But, batteries are much more expensive than shipping crates and also wear out with the sort of usage cycles that this sort of tech requires by design.

I was hearing recently about a similar energy startup that was based on cooling air to liquids as a power soak and then shunting that back through turbines to re-extract the power. Similarly less efficient than batteries for power density, but also longer lifed and much cheaper.

Who knows what the best solution is? Not me, I haven't studied physics since I was 16. But I'm glad people who are better equipped than me to find out are investigating, and I look forward to the day when we can use this sort of tech to provide the smoothing effect on renewable power sources rather than relying on burning fossil fuels.