The question is whether the round-trip inefficiency of storing energy is greater than the cost of having energy-consuming equipment that sits idle when the sun isn't shining and gets stopped and started frequently.

For example, aluminum production is famously energy-intensive, but I've read it's not good for the equipment to start and stop it frequently because the reaction happens in molten aluminum salts and it hurts the equipment when you stop and it solidifies.

And while Bitcoin is energy-intensive, it's also capital intensive for the chips so it's not cost-effective to run it only part-time.

Reverse osmosis may have a good combination of high energy:capital ratio (so it doesn't waste a lot of capital on idle equipment) and not requiring complex startup/shutdown sequences.