I’d love to see more innovation in mechanical storage.

Yep most of it is dams and moving water ATM. And while that is efficient. It takes way more space then the UK can spare.

There has been a lot of work using heat storage of late. As we develop more materials etc. I can see this becoming more common. Will always have more loss then gravity. But is much more practice to multi use the land. And build on smaller scale. It is popular in factory situations where heat is often the energy needed. Generate during the day from solar or wind store in huge heat absorbing blocks and release on the night shift.

But use of land is the main problem with all natural renewables. Except maybe tidal. But even that has negative effects on land use. Wind turbines need space beyond the structure. While much can still be farmed. Farming land is also where they are best situated. Due to lack of nearby structures. Solar is a huge land hog. And moving it into our cities. Should happen but to be effective takes a complete redesign,

But the fact that a single car park structure exists that doesn't have the roof covered. Show how little effort has been pushed. Open land car parks should do more. But effect on others light will be an issue. But if you own a building that just parks cars on the roof. It is insane that nothing has motivated you to build out solar over the last 40 years of climate change acceptance.