Mills using water as a source of energy are known for thousands of years. If oil, natural gas or even coal would not exist, that and wind energy would be used o

Mills using water as a source of energy are known for thousands of years. If oil, natural gas or even coal would not exist, that and wind energy would be used on much bigger scale. Then a solar power station using thermal solar could be built like 200 years ago. And nuclear energy would be eventually discovered.