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Comment by mrb | Hacker News Reader

I think this is a non-problem. At least for France and Germany, peak electricity consumption is in winter, because electric heating is much more common (and needed!) than air conditioning. This seasonal surplus is such that nuclear power plants actually have to reduce their power output in summer. Here is a chart showing a ±30% seasonal variation in nuclear electricity production: https://jancovici.com/wp-content/uploads/2017/10/elec-mensue...

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It is a problem, if not a very big one right now. With the climate changing, expect Europe to build out more air conditioning to cope with hotter summers, raising power usage. Dismissing this very real operational problem for the power plants is unwise.

Air conditioning is consuming much less electricity than heating, there's no scenario where it would become greater than the winter usage. And there's only a few reactors affected by this issue, you have this kind of clickbait article every year.

Doesn't have to be greater than winter usage to be problematic. All it takes is several unfortunate events occurring at the same time—the kind of curve ball father time likes to throw occasionally. Say, extra hot weather, little wind which leaves wind power lacking, a few gas power plants out for technical reasons or supply shortage and then throw in baseload nuclear power plants short on water.. Unlikely? Yes, but unlikely events occur all the time. And for something essential as electricity..such a risk should be taken seriously, not dismissed out of hand as a "non-problem"

Well, right now there is extra hot weather, little wind, little installed solar power in France (and reduced solar power output because of the heat) and no problem at all either. There is a lot of spare gas capacity, the gas plants are mostly unused right now, and the nuclear plants are more than able to cope with the power demand, as less than 60% of installed capacity is needed now.

There is really no reason to think there is, or could be any problem in summer in the foreseeable future, since we are already in a worst case situation (highest temperatures ever recorded, basically no renewables used, nuclear as almost the only source of electricity at the moment) that is not problematic.

Agree on most things except on the worst case scenario being constant with time. We should expect things to get worse and plan accordingly.

> Air conditioning is consuming much less electricity than heating, there's no scenario where it would become greater than the winter usage.

How about "most people aren't using electricity for heating"? People rarely heat their houses with electricity in Europe, that would be very expensive. It's usually gas or oil boiler, sometimes a coal one.

You have about 50% share of electricity heating in France, it's far from nothing.

Edit: And coal heating is probably close to zero to be honest, that sounds old, even for the countryside. The rest of those 50% would be gas, petrol and wood.

I am so jealous. Here in Kazakhstan we use coal-powered central heating. And here is the kind of air it gives us:

https://b.radikal.ru/b12/1902/bd/a6d615dba25b.jpg

https://d.radikal.ru/d15/1901/1b/ea0e8c26f8d2.jpg

It gets much worse in the evening.

These photos were taken in Almaty, but the situation is the same everywhere (if not worse).

At first I wanted to post this particular photo, but couldn't find it, and now I can't edit the original comment.

https://d.radikal.ru/d17/1812/fd/ed5cc5dcd4c4.jpg

Those pictures look awful, I hope it will improve in the future :/

This is very location dependent. Some nations are almost entirely warming their homes with electricity.

The problem is two-fold: maintenance scheduled in the summer when the demand is “usually” lower. And stations operating with a river for cooling, where they have severe restrictions on many parameters, including maximum output temperature, which the river itself now goes over during a heatwave, so they need to shut down. It is a paradoxical situation in which the combination of our use of fossil fuels worldwide and inadequate legislation bars us from using a decarbonized energy source.

Most offices are already airconned in Europe. There might still be a bit of market expansion in private homes, but probably not that much - due to cost and urban landscape (old houses that are hard to retrofit for aircon). The landscape is also variegated enough that one can get relief from oppressive heating with little effort (going to seashore/lakeshore/hills).

Also note that PV efficiency goes down with heat, so I fully agree with you that excessive AC reliance is a very real concern. Insulating buildings should be a big priority.

Even if it's a non-problem now it will be a growing one in future and there are a few problems here. Nuclear power makes up 70% of France's electricity, so even if they normally turn off/down some reactors it will become a huge problem if they have to turn many of them off. It's also much easier to plan for a seasonal variance then a weather one, they get much less notification of when rivers will be too hot and when they will cool down again is unpredictable. Finally it undermines the economics of nuclear power, they already take decades to recoup the build cost, if they even can against renewables in future, being able to run even less pushes that further out.

Most importantly it's a warning to other countries considering nuclear, especially equatorial ones where nuclear power is almost non-existent.

Isn't this just a design problem? Surely the temperature we're trying to reduce is much, much higher than "summer river" temps. Seems like a higher flow rate and/or a better heat exchanger would fix this.

How would a more efficient heat exchanger reduce the resulting temperatures of the river water used to dumps the heat? A river full of dead fish is even worse PR than long term radiation danger.

This is specifically a problem with building a nuclear power plant on too small a body of water. The ocean doesn’t have this problem. Neither would the Great Lakes.

Actually it's a problem that arises when you build a nuclear plant next to an intermediate body of water. When the river is too small (or irregular, like the Loire) you build cooling towers on your plant, and you are fine (or at least, you need much more extreme weather conditions to have issues). The problem with plants built on the Rhône is that there is usually enough water in the river for direct cooling, so the designers didn't bother with a cooling tower[1]. But when the water flow is low, you need to stop the plant.

[1]not all of them though, in some cases the Rhône's flow wasn't enough for direct cooling and they went with cooling towers: The Cruas-Meysse plant has cooling towers and it's not affected by the current heatwave. Also, the Bugey and Tricastin plants have a mix of both (2 reactors with direct cooling and two with cooling towers) and only the reactors with direct cooling are affected.

I thought the cooling towers at Tricastin were only for the fuel enrichment part

The problem is regulations. If the river is already hotter than the max temperature allowed as output, then it’s not possible to operate, for regulatory reasons. Temperature delta is on the order of 0.1°C

In winter some nuclear power plants also have to be shut down because their cooling rivers are frozen.

Idk about Germany, but this cannot happen in France, the climat is way too warm for that.

Edit: having looked a bit more in details, it looks like even though the rivers can't be frozen to a point it stops the plant from functioning, the water admission systems can (partially) freeze in extreme weather and it happened a few time in France already.

In Finland the nuclear plants are by the sea, I'd imagine this to be at least part of the reason.

Finnish plants have to reduce capacity during hot summers too, but it's because of their environmental requirements: the exhaust water back to the sea must not exceed a given threshold to protect marine life.

It's also because of environmental requirements in France, and I expect in Germany as well.

Nuclear plants could use warmer water, but regulation forbids them from releasing water at a higher temperature than 30°C.

Freezing rivers are less of a pfroblem in Germany and France, but the rivers can be low on water so that the cooling might be limited in the winter. And there have been winters, where the nuclear production in France was struggling keep up with the heating requirements.

It'd be technically interesting to see how expensive it is to mine the ice and shovel it into directly into the cooling system somehow. It isn't like there is a problem finding heat to melt the ice once it is on site, absorbing waste heat is the whole point.

Interesting how they didn't sell that surplus to South countries as Italy or Spain, where major consumption peaks in Summer due to air cooling systems

They most definitely try. But don't forget that you also have to transfer the electricity from the producer to the consumer. The transmission lines across Europe may not be able to carry that much energy across these distances.

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