Research from MIT scientists finds that repurposing used electric vehicle (EV) batteries to store electricity generated by large scale solar plants holds promising potential.
The team claims that even if the batteries have declined to 80% of their original capacity, it could still offer a more viable business case for grid-scale solar power in California than purpose-built systems. As a bonus, the used EV batteries are likely to cost 60% of their purchase price.
Ian Mathews, the co-author of the study, agreed that there are technical hurdles involved with the deployment of second-hand EV batteries on a large scale, including collecting batteries from manufacturers and checking which devices could be reused. Even so, Mathews firmly believes that used EV batteries still offer a strong business case that justifies the cost of recovering them, screening, and deploying them.
To estimate battery degradation, the scientists used a semi-empirical model and concluded that by operating these storage devices at 15-65% of full charge could extend their next life. “This finding challenges some earlier assumptions that running the batteries at maximum capacity initially would provide the most value,” the team noted.
According to Mathews, the feasibility of used EV battery storage would likely depend on the rate-setting and regulatory regimes under which they would function. “For example, some local rules allow the cost of storage systems to be included in the overall cost of new renewable energy supply, for rate-setting purposes, and others do not,” he added.
Additionally, the study notes that control algorithms can be modified during projects to extend the lifetime of such solar facilities. The scientists also point out that more studies are needed to assess the potential of these kinds of systems.
Mathews said:
We think this could be a great application for machine-learning methods. Trying to figure out the kind of intelligent methods and predictive analytics that adjust those control policies over the life of the project.
The MIT study was funded by the European Union’s Horizon 2020 research program, which runs until 2022, along with the Singapore National Research Foundation and the Quantum Sustainable Solar Technologies engineering research center.
