Once upon a time, there was a caveman who wanted to make energy.  Maybe he wanted to stay warm at night, or he wanted to cook food, but that's not the point. The point is, his first idea to generate energy was to gather up wood, rub some flint and steel together, and make a fire.  Setting things on fire proved out to be a handy way to generate energy. This method was the preferred way to make energy until after millenniums of progress, through the Stone, Bronze, and Iron Ages, into the Renaissance…