A study by the Massachusetts Institute of Technology (MIT) has shown that used electric vehicle batteries can be used to store electricity produced by large solar power plants.
The U.S.-based researchers claim that even if the equipment's capacity has been reduced to 80 percent of its initial capacity, it offers better investment prospects than dedicated utility-grade batteries in California solar+storage projects, especially since the price of such "used" EV batteries is only 60 percent of their purchase price.
Ian Mathews, co-author of the MIT study, acknowledges that there are still technical hurdles to large-scale deployment of used EV batteries, such as how to aggregate batteries from different manufacturers, and screening which devices can be reused. Yet Mathews insists that used EV batteries can still achieve a compelling business case sufficient to recover the cost of recycling batteries, screening performance and redeployment.
Optimal operation
The researchers used semi-empirical models (including some preformed calculations) to estimate battery degradation and concluded that running such aggregate energy storage devices at 15-65% of total power would extend their second life. The scientists said, "This finding overturns some previous assumptions that running the batteries at maximum capacity right out of the gate would provide the most value."
Mathews said the viability of used electric vehicle battery storage will depend on the regulatory and tariff-setting mechanisms by which it operates. He suggests, "For example, some local regulations allow the cost of energy storage systems to be factored into the total cost of new renewable energy supply for tariff calculations, while others do not."
Algorithm
The scholar added that long-term pilot studies are needed to assess the potential of such systems.
The MIT researchers noted that control algorithms could be modified over the life of the project to extend the viability of such facilities, Mathews said, adding, "We think this could be a good application of machine learning methods to try to figure out smart ways to adjust control strategies and predictive analytics over the life of the project."
Mathews added that successful repurposing of EV batteries for grid-level energy storage will also require collaborative support from EV manufacturers, energy storage companies, solar project developers and power electronics experts.
The MIT research project is supported by the European Union's Horizon 2020 research program, the U.S. Department of Energy and the National Science Foundation's Quantum The Quantum Sustainable Solar Technologies (QSST) Engineering Research Center, funded by the U.S. Department of Energy and the National Science Foundation, and the Singapore National Research Foundation through the Singapore-MIT Alliance for Research and Technology. MIT Alliance for Research and Technology).
The Bern University of Applied Sciences in Switzerland is also researching ways to reuse old solar modules and electric vehicle batteries. The Horizon 2020 project will run until 2022.
