long-duration energy storage

A battery that runs on CO2 - But is it efficient ?

Storing a full day of clean power is the missing piece of a wind-and-solar grid — and lithium gets expensive past a few hours. Energy Dome's answer skips lithium entirely: it banks power by squeezing carbon dioxide into a liquid. Now a US utility and Google are putting money behind it.

The Signal — A battery of iron and air could be clean energy's missing piece

Cheap storage that lasts days, not hours, is the part that finally lets a grid run on sun and wind — plus five more signals from the frontier.