As they say pumped power has been around for a long time. I think like most people with a good idea, they are overselling it, otherwise why all the cost of offshore wind if on shore pumped storage can carry all the burden and so easily?
What worries me is that I have yet to see any coherent plans about exactly how much more power generation we will need, to make our country hydrocarbon emission free and what form it should take. Currently we are becoming too dependent on renewables whose production rate is out of our control, if the wind isn't blowing, wind turbines cannot not generate electricity, no matter how high demand.. At any time the amount of our power from wind and solar can be as little as 5% of total demand or as much as a third. It jsut depends on the wind.
I would like to see a government plan, or one from a respected think tank showing how demand for power is going to grow, how it can be contained (a countrywide building insulation scheme running like the natural gas conversion scheme of the 1960s-70s for example), where the power will come from and how it can be robust enough to cope with demand 24/7/365.
Electric cars are all the fashion, but a lorry with a battery big enough to travel any distance is going to have no space to carry goods and battery technology is unlikely to solve that problem. There has been a problem with high power lithium phone batteries exploding and catching fire.
The solution to that is possibly the use of liquid hydrogen as a transport fuel, as a by-product of wind turbines producing excess power. But we hear very little about this.
The problem is we keep hearing all these aspirational demands and targets for emission free power production, but no nitty gritty detail to back it up.