Evaluating the cost and carbon footprint of second-life electric vehicle batteries in residential and utility-level applications.

The volume of end-of-life automotive batteries is increasing rapidly as a result of growing electric vehicle adoption. Most automotive lithium-ion batteries (LIBs) are recycled but could be repurposed as second-life batteries (SLBs) since they have 70-80% residual capacity, which can be adequate for stationary applications. SLBs have been proposed as potential, inexpensive, low-carbon energy storage for residential and utility-level applications, with or without photovoltaics (PV). However, it is unknown whether SLBs will be better than new batteries and whether SLBs will provide similar cost and carbon emission reduction for the different stationary applications in all locations. This work compared the levelized cost of electricity and life-cycle carbon emissions associated with using SLBs and new LIBs in the US for three energy storage applications: (1) residential energy storage with rooftop PV, (2) utility-level PV firming, and (3) utility-level peak-shaving, leading to a total of 41 scenarios. SLBs reduced the levelized cost of electricity by 12-57% and carbon emissions by 7-31% compared to new LIBs in the considered applications, with higher reductions for utility-level applications. SLBs still provided benefits at the residential level when compared to rooftop PV alone by reducing the levelized cost by 15-25% and carbon emissions by 22-51%, making SLBs attractive to residential consumers as well. SLBs offer an opportunity to utilize an end-of-life product for energy storage applications, provided the uncertainty in SLB quality and availability is addressed.