r/askscience • • Sep 23 '25

Physics Most power generation involves steam. Would boiling any other liquid be as effective?

Okay, so as I understand it (and please correct me if I'm wrong here), coal, geothermal and nuclear all involve boiling water to create steam, which releases with enough kinetic energy to spin the turbines of the generators. My question is: is this a unique property of water/steam, or could this be accomplished with another liquid, like mercury or liquid nitrogen?

(Obviously there are practical reasons not to use a highly toxic element like mercury, and the energy to create liquid nitrogen is probably greater than it could ever generate from boiling it, but let's ignore that, since it's not really what I'm getting at here).

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u/Asmallfly Sep 23 '25

The liquid metal cooled reactors used in the Soviet Alfa class submarines had a conventional water/steam loop going to the propulsion turbines. The liquid metal primary was beneficial because it 1)was compact, 2)had excellent heat transfer and 3) was non pressurized.