alt Hacker News> Nobody wants to hold 30-80 year debt on giant capital projects that could be rendered obsolete.
There isn't really an "obsolete" after it comes online because things get built when expected revenue exceeds construction costs + operating costs, but once built (or close enough to completion) they continue to operate as long as revenue exceeds only operating costs because by then the construction cost is in the past. When the construction cost is large, the amount the price of electricity would have to decline to fall below operating costs is equally large. And investing in something where you expected a positive ROI and you ended up with a slightly negative ROI clearly isn't what you'd have preferred, but it isn't nearly as bad as the -100% ROI you'd get from shutting down the plant instead of selling it for slightly less than what you put in. There's a reason the US is not only continuing to operate 20th century nuclear plants but even looking to reactivate some of the ones that have already been decommissioned.
Moreover, solar has the same problem. You invest in a solar farm because you're expecting to profitably sell power at current prices, but if e.g. the AI thing turns out to be a bubble then there will be oversupply and current prices won't stick. Solar also has the added "everybody is doing it" risk. If you and everybody else add solar then the price at times when solar output is highest is going to be lowest and vice versa, i.e. if too many people invest in the same type of generation then your output gets inversely correlated with the market price, which is bad for ROI.
I think you’re misunderstanding the economics at a fairly basic level. The cost to build is funded through debt that’s paid off over time. The construction costs aren’t in the past; they’re in the present, and in the future, in the form of debt payments.
Think of it this way: if you buy a house, the “operating cost” is fairly small: upkeep and painting, mostly. Does that mean you can buy a house, move out of your apartment, and quit your job, because your cost of living has just dropped a few thousand a month?
No, of course not. Upkeep isn’t the real cost of buying a house. The real cost is the monthly mortgage payment. Unless you were already independently wealthy, you have to keep your job. Sorry.
The cost of energy for a nuclear plant is the cost of paying back the loans. As other forms of power generation get cheaper, those loans stay the same, making it harder and harder for nuclear to compete. As they get squeezed out of the energy market, they have to raise their per-watt prices in order to continuing to service the loans.
Think of it like this. You rent your house to your cousin, who pays you enough to cover the mortgage. But then your cousin finds a sweet deal couch-surfing in the tropics in the summer. He stops paying you for June, July, and August. You can’t get anybody else in your house during that time, so you say, “Sorry dude, you have to pay more for the rest of the year. I’ve got bills to pay.” That works great until your cousin gets tired of your high prices and moves out, and now you’re left with a mortgage to pay and no one renting it.