How does this fit in with that renewable energy ( wind and or sun is unreliable - can be non of both types or one type for days at a time AND solar is only available for a 4-6 hours a day ) ) ? It seems massive storage is needed.
Not that massive. At a country scale, wind blows somewhere all the time. Overall you can get 30%+ utilisation per turbine. And newer projects only get it better (the higher you get, the more consistent the wind).
But it's not a surprise you'll need some storage. There's lots of research available with estimation for various areas.