[RyanPringnitz]

Hydro storage is gaining popularity. During the day, with over-provisioned daytime production, they pump water to higher elevation ponds. At night they let it flow down to the lower elevation ponds.

These could still freeze and stop becoming viable sources of energy, but they are a non-lithium source for energy storage. If they could be kept warm enough to flow in these conditions, they could provide generous storage capacity.

[mlyle]

Yup, but most pumped hydro is relatively short term power storage, too.

You really want something like power->gas->power to help fill in on the worst couple weeks per year.