Recommendation 9

A range of energy storage technologies will be needed for different energy system services. We are concerned that the excessive policy and investment focus on lithium-ion storage projects has left policymakers, investors and regulators less able to appreciate the need for longer-duration technologies. There is a clear distinction between technologies which perform best across hours and for daily variations (“medium-duration energy storage”), and technologies which can store energy across days, weeks and months (“long-duration energy storage”), which a definition of long-duration energy storage as anything greater than six hours may not capture.