Reimagining renewable electricity grid management with dispatchable generation to stabilize energy storage

Abstract

With the expansion of intermittent renewable energy sources, and the development of economical and scalable energy storage technologies, the management of the electrical grid has the potential to fundamentally change. Under the current grid management paradigm, balancing and stabilizing a grid with a large penetration of intermittent renewables tends to require that those balancing resources ramp power output up and down more rapidly and more frequently to compensate for output variations of intermittent resources, as well as those of load. This paper describes a strategy of combined wind, solar, and in-stream tidal intermittent generation with energy storage. The new control strategy operates dispatchable generation with the objective of keeping the energy storage at a neutral state of charge in preparation for unpredicted upcoming imbalances between intermittent generation output and system load, while limiting power ramp rates within an acceptable envelope. A case study in Nova Scotia, Canada is examined. The model reveals that approximately 4 h of storage is sufficient to permit up to 70% intermittent generation contribution to the grid at a cost about 50% higher than that of the least cost renewable generation alone.