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Comment by avianlyric | Hacker News Reader

Interesting thing is that nuclear has the exact opposite problem, it’s extremely consistent.

You can’t easily vary the output of a nuclear plant (maybe these will be different, but I doubt it), they take days to weeks to spool up and down. Which makes them only useful for base load.

Ironically pairing them with grid storage would be an enormous help, because then you could use the storage to rapidly respond to demand, while your nuclear plant ramps up and down very slowly.

In short nuclear also isn’t a one size fits all solution for power production, and if it needs to be paired with storage in a carbon free world, it makes you wonder if it’s really worth all the trouble compared to wind and solar.

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Navy nuclear reactors can ramp up and down very quickly, unfortunately for the civilian power they don’t save much money by doing so. Which is why they civilian power plants are generally designed for steady state operations.

That is the purpose of the Hornsdale Power Reserve, a giant battery in South Australia, except instead of nuclear it is helping balance gas turbines and renewables. SAs energy is produced from renewables and gas turbines, with the battery providing grid stabilizing services. It has been so transformative that it can even stabilize the grid across the country faster than their local power supply can kick in. Typically that kind of service is charged by response time and time spent responding, but the battery is so fast that the they get far less than a responding gas turbine would for the same service.

https://en.wikipedia.org/wiki/Hornsdale_Power_Reserve

France routinely varies the output of its nuclear power plant intraday to follow the demand

True, however this is a far smaller variation ("several tens of percent" [1]) and only happens slowly (~once per day). This is in contrast to gas turbine peaker plant with can ramp by 10-20%[2] of rated power per minute.

[1]https://www.oecd-nea.org/nea-news/2011/29-2/nea-news-29-2-lo...

[2]https://journals.sagepub.com/doi/10.1177/0957650920932083

I am not sure what you mean by one per day. There is only one cycle per day. And it’s not slow, fast enough to adjust for the daily cycle.

https://en.m.wikipedia.org/wiki/Load_following_power_plant

“Modern nuclear plants with light water reactors are designed to have maneuvering capabilities in the 30-100% range with 5%/minute slope. Nuclear power plants in France and in Germany operate in load-following mode and so participate in the primary and secondary frequency control.”

One of the ideas I've heard behind these smaller reactors is that since you have say 10 small reactors instead of 1 big reactor, you can decrease the overall output by just shutting down a few of the smaller reactors.

It's absolutely not perfect but it's an improvement.

And should a country end up many of these small reactors, nuclear could actually be quite flexible. The reactors could be shut down and started up on schedules such that each morning, some reactors that were shut down are coming online and in the evening, some of the reactors that were online are shutting down.

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