When it comes to energy efficiency, schools are a relatively easy target. There is a natural synergy between educating the next generation and teaching sustainability and efficiency, whether it’s telling kindergartners to turn off lights when they leave a room or running sophisticated energy efficiency competitions between graduate school departments. Schools often own the buildings they occupy, making it easier to swallow long-term paybacks for efficiency retrofits.
When it comes to moving students to and from school, however, there has been less progress. The nearly half a million school buses in the U.S. are inherently more efficient than single-car drivers, but transportation efficiency gains end there for many school districts. Most youngsters (and bummed-out high schoolers without wheels of their own) are waiting at street corners and the end of driveways for practically the same yellow bus their parents rode to school (the addition of seat belts notwithstanding).
Not so for one group of kids in San Joaquin Valley, Calif. Starting in February, the Kings Canyon Unified School District becameone of the first school districts in the nation to order multiple all-electric school bus to transport students. The bus is a modification of Trans Tech Bus' SST model, with an electric powertrain from Motiv Power Systems, which also provides electric powertrains to other heavy-duty vehicles by dropping its new technology into existing chassis. A few years ago, Smith announced the availability of an electric school bus with Trans Tech, but it did not gain success in the marketplace.
“In this way, we are answering the call of the transportation industry to build reliable EV trucks that fit seamlessly into the existing diesel truck manufacturing and service infrastructure,” Jim Castelaz, founder and CEO of Motiv, said in a statement. “We are absolutely thrilled to see the Kings Canyon all-electric school bus on its route, transporting students, without exposing them to diesel exhaust. I hope that by the time my daughter is ready to go to school, she will be able to ride clean, zero-emission school buses like this one.”
Many states across the U.S. already have anti-idling laws that apply to school buses to cut down on air pollution. But there is often an exception when the buses need to be powered on to run the heat or air conditioning. The federal government has also ensured that school buses will have to become more efficient in coming years. President Obama has introduced the first fuel efficiency standards for medium and heavy-duty vehicles during his time in office, which will now become even more stringent.
Even with the more efficient use of the buses and gains in gas mileage, they could still be an attractive fit for electric powertrains. Like other fleet vehicles that have gone electric, such as Proterra buses in San Antonio, Motiv's garbage trucks in Chicago or FedEx’s delivery trucks, school buses have prescribed routes that can work well with a limited battery range.
School buses often sit idle for part of the mid-day and overnight, which could allow them to participate in demand response or frequency regulation markets, as that option becomes more widely available. Frequency regulation might be more realistic than demand response, since school buses are on the roads during the afternoons when peaks usually happen in summer. In PJM and Texas’s ERCOT, there are already pilots to allow fleet EVs to participate in the energy markets. One Chinese electric bus manufacturer operating in California is calling for utility rate redesign that would further incentivize electric transportation.
And then, of course there are, the children. Many parents don’t like the idea of their kids sucking diesel exhaust as they climb on and off a bus every day? In theory, it sounds like a win, but some school buses have already gotten much cleaner than they were a generation ago, and the electric school bus comes in at about twice the cost of a traditional diesel bus. Like other heavy-duty vehicles, there are also other low-emission options, such as natural gas, to choose from.
“Kings Canyon Unified School District has taken major strides to reduce diesel particulate emissions by as much as 85 percent with the installation of diesel particulate filters and the use of low-sulfur diesel fuel years before the mandates, plus converting one-third of our school bus fleet to clean-burning natural gas,” Jason Flores, transportation director for KCUSD, said in a statement. “Going electric with these new green school buses is just one more important step in KCUSD's ongoing portfolio of measures to protect our children, serve our community and be good servants of our environment.”
Like other EVs, one advantage of the electric school bus is that its lifetime operating cost is far lower than that of its conventional counterpart. If diesel prices continue to rise, the savings only get better, especially if battery breakthroughs can lower the cost of electric transportation.
"The buses cost about twice as much as a comparable gas bus, but cost one-eighth as much to fuel and one-third as much to maintain,” said Castelaz. “Over the life of a school bus, two to three times the cost of the vehicle is spent on fuel and maintenance."
Electric municipal buses are more common, but all-electric school buses have struggled to make inroads. In the 1990s, Westinghouse tried developing technology but it was never commercialized. Some other all-electric school buses have been piloted but not used for daily transport. One all-electric school bus was put into operation at Mid-Del Technology Center school in Oklahoma. It is unclear as to whether it is still in operation. There are also other efforts underway in New York City and Chicago to test out electric school buses.
The pilot for the buses in California was funded with $400,000 from the California Air Resources Board AB 118 Air Quality Improvement Program Electric School Bus Demonstration Project. The smaller buses are outfitted with four or five battery packs for a range of 80 to 100 miles. According to Motiv, when incentives for zero-emission buses are combined with battery leasing, the buses cost the same or less than conventional buses, making the long-term cost far lower.
The goal, however, is not just to electrify smaller buses, but to enable big yellow to go green too. Castelaz said there has been some interest from fleets in full-size electric bus fleets, and Motiv has the technical capabilities since it has outfitted other heavy-duty fleet vehicles, such as other buses, with electric powertrains.
The smaller buses were a natural place to start, according to John Clements, retired director of transportation for KCUSD, who is now an active clean fuels advocate in California. He noted that larger buses could be an option if there is interest based on the pilots. Kings Canyon has two buses, and federal highway funds will purchase two more for California pilots. “They will be available to public school districts to try out at no risk to them,” said Clements. “In this way, we hope to educate districts about going electric and make it easy for them to experience for themselves.”
Editors' Note: The original story stated that this was the first all-electric school bus used to transport school children on a daily basis. This is one of the first that is not just a demonstration, there have been other one-off orders for fully electric school buses.