Re: Sub-sea nukes
Yes, I remember that. But if you checked out how demand was being satisfied you would have seen the Norwegian interconnector peaking out on delivering hydro power and the French with mostly nuclear. The Dutch wasn't doing much because wind was presumably not contributing much there either. Oh, and stored power in that Welsh lake plus hydro was also maxing out.
Hence there is already non-fossil stuff around to bridge some of the gap. OK if we quadruple wind power that means under the same conditions it would only deliver 10% of demand directly. On the other hand when the wind blows it could easily produce surplus demand - around 200% of demand alone. Right now we don't have the infrastructure to balance out the surpluses and famines sufficiently. Hence there are times now when wind blows hard we can't use 100% of capacity.
Building that infrastructure is a massive technological challenge but may be easier and cheaper the trying to clean fossil power co2 emissions. An example using the surplus to generate green hydrogen that could be briefly stored and burnt at modified gas turbine stations is a major opportunity to use some of the most efficent CCGT fleet in future. Using last night's surplus to satisfy tonight's evening peak.
There is also intelligent demand management to keep the lights on at all times but allowing your fridge to skip an hour cooling to flatten the peak without noticeably affecting you, except reducing your cost of buying peak power.
There are no magic bullets, just a clever combination of sources (including nuclear), that with imagination can be balanced to approach a non-fossil fuel future. If we have to keep a few mothballed CCGT plants for exceptional still winter evenings so be it - then we might still be looking at 90% less fossil over the year than a decade ago.
Getting the last 10% or so of completely pure renewables will be very difficult verging on the impossible.We, or our children will see, but that shouldn't stop us going for the 90% in our lifetimes.