About 20 million students in the United States ride to school each day on the familiar yellow bus. The vast majority of the nation’s roughly 490,000 school buses — which comprise the nation’s largest public-transportation fleet — are powered by diesel engines. “We’re poisoning our kids on the way to school,” said Jessica Keithan, cofounder and director of the Texas Electric School Bus Project, of the exhaust that inevitably infiltrates bus interiors and children’s lungs.
But that’s slowly beginning to change. Thanks to a slate of federal and state incentive programs, school districts all over the country are starting to swap out old diesel buses for new, zero-emissions electric-powered models.
This transition is reaching districts of all sizes and demographics, from Martinsville Independent School District in East Texas — which last year became the first in the country to go fully electric with four new buses — to Oakland Unified School District in California — which last month became the first large urban district to fully electrify its fleet, with 74 buses.
As the Environmental Protection Agency, through its $5 billion Clean School Bus program, and state initiatives continue to fund electric bus purchases, advocates are identifying challenges to wider adoption and grappling with how to surmount them.
Replacing decades-old buses may lead to benefits in educational performance and school attendance rates, said one study.
Five years ago, there were fewer than a thousand electric school buses operating nationwide, the majority of them in higher-income suburban districts. But since the EPA launched its Clean School Bus (CSB) program in 2022, authorized by the Bipartisan Infrastructure Law, the number of electric buses on the road has climbed to nearly 5,000. And more than 7,000 additional buses are under contract, awaiting delivery, or have been awarded funding and will soon be ordered.
From a health perspective, there’s urgency to replacing the nation’s diesel buses with cleaner alternatives. Health experts have long known that children are uniquely vulnerable to air pollution because their lungs, brains, and other major organs are still developing. They breathe faster and take in a higher volume of air relative to their body weight.
Diesel exhaust is classified as a carcinogen by the World Health Organization and contains fine particles and nitrogen oxides, both of which are well-documented asthma triggers. Research shows that children in lower-income areas and communities of color are exposed to higher levels of outdoor air pollution — from major roadways, industries, and ports with diesel truck operations. They also suffer much higher rates of asthma and respiratory illness. And so it’s particularly important, say public health experts and school officials, to get polluting school buses off the streets.
Children aboard an electric school bus in Chevy Chase, Maryland, last February. Tom Brenner / AP Photo.
Meredith Pedde, an environmental epidemiologist at the University of Michigan’s School of Public Health, led a study published earlier this year that found that replacing decades-old buses may lead to proportionately greater benefits in educational performance and attendance rates. She and her colleagues drew on data from an earlier EPA program that randomly allocated funding for cleaner diesel, gas, or propane school buses from 2012 through 2017. They found that districts that received funding for bus upgrades saw significant improvements in students’ attendance rates and in math and literacy test scores.
“One of our hypotheses is that higher exposures could lead to missed days of school, and that’s associated with lower performance,” said Pedde. “But there’s also evidence that air pollution can directly impact the brain and impair cognitive performance.”
Pedde and her colleagues found that those educational performance gains happened only in districts that replaced pre-1990 diesel buses (there are nearly 5,000 pre-1990 buses in the U.S. fleet, her paper estimated). Those that replaced newer diesels saw test-score changes comparable to scores in districts that were not selected for funding to receive cleaner buses. Her research suggests there are greater health benefits from getting the oldest diesel buses off the road than from replacing more recent models, which must meet more stringent emissions standards.
Low-income and minority communities still have the highest shares of older, polluting diesel buses.
The EPA’s CSB program stipulates that electric buses must be replacing diesel buses from 2010 or earlier. Many state programs have similar requirements. “In addition to socioeconomic factors, we need to make sure that programs are also targeting the oldest buses,” Pedde said. In Texas, there are at least five school districts still running buses made in the 1970s, according to Keithan.
The CSB program is designed to give preference for new bus funding to the highest-need districts. According to a recent report from the World Resources Institute’s Electric School Bus Initiative, districts with higher shares of low-income households generally have more students riding polluting buses to school than do other districts. The good news is that 74 percent of the grants or rebates awarded to date are in low-income, rural, or tribal school districts, according to the EPA.
“The greatest burden of air quality and health impacts is on students of color, students with disabilities, low-income students,” said Sue Gander, director of WRI’s initiative. “They are the ones who need to be part of this transition first.”
“The [EPA] policy has led to this desired outcome,” Gander said. “That’s really encouraging.” But she and other advocates readily acknowledge there’s a long way to go, because low-income and minority communities still have the highest shares of older, polluting diesel buses. And across the nation, only 2.5 percent of all school buses are electric.
There are many reasons for this gap but the biggest is, not surprisingly, money. While a new diesel school bus costs between $125,000 and $150,000, a new electric bus costs between $300,000 and $400,000. And then there are the ancillary costs, including the installation of chargers (which can cost up to $140,000), upgrading transformers and lines to bring power to them, and training employees to manage these new systems.
