Exploring Hybrid School Bus Technology Where it Started

Exploring Hybrid School Bus Technology

Where it Started

And Then

And Finally, Modern Technology

Internal Combustion Engine • Nikolaus August Otto, patented 1876 • Incorporated into nearly all private passenger vehicles • Plentiful petroleum led to gasoline • Fuel mixed with air then injected • Uses electric spark for explosion • 250+ million cars now registered in U. S. Hybrid Buses 2018 ©The NEED Project

Diesel Engine • • • Rudolph Diesel, inventor 1878 Another form of internal combustion engine Direct fuel injection No spark plug Fuel ignites at its flash point More efficient than gasoline engines of day Hybrid Buses 2018 ©The NEED Project

Current IC Engines • • Thermal efficiency (26 -34%) Mechanical efficiency (94%) Overall efficiency (20%) Emissions • Particulate matter • NOx • Sulfur oxides • Carbon monoxide • Carbon dioxide Hybrid Buses 2018 ©The NEED Project

Most school buses today have diesel engines.

Alternatives to Petroleum-based Fuels • Compressed Natural Gas (CNG) • Cleaner because do not emit nitrogen and sulfur oxides, or all the particulate matter • Still releases carbon dioxide • Hydrogen fuel cells (used at Vancouver Olympics) • • Only emission is water vapor Lots of energy required to generate hydrogen Lack of infrastructure Currently prohibitively expensive Hybrid Buses 2018 ©The NEED Project

Diesel-electric Hybrid • Combines diesel engine and fuel with rechargeable battery system • Greatly improves miles-per-gallon • Captures energy otherwise lost during braking – ideal for routes with frequent stops • Somewhat more expensive up-front cost • Long-range savings realized by purchasing less fuel and less maintenance on engine Hybrid Buses 2018 ©The NEED Project

Parallel Hybrid System Power is stored in the lithiumion battery when the bus is coasting or brakes are applied. An electric motor/generator mounted between the engine and the transmission generates electric power. The vehicle uses stored energy to add power back into the transmission when the throttle is depressed. http: //www. thomasbus. com/bus-models/green-buses/saf-t-liner-c 2 -propane. asp Hybrid Buses 2018 ©The NEED Project If the hybrid system goes offline for any reason, the bus automatically switches back to the conventional powertrain system.

For More Information The NEED Project • www. need. org • info@need. org • 1 -800 -875 -5029 Energy Information Administration • U. S. Department of Energy • www. eia. gov Hybrid Buses 2018 ©The NEED Project

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