Here’s a fact you don’t often hear: electric cars are a tiny portion of the global market. “Tiny” here means 0.5 percent of all cars on the world’s roads. In absolute numbers, however, this “tiny” portion translates into millions of EVs, and this number is growing. But what do we do with all those batteries when they’re done with them?
The idea of giving EV batteries a second life rather than recycling them has been around for a while. The most obvious direction for this second life is energy storage. After all, this is what rechargeable batteries do: they store energy for when it is needed. And they need to be replaced in an EV long before they are completely exhausted. In fact, EV batteries are considered to be at the end of their productive life for a car when it falls to 80 percent of their original capacity, which is still plenty of capacity that could be repurposed.
Perhaps the first thing that springs to mind here would be behind-the-meter storage—the kind of storage system you can put in your house to reduce your reliance on the grid. But there is also another option: using EV batteries for utility-scale energy storage.
Researchers from the Massachusetts Institute of Technology recently published a study of the feasibility of a utility-scale solar farm combined with a storage system made from used EV batteries. What they found was that this could be a better choice than building a new energy storage system.
The study involved looking into three scenarios: building a 2.5-MW solar farm with no storage system, the same farm but with new storage, and the same farm with a storage system from reused EV batteries. Their findings showed that the energy storage system using EV batteries (at 80 percent of capacity) was the more cost-effective choice, assuming a solar farm with no energy storage is the least desirable option in general.
All this sounds great in a world that will soon generate a lot of “waste” EV batteries. But, as usual, there are caveats. First, the solar farm plus reused battery storage system scenario is economically viable only if the batteries cost less than 60 percent of their original price.
Then there is the issue of battery consistency, the researchers note.
When you build a battery storage system out of used batteries, you have to make sure they are all at the same stage of what scientists call battery degradation. But battery degradation depends on many factors, as one battery expert from the Union of Concerned Scientists pointed out in a recent article on battery second life.
“Repeated utilization of the maximum storage potential of the battery, rapid charge and discharge cycles, and exposure to high temperatures are all likely to reduce battery performance,” Hanjiro Ambrose wrote. And if you want to use such batteries for utility-scale storage, you would need to test them in advance to determine their level of degradation.
Indeed, the authors of the MIT study note this fact, too. Screening batteries and then combining batteries from different cars in an energy-storage system is challenging, not to mention expensive.
There is also the question of how long a reused battery energy storage system would last. According to the UCS’s Ambrose, they could last between five and eight years after they are retired from a car. According to the MIT team, this requires further studies--long-term studies. For now, the team is assuming that the batteries would be able to store and release energy on demand until they decline to 70 percent of capacity. One of the authors, Ian Mathews, noted that they could even continue to operate safely and productively at a capacity of 60 percent or even less. Carmakers are beginning to do tests to check this.
With such serious challenges, is it even worth considering the reuse of EV batteries as energy storage systems?
In California alone, there will be some 45,000 EV batteries retired from cars by 2027, according to Ambrose. This means about 1 GWh per year in energy storage capacity is just waiting to be used. The alternative to EV battery reuse is recycling, but this is also tough, and it is one of the factors that make EV batteries so expensive right now. In fact, if they are reused, Ambrose notes, batteries could become cheaper, in turn making EVs more affordable.
For all these battery issues, EV sales will only continue to increase in the coming years: by 2030, according to Wood Mackenzie, the market share of EVs among new car sales would rise from 3 percent in 2019 to 14 percent. Even the temporary slump in sales amid the coronavirus pandemic is unlikely to affect the long-term outlook for the industry much. And less than ten years later, there will be many gigawatt-hours of storage capacity ready to be reused at renewable power farms. So, it is certainly worth looking into utilizing this capacity rather than just recycling it for its component minerals.
By Irina Slav for Oilprice.com
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