Comment by jdlshore
5 hours ago
Okay, let’s say that we use solar + battery to cover everything but Nov, Dec, Jan, when the days are too short. Solar is cheaper than nuclear the rest of the time, so (due to the way energy markets work) we pay solar producers the cost of nuclear generation, creating strong incentive to build out more solar + battery.
So we end up using nuclear 1/4 of the time. But unfortunately, nuclear’s cost is in the capital expense, not the operating expense. We pay about the same amount for it regardless of whether we’re using it or not. So if we’re only using 1/4 the energy, the cost per watt of nuclear energy is effectively 4x larger.
This incentivizes further build-out of solar, catching those sweet winter profits (now 4x larger!), further squeezing nuclear’s usage, driving up its prices, and incentivizing even more solar.
Eventually nuclear gets squeezed out and solar’s profit margins go from “astronomical” (naturally, it’s power from the sun, nyuck nyuck) to “low margin.” But they’re still making money. Whoever built the nuclear plant is left with a very expensive stranded asset.
At least, that’s my understanding. I’m not a power company accountant. What I observe, though, is that power companies who do employ accountants aren’t building nuclear. They’re building shit-tons of solar. And I’m pretty sure it’s not because they’re hippies who hate nuclear.
> Solar is cheaper than nuclear the rest of the time, so (due to the way energy markets work) we pay solar producers the cost of nuclear generation, creating strong incentive to build out more solar + battery.
The way energy markets work is that prices change based on supply and demand. So you build a lot of solar and then the price goes down at times when solar generation is high. (There isn't really enough solar in the grid for this to have happened yet in most places.)
Because nuclear has high capital costs but low unit costs, it continues generating all the time even if prices are lower some of the time. It needs to hit a particular average price but will take essentially any instantaneous price. It can't operate with an average price of $0.02/kWh but it can sell for that at noon in July as long as it's getting enough to offset it at midnight in December.
So, you add a bunch of solar to the grid and as a result the price of electricity during daylight hours in the summer falls below the average breakeven cost for solar. Nuclear is still getting more than that at night, when the price won't fall below the daytime price plus the cost of storage, and in the winter, when solar output is lower and heating demand is higher.
Because it's still recovering a lot of its costs on summer nights and even a little bit on summer days, the winter price nuclear needs never gets to be 4x as high, but it goes up some.
Now the solar companies are looking at that price and trying to decide whether it's worth getting. If they add more solar it's going to generate e.g. 4kW in summer, 2kW in spring, 2kW in fall and 1kW in winter. So for every 9kWh they generate, only 1kWh comes in winter, and that's during the day.
Suppose solar needs to average $0.04/kWh to be sustainable but we're already at $0.02/kWh in the spring, summer and fall. Then solar needs the price during the day in winter to be at least $0.20/kWh before wanting to add more. On top of that, if they do add more, then the price during other seasons drops. If those hit $0.01/kWh during the day then solar needs the price during the day in winter to be $0.28/kWh. And, of course, then the price in the other seasons would drop again, until solar would need to have $0.36/kWh in the winter because by then they would only be getting paid in the winter. Whereas nuclear still makes some in the summer at night.
On top of this the demand is higher in the winter at night, but it's not higher in the summer at night. So to use solar with storage, you would also have to amortize the cost of the additional storage during only the winter months. And the winter nights have more hours than the days, don't forget. So for solar to supply all power in the winter it needs the daytime price to be $0.36/kWh and the nighttime price to be more than twice that.
Then solar is intermittent. People still need heat when it's cloudy. Overbuilding solar sufficiently to handle the heating load on a cold cloudy day in winter? Nope. Hopeless. You'd have to use long-term storage in addition to short-term storage and that's a whole new category of expensive when we were already looking at prices nobody was going to like.
So what happens instead? Well, probably the daytime price in the non-winter months gets to something like $0.02/kWh and the daytime price in the winter gets to something like $0.20/kWh and you fall below the breakeven point for building more solar. Then nuclear takes the same $0.02 and $0.20 during the day and something more than that at night and continues to cover its costs.
Really the problem here is not that solar is going to push out nuclear in the winter, it's that natural gas could unless you have a price on CO2. Or more likely, without a carbon price people might not switch to electric heat instead of continuing to heat with natural gas and fuel oil.
So we kind of need a carbon price to do heating. Or to solve it from the other side (which would be even better), we need to get nuclear to be more cost efficient so it can out-compete natural gas since solar won't.
Hey, just wanted to say thanks for your comment. I'm usually very apprehensive against nuclear (still kind of am) but I think one of my main points against was that "base load" (i.e. inflexible generation) would be bad in countries with high intermittent generation.
But I guess the whole calculation of 100% renewables is overprovision+storage. This wouldn't change with nuclear in the mix, nuclear would just generate all the time at whatever price it can get, just bringing the point of overprovision for renewables closer.
Then in countries in more extreme latitudes the calculation of if nuclear is worth it just becomes how cheap and viable the (long and short-term) storage part will get over the lifetime of a new nuclear reactor.
If storage gets so cheap that a nuclear reactor would be consistently in the red, even in the depths of winter, then it wouldn't make sense to build one today.
But I haven't done any calculations on that yet. For example for the Netherlands or Germany which still have a high reliance on gas but a large portion of solar+wind, how expensive nuclear could be for it to make sense to build a new reactor. And under which scenarios of development of storage prices it would potentially seize to make sense.