exploring hybrid school bus technology. where it started
TRANSCRIPT
Exploring Hybrid School Bus Technology
Where it started
And then
http://content.lib.washington.edu/u?/imlswrvm,61
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• NOx
• 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
http://www.thomasbus.com/bus-models/green-buses/saf-t-liner-c2-propane.asp
An electric motor/generator mounted between the engine and the transmission generates electric power.
Power is stored in the lithium-ion battery when the bus is coasting or brakes are applied.
The vehicle uses stored energy to add power back
into the transmission
when the throttle is
depressed.
If the hybrid system goes
offline for any reason, the bus
automatically switches back to the conventional
powertrain system.
For More Information
The NEED [email protected]
1-800-875-5029
Energy Information AdministrationU.S. Department of Energy
www.eia.gov
The NEED Project