The alternative is fossil fuels in combination with wind/solar, the most cost effective grid that currently exist. During optimal weather conditions renewables are the cheapest energy on the planet, and during non-optimal weather conditions fossil fuels is usually the cheapest energy that can meet demand.
Living in Sweden, I am slightly hopeful that the nuclear plant in Finland might reduce the need to run the oil power plant located in southern parts of Sweden. The oil power plant is the single highest contributor for carbon emissions in the south of Sweden, despite the fact that Sweden mostly operate on hydro and nuclear. 70 tons of oil per hour goes up in smoke in a time where the oil need to stay in the ground. More solar/wind will not have much of an effect on this oil power plant since it only operates during non-optimal weather conditions. Currently we are several weeks in with a weather of low wind conditions, with energy prices skyrocketing as a result. The Finish project had some good luck in term of timing by turning on the nuclear power plant right in the middle of exceptional high energy prices.
And, as you mentioned, having fossil in reserve for edge cases is definitely a viable option.
Overcapacity has its issues. It does not remove the dependency on fossil fuel, and you still need to have independently the same capacity in fossil fuel plants. A big part of the fossil fuel cost in term of economics is have them standby and operational, which today is paid primarily through subsidies. Having a bunch of wind turbines running at 20% efficiency while at the same time paying a fossil fueled power plant be ready to step is not cheap. Is it _still_ cheaper than nuclear? Hard to say. All the comparisons I have seen are done on the theoretical cost per watt produced, not what the grid costs to operate on a year to year basis in order to provide the service of a stable grid.
Looking at the day prices per local zone around Sweden and Finland, the prices goes down the closer you get to hydro and nuclear and goes up the closer you get to wind and fossil fuels, with as high as 10x. Economically that makes the case for wind + fossil fuels a bit harder to buy, through I am not blind to the fact that its previous generations that enabled it. Living next to wind+fossil fuel is right now very expensive, with industries moving north as a direct result.
Wind can work but also partially has the same problem but to the same extent. Usually the colder it gets the less windy it gets. Basically in Finland during the winter it gets cold when there is no wind bringing warm air from the Atlantic (gulf stream) usually as a result of a high pressure zone parking itself over the country.
It does mean you depend on processes you have little say in. Somebody else specifies and builds much of the transmission line, and all of the generating capacity.
https://www.fingridlehti.fi/en/ja-kantaverkkokeskuksesta-soi... (this article is from summer about moving it the other way but the same happened now during the winter but other direction)
This is one of the reasons why the electricity prices hiked up as high as they did here. Basically Norway and Sweden do have some electricity available for cheaper then running reserve gas plants in Finland but they can't get that electricity from the south all the way up north.
And being that reliant on another nation is not good for the national safety of a country. Imagine if a significant portion (like lets say 30%) of the electricity used in US came from solar farms in Mexico (or even further south being transmitted through multiple countries). This would make US economy and national defense really vulnerable (both require massive amounts of energy to really function)
> "It does mean you depend on processes you have little say in. Somebody else specifies and builds much of the transmission line, and all of the generating capacity."
The fact that China, which is an absolute leader in nuclear power, wasn't able to scale up this energy source as fast as wind and (soon) solar (in terms of GWh delivered) and the planned 150 reactors will barely catch up with renewables speaks volumes.
I mean, it's a safe and environmentally friendly technology, but it just can't be built fast enough.
I see: <<The country ranks third in the world both in total nuclear power capacity installed and electricity generated>>
Can you please explain what you mean by <<The fact that China, which is an absolute leader in nuclear power...>>?
https://world-nuclear.org/information-library/current-and-fu...
By leadership I mean that they're one of the few countries which in the last 20 years managed to consistently deliver new nuclear capacity on time and (roughly) within budget.
The US generally ranks first, but delivered what, one power plant in the XXIth century so far?
And as if this was the only problem and it hadn't a lot of huge others, nuclear proponents will use this now as an example how nuclear is the way out of the climate crisis, and how comparing nuclear with renewables is wrong..
No, the best future would be neither fossil nor nuclear.
France's EDF takes more nuclear reactors offline after faults found - 2021-12-17
https://www.reuters.com/markets/europe/edf-extend-civaux-nuc...
Do you propose to build so many nuclear plants that you can provide peak electricity including heating in cold winter months? Do you have numbers for that? (I imagine that'd be the most expensive solution ever, as nuclear plants are high in capital costs and you're basically proposing to have lots of nuclear plants that only run on very cold winter days.)
I guess what many nuclear proponents seem to forget is that you need flexibility no matter what source of electricity you have - because even if your plant runs 24/7 (which it doesn't), energy needs aren't constant.
In Finland, the coldest weather is experienced when, during winter months, there is a persistent anticyclone parked overhead. Those can cover the entirety of the country, and inside them there is negligible wind. For example, on 8th of December it was -20°C, and the average output of wind power (nominal installed capacity ~2800MW) over the day was 330MW. The average output of grid-connected solar was <1MW (It's December in Finland, what did you expect?).
Anticyclones can remain in place overhead for weeks. The value often used to calculate the cost of renewable+storage is 3h. This is a reasonable value for California, where solar production correlates well with use. If you built the grid in Finland based on that, we would just die when it gets cold.
There are no renewables that work well in Finland. Water power is fully built out. Solar only produces power when we don't need it. Wind reliably does not provide power when we need it. Compared to renewable with enough storage, even with all it's overruns, OL3 is remarkably cheap.
Many current heating fuels are fossil and not great either, but they can be replaced with renewable fuels which solves storage vs renewable-produced electricity.
Next year, I think, they're building a storage not far from where I live with 200.000 m³ capacity.
For individual house heating it is some combination of pure electric, heat pump, wood and oil.
Gas in general is used very little for electricity here (only ~7% of total energy production) and gas cooking stuff is also relatively rare.
nuclear is the highest density of energy available to mankind. Refusing to using it is kind of a huge missed opportunity.