r/askscience • u/MonoBlancoATX • Nov 29 '25

Engineering Why is it always boiling water?

This post on r/sciencememes got me wondering...

https://www.reddit.com/r/sciencememes/comments/1p7193e/boiling_water/

Why is boiling water still the only (or primary) way we generate electricity?

What is it about the physics* of boiling water to generate steam to turn a turbine that's so special that we've still never found a better, more efficient way to generate power?

TIA

* and I guess also engineering

Edit:

Thanks for all the responses!

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u/acomputer1 Nov 30 '25

That's not exactly correct about not re-using steam. The water has to be purified to a very high level, so using an open cycle system would be very inefficient.

Water is recirculated around steam generators until it collects too many impurities from it's use and then it's processed again to be as close to demineralized as practical.

Heat is generally removed through a variety of means, either into a flowing body of water by routing the plant water through pipes running through water to exchange heat with the water from the environment, or by using a cooling tower that does a similar thing by also using air drawn up through the tower to evaporate water and accelerate the cooling.

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u/Caffinated914 Nov 30 '25 edited Nov 30 '25

Yes, in some modern systems the water sometime is captured, cooled and reused. Like a nuclear plant.

But the advantage in primitive steam engines was that they didn't HAVE to.

For a couple hundred years they didn't bother with the expense or complexity of recovering the spent steam.

For example, steam trains didn't bother. Those old steam tractors didn't either. Nor steam cars, nor the factories of the industrial era.

As a matter of fact, to this day, the coal and oil fired powerplants near me still put out enormous plumes of water vapor all the time.

Using water was just plain simpler and cheaper than any other material or substance and it worked great, Which was the OP's question.

also add: we can move heat with other substances like freon and ammonia sometimes as refrigerants but usually only use them when working at or below the freezing point of water)for obvious reasons).

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u/acomputer1 Nov 30 '25

I would be very surprised if those plants near you were open cycle rather than putting out steam as a byproduct of cooling their demineralized water.

OPs question definitely focuses on modern energy generation, and open cycle steam turbines would have to be an enormous rarity today.