Exploring Hybrid School Bus Technology

Where it started

http://content.lib.washington.edu/u?/imlswrvm,61

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.

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

Current IC Engines

    Thermal efficiency (26-34%) Mechanical efficiency (94%) Overall efficiency (20%) Emissions • • • • • Particulate matter NO x Sulfur oxides Carbon monoxide Carbon dioxide http://ffden-2.phys.uaf.edu/102spring2002_web_projects/z.yates/zach%27s%20web%20project%20folder/eice%20-%20main.htm

Most school buses today have diesel engines.

The NEED Project

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

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

Parallel Hybrid System

Power is stored in the lithium ion 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-c2-propane.asp

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

[email protected]

1-800-875-5029

Energy Information Administration U.S. Department of Energy

www.eia.gov

The NEED Project

NEED IS SOCIAL

Stay up-to date with NEED. “Like” us on Facebook! Search for The NEED Project, and check out all we’ve got going on!

Follow us on Twitter. We share the latest energy news from around the country, @NEED_Project.

Follow us on Instagram and check out the photos taken at NEED events, instagram.com/theneedproject. Follow us on Pinterest and pin ideas to use in your classroom, Pinterest.com/NeedProject.