Techno-economic analysis of energy storage systems using reversible fuel cells and rechargeable batteries in green buildings

Green and energy-efficient buildings have gained wider acceptance in the last few years due to their ability to save energy and, in certain cases, the ability to generate electricity using rooftop photovoltaic solar cells or other renewable energy sources. One of the major challenges for these buildings is having economic energy storage systems (ESS) that can reduce the effect of electricity curtailment. This paper proposes a techno-economic model that evaluates and compares three ESS technologies linked to a stand-alone photovoltaic system, namely lithium-ion (Li-ion) batteries (LIB), proton-exchange membranes reversible fuel cells (PEM RFC), and reversible solid oxide cells (RSOC). The model accounts for the degradation of the considered systems while evaluating their economics using the Levelized Cost of Energy Storage (LCOS) metric. The capabilities of the model are illustrated using a case study of a typical commercial building located in Los Angeles, California. The resulting LCOS levels without considering degradation are 41.73 ¢/kWh for PEM RFC, 28.18¢/kWh for RSOC, and 25.85¢/kWh for LIB. On the other hand, while considering the degradation the resulting LCOS at the end of the first year are 41.79 ¢/kWh for PEM RFC, 28.29¢/kWh for RSOC, and 27.35¢/kWh for LIB. Sensitivity analyses show that the LCOS of three considered ESS is sensitive to changes in capital costs, lifetime, discount rate, and round-trip efficiency. Moreover, the changes along the polarization curve show the most efficient configuration (highest efficiency and lowest LCOS) for PEM RFC. The study shows how Li-ion batteries and fuel cells are economically attractive and help improve the reliability and resiliency of power grids in the long term although they are prone to degradation.