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By Brian Zepka March 6, 2024
As electric school buses hit the road across the United States, it’s important for school districts and school transportation providers to prepare for how these clean-running buses will perform in different climates. The good news? Electric school buses are tested and ready, with advanced batteries and operational systems that perform well in all weather, from the heat of Arizona to the winter cold of Salt Lake City.
Here’s what to know about electric school buses and cold weather.
Electric school buses are successfully delivering clean rides for students in areas that consistently face extreme cold weather including Michigan, Utah and Canada. That’s because today’s electric school buses — equipped with powerful batteries and thermal management systems — are designed to handle the tough cold and can be deployed successfully with proper planning, including route selection, charging scheduling and pre-heating.
Electric school bus batteries lose a percentage of their capacity in extreme cold weather, though the exact percentage varies based on temperature, terrain, heating source and other factors. So, it’s crucial to plan routes and charging schedules with the winter months in mind, ensuring that buses have plenty of range to cover all necessary routes.
Already, school districts in cold weather climates are seeing great results when deploying electric school buses throughout the winter months:
These on-the-ground stories are backed up by real-world performance data collected over the past few years. Barre Unified Union School District (BUUSD) in Barre, Vermont participated in a one-year evaluation of their two Type C electric school buses by the Vermont Department of Environmental Conservation (DEC). Barre, located in central Vermont among the Green Mountains, has an average low temperature in the winter of 12 degrees Fahrenheit and an average monthly snowfall of 20 inches. Approximately 60% of the bus routes used by the electric school buses in the pilot were considered rural, with elevation changes up to 600 feet.
Despite harsh mountain winters, DEC found that the electric school buses in Barre performed well on daily routes. Barre’s electric school buses retained enough battery range, achieved emissions reductions when compared to their diesel-burning counterparts and realized operational savings over the winter months. The report found that the average, annual real-world range between charges of the two electric school buses was 74 and 78 miles, a 25% reduction in range yet well above their average daily trip totals of 37 and 32 miles.
Emissions reductions were considerable for Barre electric school buses when compared to both diesel-burning buses put out of service and new diesel-burning buses. The following tables present the well-to-wheel emissions reductions seen for Barre’s electric school buses compared to both scenarios. The differences in nitrogen oxides (NOx) and particulate matter reductions observed between the two replacement options can be attributed to the Environmental Protection Agency’s stricter emission standards for NOx on new diesel-burning buses, reiterating the need to prioritize replacing the oldest diesel-burning buses in school fleets.
The operational savings of the electric school buses when compared to their diesel-burning counterparts were also seen as an advantage. Total dollar per mile savings were $0.24 to $0.25 in Barre.
This finding is reinforced through similar school district experiences operating their buses in cold weather.
The school bus fleet manager at Havre School District in Montana, where the temperature reached minus 44 degrees Fahrenheit this past January, found that their electric school bus’s per-mile cost is one-half or one-quarter of the cost for a gas- or diesel-burning school bus. In West Grand County School District in Colorado, the director of transportation reported their electric school bus averages $0.26 per mile and the diesel-burning buses average $0.58 per mile, which they noted does not include oil changes, filter, lubes and other maintenance costs that diesel-burning buses incur.
Unlike a diesel-burning bus with weight concentrated in the front, electric school buses’ battery weight is more evenly distributed between the front and rear wheels, improving driving ability in the snow. School bus drivers across the country have shared their experiences with improved stability:
Tom Godbee, a veteran bus driver in South Dakota said his electric school bus is a safer mode of transportation in the winter: “I’ve driven a diesel bus, a propane bus, and now an electrical bus… In the other buses, all the weight was in the front. [Now,] I’ve got more control, and better traction and they handle better.”
In Virginia’s Appalachian Mountains, Carroll County public schools found during the Arctic cold of the winter 2024 that the weight of the batteries has given “a more solid feel” to the vehicle on the road compared to diesel-burning buses because there is no movement of gallons of fuel moving from side-to-side.
