Many states around the United States like California, Indiana, Connecticut, Mississippi, Pennsylvania, Kentucky, Tennessee, and Texas have adopted hybrid electric school bus fleets in an effort to be more environment-friendly. As more states deploy hybrid buses to reach their sustainability goals, schools, too, have started deploying them to reduce their environmental impact.
Here, we delve into what a hybrid electric school bus is, its costs vis-à-vis conventional buses, safety, and how more schools and transit agencies can transition to it. After this article, be sure to check out our report, "How to Electrify a School Bus Fleet," to learn how to electrify your school bus fleet in six steps, from funding opportunities to the operation of charge points.
What Are Hybrid Electric School Buses?
A hybrid electric school bus is a type of school bus that uses two propulsion systems: a conventional internal combustion (IC) engine and an electric motor. This hybrid electric vehicle (HEV) typically uses a diesel-electric powertrain and is, therefore, also called a hybrid diesel-electric bus.
A school bus hybrid electric uses energy that is stored in batteries. It combines the benefits of an electric vehicle’s (EV) low tailpipe emissions and high fuel economy with the range and power of diesel-powered vehicles.
Are Hybrid Buses Less Expensive Than Conventional Buses?
Let’s look at the cost differences between hybrid and conventional buses on various parameters:
Buying hybrid buses costs substantially more than conventional ones. Hybrid buses have extra parts which include the drivetrain and charging infrastructure. However, it is possible to recover a certain portion of the costs through various state incentives.
Participation in government programs has allowed transit agencies to offset the purchase costs of hybrid buses and obtain these vehicles at relatively affordable prices. These programs include:
- The American Recovery and Reinvestment Act (ARRA)
- Clean Fuels Grant Program
- California’s Hybrid and Zero-Emission Truck and Bus Voucher Incentive Program (HVIP)
These funding packages allow transit companies to invest in technologies that bring down the total cost of ownership (TCO) of hybrid buses.
Despite the high initial costs of hybrid buses, school districts can also recoup some costs through savings on fuel.
The use and costs of diesel impact actual savings. Fuel economy helps transit agencies slash their fuel costs which make up a major portion of their budgets. So, deploying hybrid electric school bus fleets helps agencies significantly reduce their operating costs and improve profitability.
The “Can a Hybrid Save Me Money?” tool on FuelEconomy.gov allows you to compare hybrid and conventional buses. It helps you compare the costs of a particular hybrid model with a conventional one from the same manufacturer. It also offers estimates on fuel savings that can be had with hybrid vehicles.
Short-Term Maintenance Costs
A few transit companies have reported short-term maintenance problems with hybrid electric school buses. These include battery issues and the need for changes in the software to achieve greater fuel economy.
However, in light of the fact that early maintenance issues are mostly covered by manufacturer warranties, transit companies won’t have to incur additional costs in this aspect.
Long-Term Maintenance Costs
Hybrid electric school buses have many long-term cost benefits that improve their lifecycle compared to regular school buses. Some potential benefits include reduced costs on engine wear, battery pack replacements, and added bus weight.
But hybrid electric school buses come with replacement battery costs which increase their lifecycle costs.
Safety of Hybrid Electric School Buses
In 2018, the United Nations Economic Commission for Europe (UNECE) imposed Regulation 107 to improve bus and coach safety. This law makes the installation of a fire suppression system compulsory for commercial combustion engine buses.
As hybrid electric school buses have combustion engines, they must have this safety system installed to mitigate fire risks. In case a fire breaks out, the fire suppression system will control its spread and reduce operational downtime.
This system can also help identify battery failures early, adding another layer of safety. It can help vehicles release cooling agents when a rise in temperature is detected, greatly minimizing the risk of fire.
Hybrid buses also have electric motors. UNECE Regulation 100 (Construction and Safety of Electric Powertrains) supports the use of an early warning system in EVs and HEVs for safety. This system along with spot cooling can quickly detect thermal runaways, thereby localizing and suppressing fire risks.
Addressing fire risks can enhance safety in hybrid electric school bus fleets while improving their viability.
Conducting Fire Risk Assessments
The Research Institutes of Sweden (RISE) offers a vehicle fire safety assessment that transit agencies can use to mitigate risks in hybrid buses. The assessment includes the following points that transportation companies must take care of:
- Identification of hazards
- Estimation of risks
- Evaluation of risks
- Reduction of risks
Vehicle manufacturers and transportation companies can identify and prioritize hazards using the failure mode and effects analysis (FMEA) framework. They can then list hazards in risk maps and create a comprehensive picture of the situation. It will help them weed out “acceptable” risks from those that need addressing.
Risks can then be addressed with appropriate action plans that highlight required measures to reduce them. It may include:
- Reduction or elimination of risks by design
- Active and passive systems for fire safety
- Better cleaning and maintenance procedures
- Better quality and training procedures
This helps maintain high safety levels in hybrid buses, allowing students to travel risk-free.
Transitioning to Hybrid Electric School Buses
A major challenge in the transition to hybrid electric school bus fleets is their high initial costs, especially in low-income communities. To facilitate the deployment of hybrid electric school bus fleets in these areas, schools and transit agencies need to adopt innovative strategies.
To provide access to hybrid buses for schools in low-income communities, many cities in the United States have introduced financial programs and packages. They promote the adoption of these vehicles in low-income schools while improving air quality and making the other benefits of HEVs more attainable.
Other strategies to promote the transition to hybrid school buses include:
- Installation of charging systems in low-income areas
- Implementation of car rental programs for these communities
These will help schools and transit agencies overcome the high purchase costs of hybrid electric school bus fleets and encourage their deployment.
Transitioning from conventional diesel-run school buses to a hybrid electric school bus fleet is increasingly important. It cuts down on citizens’ — especially students’ — exposure to air pollutants and reduces greenhouse gas emissions.
The adoption of these buses combined with the right optimization solutions can help us collectively minimize our carbon footprint, improve our health and well-being, and safeguard our future. With regulatory and public support, government financing programs, and improvements in technology, we can hopefully embrace a sustainable future that no longer relies on fossil fuels while still meeting our transportation needs.
To learn more, check out our report, "How to Electrify a School Bus Fleet," to learn how to electrify your school bus fleet in six steps, from funding opportunities to the operation of charge points.
Want more information on how to start a transition to electric vehicles? Contact us today!