Even the process of navigating incentive applications can impose prohibitive costs on some school systems. “I don’t have grant writers,” said Kim Raney, executive director of transportation for the Oakland Unified School District. Instead, Raney worked with Zum, a transportation service provider that financed and manages the new fleet, to obtain various EPA and state incentives to make the math work and with the California utility PG&E to install the charging equipment.
While school administrators may want to improve air quality on buses and on school grounds, they are operating under tight fiscal constraints, especially in rural districts, which tend to have not just older buses but also longer routes, meaning students can be exposed to more pollution per mile. Rural districts usually have smaller budgets, making it difficult to hire technical consultants to help apply for grants or rebates, train drivers, and coordinate with utilities to run power to the chargers in their bus yards.
Thousands of electric school buses with their batteries plugged into the grid could effectively function like a power plant.
And yet some rural districts have made the leap, like one in southern Illinois’ Hardin County, which now operates 12 electric buses in partnership with Highland Fleets, a “electrification-as-a-service” company that helps reduce the cost of going electric for school districts.
Highland purchases the buses, oversees permitting and installation of equipment, trains maintenance staff, maintains the fleet, and pays for the electricity. The company charges school districts a fixed annual fee.
Protecting students’ health is front of mind for many school officials interested in making the transition to electric buses, Gander said. “There are also clear greenhouse gas emissions reduction benefits to electric buses, and a lot of areas with climate plans are motivated by those goals.” But there are other benefits, too.
Electric buses are much cheaper to operate than diesels: According to a government-funded study published by the National Renewable Energy Lab, they reduce maintenance costs by 44.1 cents per mile compared to their diesel counterparts. Keithan has found that the prospect of saving money is the most persuasive selling point for school administrators with tight budgets, while the health benefits are, she says, icing on the cake.
A technician converts a conventional school bus to an electric school bus at a facility in Holbrook, New York, March 2023. Gabby Jones / Bloomberg via Getty Images
Another prospective financial benefit for districts is the bus’s capability of feeding power back to the grid, especially during times of peak demand. Thousands of electric school buses with their batteries plugged into the grid could effectively function like a power plant, which can help utilities avoid the expense and pollution of ramping up “peaker” plants to meet spikes in electricity usage. Pilot programs in Colorado and Massachusetts are currently seeking to demonstrate how electric school buses can provide these “vehicle-to-grid” charging services — and make money doing so.
Getting more utilities on board to quickly install chargers and deliver power to them is essential, said Matt Stanberry, vice president of Highland Fleets. So is encouraging utilities and state public utility commissions to create special rates and programs to compensate school districts for sending power into the grid when their buses are sitting in the yard, which is about 70 percent of the time during the school year and most of the summer, when many states see peaks in power demand
The Clean School Bus program, which ends in 2026, has awarded nearly $3 billion of its $5 billion total. The EPA is planning to announce a fourth round of funding this fall, offering up to $932 million. But incentives alone can’t push all dirty diesel buses off roads, said Keithan. “This market has to be able to support itself.” Of course, like other clean energy technologies, electric buses are expected to become more affordable with wider deployment. EPA officials say that they anticipate “that bus prices will decline as production scales, EV battery costs fall, and more electric buses are deployed.”
A month after going fully electric, Oakland’s school bus fleet is working well, the district’s transportation director says.
For districts that struggle to afford new electric buses and have more recent diesel models in their fleet, there are other, less-discussed options: repowering them. The process involves swapping out diesel engines for electric drivetrains, at a cost of between $110,000 and $180,000. It would also prevent older diesels from being sold to poorer districts or being shipped abroad, where they would continue to pollute other children’s lungs. “It’s a faster way to serve underserved districts, to repower assets they already own,” said Keithan. “It can be done more quickly, with regional labor, at a fraction of the cost.”
Despite those advantages, repowers are not that common because districts must ensure their buses comply with federal, state, and city safety regulations, and mechanics willing to do the work may be hard to find. What’s more, repowers aren’t eligible for the EPA’s CSB funding.
Keithan said policymakers should think more broadly and creatively about how to reduce the logistical and financial barriers to accessing this new technology. Making it easier to do repowers and requiring utilities to set aside money for programs that equip schools for charging buses, she said, are two key ways they can accelerate the transition for everyone.
In the meantime, going fully electric may be a “leap of faith,” said Raney, of the Oakland Unified School District, but one well worth taking. A month into the school year, her district’s fleet of new electric buses are working well. And just last week the district performed the first test of its vehicle-to-grid system, with buses sending power back to PG&E for three hours. “It went off without a hitch,” she said.
Correction, September 12, 2024: An earlier version of this article incorrectly stated that a Hardin County, Illinois, school district is operating 18 electric buses. It is operating 12, as the article now states.
