Liquid Air Batteries. Literally energy from thin air. Seriously. Literally!
Energy storage from thin air sounds a bit too good to be true, but the beauty of this potentially transformational technology is the simplicity of a design that utilises tried and tested components that have been reimagined and re-engineered to perform a vital function for electricity grids, now and in the future.
Research links: https://youtu.be/tMLu9Dtw9yI