by rstuart4133 | 2025-06-01 02:26:43+00:00
> Why on earth would you run a nuclear power plant as a peaker? That’s inefficient and wasteful. You run a nuclear power plant at full tilt, all the time. Then you divy up any excess demand to other sources of power.

When solar is producing, it's at a faction of the cost of nuclear. So when you say "you run it a full tilt", who is going to voluntarily pay the nuclear price for power when it costs far more?

You see that play out in countries with lots of solar now. Where I live the wholesale price goes negative most days [0]. I think driver behind this is coal makes it's money overnight, but can't ramp down quickly. Consequently when the sun comes up they have to dump power onto the grid while ramping down, forcing the other suppliers (solar, wind) off. The coal generators end up paying for the privilege of doing that. It's even worse than it seems because by the time that dumped power arrives at the consumers, it's had transmission and other changes added to it - which means the consumer is still paying something for it. Therefore any consumer that has solar doesn't take it, which reduces the market still further. That mechanism has sent a number of coal generators into early retirement here.

Nuclears ramping is worse than coals, so if the invisible market forces are left to operate freely, if the are going to have to pay someone for the privilege of running full tilt as you suggest. That can only work if governments artificially subsidise the price, or force consumers to pay more.

It is getting worse for coal here as batteries get cheaper. Coal makes most of it's money between 4PM and 9PM - which is both peak consumption and there is no solar. So they charge like a wounded bull. But batteries have halved in price over the last 5 years or so, and 5kWh battery will get you through that high price period. Because the price is so high, the battery prices have just crossed the line - it's now break even to install a small battery. In a couple of years, it will become a "no brainer". And with that coal will lose it's major market.

I have no idea what the end game is. May the price coal charges for 9PM .. 8AM goes through the roof - but that will just make a 20kWh battery cost effective. So then what? Does coal shut down completely? How does that work for industries that need a lot of power overnight? I don't know - maybe it becomes cost effective to build pumped storage at that point. I know for me personally coal shutting down won't not matter. We have a 25kWh battery (and once V2G becomes a thing we will have a gob smacking 150kWh of storage for the house), we have over provisioned solar that means even on dim days we make enough power to get by is we are careful.

I have no idea what happens for everyone else - but I'm pretty sure whatever it is, it won't be nuclear. It's too expensive, and too inflexible. So inflexible the nation with most pumped storage per unit generation was ... Japan. Because it used mostly nuclear, can't even ramp well enough to cope with the day / night transition.

[0] Download a month from here to see negative prices in the RRP column: https://aemo.com.au/energy-systems/electricity/national-elec...