ABSTRACT
A power plant of any type requires energy for its build-up phase and also, during its entire operation. This is also true for renewable energy sources, like solar energy or wind energy, because all power plants require maintenance and repair. The cost factor for the latter ones is; of course, lower than expenditures for transportation of coal or uranium ore. Coal supply plus transportation over an assumed lifetime of 25 years is the most important cost factor. Energy gain factor is produced electrical energy in 25 years divided by construction cost energy plus operation expense energy plus coal supply and transportation. The potential for an increased use of hydroelectricity exists especially in countries like Canada and parts of Asia and South America. A listing of the hydroelectric potential available on Earth and the present in use in percent shows that Europe and the US and Canada have largely exhausted this useful source of energy.
