> The problem spain needs to overcome is the morning and evening peaks. From memory it's something like 1-2 gigawatts (but it could be more.)

The EU has collectively added 27 Gwh of battery capacity in 2025 alone. If Spain only needs anything close to 2 GW of load for around 2 hours in the morning and evening each, this seems to be inherently achievable.

> you totally can, and for keeping the grid stable, they are absolutely grand.

Nuclear plants can load follow at about 5% of their rated capacity per minute. This is glacial in the world of electricity.

At the moment, this would theoretically work, because you have gas peaker plants that can adjust much faster and pick up the slack while nuclear plants come up (or down) to speed.

But countries like Spain and Denmark want to have a 100% renewable grid within two decades (much shorter than the typical lifetime of a nuclear reactor). So gas peaker plants are increasingly not an option.

The reality of the grid at that point will be a lot of wind and PV capacity (because it is dirt cheap). Nuclear is not compatible with those on its own, because a cloud passing over a large PV installation will drop power much quicker than nuclear will be able to follow.

Of course you can build a ton of batteries to act as a buffer. And guess what, that's exactly what we are doing right now. But at that point, why do we need nuclear again? Simply building batteries is already much cheaper than building a substantial nuclear generation capacity and while batteries will continue to become cheaper while nuclear won't.

Also, if you require new nuclear plants to load follow on a regular basis, it completely destroys the already bad economics of the technology. You need to run those at capacity continuously to make even remotely sense.

> Nuclear plants can load follow at about 5% of their rated capacity per minute. This is glacial in the world of electricity.

which is why batteries are really great. We have couple of batteries that are 180 and 300gwh, which can turn on frighteningly quick. The iberian market is really young at the moment for batteries, they have a way to go before batteries make a dent in prices (which is great for us)

The spanish grid has about 16% nuclear: https://www.ree.es/en/datos/todate Now spain's grid usually has a whole bunch of solar sites in curtailment, which means they can turn on power fairly quickly. Which is where batteries come in, as the curtailment could be flowing into batteries, and that sweet sweet energy sold at a stonking profit in the evening.

But!

Denmark isn't the spanish grid. They have less predictability, so need bigger storage to account for the variability of wind.