Introduction to Hybrid Buses

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Transcript Introduction to Hybrid Buses

Exploring Hybrid School Bus
Where it started
And then,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%)
Particulate matter
Sulfur oxides
Carbon monoxide
Carbon dioxide
Most school buses today have diesel
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 lithiumion battery
when the bus is
coasting or
brakes are
An electric
between the
engine and the
electric power.
The vehicle uses
stored energy to
add power back
into the
when the
throttle is
If the hybrid
system goes
offline for any
reason, the bus
switches back to
the conventional
For More Information
The NEED Project
[email protected]
Energy Information Administration
U.S. Department of Energy
The NEED Project