Allison Hybrid Bus
The GM Allison Hybrid Bus is a 40-foot transit bus that features
the Allison Electric Drives EP SYSTEM, making it one of
the first large vehicle commercial hybrid parallel systems featuring
a diesel-electric hybrid power-train. Allison Transmission,
a unit of General Motors, in partnership with the U. S. Department
of Energy, developed the propulsion system under the DOE's Advanced
Heavy Hybrid Propulsion System (AH2PS) Program.
When the bus takes off from a stop, one thing you won't
notice is a large puff of black smoke coming from the rear
of the bus. This is because GM Allison Hybrid Bus is a full-hybrid,
meaning the electric motor will propel the bus at low speeds
and only at higher speeds does the diesel engine kick in.
The diesel engine is also used to recharge the battery pack
along with the regenerative braking system.
Currently the Allison hybrid buses are used to carry passengers
in Seattle, Philadelphia, Minneapolis, Portland, Salt Lake
City, Austin, Hartford, Houston and Orange County, California.
According to GM, the Allison Hybrid Bus delivers up to 60
percent better fuel economy than the conventional diesel
systems used in city buses.
There's even better news from the National Renewable
Energy Laboratory, "AH2PS Program has awarded a
$9 million, cost-shared, three-year subcontract with Allison
Transmission, General Motors Corporation. As part of the 21st
Century Truck Partnership (under the FreedomCAR Program), the
project will develop and validate advanced, next-generation
heavy hybrid propulsion components and systems to significantly
increase fuel economy in medium- and heavy-duty vehicles. The
project will also advance this technology's development toward
the DOE's fuel economy goal of 100%, while maintaining the Environmental
Protection Agency's emission standards. AH2PS-developed technologies
are projected to save 20 million barrels/year of oil in 2010
and 250 million barrels/year of oil in 2020."
The GM Allison Hybrid Bus deliver 90-percent less nitrous
oxide into the atmosphere while achieving 50-percent better
acceleration than a bus equipped with a normal diesel power-train.
Tom Stephens, group vice president of GM Powertrain says,
"The parallel hybrid electric system is the most efficient
hybrid architecture available in the world today. In addition
to bringing the benefits of hybrid electric technology to
commercial vehicles, our Allison Electric Drive System is
helping establish hybrid technologies as effective, practical
and commercially viable beyond mass transit applications."
This is right in line with the General Motor's game plan
of introducing hybrid technology to the largest, most fuel
consuming and polluting vehicles first. GM has also developed
hybrid technology for its larger truck and SUV market and
plans to develop hybrid technology for its automobile market
last according to its project schedule.