CO2 Battery 20 MW / 200 MWh Latrobe Valley (SEC)

A 20 MW / 200 MWh CO2 Battery planned at SEC's innovation precinct in Victoria's Latrobe Valley, giving 10 hours of discharge, which Energy Dome says will be the longest-duration grid battery in the state. The plant charges by drawing CO2 from an atmospheric gasholder (the Dome) and storing it as a liquid under pressure at ambient temperature; it discharges by evaporating the CO2 and expanding it through a turbine back into the Dome. As a rotating machine it also provides mechanical inertia and grid services. Energy Dome quotes a net AC-AC round-trip efficiency of 70% or more and 30+ years of life without capacity degradation.