Turning Heat into Power: The Fundamentals of Energy Generation
Apart from gravity, heat is the form of energy with which we are most familiar. As warm-blooded animals, we convert a significant part of the chemical energy in our food into heat. About half a million years ago, we also learned to generate heat from external sources by burning biomass. Since then, we have greatly expanded the range of fuels we burn to produce heat, but we still rely in most cases on combustion (the exception in our modern energy system is nuclear power, where heat is generated by exploiting a chain reaction of uranium atoms). However, while we still rely largely on combustion to generate heat, we have learned to turn heat into a far more portable and flexible form of energy – electricity.
Most ancient civilizations developed along waterways: the Mesopotamian along the Tigris and Euphrates, the Egyptian along the Nile, the Chinese along the Yellow River, the Indian along the Indus, the Roman along the Tiber. Water is essential to human life, for agriculture, fishing, and as a transportation medium. It is also valuable for washing (clothes, food, and bodies) and for industry. In the last 150 years, another inducement has been added to the list: water is an essential resource for generating electricity.