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Comment by Gwypaas | Hacker News Reader

Nuclear is awful for peak demand. The cost model of super expensive CAPEX and low OPEX only lends itself to running at 100% 24/7.

Let us say you run a peaking nuclear plant. It can run for 30% of the time, optimistically. It now costs ~3x the price, so $390 to $600 per MWh. That's insane energy prices. Worse than Europe in a haphazard energy transition from Russian gas due to the largest war in Europe since WW2 breaking out.

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Point of clarification: nuclear does not have low OPEX. Nuclear operators in the US (Illinois, Ohio, Pennsylvania) have been reporting that their 40 year old nuclear plants were no longer competitive with natural gas (before the Russian invasion of Ukraine drove up prices).

Nuclear has high CAPEX and high OPEX. Nuclear plants have lots of employees and maintenance on an irradiated nuclear reactor is expensive.

What they have is low fuel costs.

This is actually the origin of my idea for using nuclear power to produce zero-emission synthetic conventionals. Peak demand is a terrible use-case for nuclear, what you really want for peak demand is rapid-delivery storage like batteries. A Teslawall that charges from the grid during off-peak and discharges to the home during peak, for example. The best use-case for nuclear is, as you say, 100% 24/7, and the best utilization of that I could think of is producing stored energy with maximum compatibility for legacy power infrastructure.

Also, coupling nuclear power plants with pumped storage is a good way to store energy for on demand use. I think that’s what the Washington state nuclear power program was originally planning given grand coulee could pump up (we eventually just got one small commercial reactor).

Wind can probably do the same today, and we have plenty in Washington and adjacent Oregon. Though I’m sure unsure if they are actually storing excess grid capacity via hydro right now.

The major energy consuming step for synfuels is hydrogen production. Electrolysers are getting cheap, so there's not much penalty to having the input energy be intermittent. Nuclear will therefore be competing directly against renewables on a levelized cost basis here. That's a competition it can't win.

If you can yse storage to mamage peak with renewables, you can use smaller amount of storage to manage peak with nuckear and charge at night

Why charge the storage with expensive nuclear when you could charge it with cheap renewables?

The missing competitor is natural gas, which is good at peak demand, and not very good at carbon emissions

Ultimately the rare high price peaks can be shaved with green hydrogen instead of natural gas. Hydrogen can be stored underground, with a cost per unit of energy storage capacity of about $1/kWh, some two orders of magnitude cheaper than batteries. Round trip efficiency sucks, but that's not important for rarely used storage.

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