Have you ever heard of a hydroelectric dam?
The source of energy in a hydroelectric dam is not the water but rather force it exerts as it falls down from the lake level upstream of the dam to the outflow. If you could magically transform the water in the lake to benzene or alcohol or any other liquid the effect would be essentially the same. (Before anyone jumps in, I said "essentially". I well understand that differences in density, volatility of the liquid, etc. would affect the design and efficiency of the power generation.)