The biggest battery we could reliably pull energy from is the earths core it can provide geothermal while been regulated by flow rate.
Its very early days in such projects with deep depths but to me logically its the answer to clean energy thats going to have good life span and serviceability no need for battery back ups and masses of hard to obtain metals and such.
But from what i can see in uk is theres large investment in solar thats to big to fail now it simply won't be allowed the corruption is large and when a choice is made there's little going back when money dictates.
Solar generation is going to be the asbestos of the future its useless in reality the amount of over capacity needed is insane makes wind turbines look a good idea and the fact storage is needed just amplifys the cost down the line.
And what do we build battery back ups from ? A cell that was designed for portability ffs face palm it's lazy engineering on one hand we developed nuclear reactors that take best part of a decade to get up an running looking at hinckley point but we also then deaign and install battery backup on same grid thats not really fit for purpose and burst into flames giving munitions for the naysayers to jump on we need an electrical isambard kingdom brunel to grab the reigns of the system and shake its core becuase its lost it ways of grand gesture and delivers little impressive but it's corruption.
Aberthaw coal power station as been payed to be demolished twice by uk tax payer and thats the fix for the situation after that a field of solar will be used on its grid connection when it has all the facilities and grid connections to be a test plant for much higher loads but instead for a few hours a day in summer it might get near its name plate rating, face palm the whole energy department of c02 hating idiots cant even see the cleanest solution plebs.