What happens to electric car batteries after they die? With almost no electric cars on the road older than four or five years, a large-scale infrastructure for battery recycling or second-life recovery hasn’t been established for long. Companies are looking to the future, though. BNEF (Bloomberg New Energy Finance) senior analyst Claire Curry compiled a report about new lives for used EV batteries, and showed that EV batteries may be able to be used for low-cost energy storage sooner than expected.
The report projects that there will be 29 GWh of used EV batteries coming out of cars in 2025, enabling the size of the current stationary storage market to grow.
Almost one third of these batteries will be used as stationary energy storage for homes or communities.
These could cost as little as $49/kWh in 2018, or $400/kWh to convert to stationary, compared to today’s stationary storage systems, which cost up to $1,000/kWh
BMW, Nissan, and Mercedes Benz also have plans in place for second-life stationary storage. Nissan partnered with a startup, Green Charge Networks, and 4R Energy Corporation in June 2015 to turn used lithium-ion batteries from the Nissan Leaf into stationary commercial energy storage.
BMW i introduced a stationary energy storage system in June 2016 that uses i3 batteries. It can use either the new high-voltage batteries which are also manufactured for the cars, or second-life batteries once they are introduced into the market.
Daimler established a group to manage commercial stationary storage in June 2016, in partnership with other energy providers and a solar energy specialist group. GM is using Chevrolet Volt batteries and a solar array to power the General Motors Enterprise Data Center in Michigan.
Curry says that the predicted cost of stationary storage systems made from second life batteries is predicated on the industry scaling up. The availability of batteries isn’t the only concern: transport may also be expensive, she said, because presumably the batteries will still be classified as toxic or some sort of waste and require special handling. Batteries will need to be designed for their second life, with standardized performance and standardized shapes.
Half of the cost could be shaved off if a company utilized a big, completely automated plant with low transportation cost, she said.
For example, Tesla is known for its closed-loop system. Instead of partnering with a storage company, they have already put out feelers in the area of home storage with the Powerwall and the acquisition of SolarCity, although these utilize new batteries, not used ones.
However, the only EV batteries Tesla could conceivably put back into this ecosystem at present would be Roadster batteries, Curry said, which are high in valuable cobalt. Tesla has several partnerships in place in order to recycle those batteries, including with the Kinsbursky Brothers battery recovery company in the United States and Umicore in Europe.
However, Tesla itself is nervous about the prospect of second life, CTO JB Straubel said in August. Second life stationary storage would be too costly and would be fighting against the degrading quality of the batteries, he said. He suggests that ‘smart charging,’ in which electricity could be sent from an electric car back into the grid at optimal hours, is definitely on the way. However, he said, it isn’t “a very economic or viable solution.”
Because batteries do degrade, stationary storage might be an uphill battle.
In 2015 the National Renewable Energy Laboratory ran a study which concluded that automotive batteries could live for ten or more years in second use service. The biggest factor in determining how much value can be gotten out of a second-life battery was temperature or climate. Therefore, the report said, it is important to make sure that the temperature sensors, as well as the batteries themselves, will survive and be effective in a second life.
Their conclusion was that second use batteries could be a viable source of energy – but only if the economic factors fall into place, and if onboard diagnostics data is used effectively and accurately.