitational force) When it moves ocean waters Anything else is just a secondary energy source. There could be 4th source of energy in the future. Annihilation of matter. What do you think?