Relying on only renewables and long distance transmissions introduces significant geopolitical risks and fragility.
It would be, let's say, less than ideal if Europe were dependent on North Africa for their energy security.
In practical terms this would mean that large countries would feel the need to establish military control over critical energy production areas.
Energy security is no laughing matter in the Nordics. In the winter, without power, people die.
Even if the political and operational risks are acceptable, building long distance transmission is no simple matter. Everybody knows that more transmission lines are needed between Norway, Sweden and Finland, but regardless no real progress has been made. Heck, Sweden can't even manage to connect their north and south regions!
The vagaries of weather and the requirement for redundancy would require significant over-investment in generation capacity and long distance transmission networks.
Looking at averages in weather and wind is also very myopic. Power generation is instantaneous, so you have to look at sustainable base load. But the question is, can wind sustain any kind of base load since it is so variable?
On Saturday wind production was down to 53 MW in Finland, less than 2% of peak production. And that wasn't even the lowest this month. What are you going to do, build 100x more wind power? And even if you do, you are only producing less than 20% of total power required to power the country, so it's more like you need 500x more wind power.
Since you cannot do base load with wind power, nuclear is off the table, what are you going to do? Hydro power?
You cannot run off hydro power for days or weeks since the generation capacity just isn't there. For the Nordics, Denmark has no hydro, Finland only has about 20% of generation capacity and Sweden has about 45%. Norway is the only country that can run off hydro and Iceland is a very far away.
This means you are back to peaker plants. Say bye-bye to zero carbon emissions.
So all this brings us back to the questions, are renewables really a realistic and cost effective option compared to nuclear?