Earlier quoted context omitted.
When I said Scando I meant Finland. So, mountains are out of the question! Also tidal races. OTOH there's mines, but oddly enough I've seen no discussion in the media of using them. So.. there's no simple land/geographic features worth exploiting. OTOH some storable liquid/gas is more realistic. There's also sand batteries - Helsinki city has one - but they're maybe not so easy to do residentially/DIY, I would expect…
I figured there'd be issues - see peer reply: https://news.ycombinator.com/item?id=42001934
Methanol eh ?