The question of what to do with old electric vehicle (EV) batteries when the owner decides to upgrade to a newer higher capacity battery or at the end of the vehicle life cycle, typically at 5-8 years of age, has been exercising minds in the industry.
And it is more than academic. An April 2016 study for the German Renewable Energy Federation (Bundesverband Erneubare Energie e.V., BEE) projects a potential cumulative capacity availability of second use batteries of 230GWh by 2025 increasing by more than four times to 1,000GWh by 2030. This is based on a battery size of 40kWh, a repurpose rate of 80% and a replacement timescale of 7 years, together with Bloomberg Finance’s figures of 6.7 million EV cumulative sales by 2020 and 88 million by 2030.
BEE's projections for global cumulative sales of EV and second life batteries
EV battery reuse
Much of the focus to date has been on the reuse of batteries. For example, BMW has been piloting projects since as far back as 2009. The latest is the development of a 2MW/2.8MWh storage facility in the Hamburg Harbour district, which will be used to deliver reserve power for frequency control on the grid. [Engerati-Grid storage gives new life to old batteries]
Elsewhere in Germany, as around the world, there are other projects, including what is understood to be the world’s largest – a 13MWh facility in the final stages of development by Daimler AG, The Mobility House AG and GETEC in Lünen, which will also be used to deliver reserve control to the German grid.
With these projects, obviously a lot of experience is being gained in the repurposing and reuse of EV batteries. However, a key unknown at this stage is their likely lifetime in second use. A standard currently under development by Underwriters Laboratory with input from automakers, battery reclaimers, utility providers and academics is intended to assure the safety of batteries for second use. This will supplement the so far limited data on battery performance histories from battery management systems.
According to the BEE study, the current price of second use batteries, which includes their reconditioning, is around €150/kWh, or about half that of new battery packs. However, it also notes that not all batteries are suitable for reuse. For example, for the Tesla and Panasonic cells with their cylindrical and small size, the cost of reconditioning is prohibitive. More suited are the rectangular shaped batteries from LG Chem, for example.
EV battery recycling
The alternative to reuse is to recycle, which also comes with costs but also benefits in terms of the sale of the recycled materials and components.
According to Lux Research in a new report, recycling, rather than reuse, is likely to be the more attractive option for what they say is up to 65GWh of second-life EV batteries poised to enter the market in 2035 with the retirement of the first generation of plug-in vehicles. This is because the reuse of these batteries will deliver questionable returns on account of reduced performance, limiting them to application with less frequent and shallower depth of discharge cycles. For example, an oversized 11.2kWh residential system from second-life batteries will cost just over $4,600, compared with nearly $6,000 for a new 7kWh system. But reduced round-trip efficiency and cycle life make residential units and other daily cycling applications a poor fit compared to some others.
Lux Research's projections for annual global second life battery supply
“With present technology, recycling old batteries for new materials is the more economical option for creating the most value from existing materials,” says Christopher Robinson, Lux Research associate. However, he doesn’t rule out innovations in areas like packaging and testing that could tip the balance in the future, and suggests that companies should have plans for both recycling and reuse.
Comparisons between different projections are inevitable and difficult to unravel and for example in this case, the Lux Research projections appear more conservative than those in the BEE study (see above). Regardless, there is no doubt that a significant capacity of used EV batteries will become available and there is clearly place for both reuse and recycling. Ultimately, which dominates will depend on the economics and as long as recycled batteries are cheaper than new, there will likely be a market for them. However, with storage en route for €100/kWh by 2020, the recycling costs will also need to drop significantly to remain competitive.
The other big unknown at this stage is the disruptive potential of new battery technologies a decade and more hence. From the current perspective, lithium-sulphur (Li-S) technology is the most promising in terms of improvements in performance and reductions in costs with the potential to tip the scale in favour of recycling over reuse.