Amory B. Lovins, Cofounder and Chief Scientist, Rocky Mountain Institute

Impressive battery progress has led many to think bulk electrical storage necessary for largely or wholly renewable electricity supply. Cheap electrical storage would be very useful but isn’t necessary. As www.rmi.org/storage_necessity_myth_amory_lovins explains, four European countries with modest or no hydropower now get half their electricity from renewables, with no added bulk storage but superior reliability, by choreographing existing resources. Even the isolated Texas (ERCOT) grid can be 100% renewable with no bulk storage and good economics. This requires integration of some or all of six grid-flexibility resources cheaper than bulk storage or fossil-fueled backup: (1) end-use efficiency, (2) accurate forecasting of variable renewables (PV and wind), (3) flexible loads, (4) a portfolio of variable renewables diversified by type and location, (5) integrating dispatchable renewables and must-run CHP, and (6) integrating distributed thermal or electrical storage bought anyway for other reasons, such as ice-storage air conditioning and smart electric vehicle charging/discharging. Only after exhausting these lower-cost resources would one need bulk storage or fossil backup. The emerging evidence increaisngly suggests that a well-designed and -operated renewable-based grid may need less storage and backup than utilities have already installed to manage the intermittence of their large thermal power stations.