School's out. The buses spent July feeding the grid

Four school buses in Shawnee, Oklahoma spent a July afternoon running backwards. Over four hours they pushed more than 800 kilowatt-hours into Oklahoma Gas & Electric's wires through the same ports that had filled them overnight, on a day the heat had the regional grid stretched thin. The transport director, John Wiles, started it from a desk. OG&E will credit the district at a per-kilowatt-hour rate several times what Shawnee paid for the electricity going in — an arbitrage the World Resources Institute wrote up on 20 August.

Wiles is the district's transportation director. The students those buses usually carry were on break. Passenger-car vehicle-to-grid still lives mostly in incentive PDFs and a short list of bidirectional wall boxes. The yellow bus already has the three things a grid operator can actually book: a pack over 200 kWh, a night-time charge window, and idle hours that land on summer afternoons, when air conditioners pull hardest.

Russell Vare, vice president of vehicle-grid integration at The Mobility House, told School Bus Fleet at ACT Expo in May that the company has vehicle-to-grid projects "in the ground in California, New York, Massachusetts." Fremont Unified, he said, "we interconnected them last fall and they've been doing demand response services." The site is now stacking dynamic hourly rates and demand-charge optimization on top of that.

The shift that interested him was no longer the demo. "We're starting to see customers just choose bidirectional charging as the default option."

WRI's Electric School Bus Initiative now counts 32 utilities in 21 states working vehicle-to-everything schemes with districts. More than 1,500 US districts run at least one electric school bus. Reuters, writing in early July from WRI figures, put deployed school-bus V2G at about 230 vehicles of roughly 6,700 electric buses on American roads, with about 8 megawatt-hours available at a given time. That is a rounding error on a regional grid. It is also real export, which is more than most bidirectional passenger cars managed this summer.

Shawnee's eight electric buses are half of a 16-bus fleet serving 3,500 students. A $1 million National Science Foundation grant, with the University of Oklahoma, IC Bus and InCharge Energy, put bidirectional hardware and software in this spring. The buses are 210 kWh. In the 2024-25 school year the district saved about $40,900 on fuel just by running them.

California already requires V2G capability on state-funded electric school buses. WRI says districts in Oakland, San Francisco and Fremont are earning roughly $5,000 per bus per year.

Fremont is the working example the industry keeps putting on panels. WRI, citing Fremont transportation director Ernest Epley, reports that one discharge session from one electric bus generated enough energy to power six to ten homes; the district has 22 electric buses and nine bidirectional chargers, enough, on that math, for up to 90 homes in a session. Sarah Woogen, vice president of product and delivery at The Mobility House North America, told an Electric Autonomy panel in November that the fleet is in Pacific Gas & Electric's Emergency Load Reduction Program. "The program we're participating in in California compensates $2 per kilowatt hour that is discharged during that event." The meter runs backwards. "We're seeing negative amounts on the total meter." Stop charging during an event and you still get paid; "when we start actually pushing the energy back to the grid, our compensation almost doubles."

Epley was careful about the money. He joked that the district will not be buying yachts. The export, stacked with low-carbon fuel standard credits, trims the PG&E bill and is not yet fiscally neutral. "It's my job to ensure that our operations have the least amount of budgetary impact on the classroom as possible so that every dollar is leveraged toward actual student education."

San Francisco's new fleet, launching in August, is 104 buses serving 50,000 students across 122 schools. WRI says it is expected to send about 3 gigawatt-hours back to the grid each year, enough for 300 homes.

Blue Bird's Brad Beauchamp told a Mobility House webinar in June that of nearly 4,000 electric buses the company has put into the United States and Canada, all but about 500 have some form of vehicle-to-grid capability, going back to 2018 and 2019. Demonstrations have happened. "The interconnect is still a challenge."

On warranty he was specific. The Cummins Accelera warranty on the PowerDrive 7000 system Blue Bird supplies "does actually spell out gross discharge" and is "warranted up to 75% of its total usable capacity for 390 megawatt hour of throughput." That is a throughput cap, not a mystery cycle count. Epley remembers a night custodian walking a district lot at 9:30 p.m. to plug buses in before he left, purely to catch the off-peak rate. Woogen's description of the current setup is that they plug in; OpenADR handles the rest, sometimes with 24 hours' notice, sometimes with one.

Sébastien Fournier, Polara's president, walking through Fremont's hardware on that panel, said the V2G phase added three 60 kW bidirectional DC chargers and 2,500-amp three-phase distribution. Undersize the site, he warned, and the charge window is too short to refill and still discharge for revenue. Interconnection, the operators said, still takes months, sometimes quarters.

Ryan Jones, OG&E's manager of innovation, put the utility case without romance: "If we can use those demand response programs to effectively avoid increasing our system peak demand for the year, then that allows us to keep rates low for all customers by avoiding additional investment in additional generation."

Wiles, who has already lived through a tornado that left Shawnee without power for ten days and cost the district $18,000 in spoiled food, is looking at the same buses as backup for refrigerators next time. "We saved so much money just running the electric bus. Now that we're going to the V2X, we're going to save even more money."