On a barren field in Lancaster, California, where the temperature often tops 100 degrees Fahrenheit in summer, sit eight white boxes that might be a key to a greener future. Each 10 x 22-foot rectangle holds 20 battery packs that once powered Nissan Leafs. But they’ve lost some of their juice. Inside a car, they can no longer power speedy accelerations, and their 85-mile ranges have been reduced to about 55 miles.
But the batteries still work. Research suggests they may retain two-thirds or more of their original capacity. So for the past 18 months, these batteries have been living a second act: storing energy from nearby rows of solar panels. Their owner, B2U Storage Solutions, wants to know how effectively, and for how long, they can do that.
B2U sprung up in 2019 to solve a problem that doesn’t really exist yet. Automakers, spurred in some cases by government mandates, are frantically converting their fleets to run on electricity, rather than petroleum. By 2030, the International Energy Agency estimates that between 145 million and 230 million electric vehicles will be on the road, saving 120 metric tons of carbon emissions annually. But the batteries inside those vehicles will be heavy, expensive, toxic, and sometimes fire-prone. What will happen to them when they can no longer power a car? How to keep them from hurting people, or the environment?
Some researchers and entrepreneurs are working hard on ways to recycle the materials inside batteries. They hope batteries will become part of what’s called a “circular economy”—that energy and value will be wrung out of every natural resource and material.
Others say, yes, let’s do that. But we should also look at reusing batteries that have already been built. Recycling a battery, after all, takes energy and releases emissions of its own. The heavy battery pack has to travel somewhere and be taken apart and then ground down, via water or chemical processes, to its raw materials. Those materials then travel somewhere else—often overseas—to be remade into something new. “Making a battery back from recycled material is more energy-intensive than just using a battery that is already out there,” says Ahmad Pesaran, chief energy storage engineer for a National Renewable Energy Laboratory center that focuses on transportation. Instead, why not do something useful with that old battery?
Automakers are by and large not yet focused on that possibility. General Motors, Toyota, BMW, Nissan, and others have experimented with using retired batteries around their manufacturing or vehicle charging facilities but are still firmly in the demonstration phase. Figuring out second lives for batteries is “not a next step that takes a long period of development,” Ford chief operating officer Lisa Drake told reporters last month.
But entrepreneurs have plenty of ideas. Already, used car batteries have been tapped to power streetlights in a Japanese town, chill beer at convenience stores, and move elevators. Modules and cells from old batteries power household appliances and bicycles. A spokesperson for the automaker Stellantis says it plans to use retired EV batteries to power motorized wheelchairs.
But many experts say “spent” EV batteries would be best used to store energy, where research suggests they could support power grids for up to 12 years. They could reduce the power costs for offices or homes by supplying it during peak periods, when utilities charge the most for electricity. They could provide back-up power for places that really shouldn't lose it, such as hospitals, eldercare facilities, and grocery stores, and places that don’t want to, like soccer stadiums. They could supplement renewable energy sources like solar and wind, storing energy when the sun is shining and the wind is blowing for moments when they’re not.
By 2030, retired EV batteries could provide 200 gigawatt-hours of energy storage globally each year, according to analysis from the consulting firm McKinsey—roughly 50 times the annual output of the Hoover Dam. B2U wants to be a part of that.
Reusing old electric car batteries is a topic of much academic excitement, supported in the US by grants from agencies like the Department of Energy and the California Energy Commission. But to many in the industry, reuse still feels like a fantastical science experiment, one that might end up in the dustbin of fabulous ideas that didn’t quite work out.
One question: Who owns the reused batteries, and who’s responsible if something goes wrong? Automakers know they may be blamed if one of their old batteries is involved in a fire. GM recently recalled every Chevrolet Bolt because flawed batteries made by the Korean company LG Chem led to fires. “It’s legally a bit of a gray area,” says Pesaran, the NREL engineer. “And with lawyers—they can argue anything.”
There are technical issues, too. Before you can reuse an EV battery, you have to know how much juice it retains and whether it’s worthy of a second life. “Evaluating the health of batteries is pretty essential to understanding whether it has value,” says Andy Latham, an electric vehicle salvage consultant at Salvage Wire.
