Turning air into a cryogenic liquid could store energy generated by intermittent renewables

Batteries and hydrogen fuel cells have a new competitor, says the Institute of Mechanical Engineers: Air from which water vapor and CO2 have been removed, which is then cooled to -190C. The resulting liquid, mostly nitrogen, is stored in a vacuum flask until energy is needed, at which point it’s allowed to come to room temperature, in the process driving a turbine to produce energy.