I think you don't understand what co-generating heat is. It's a part of generating electricity. You use that heat to heat up the next batch of water, so you end

I think you don't understand what co-generating heat is. It's a part of generating electricity. You use that heat to heat up the next batch of water, so you end up spending less fuel turning it into steam. https://en.wikipedia.org/wiki/Cogeneration https://en.wikipedia.org/wiki/Cogeneration