That’s not as simple as it sounds. Battery makers and automakers regularly change the cell chemistry and architecture of their batteries, making it hard to develop a standard process. Moreover, batteries coming out of service today are likely damaged from crashes, or have some manufacturing defect. Even finding old batteries to test can be a challenge. Chris Mi, an engineering professor who studies lithium-ion batteries at San Diego State University, talks to salvage yard operators and automakers. Other teams start on Google.
ReJoule, a startup based in southern Los Angeles County amid strip malls and rocking oil derricks, wants to streamline that process. Its prototype is a lightweight, desktop computer-sized device that can diagnose in less than five minutes, and as little as 30 seconds, whether a battery is suitable for a second life. Today, the process can take hours and requires machines that can be heavier than the battery packs they’re diagnosing. ReJoule plans a second machine, the size of a dorm room fridge, to diagnose a battery pack before it’s even taken out of a car. Its tech relies on electrochemical impedance spectroscopy, which uses an alternating current scanned over many frequencies to measure the health of the materials inside a battery cell. Eventually, the company would like to see its software embedded in new batteries so they can be monitored through their stressful lives on the road. It would also like help from regulations, or at least industry standards to make the job easier.
For now, though, ReJoule’s engineers have to get inside the batteries. Battery packs are sealed with industrial glues and aren’t built to be disassembled. Years of hard service on bumpy roads can warp their screws and bolts. So it can take ReJoule’s engineers hours just to pry one open. Once inside, lots can go wrong. One graphic reminder: a switch called a contactor that is firmly welded to a metal tool. It’s not supposed to be. The contactor fell across the tool while an engineer was setting up a test, and “there were, you know, some fireworks,” says Steven Chung, ReJoule’s CEO, who founded the company with his sister Zora. ReJoule keeps the thing around to remind everyone to stick to the safety rules.
Another looming question is whether old EV batteries are a reliable way to store energy for the grid. That’s why the old Nissan Leaf batteries are out in that field in Lancaster. One fear is that those batteries—or certain kinds of batteries—will work for just a few years before degrading rapidly. Utilities won’t want batteries they have to swap out often. B2U president and cofounder Freeman Hall says his company wants to prove the long-term value to energy experts and investors. If B2U can show that old lithium-ion batteries can charge and discharge many times while sitting out in the hot sun and the strong wind for years and still do good work, “it changes everything” in terms of the company’s ability to raise money, Hall says.
B2U’s Lancaster project looks promising. The company says its solar panels generate up to 1.65 megawatts of power, while its retired Nissan Leaf batteries can retain 10 megawatt-hours of storage—about as much as the average US home uses in a year. Freeman says the company is profitable, and planning expansions. The state organization that manages California’s grid can, in moments of peak electricity demand, pay $80 or more for a megawatt-hour of electricity, while the company says it costs between $20 and $30 per megawatt-hour to charge its batteries. It’s classic arbitrage: Store electricity when it’s cheap, when the sun is shining, and discharge it for a higher price when it isn’t. Soon, the company says, it will also be able to charge its batteries directly from the grid.
But it’s getting tougher to exploit the potential of reused batteries as battery makers find cheaper ways to make their products. A recent McKinsey analysis estimated that used EV batteries may be only 25 percent cheaper than new ones by 2040. Factor in the costs of transporting 1,000-pound battery packs, and the economics of battery reuse begin to look dicey. If battery storage turns out to be a great business, why not use new batteries to do it? Entrepreneurs have to show that reuse beats sending a battery off to be recycled.
“We're hoping that we will be able to prove that you would have a significant cost savings by using second life batteries, in addition to sustainability benefits,” says Kevin Wood, a colleague of Mi at San Diego State. The two electrical engineers hope to launch their own reuse demonstration project in the San Diego area next year to provide backup power in case of a blackout.
These researchers have time, but not too much. An entire infrastructure around electric vehicles is sliding into place. Once the systems and rules are established, they’ll be difficult to undo. Ask the ReJoule team. Zora Chung, the company’s cofounder and CFO, points to an oil derrick lodged in the startup’s parking lot. The company’s landlord has complained bitterly to the city about it. The thing is, after all, pretty ugly. But it’s complicated, and expensive, to move. Of course it’s a metaphor. The systems we build today will be around for a while.