Techno-economic analysis of a flywheel energy storage system performing a dynamic frequency response service

Frequency response services are an increasingly essential service to the stability of the UK electrical distribution system. Due to this, it is a prime target for deployment of energy storage systems. This market is currently dominated by conventional Battery Energy Storage Systems (BESSs) due to their maturity as a technology and favorable technical characteristics. Flywheel Energy Storage Systems (FESSs) are not commonly deployed for this service due to their generally high power/energy ratio and traditionally high manufacturing costs, however, the ongoing development of new FESSs with a wide range of technical characteristics and reduced costs presents an opportunity for re-evaluation. Here we show the results of a techno-economic study that identifies an appropriate target power/energy ratio range and necessary target cost (£/kW) for a FESS to be a viable option for providing frequency response services. The study subsequently discusses the techno-economic effects of hybridization of the system with BESS technology providing the framework for further analysis. The results of this study provide potential flywheel manufacturers with the information necessary to develop commercial systems for this application.