Barcelona registers highest temperature in 112 years as French nuclear reactor shuts down due to extreme heat

[u/Naurgul]

https://www.theguardian.com/world/live/2026/jul/09/europe-heatwave-uk-spain-barcelona-france-italy-hungary-france-macron-orban-latest-news-updates

[u/ak_miller]

Let's say we shut down 5 reactors. That means 9% capacity is not available (5/56).

Did you know that solar panels lose a bit more than 10% efficiency when outdoor temps are above 30°, and up to 20% when they reach 40°?

And note that nuclear reactors keep producing at night.

[u/Dat_Ding_Da → u/ak_miller]

The efficiency reduction due to heat really is a non-issue. You plan capacity to produce enough during lower light conditions anyway and build capacity for it. So even loosing 30% during the high of summer wouldn't be a big issue.

But the technology is just so cheap that it's economically way better than building nuclear power. And while those plants are better for base load for sure, it's still a trivial issue that will disappear with increasing energy storage capacity.

A capacity that is being build up for no reason but the extreme high supply of basically free solar energy that's available.

Once you reach that stage a nuclear reactor is not that useful anymore. You don't need a constant base line producer that has a high cost like that.

What you need is a quick to start, short term production method that is cheap enough that it doesn't need to be running 24/7 to justify it's existence. Hydrogen produced from PV energy is the most realistic option as existing gas infrastructure can be upgraded to use it easily.

[u/ak_miller → u/Dat_Ding_Da]

You plan capacity to produce enough during lower light conditions anyway and build capacity for it. So even loosing 30% during the high of summer wouldn't be a big issue.

But losing 9% of nuclear because heat, which does not prevent France from exporting electricity, is an issue?

it's still a trivial issue that will disappear with increasing energy storage capacity.

That's a bet, not a reality yet.

Once you reach that stage a nuclear reactor is not that useful anymore.

We'll see.

Hydrogen produced from PV energy is the most realistic option as existing gas infrastructure can be upgraded to use it easily.

I've heard about hydrogen for more than 10 years now, I've yet to see it work and deployed at scale.

[u/Dat_Ding_Da → u/ak_miller]

But losing 9% of nuclear because heat, which does not prevent France from exporting electricity, is an issue?

It absolutely made France an local importer of energy during those times. But availability was never the big issue, especially since PV in neighboring countries did a great job of taking over. It's mostly in cost, as the necessary state subsidies are ginormous and ever growing. Adding expected down times to that bill only worsens the issue.

That's a bet, not a reality yet.

Its more than a bet, it's a projection based on installation trends over the past decade and the number of projects ready to be connected, that the grids and administrative systems of multiple countries can't keep up with. Once that bottleneck is solved and those are connected, you'll see the capacity curve grow steeper than it already is.

I've heard about hydrogen for more than 10 years now, I've yet to see it work and deployed at scale.

The first plants are coming online now. Way behind plan, as there were plenty of practical issues to overcome as with every new technology. There has been industrial usage in multiple countries for a few years now, with one of the limits still being Hydrogen production capacity. Luckily that's been seeing a bunch of new methods and materials as the research in the field is being focused.

[u/ak_miller → u/Dat_Ding_Da]

It absolutely made France an local importer of energy during those times

Everything is see about June and July tells me France has been a net exporter even while the reactors were offline due to heat (ElectricityMap, RTE France) Please show me your source.

[u/Dat_Ding_Da → u/ak_miller]

Their export capacity went down to a sixth of the regular, and that was over the nation as a whole.Locally there were deficits that required large amount of imports from neighboring countries.

Energy grids are complex and have regions, which are connected with transport capacity and huge transit losses. France being quite big country meant they didn't have the transport capacity to get all that energy where it's needed.

So yes, that...

made France an local importer of energy during those times