Towards Circular Economy : Technoeconomic assessment of second-life EV batteries for energy storage applications in public buildings

Sammanfattning: With the accelerated tendency of renewable energy penetration in the electricity grid, energy storage becomes a crucial asset for matching generation and demand. The growth of energy storage systems requires adequate new policies and regulatory frameworks. The battery value chain also requests for new ways of end-of-life management since battery recycling is not a viable single option yet. This is where circular economy offers different solutions and alternatives for prolonging the battery life and reducing the negative impact. This study analyses the technoeconomic feasibility of giving electric-vehicle (EV) batteries a second life as stationary energy storage systems in buildings with integrated on-site renewable energy production, such as for instance PV panels. Four different scenarios have been considered, including the refurbishment of the battery or its direct reuse, taking into account the degradation of capacity and thus, the amortisation price; against the possible load shifting benefit and the reduction of contracted grid power for the building. Results show that, effectively, the reuse of batteries for stationary energy storage is economically justified but may not be worth only in self-consumption applications, that is, for prosumers with some little renewable generation installed on site. The simulations reveal less than 2% relative energy cost savings on annual basis and up to 25% savings related to reduction of grid-contracted peak power, for the chosen case study of a mid-size office building. Second-life battery applications are still dependent on the development of tools for estimating and monitoring the battery’s state of health and potential performance in the new setting, for the technology to succeed. The increasing interest and necessity for circular economy together with the high volume of EV batteries expected to be released on the second-hand market, not suitable for automotive purposes anymore but reasonably applicable for stationary energy storage, will place this topic in the spotlight in the near future.