Which energy source generates the most electricity?

 The efficiency of a source of energy is determined by how much of the chemical, mechanical or thermal energy that has 'gone in' is rendered usable as electrical energy-depending on the process and machine used to effect the transformation. Typical efficiencies are as follows: hydro electric power 80-90%, wind power up to 85%, natural gas power 55-60%, coal-fired power 25-45%, nuclear power 33%, fuel cell 20-70%, solar power cell 5-29%.