C
omparing the cost per mile for an electric school bus with a diesel bus is not easy. It requires a calculation of the amount of charge needed to travel a certain distance, which varies
based on weather and other factors including the of- ten-variable price of electricity. But analysts using calculations, and transportation
directors using their own observations, can compare the approximate cost per mile of electric, diesel, CNG and other types of school buses. Electric bus operators say they are stacking up well. “The fuel economy of battery-electric powered buses
is five times higher than that of diesel buses operated on equivalent routes,” observed John Burciaga, the fleet maintenance manager for California’s San Diego Unified School District, which has a dozen electric school buses in use and another 30 on its way via the EPA Clean School Bus Program. “Each zero-emission bus can cost hundreds of thou- sands of dollars per year less to fuel than diesel buses,” he said. “In addition, maintenance costs for electric motors are much lower because they have far fewer moving parts than conventional motors and are far more efficient.”
Doing the Math Operating two Lion electric buses saved Three Rivers
Community Schools in Southwest Michigan $34,000 in fuel between January 2020 and October 2023, explained Brian Leonard, director of facilities and operations. It costs $12,034 to charge the buses to drive on average 72,066 miles per month, compared to about $46,000 it would have cost diesel buses to fuel for those same trips. Three Rivers also has 22 diesel buses in its fleet. Patrick Couch, senior vice president of technical ser-
vices at clean transportation consulting firm Gladstein, Neandross & Associates, said that “ballpark,” electric buses often cost about half as much to run per mile compared to diesel. “A diesel school bus is probably getting six to seven
miles per gallon, spending about $4 per gallon for fuel, whatever the local cost is. That’s like 55 to 60 cents per mile for baseline diesel fuel cost,” he explained. “With electricity, you’re going to ask how many kilowatt-hours per mile does it take for me to operate my bus? That’s going to depend on a lot of things. It might be 1.5 kilowatt-hours per mile, for example. Then ask, what’s my electricity rate? If on average it’s 20 cents per kilo- watt-hour, that’s about 30 cents per mile.”
But he noted that electricity cost and efficiency can vary greatly based on facilities and when and how long vehicles charge. A fuel properties comparison chart from the U.S. De- partment of Energy notes that one kilowatt-hour equates to about a 0.03 gasoline or diesel gallon equivalent. A gallon of propane, by comparison, equates to about two- thirds of a gallon of diesel. A pound of compressed natural gas is the equivalent of 0.16 diesel gallons. Biodiesel is nearly a one-to-one equivalent to straight diesel, no mat- ter if the blend is 20 percent or 100 percent. Highland Electric, which owns and manages the
country’s largest electric bus fleet of 206 buses for Mont- gomery County Public Schools in Maryland, calculated how much it would cost to power an electric bus to go 12,000 miles versus how much diesel would cost for that same mileage. At average U.S. prices of 12 cents per kilowatt-hour for electricity and $2.80 per gallon for diesel—when distribution costs and taxes are stripped out—the cost for an electric bus would be $3,020 and for diesel would be $5,420. Meanwhile the Environmental Defense Fund found
that electric buses are almost 60 percent more fuel efficient than diesel buses, at 8.2 miles per gallon for diesel nearly 20.9 miles per diesel gallon equivalent, with energy value measured in BTUs. “You have to go through conversions for energy-
equivalent,” said Couch. “I personally think it’s an unnecessary convolution. At the end of the day, what you care about is how many cents per mile you are spending.”
The Price of Electrons The local cost of electricity is central to the cost-per-
mile of driving an electric bus. This varies by state: California, Hawaii and Massachusetts generally have high electricity prices, while Washington, Utah and Wyoming are on the low end. The rate structure and various billing programs of-
fered by utilities that work with districts and school bus companies are extremely important. Utilities may offer time-of-use or similar billing, where as charging a bus overnight or at other times of low demand means lower rates. Meanwhile, billing that includes demand charges when electricity use is at its peak can cause unexpected spikes in costs. Demand charges essentially base a significant por-
tion of a bill on the highest amount of electricity that a customer demands, even briefly. That means if a fast
Read an overview of the Environmental Defense Fund’s analysis of electric school buses at
stnonline.com/go/i3.
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