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by taylodl 1066 days ago
Nuclear power plants and coal-fired power plants work off the same principle:

Use the heat to boil water to create steam, run the stream through a steam turbine, and condense the steam back to water. This water is continually recycled throughout the system.

The river water is used to condense the steam back to water and then the water is discharged back to the river - warmer than it came in. If the water coming in from the river is too warm then the condensation rate increases until you get to the point it's out of spec. You can't condense the water fast enough. You need to reduce the plant's output, i.e. reduce the heat.

On the other end the discharge water is always warmer than the intake water. As the intake water warms then the discharge water will also warm - all other things being equal. You'll get to the point the discharge water will raise the water temperature to the point where aquatic life is negatively impacted. There are also laws mandating the maximum temperature for the discharge water.

So, you have to reduce output. That's just how these plants work.

That's the nice thing about natural gas plants - the gas turbines are essentially jet engines - they're fueled directly, no steam or cooling required.

This is something rarely talked about in the solar and wind discussion. People love to point out that the wind and the sun provide intermittent power, while ignoring more and more traditional power plants are curtailing output as water temperatures rise or water levels lower (water intake pipes would be exposed).

4 comments

We don't talk about it, because we want to get _away_ from igniting huge amounts of underground carbon-based material and putting it straight in the atmosphere. We want to move to methods of power generation that do _not_ significantly upset the delicate balance of a livable planet.

Continuing adding more carbon to the atmosphere is only worsening the situation.

There are so many people that only think in extremes - we should go all in on nuclear and there's no other way. They are the ones that ignore limitations that parent mentioned. Their fantasy will not work and strong opposition to renewables is detrimental to our future.
I don't think anybody except lobbyists argue for that. In most projections i saw from pro-nuclear anti-carbon think tank (such as the one i was memebr of during Covid), the nuclear part in the energy mix vary from 30 to 50% (Depending on what the nuclear would be present for: i think in the 50% model, 60% of nuclear should be controllable plants, vs 100% for the 30% model).
Not talking about something doesn't mean it's gone.
Large gas power plants are combined cycle steam plants. Only the smallest ones are simple cycle as you describe. Large gas power stations are as complicated as any other thermal power station.
We have this problem with coal plants in Australia - in Summer often there are unplanned coal unit outages on hot days (due to this kind of thing, among other reliability issues with the aging plants - I don’t think ours use river water but this kind of cooling issue), and it’s always right when the grid is stressed with all the air conditioners running…

And of course the rightwing media starts the chorus of ‘those bloody renewables’ causing problems, even when solar especially is actually helping us ride through some of the coal unreliability!

Look what happened in Texas - major Winter storm hit and it froze the gas generation plants. Of course all the right-wingers could talk about were those "frozen windmills" failing them. Meanwhile in my state, which is considerably further North than Texas, the temperature was even colder yet our windmills were spinning just fine. Of course they "forgot" to mention that. They also "forgot" to mention all the gas generation plants that couldn't operate in subfreezing temperatures. You can better believe when generation is taken offline due to the river water being too warm or the water level being too low they're going to blame solar and wind generation for the outages. It'd be funny if it weren't for the fact that there are idiots who believe what they say.
You can do air cooling with nuclear plants as well, for locations that don't want to or can't use a water supply. Costs more, but totally doable.

https://www.youtube.com/watch?v=T9S1P54n1FA