Quantifying the emissions impact of repurposed electric vehicle battery packs in residential settings

Abstract

The market share of plug-in electric vehicles (PEVs) is growing, thanks to improvements in battery efficiency, declining production costs, and sustained policy support. Concurrently, concerns are growing over the supply of decommissioned PEV batteries. This has attracted a growing interest among scientists to determine the utility of repurposing PEV batteries for energy storage. Previous work has optimized behind-the-meter (BTM) battery storage systems (BSSs) for self-sufficiency and energy arbitrage, but few have used the system to lessen a home's electricity-related carbon footprint. This study uses high-resolution 2018 electricity demand from energy-efficient homes in Austin, Texas and grid generation data to simulate the daily operations of a 6 kWh BTM-BSS to minimize daily CO2e emissions. Results suggest that such homes with rooftop solar can reduce electricity-related household CO2eemissions by 21%, on average (about 1 ton of CO2e annually), while homes without solar could reduce their CO2e emissions by just 2% (about 0.12 tons per year). Pairing a BSS with rooftop solar increases average annual carbon savings by greater energy retention and lessening demand from the grid during carbon-intense generation periods. To make BTM-BSSs cost-effective for Austin homeowners, the price of repurposed PEV batteries must fall to $5.71/kWh or per-ton carbon pricing must rise to $70.34 for homeowners to reach break-even over an estimated 10-year BSS lifespan.