There are no guarantees in life, only probabilities. People much smarter than us can determine how much spare capacity the EU needs from non-intermittent source

There are no guarantees in life, only probabilities. People much smarter than us can determine how much spare capacity the EU needs from non-intermittent sources to make electric blackouts a 500-year event, just like they do with building standards related to earthquakes. I don't know what the number is, but it's probably greater than 0 and definitely less than the total peak EU demand, and if I had to guess I would say it's probably closer to 20%.