School Buses

Diesel powers over 91% of all school buses thanks to its combination of fuel safety, energy efficiency, reliability, durability, established fueling and maintenance network, range and operational flexibility, secondary markets and low acquisition and operating costs. All diesel-powered school buses can also use low-carbon renewable biodiesel fuels. The new generation of advanced diesel technology continues to be the technology of choice for pupil transportation.

Approximately 560,000 school buses transport more than 26 million public and private school students each day to and from school and school-related activities, travelling more than 6 billion miles each year. 95% of all school buses in America are powered by diesel engines because of their reliability, durability, and safety. Over half of these (58%) rely on the cleanest, near-zero emission diesel engine technology.

Since 2011, the combination of ultra-low sulfur diesel (ULSD) fuel and advanced technology diesel engines means that these new buses achieve near-zero levels of emissions compared to previous generations. Emissions of particulate matter (PM) and hydrocarbon (HC) and nitrogen oxide emissions are reduced to near zero levels.

In addition, a growing number of school districts now use blends of high-quality biodiesel and renewable diesel to power those buses, further reducing smog-forming and greenhouse gas emissions.

About electric buses

New federal policy in the US (2021) provides funding assistance for school districts to purchase electric buses and to install necessary charging infrastructure. Electric powered school buses are sometimes referred to as zero emission vehicles, however while electric buses have no tailpipe emissions, there are still emissions associated with creating the electrical energy to charge the buses. 

In the US, according to the Energy Information Administration of the energy used to create electricity, 40% comes from natural gas, 20% from nuclear power, 20% from renewables, and 19% from coal.

  • 40 %

    Natural Gas

  • 20 %

    Nuclear Power

  • 20 %


  • 19 %


Beyond the source of electric generating emissions, considerations include the cost and availability of corresponding upgrades to electric service and installation of charging infrastructure to support the bus fleet; driving range during all kinds of weather conditions in the service area (extreme heat or cold reduces electric battery range), secondary market resale considerations (the used vehicle market is strong for diesel buses but unknown for electric ones), and utility of an electric bus for charter or other off-time uses. 

Clean Diesel Progress Chart - Heavy Duty On-Highway (Trucks, Transit & School Buses)