Intermittent renewables are making less than 5% of our primary energy today. At scale, the intermittency problem becomes significant because you have to build all this storage. The energy required to build the storage reduces the total Energy Return on Investment below what is necessary to sustain industrialized civilization. Nuclear EROI is about 50:1, well into the safe range.

https://www.sciencedirect.com/science/article/pii/S2211467X1...