system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why can't we use materials with lower boiling points to generate power?

My understanding is that water is commonly used in coal-fired power plants and the like, and that water has a rather high boiling point. Wouldn't using something with a lower BP like acetone produce the same amount of energy at a lower temperature, making it easier to generate with heat sources like the sun or geothermal? I also understand that according to thermodynamics more energy can't be gotten out of a system than is put into it, but shouldn't the turbines spin just as fast no matter what gas is being passed through them/what temperature that gas is?
gpt
Water's volume expands 1600-1700 times when it turns to steam. That increase in volume allows the pressure it creates to be used for mechanical motion.

Acetone doesn't expand that much, so it is not as efficient or useful. Acetone is also quite dangerous when heated while water is not.