Why electric school buses are the ‘ideal asset’ to send energy back to the grid

The big yellow buses that ferry more than 20 million kids across the country to school increasingly feature assets that could transform school transportation as we know it: big batteries.

With decarbonization targets looming and an influx of federal funding in the last few years, the largest public transportation system in the US––nearly 500,000 school buses––is in the early phases of going electric.

There’s uncertainty about how much progress on this effort will be made during a second Trump administration. But the groundwork has been laid not only to decarbonize school buses but to use them to unlock the benefits of vehicle-to-grid (V2G) technologies, which allow assets to push energy back to the electric grid in times of need, potentially making the grid more reliable and resilient.

In fact, stakeholders across the clean-energy sector tend to view school buses as the perfect use case for V2G. That’s because they’re uniquely suited for it: They contain massive batteries, run predictable routes, and spend lots of time idling, particularly during the times of day when energy demand peaks and renewable sources like solar are in short supply.

“School buses are the ideal asset for electrification and V2G,” Ritu Narayan, founder and CEO of electric school bus startup Zum, told Tech Brew. “They are a very large battery on wheels.”

Zum in: Zum this year debuted the country’s first all-electric bus fleet serving a major school district, California’s Oakland Unified School District. The startup owns and operates the 74-bus fleet, while the district pays Zum for its transportation services.

The fleet is unique in another way, which is that each bus has bidirectional charging capabilities––meaning the vehicles’ batteries can discharge energy to the grid. The fleet is slated to give back 2.1 gigawatt hours to the grid each year––enough to power hundreds of homes in the area, per Narayan.

“It’s a cleaner, safer, quieter ride for the children,” she said. “But [we’re also] giving energy back to the grid.”

The program involves close collaboration with the local utility provider, Pacific Gas and Electric Company. Selling energy back to the grid generates revenue that Narayan said was crucial in proving out the financial case for going 100% electric in Oakland, given that electric school buses run several times the upfront cost of a diesel bus. Local, state, and federal grants also were crucial to making the program viable.

Narayan said Zum will look to replicate its results in Oakland in other districts across the country as the startup works to get 10,000 electric school buses on the road in the coming years.

Helping hand: Zum’s deployment in Oakland received support from the Environmental Protection Agency’s Clean School Bus Program, which allocated $5 billion through 2026 to help school districts electrify their fleets. The agency made another $1 billion available to decarbonize heavy-duty vehicles, with 70% set aside for school buses.

The effort in part aims to improve health outcomes for children and communities who face the risk of negative health effects from diesel-spewing buses. It’s an issue that is relevant to many communities; four in 10 people in the US live in counties with unhealthy levels of air pollution, according to the American Lung Association, with people of color making up a disproportionate number of those affected.

“This is something that we know disproportionately affects low-income populations and people of color,” Margarita Parra, transportation decarbonization director for clean-energy nonprofit Clean Energy Works, told us. “It’s an environmental justice issue, too.”

Clean Energy Works has advocated for the inclusion of funding and resources for bidirectional charging in the EPA’s programs, Parra said. The organization also participates in state regulatory processes, urging public utility commissions to adopt policies that enable clean-energy advancements like V2G.

“The most important thing for the state regulators is to start mandating proactive grid planning, and comprehensive grid planning,” Parra said. “Right now it happens piecemeal.”

Lidiya Kassahun, Clean Energy Works’s senior associate of transportation decarbonization, said that V2G technology can even help offset some of the costly grid infrastructure investments that will be needed in the coming years as electricity demand grows and states work to meet decarbonization goals: “This is one of the value propositions for utilities.”

It’s still early days for this technology. Most V2G programs are still in the pilot phase and utilities are still figuring out how to make pricing models work.

“The value for V2G is still a tough puzzle to figure out,” Stacy Noblet, VP of transportation electrification at consulting firm ICF, said. But she said it’s definitely on utilities’ radar.

“We still have a ways to go on education, outreach, testing that theory,” she said, “but I still think school buses are probably at the top of the list for the application that will likely see promise.”

Penciling it out: Andrew Blejde, CTO and co-founder of software startup Synop, which helps commercial fleets transition to EVs, told us that he’s seen significant growth in V2G deployments just in the last couple of years, with electric school buses leading the way.

“Especially for school buses,” he said, “turning that into a battery is part of the cost equation for helping customers reach that break-even point sooner.”

In just one month this year, Synop helped with roughly the same number of V2G deployments as it did in all of 2023, according to Blejde. And Synop’s customers are starting to generate meaningful cost savings from the technology, helping to prove the case for electrification.

“It’s becoming a much more reliable and forgettable part of what we do,” Blejde said. “It just works. [We] certainly couldn’t say that two years ago.”

Synop is now getting outreach directly from utilities that are turning to the startup’s customers for backup power rather than simply generating more from power plants.

“That’s the big rubicon to cross, is getting more utilities comfortable with essentially us subscribing assets to their demand-response programs and their confidence in us being able to deliver that,” he said. “What we’re starting to see is comfort in subscribing school buses first to those demand-response programs.”

Looking ahead: To date, school districts have committed to about 12,000 electric school buses––only about 2.5% of the US fleet, per the World Resource Institute. But that number is up significantly from a couple of years ago, and the initiative’s data suggests that the transition is playing out fairly equitably, with the largest share of electric school buses in the most disadvantaged school districts.

Now, advocates are uncertain about what the next few years will bring amid a likely change in federal environmental policy. Industry stakeholders say that the sector still needs subsidies to fill in funding gaps until manufacturers are able to scale up enough to bring prices in line with diesel buses.

“I think we have to focus our attention [on] the money that was already implemented…because they will continue to demonstrate the case,” Parra said. “It’s just going to be protecting what we got.”