Hybrid Electric School Bus Deployment and Evaluation

Principal Investigator: Shauna Hallmark
Co-Investigators: Randy Boeckenstedt & Dennis Kroeger
Organization: Center for Transportation Research and Education (CTRE), Iowa State University
Technical Area: Energy Efficiency

Executive Summary

In recent years, several studies have been released detailing the negative public health impacts of vehicle emissions on young children and even demonstrating the amount of pollutants present in and around vehicles such as school buses. One such study indicated that the pollutant levels inside buses are actually higher than outside the buses. With more than 5,600 school buses in Iowa, traveling more than 42,000,000 miles burning $14,610,467 worth of diesel fuel each year and carrying hundreds of thousands of children every day, it is important that we intercede to create a program that helps us meet our larger air quality goals while also improving the air quality on the local level. It would be even better if we could do that without increasing life-cycle costs to school districts as some bus retrofit programs do.


A solution that meets all of these needs can be achieved in a single project: the development and deployment of hybrid-electric school buses. With the potential for a plug-in hybrid bus we see even better emission reduction opportunities. Potential benefits of this development follow:

  • Reduce fuel consumption in school buses
  • Help achieve emission reduction demands
  • Reduce pollutants inside and outside school buses
  • Reduce life-cycle costs of school bus fleets
  • Stimulate economic development
  • Set an example to residents of Iowa for purchasing hybrid vehicles

The deliverable of this project is to purchase three (3) hybrid electric school b uses from a major manufacturer and to deploy them in three (3) school districts in Iowa. Originally, the three (3) districts that have come forward and offered to test and deploy these buses are: Indianola,Sigourney-Keota, and Nevada. However, the Indianola School District decided against proceeding with the project. The Iowa consortium, though, still has two districts, Sigourney-Keota and Nevada. These will potentially be the first hybrid electric school buses in the state. The Iowa research team, consisting of CTRE, the Iowa Department of Education, the Iowa Association of School Boards, and the two school districts of Indianola, Sigourney-Keota, and Nevada, is part of a larger consortium Advanced Energy of North Carolina that is advancing the purchase of these buses nationwide. The Iowa contingent, along with the consortium plans to purchase as many as twenty (20) hybrid electric school buses to deploy nationwide. The Advance Energy Buyers’ Consortium was recently awarded a grant of $840,000 from the State Technologies Advancement Collaborative (STAC) toward the hybrid electric school bus development and deployment effort.

By manufacturing school buses that use plug-in hybrid electric vehicle technology, one of the hybrid configurations under consideration, the majority of emissions move from the vehicle tailpipe to the electric utility. The electric utility is far more regulated and, according to the EPA, energy produced at power plants is much cleaner than that produced by a vehicle, including commercially0avilable hybrid vehicles. Additionally, using these hybrid buses may reduce the consumption of petroleum by a half or better, reducing imports and saving school systems valuable operational dollars.

For the past two years, Advanced Energy has facilitated a Hybrid Electric School Bus Buyers Consortium comprised of school bus purchasers, suppliers, and other stakeholders, who have come together to discuss school bus technologies and investigate solutions together for problems facing various group members