[rsj_hn]

> Nuclear as baseload remains very useful. What's more, we don't just seek to replace current capacity but also to quickly increase generation.

The problem is that Nuclear may not be economical if it is only used when both solar and wind run out. Nuclear has large fixed costs. And almost zero marginal costs. So the average costs -- what needs to be charged in order to avoid bankruptcy, increase as you use it less.

That means every solar panel you add makes the nuclear power a bit more expensive. And that incentivizes adding more solar. Up until you drive the nuclear out of business, and then suddenly you don't have reliable power anymore.

Then you are faced with a situation of

a) only having nuclear power which can provide for all of your needs, in which case adding solar is an unnecessary expense

b) only having solar+wind and an unreliable grid, which means you need to add batteries to cover solar+wind. And the price of those batteries may be more than the price of the nuclear plant.

c) having nuclear and solar both, with enough subsidies given to the nuclear plant to keep it in business so that the total solution is more costly than just going with nuclear.

So yeah, there really is a tension between nuclear and solar.

This is not the situation, however, with solar and coal. Because coal plants are damn cheap, and they have higher marginal costs. Thus solar can coexist with coal or with gas much better than with nuclear.

Therefore the economics is such that as people promote solar the result is a decrease in nuclear and an increase in coal and gas.

[Retric]

Your model is overly simplified. Nuclear runs into the exact same issues in the other direction as you try to scale it to take over more of the grid. Frances nuclear reactors where at 70% capacity factors vs 90% in the US even with France exporting and importing vast amounts of electricity with the rest of Europe. It’s really not Nuclear vs Solar it’s simply Nuclear’s high cost and thus inflexibility that’s at issue.

Current electricity demand is heavily biased to daytime use even with cheap nighttime prices causing people to shift demand to use that. Start to ramp up solar to the point where daytime demand is higher and a great deal of nighttime demand drops off.

Grid storage isn’t cheap enough to store energy at current nighttime rates, but it’s cheap enough to have a balanced grid backed by hydro, wind, and solar even with zero fossil fuels. The tipping point to cheap daytime rates and expensive nighttime rates isn’t inherently better or worse, it just reflecting the future economic reality.

[rsj_hn]

> Your model is overly simplified.

You are correct that my model is simplified. I ignore the issue that demand isn't really stable, and you need some peaker plants.

The problem is that Solar isn't really a good solution for peaker plants, because those need to be reliable. So I don't think this simplification undermines the tradeoffs I was describing, although I agree that in the space of peaker plants, there can be some combination of solar and gas to handle peaks when it is sunny and also when it is not sunny. Just be prepared that you need enough gas and coal to cover all the generating capacity you are getting from solar and wind, which is again very expensive.

> grid backed by hydro, wind, and solar even with zero fossil fuels

This requires a lot of hydro, more than most nations have together with really punitive electric rates when there is an absence of wind or solar. I mean, massively punitive rates, because demand for electricity is highly price inelastic. So be prepared for rates to go up 10x or 20x or even 100x when there is a stretch of windless days with weak sun. I think there is a reason why no nation has gone this route except oddballs like Iceland with their reliable geothermal.

[Retric]

Solar is the economic equivalent of base load power in that it’s cheap, and doesn’t follow the demand curve. Batteries then fill the role of peaking power plants as long as they can be filled cheaply. How you get from there to a balanced grid isn’t to have exactly as much generation on average as you need. Instead you install about twice as much as you need on average because it’s just that cheap vs any other source that even half of all generated solar is wasted it’s still cheaper than any other alternative.

At that point you are still going to get multiple day stretches where wind and solar only cover ~1/2 of daily demand but hydro can make up the difference on such occasions even if it’s only supplying 6.6% of annual US demand. Basically you get 1-2% hydro on most days and on 5% of days you a lot of energy stored.

As to high costs, because of the excess solar you’re generally filling batteries with nearly free electricity. Average nighttime wholesale prices therefore end up at ~10c/kWh or whatever the battery storage costs settle on, but daytime rates when most demand actually takes place are going to tank. That’s a net reduction in average prices. Trying to make a grid from Nuclear + batteries on the other hand means your paying Nuclear prices at night, but nuclear + battery prices in the daytime which is the opposite of what you want. Nuclear + fossil fuels on the other hand simply doesn’t go far enough.

Now in a mostly solar world a very low percentage of electricity may end up generated by fossil fuels, but a 99.X% solution is success by any reasonable metric.

PS: As a sanity check you can look at what people are paying when their off grid and then realize that’s very much a worst case.