[defrost]

> This is in the Netherlands. It's kind of sad to see all that electricity unused in summer,

This is literally what local and state government is for; talk to others and get policy moving on excess energy being used to generate bulk stored energy at scale for winter months, be that gas, deep thermal storage, tradable goods to offset winter costs, etc.

[euroderf]

Doesn't anyone smelt their own bauxite anymore ? sigh

[defrost]

Ammonia products are easier, particularly with excess peak energy.

Yes, we still have six active bauxite mines providing feedstock for six alumina refineries ... they're optimal as pipelined processing and not great at switching on|off with energy surges.

[euroderf]

I wonder if ammonia might be doable at residential/DIY scale. Then you have to (a) store it safely, and (b) have a way to use it - not many people have a personal marine application.

[defrost]

Maybe .. but in an urban area with many houses, each with solar panels, it seems inefficient to have mini home chemical process factories, particularly with intermediate steps involving explosive gases.

I'm in favour of home PV and community batteries | larger area "peak" use industries - it's a sensible long term use of cyclic energy production.

[euroderf]

To further follow up... outside of the cities, Finland has a LOT of lightly populated land, and since EU entry, farming is not exactly going great guns. Land is cleared.

So AFAICT mass PV is a distinct possibility, and if it can be leveraged to reduce the cost of wintertime energy usage, it will find a firm foothold.

[euroderf]

My use case is Scandinavia. The summer has an absurd oversupply of sunlight (weather permitting). Capturing this for winter usage is the poser.

[defrost]

The obvious (but often incorrect) thought is gravitational potential given mountains.

What are the challenges to incline rail lifting a lot of material up a mountain to roll down later?

Water freezes, slopes with snow can be unstable, cold weather is hard on gears, etc.

Large (in old mine shafts and chambers?) thermal mass storage has potential, not dissimilar to "heavy" (not suitable for EV) recent battery technologies.

Are there any serious tidal races in Scandy lands that can be tapped?

It's a poser alright.

[woleium]

electrolysis of water to hydrogen and oxygen seems sensible. could be done at home, but probably best at community scale