What is Clean Diesel?

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About Clean Diesel

School Buses

Diesel power offers the best all-around choice for school transportation through a 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. Coupled with the now near zero emissions, diesel continues to be the technology of choice for pupil transportation.

The modern yellow school bus powered by today’s diesel engine is the right choice for student transportation — and it will continue to be as federal clean-air rules tighten. Thanks to diesel-powered school buses, millions of children will have a safe, reliable, energy-efficient, and environmentally sound trip back to school this fall.

As schools around the nation welcome children back to their classrooms, our attention turns to assuring that kids get to school in the most safe and reliable means possible; the familiar yellow school bus. Approximately 550,000 school buses are gearing up to transport more than 25 million public and private school students each day to and from school and school-related activities, travelling more than 3.4 billion miles each year. 94 percent of all school buses in America are powered by diesel engines because of their reliability, durability and safety. Almost half of these (46 percent) rely on the cleanest, near-zero emission diesel engine technology.

School Bus Infographic

Despite the many miles traveled, school buses are generally considered to be the safest motor vehicles on the highway. Today's new school buses are more high-tech than ever with advanced safety features like warning systems and enhanced driver visibility, and they also come with a new generation of clean diesel technology under the hood. Ultra-low sulfur diesel (ULSD) fuel and advanced technology diesel engines helps these new buses reduce emissions of particulate matter (PM) and hydrocarbon (HC) emissions 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 emissions and reducing reliance on imported oil.


The Diesel Advantage

Lower Emissions

Today's diesel school bus engines are significantly cleaner than engines built in 1988. Advances in diesel engine technology have virtually eliminated the old smoke and smell many of us remember from yesterday's engines. New school buses using clean ultra-low sulfur diesel (ULSD) fuel are able to reduce particulate matter (PM) and hydrocarbon (HC) emissions to levels equal to or lower than comparable natural gas buses.

In addition, every school bus on the road eliminates approximately 36 cars. For every bus on the road, that's 36 fewer cars clogging the morning commute, saving fuel and emissions. School bus transportation makes our students and communities cleaner and healthier.

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

Global Warming

Because of their superior fuel efficiency, the use of diesel-fueled engines contributes less carbon dioxide emissions, which has been identified as a greenhouse gas that affects climate change, than the use of gasoline or natural gas-fueled engines.


Diesel has provided the safest, most reliable power for transporting children to and from school on the overwhelming majority of the nation's school buses for many years.

Fuel Efficiency

Diesel is the most efficient and cost-effective fuel for school buses - providing better fuel economy over comparable natural gas buses. Conservatively, it provides 25 to 30 percent better mileage than comparable natural gas in buses.


In addition to new, cleaner engines, cost effective retrofit technology is helping school transportation officials cut emissions from many of the older school buses still in service.

The U.S. Environmental Protection Agency's Clean School Bus USA and voluntary diesel retrofit program are encouraging this effort. EPA, as well as some state and local governments, now offer economic incentives to retrofit diesel school buses.


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