> Because energy storage is currently not a problem, and consequently not profitable.

All the big pumped storage in the UK is owned by for-profit companies.

Are they making the big money from running school tours? Maybe the gift shop? I don't think so.

In the UK they can buy 1.5GWh of electricity for say £75000 on a windy Sunday night and then sell say 1.2GWh (pumped storage is maybe 80% efficient) for £200000 on Monday afternoon. That's a £125 000 profit in under a day. And this wouldn't be their best case it's just a pretty good day although there are always worse days because doing this well involves predicting weather and other factors so as to judge when to buy and sell.

They're not going to become the next Apple doing this, but it's a healthy business.