Levelised cost of storage comparison of energy storage systems for use in primary response application

The intermittent nature of renewable energy sources brings about fluctuations in both voltage and frequency on the power network. Energy storage systems have been utilised to mitigate these disturbances hence ensuring system flexibility and stability. Amongst others, a novel linear electric machine-based gravity energy storage system (LEM-GESS) has recently been proposed. This paper presents an economic analysis of the LEM-GESS and existing energy storage systems used in primary response. A 10 MWh storage capacity is analysed for all systems. The levelised cost of storage (LCOS) method has been used to evaluate the cost of stored electrical energy. The LCOS of the LEM-GESS was compared to that of the flywheel, lead-acid battery, lithium-ion battery and vanadium-redox flow battery. The results show that the LEM-GESS has great potential as a cost-competitive technology for primary response grid support, with several distinct advantages. The LEM-GESS is about 26% more cost-effective than the currently competitive flywheel energy storage technology. Further, a sensitivity analysis highlights that the LCOS of the LEM-GESS is sensitive to capital expenditure, efficiency, discount rate and discharge duration.