> given current pricing for storage

https://ourworldindata.org/battery-price-decline

Complement: V2G will be a key, here.
https://en.wikipedia.org/wiki/Vehicle-to-grid

Many other ways to store will emerge as complements?

> Denmark's current wind power productin already relies on Sweden and Norway to store surplus production in hydro plants.

Such efficient use of available resources is one of the (already actively pursued) benefits of a large grid.

Fully-nuclearized France is nowadays very happy to benefit from Germany's electricity: https://twitter.com/HolzheuStefan/status/1529874075220381696

> this storage capacity will reach its limit

This depends heavily on the efficiency of many parameters, mainly: spreading unit out, mix, other vectors (hydrogen), curtailing, backup.

> the electricity trade is becoming extremely unpopular

A global price raise then ratchet is very probable, and maybe already triggered. Fossil fuels are very convenient and cheap, but the good'ole days are over.

> Such storage is not available for the larger Europen countries, such as Germany

Germany already does it with Switzerland. Some nations need more storage (and other indeed already have too much of it). Storage characteristics (volume, min/max discharge rate, term...) are more and more clear

>> we know how to compensate for most of intermittency by spreading out (at continental scale) production units and using a mix (wind, solar...)

> As far as I can tell, the development has been in the opposite direction. More trade has led to greater fluctuations

Prices fluctuations? I petition that it is an effect of the transition towards renewable sources (from the relative comfort and stable logistics of fossil fuels) more than a problem intrinsic to renewables. Competing markets will cope.

Grid stability is up (by impressive margins) everywhere.

> since many countries produce too little for their own consumption

> Denmark imports 17% of their consumption

Denmark officially targets 84% electricity wind by 2035.

> If this continues, it is highly likely that the Norwegian (and possibly Swedish) governments is forced to withdraw from such cooperation due to public outrage

This is mainly a financial matter. A 'cooperation' achieved thru a market lets some buy production surpluses on the spot market at a bargain, store them then sell with a profit wipes out such outrage. This is already the case for the Germany-Switzerland deal, and a natural way for such deals: surplus is cheap, needed energy isn't. It will boost storage projects and innovation, adjusting the market.

> the only way to reach 100% non-carbon-based power

There is no way, each and every type of source emits and needs combustible fuel backup. The next goal is to transition to reach approximately 10% (max) of such backup, just like France's production fleet does for decades.

> is for consumers to be able to buy it at prices

Yes, a very low LCOE offers financial provisions for the infrastructure (grid, storage...). Renewable sources' LCOE is low and falls sharply. Nuclear-produced electricity cost, on the other hand, is way higher and raises. Surprises (real building costs, waste management, decommission, accident...) may further extend the gap.

> need to add a lot of storage capacity, at least several days

A continental mix reduces this need.

> that this will become realistic around 2050, possibly a bit sooner.

The current (awful) nuclear-building capacity needs a miracle to adjust, restart and gain significant and reinsuring successes before 2050. Even France best hope is to start more than 3 new reactors by 2040.

> levelized costs for nuclear may, for countries able to do it as efficiently as Korea and China, already be there.

China? Not really. There is some opacity, but established facts aren't keen for nuclear projects. 2 to (rarely) 6 new reactors per year. At least some are problematic. Their pair of EPR (Taishan), for example: 5 years late, 60% overbudget, and out of 2 reactors one is stopped since mid-2021 after an incident, and the other one works at low capacity in order to avoid problems.

This trend is old and clear: nuclear produces 6% of China's electricity with 50GW nominal electric power, long-term plans for future capacity are 120 to 150 GW by 2030 ( https://en.wikipedia.org/wiki/Nuclear_power_in_China ) while China already has 253GW solar and 281GW wind (plan for combined solar and wind: 1,200 gigawatts by 2030) ( https://en.wikipedia.org/wiki/Solar_power_in_China , https://en.wikipedia.org/wiki/Wind_power_in_China ). In 2020 alone China added 71.6 GW windpower... Even taking into account the load factors (nuclear may reach .9 while wind-solar combined are at .3 to .5, mainly depending on the proportion of off-shore wind turbine power) this seems quite clear to me.

Korea was somewhat efficient while building the Barakah plant (in the United Arab Emirates), however it is not fully started (then time will tell if it runs well), and maybe thanks to some now known dirty tricks https://en.wikipedia.org/wiki/South_Korean_nuclear_scandal
The last Korean president was against nuclear and practically froze it in Korea.

> If there is enough focus on building affordable nuclear

There is focus. What nuclear needs is successes.

> Europe would be able to shift a significant percentage of its energy production over to emission-free production

Nuclear isn't emission free (building, obtaining the fuel, waste management, decommission... aren't emission-free).
https://en.wikipedia.org/wiki/Life-cycle_greenhouse_gas_emis...

> An ideal mix for the total EU area
> 50% nuclear

This seems impossible, at least if we hope for real progress towards an adequate energetic system by 2050.

See https://ourworldindata.org/grapher/elec-mix-bar?time=latest&...

Year 2000: 27% nuclear / 19%
2022: 23% / 35%

There are 106 active nuclear reactors in Europe, producing 23% of its electricity. Therefore to produce 40% of it we need to build approx 80 new reactors. Theoretically a bit less, as more recent types are more powerful, however we have to account for replacements (many existing ones are quite old). Who really hopes to build ~80 new reactors in Europe before 2100?

In any case who will build them?

Even France, historically nuclear's king, tries hard to build but: 27/19 (2000) to 23/35 (now)

French Areva NP is dead. Its successor EDF, with its hands full thanks to 2 projects (a disaster at Flamanville and a difficult one at Hinkley Point C)?

Westinghouse filled for Chapter 11 ( https://en.wikipedia.org/wiki/Westinghouse_Electric_Company ) and Toshiba recently sold it to BBP ( https://en.wikipedia.org/wiki/Brookfield_Business_Partners ): not sure which european nation would order anything from them(?)

GE Hitachi is fleeing the European market after the Horizon debacle ( https://en.wikipedia.org/wiki/Horizon_Nuclear_Power ), and probably busy for quite a while in Canada (Ontario, BWRX-300) because they never worked together, while GE is being divided after a major loss of revenue ( https://en.wikipedia.org/wiki/General_Electric ).

KEPCO (Korea) may be interested in deals, but some european nations may not be enthusiastic.

Another potential candidate is Rosatom, but which European nation is willing to sign with Russia, especially after its inept move in Ukraine?

China? Maybe, albeit reserves are probably even higher than towards Korea: their recent efforts towards UK weren't well-received nor conclusive, and they are busy obtaining mediocre results at home.

Canada may be able to propose but didn't build for quite a time, has its specific architecture (CANDU) and now prefers to target a SMR.

SMRs may be an option, but at best in 2030 (Rolls-Royce's announces it), and with the usual "let's someone else suffer with the first project then wait to be quite sure" will add latency. Moreover SMRs amplify the NIMBY effect.

Who/what else?

We more and more know how to build 'renewables', and less and less know how to build nuclear.