[Retric]

>What do you call viable?

Something that might happen Aka Reasonably competitive with alternatives.

It’s physically possible to build infrastructure allowing 100’s of GW of solar electricity to move from Africa to South America across a single grid. But, there’s noway that is actually going to happen as it would be a horrific waste of resources vs local storage even ignoring political problems etc.

The same thing is true of Nuclear. There’s no way you’re going to see anything close to a 100% nuclear grid when adding hydro, batteries, wind, and or solar would drastically lower costs.

However, once you accept people aren’t going to do something that stupid you need to consider what mix of generation and storage is cheapest and how far from that we’re willing to go. That same logic is why nobody is every going to build days worth of battery storage, it’s simply cheaper to have extra capacity that mostly sits unused than extra storage.

[pyrale]

> adding hydro, batteries, wind, and or solar would drastically lower costs.

What does "drastically" means? Fine tuning of the grid doesn't require hydro specifically, batteries are not actually used in any meaningful way in countries currently using nuclear, and the projected savings of having such tech aren't transformative: the intraday difference between peak use and low use in a typical winter day in France are about 20-25% [1]. Sure, shaving 25% off your bill is great, but typically it's significantly less than the difference in price between different European countries.

As for wind and solar, it doesn't really lower costs of nuclear as there's no correlation (wind) or a negative correlation (solar) with peak winter hours.

[1]:

[Retric]

First for 100% nuclear you need to compare the difference between peak demand across decades + reserve capacity on top of that or you get brownouts when even just one power plant goes offline unexpectedly. The number you want to find is approximately 115% of the maximum demand in a single year, and now you need to build enough nuclear power plants to hit that or you’ll see brownouts. (I’m not looking for the highest demand for the year but in France Monday January 2 high 59GW, last week the low was 30 GW and the high 54 GW.) https://www.rte-france.com/en/eco2mix/electricity-consumptio...

Further, there are multiple kinds of nuclear power plants and different ways of operating them, if you want load following you pay a premium that increases as you need to ramp up and down ever faster, and another premium for increased thermal stress etc.

As to wind and solar, you don’t need to match peak production and demand when the energy is so cheap. The goal is cost optimization, if you “waste” 95% of the output from a solar farm over a year but that saves you a few million over doing something else then you build that farm. Further, the cheapest grid includes lots of hydro which is extremely flexible and some batteries. Wind and Solar alone aren’t that dependable but add even just 10% hydro to the mix and the economics look wildly different.

To be fair the economics also dramatically better for 90% nuclear 10% hydro vs 100% nuclear alone.

[pyrale]

> last week the low was 30 GW and the high 54 GW.

Summer numbers are irrelevant, because winter power draw is much higher.

> I’m not looking for the highest demand for the year but in France Monday January 2 high 59GW

Typical year might see 80GW in the winter. The record is north of 100GW, but that's something for which a country will import, restart decomissioned thermal plants and/or curb industrial consumers.

> Further, there are multiple kinds of nuclear power plants and different ways of operating them, if you want load following you pay a premium that increases as you need to ramp up and down ever faster, and another premium for increased thermal stress etc.

Yes, that's part of the issue. My point was, the constraint for storage is an economic optimization constraint. It's not in the same category as "tomorrow there's no wind so there's no power".

> As to wind and solar

I know the theory, my point is that wind/solar don't synergize with nuclear. There's a reason renewables proponents bash so hard against the baseload concept. If your renewables don't produce during peak hour, you have to build capacity ; that necessary capacity will see its load factor deteriorated because it then has to give way to renewables when they come online. The only way this is profitable is if you profit from not spending fuel - i.e. if your plants would have used gas.