The electric car industry has been grappling with an elephant in the room for years: what to do with the millions of battery packs that, while no longer useful to power a vehicle, still retain enormous energy capacity. Now, the answer could come with autonomous driving.
Waymo has formalized a strategic agreement with the company B2U Storage Solutions to give a “second life” to the spent batteries of their robotaxis, preventing them from ending up directly in recycling plants to convert them into gigantic solar energy storage systems.
The paradox of the robotaxi. To understand why this movement is so relevant, you have to understand how an autonomous car ages. As detailed Wall Street Journalthe life of a robotaxi is nothing like that of a private car. While our personal vehicles spend most of the day parked, Waymo vehicles operate as high-use shared assets. In statements to the financial newspaper, Adam Lenz, director of sustainability at Waymo, explained that this high utilization causes its cars to accumulate kilometers at a dizzying rate, forcing the batteries to be removed from commercial service much earlier than usual.
According to data from Geotaba consumer electric car loses just 2.3% of battery capacity per year, retaining more than 81% after eight years of use. Robotaxis, however, suffer much more rapid degradation. But just because a battery no longer offers the range needed to safely carry passengers doesn’t mean it’s dead. The new business model seeks to squeeze the residual value of these batteries to use them in stationary applications, avoiding waste and taking advantage of critical materials that have already been manufactured.
“Energy sponges.” When Waymo vehicles can no longer perform, B2U removes the batteries, tests their performance, and packages them in large metal cabinets about 2.7 meters high, similar to small shipping containers. Each of these containers houses dozens of units. From there, they function as true “energy sponges” for the electrical grid. During the day, when there is plenty of sun or wind and prices are low, the system absorbs and stores that electricity. It then injects that energy back into the grid during nighttime demand peaks, just when solar production drops.
The economic and energy impact is notable. Freeman Hall, CEO of B2U, details that each reused battery can add between $8,000 and $10,000 in electrical value. Additionally, a single storage container has enough capacity to supply an average home for up to three months. Although Waymo has not specified an exact number of units, the goal in the long term it is to deploy “hundreds of megawatt-hours” of capacity, concentrating initial efforts in California and Texas, two states with great dependence and growth in renewable energy.
The figures of an unstoppable fleet. As detailed Ars TechnicaWaymo currently operates about 4,000 vehicles, mainly consisting of Jaguar I-Pace with 90 kWh batteries, to which are being added the new “Ojai” models from the Chinese manufacturer Zeekr, equipped with 93 kWh batteries. This fleet makes about 500,000 trips a week, a rate that will only grow: the Wall Street Journal cites Morgan Stanley estimate which predicts that autonomous journeys in the US will go from 15 million in 2025 to 36 million at the end of this year.
However, Waymo’s purely “green” narrative has its chiaroscuros, and the specialized press does not ignore them. Ars Technica Enter critical and necessary information: Although the company assures that its electric fleet avoids 530 tons of CO2 every half a million trips, its recent landing in Austin (Texas) together with Uber raised blisters. There, they used mobile generators from the company L-Charge powered by natural gas to recharge the robotaxis, which generated neighborhood complaints about noise and highlighted the logistical difficulties of operating electric vehicles without adequate charging infrastructure.
On the other hand, companies like Redwood Materials (backed by Waymo’s own parent company, Alphabet) are also launching their own second-life storage divisions. All this occurs in a context of absolute record: in the first quarter of 2026, the US installed 9.7 GWh of stationary storage, an increase of 32% year-on-year.
Beyond the green posturing. In short, this agreement seals a perfect urban circularity. As Adam Lenz reflectsthe same batteries that today transport passengers through their streets, tomorrow will be supporting the local electrical networks of those same communities.
However, behind the obvious environmental benefit is a movement of pure business strategy: this is not just green philanthropy. Waymo depends on the electrical grids of the cities where it operates to be stable and robust to be able to keep its fleets operational 24/7. In the age of mass automation, shoring up the electrical grid with batteries from your own retired cars is no longer just an ecological medal; It is a strict necessity of business survival.
Image | Daniel Ramirez
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