Waymo and B2U Partner to Repurpose EV Batteries for Energy Storage

Thousands of electric vehicles in Waymo’s autonomous robotaxi fleet may eventually give up their used batteries for a very different purpose—contributing up to hundreds of megawatt-hours of stationary energy storage to local power grids.

That prospect comes from a “strategic supply agreement” announced by Waymo and B2U Storage Solutions on June 4. B2U has been repurposing thousands of used batteries from various electric vehicles by installing them in large stationary energy storage projects. Such energy storage facilities can capture excess renewable energy during low demand periods and release such energy when local power grids are experiencing peak demand periods.

“Our business is getting the full residual value out of electric vehicle batteries after they’re no longer suitable for automotive use,” Freeman Hall, CEO of B2U Storage Solution, told Ars. “Waymo puts a lot of miles on EVs and their model is expanding rapidly, and so we’re just very pleased and honored to be able to work with them.”

The agreement would allow B2U to repurpose Waymo batteries that become available at the end of a vehicle’s lifespan, along with obtaining used batteries that are being swapped out from operational vehicles. Waymo’s “proactive maintenance” for its autonomous vehicles includes identifying opportunities to “refresh the battery to improve efficiency overall for our fleet,” Adam Lenz, head of sustainability and environment at Waymo, told Ars. “That’s when we look to these second-life applications, because there’s still a lot of life left in the battery,” he said.

Waymo did not specify the average mileage at which it swaps out batteries or retires vehicles from service. But Waymo robotaxis drive around much more each day than the typical EV, which means the Waymo fleet is likely to experience faster usage-related degradation of battery capacity over time. The company confirmed to Ars that “some of these vehicles have now been serving riders for years and have mileage beyond what a normal consumer drives.”

A 2025 analysis of over 22,700 electric vehicles across 21 models found that average battery capacity loss was about 2.3 percent per year, according to the telematics company Geotab. That translates to such batteries still having more than 81 percent of their original capacity after eight years.

Waymo’s current fleet of nearly 4,000 vehicles mainly consists of Jaguar I-Pace electric vehicles that have a 90 kWh lithium-ion battery. The company has also begun rolling out the Ojai robotaxi made by the Chinese automotive brand Zeekr with a 93 kWh battery.

“Put a little haircut on that in terms of degradation and the effective capacity that would be left in those batteries when they’re suitable for repurposing, and we’re still talking about pretty significant capacity per battery,” Hall said.

The growing Waymo robotaxi fleet could lead to “pretty large numbers in terms of megawatt hours of capacity that can be deployed pretty quickly” for stationary energy storage supporting power grids, he suggested.

The agreement gives Waymo discretion over when and how many used batteries will be turned over to B2U. But the companies confirmed that B2U has “already started receiving smaller initial quantities of batteries” from the Waymo fleet. Over time, the agreement could give B2U “hundreds of megawatt-hours” of additional storage capacity from Waymo’s thousands of electric vehicles, Lenz said.

Local grid synergy

The B2U grid storage solution could do more than simply extend the usefulness of lithium-ion batteries from Waymo’s fleet by several years. The new partnership is intended to support B2U projects in regions where Waymo’s autonomous robotaxis operate—meaning the used Waymo batteries could bolster the local power grids that Waymo vehicles rely upon for charging.

“What we think is really cool and unique about this opportunity is that these are the batteries that are helping serve our riders in these communities, and then they’re actually going to BTU to then be deployed in local grids that are near communities that we serve as well,” Lenz told Ars. “So there’s a nice circularity here for our commitment to clean technology and supporting renewable energy on the grids.”

Used Waymo batteries will be received at B2U’s Lancaster facility in Los Angeles County, which already houses more than 1,300 repurposed electric vehicle batteries. From there, the batteries will also be deployed to other B2U energy storage projects at sites across California and Texas, including a 24 megawatt-hour energy storage project in Bexar County, Texas, that could support Waymo’s growing deployment in San Antonio.

The all-electric fleet of Waymo robotaxis prevents 530 tons of CO2 emissions with every 500,000 weekly trips, according to company estimates. Waymo has typically sourced the electricity required for charging its vehicles from local wind and solar power generation projects, and by sometimes purchasing renewable energy certificates to cover any gaps.

One exception to that clean energy prioritization has been Waymo’s partnership with ride-hailing giant Uber in Austin, Texas. Uber installed a “temporary charging solution” for Waymo vehicles serving Austin riders that involved mobile L-Charge generators running on natural gas, which subsequently drew local attention and complaints because of the generator noises.

In any case, Waymo’s agreement with B2U fits with a more promising and broader trend of the United States installing record amounts of battery energy storage. A report by the Solar Energy Industries Association showed that US battery energy stationary storage installations reached 9.7 gigawatt hours in the first quarter of the 2026 fiscal year—the “largest Q1 in history” and a 32 percent year-over-year increase.

B2U is already managing more than 4,000 EV battery packs across its energy storage projects, including used Nissan Leaf batteries that were first installed in 2020 and are still going strong after approximately 2,500 cycles. The company currently has a “nice supply of batteries, but it’s great to add to this supply because the demand for storage is very high,” Hall said.