Maybe they could convert it to petroleum and store it in the ground.
You can do exactly this power to gas tech is already being used in the EU. AUDI is making synthetic natural gas and running cars on it.
You can turn surplus wind or solar to SNG and inject it into a storage cavern or plan has well to store it for another day.
https://www.powermag.com/why-power-to-gas-may-flourish-in-a-renewables-heavy-world/
As soon as electrolysis machines cross under $400 kw in capx off peak H2 is cheaper than gas from the ground. Add in carbon tax and it’s already cheaper in the EU in windy or sunny places.