The dramatic increase in electric vehicle (EV) sales has led to a rapid increase in deployed lithium-ion battery (LIB) capacity over the last decade. As EV batteries age and are retired from use in vehicles, they will require management. Second-life applications are often proposed as an environmentally and economically preferable management strategy to direct recycling or disposal. In particular, the repurposing of EV LIBs in stationary applications is expected to provide cost-effective solutions for utility-scale energy storage applications. However, the adoption of second-life battery energy storage systems (BESS) has been slow. One barrier to adoption is the lack of meaningful cost estimates of second-life BESS. Thus, this study develops a model for estimating the Levelized Cost of Storage (LCOS) for second-life BESS and develops a harmonized approach to compare second-life BESS and new BESS. This harmonized LCOS methodology predicts second-life BESS costs at 234-278 ($/MWh) for a 15-year project period, costlier than the harmonized results for a new BESS at 211 ($/MWh). Despite having a higher LCOS, the upfront costs for second-life BESS are 64.3-78.9% of new systems' costs. Results for second-life BESS are highly sensitive to assumptions of discount rate, depth of discharge, and module repurposing costs. If deemed environmentally or societally beneficial, policies should stimulate the use of second-life LIBs, such as providing incentives equal to or greater than those available for first life BESS. Further work can explore comparative economics at smaller scales and quantify non-economic benefits of second-life BESS.
