Investigating the impact of wind-solar complementarities on energy storage requirement and the corresponding supply reliability criteria

This paper explores various questions regarding very high penetration of intermittent renewable to electricity grid. The study was performed using one-year hourly demand data of California's electricity grid together with the hourly-simulated output of various solar and wind technologies distributed throughout the state. The result shows that wind-solar complementarities carry significant multidimensional benefits to the future grid as compared to a stand-alone wind/solar based grid. Specifically at 20% total energy loss, it was shown that their optimal complementarities lead to very high renewable penetration with smaller storage and backup requirement. Our study of system dispatch shows that storage provides flexible dispatch strategy, which makes it applicable for various services depending on season of the year including reduction of summer backup capacity need. We have also found that the existing peak load based long term planning reserve criteria may no longer be applicable to very high renewable grid. Finally, comparing our result to literature data, we conclude that some of the pessimistic views of storage technology are borne out of our lack of understanding about its role and design requirement.