Extending the useful life of EV batteries mitigates the impact of manufacturing them, said Maria Chavez, energy analyst at the Union of Concerned Scientists.

“The whole point of trying to deploy electric vehicles is to reduce emissions and reduce the negative impacts of things like manufacturing and extractive processes on our environment and our communities,” Chavez told Grist. “By extending the life of a battery, we reduce the need for further exploitation of our natural resources, we reduce the demand for raw materials, and we generally encourage a more sustainable process.”

Just as batteries have become crucial to reducing emissions from transportation, they’re also needed to fully realize the benefits of clean energy. Without stationary storage, wind and solar power can only feed the grid when the wind is blowing or the sun is shining.

“Being able to store it and use it when it’s most needed is a really important way to meet our energy needs,” Chavez said.

The use of utility-scale battery storage is expected to skyrocket, from 1.5 gigawatts of capacity in 2020 to 30 gigawatts by 2025. EV packs could provide a stockpile for that buildout. Hall said there are already at least 3 gigawatt-hours of decommissioned EV packs sitting around in the United States that could be deployed, and that the volume of them being removed from cars is doubling every two years.

“We’re going from a trickle when we started four years ago to a flood of batteries that are coming,” he said.

B2U says its technology allows batteries to be repurposed in a nearly “plug-and-play fashion.” They do not need to be disassembled, and units from multiple manufacturers—B2U has tested batteries from Honda, Nissan, Tesla, GM, and Ford—can be used in one system.

The packs are stored in large cabinets and managed with proprietary software, which monitors their safety and discharges and charges each battery based on its capacity. The batteries charge during the day from both the solar panels and the grid. Then B2U sells that power to utilities at night, when demand and prices are much higher.

Hall said using second-life batteries earns the same financial return as new grid-scale batteries at half the initial cost, and that for now, repurposing the packs is more lucrative for automakers than sending them straight to recyclers. Until the recycling industry grows, it’s still quite expensive to recycle them. By selling or leasing retired packs to a grid storage company, said Hall, manufacturers can squeeze more value out of them.

That could even help drive down the cost of electric vehicles, he added. “The actual cost of leasing a battery on wheels should go down if the full value of the battery is enhanced and reused,” he said. “Everybody wins when we do reuse in a smart fashion.”

B2U expects to add storage to a third solar facility near Palmdale next year. The facilities are meant to prove that the idea works, after which B2U plans to sell its hardware and software to other storage-project developers.

At the moment, though, planned deployment of the technology is limited. B2U predicts only about 6 percent of decommissioned EV batteries in the US will be used for grid-scale storage by 2027.

“People are skeptical, and they should be, because it’s hard to do reuse of batteries,” said Hall. “But we’ve got a robust data set that does prove reliability, performance, and profitability. We’re at a point where we really can scale this.”