2021 was the year clean energy finally faced its mining problem(theverge.com)
theverge.com
2021 was the year clean energy finally faced its mining problem
https://www.theverge.com/22858437/2021-mining-critical-minerals-clean-energy-renewables-climate-change
Mechanical storage - i.e. pushing loaded freight cars up a hill while the sun is shining and letting their weight pull a chain which turns a crank (like a cuckoo clock) when it's dark out - is not all that common right now, but not completely unheard of. It could grow in popularity as we develop more clever techniques that are more space efficient. Either way, it's only meant to highlight the differences in mechanisms for energy capture (e.g. solar panel, wind turbine) vs energy storage (e.g. batteries).
This article seems to be primarily around materials for energy storage.