And in Michigan, Three Rivers Community Schools reports that their electric school buses often outperform their diesel-burning counterparts in winter weather. Specifically, they found that electric school buses’ overall heavier weight and the fact that their weight is centered between the axles have made them less likely to fishtail in snowy conditions.
Cold weather does reduce electric school buses’ range by slowing reactions within the battery and because more energy is needed to maintain the cabin temperature and the temperature of the batteries themselves. When the ambient temperature is warmer, an electric school bus utilizes all its energy to exclusively propel the vehicle and therefore achieve peak driving ranges. The impacts from cold weather on range can vary depending on several factors like the bus’s route terrain and heating system; however, electric school buses are designed with technology to minimize these impacts.
First, electric school buses are equipped with battery thermal management systems that maintain an internal temperature range for safe battery function. The battery thermal management system draws energy from the batteries both during operation and while idling or charging, which helps the battery operate at its optimal temperature in all conditions. This pulls some power from the battery and helps ensure that the bus can safely and effectively perform even in extreme cold.
Also, electric school buses can recover energy during colder temperatures that would otherwise be lost through regenerative breaking. Regenerative braking occurs on downhill rides or during slow stopping like at stop signs, traffic lights and bus stops, or while in traffic. Specifically, battery power turns the motor — but while braking, the motor can be reversed and recharges the battery, thus extending the range of the bus, which proves especially beneficial during cold weather. Salt Lake City School District in Utah found that they can get around 16% additional range from regenerative braking. It also has an added benefit of lower wear and tear on braking systems.
Heated driver seats also allow electric school buses to conserve battery power since they require less energy than heating the entire bus cabin. With a heated driver seat, a driver can turn off or lower cabin heat when students exit the bus, extending the bus’s range.
Some school districts in cold weather climates have opted for auxiliary, fossil fuel heaters on their electric school buses to heat their cabins and save battery power. These auxiliary heaters can negatively impact emissions reductions and operational savings from fuel costs but help preserve battery life in cold weather. In Vermont, the DEC found that the diesel auxiliary heaters used about 80 gallons of diesel and cost approximately $0.07 per mile. Since the buses traveled around 35 miles per day, this amounted to approximately $12 per week in diesel fuel costs. Morris Area Schools in Minnesota have diesel-powered auxiliary heaters on their electric school buses, but the district’s senior vice president of operations says that they haven’t been used much as the buses stay warm running on battery power alone.
Routine maintenance and care can optimize an electric school bus’s performance in the cold. The federal Joint Office of Energy and Transportation recommends several approaches that include:
Electric school buses offer a safe, clean way to bring students to and from school – and the benefits of electric school buses should not be denied to children living in colder climates. With strong evidence that electric school buses perform well in cold weather, school districts have the opportunity to provide clean, tailpipe-emissions-free rides to their students no matter their location.
And while shorter routes can be easier to transition to electric school buses when there are concerns about range, particularly in cold weather, it’s important to remember that students with long trips to school stand to benefit most from electric school buses due to reduced exposure to tailpipe emissions.
Rural students, for example, face long bus rides that extend their school day, increasing their exposure to toxic school bus exhaust along the way. Data also shows that Black students tend to have longer rides to school — on average 45 minutes to an hour — than their white and Hispanic counterparts. And students with disabilities travel longer distances on their school bus than other students.
That’s why it’s important to consider equity when planning which routes to electrify first. While cold weather impacts range, students in cold weather climates and on longer routes should not be left behind as school districts transition to clean rides. By sharing electric school bus experiences in cold weather, efficiency data and training best practices, school bus fleets can ensure the transition to electric school buses happens equitably across varying climates and for all students.
A version of this article originally appeared on ElectricSchoolBusInitiative.org.
Brian Zepka is Research Manager, Electric School Bus Initiative, for WRI Ross Center for Sustainable Cities.
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