The repurposing of nickel metal hydride hybrid electric vehicle batteries for solar energy storage applications in rural Pacific Island communities

With the transportation sector taking a significant proportion of global emissions, the production of hybrid electric vehicles has been increasing. These vehicles have begun to penetrate emerging economies that do not have battery recycling programs seen in developed economies. In Fiji, there are an estimated 15,000 spent Toyota Prius nickel metal hydride batteries in landfills that have a substantial environmental footprint that can be repurposed for off-grid rural solar applications. Using a sample of 62 used Prius modules, constant current tests were performed to characterize the modules and were sorted to develop packs suitable to deliver one day of the World Bank’s Tier 2 electricity access. The packs can deliver the daily required 15.4Ah of power for rural households in Fiji and maintained Coulombic efficiencies between 85-95 percent. To pilot these systems, algorithms for a solar charge controller need to be developed using parameters determined in this study. Additionally, electrochemical impedance spectroscopy measurements should be made to create relationships between impedance, capacity, and state of health that will reduce the testing time to characterize modules. Utilizing these methodologies, a product life extension model can be implemented to reduce the batteries’ environmental impact while providing cost-effective rural energy access.