Long Beach Transit will take delivery of the first of 27 gasoline-electric hybrid buses next month.
The acquisition of the gasoline-hybrid buses, approved in 2003, marks the first volume purchase of transit buses using a gasoline-hybrid drivetrain. Nearly 100 of the gas-electric hybrids are currently on order (including options) by California municipalities for delivery this year.
Manufactured by New Flyer, the 40-foot coaches use ISE’s Thundervolt gasoline-electric series hybrid system. A Ford ULEV 6.8-liter V-10 gasoline engine is mated to a 650V, 150 kW Siemens ELFA generator and motor system. The dual drive motors each deliver 85 kW (114 hp) of power and maximum torque of 450 Nm (332 lb-ft). Energy is stored either in an ultracapacitor or a nickel sodium-chloride battery pack.
The bus can operate on battery power alone for 5–15 miles and in emergency situations. Regenerative braking recaptures up to 30% of daily operating energy.
ISE has fit the drivetrain components into a cradle to enable easier manufacturing and maintenance, while the hybrid controller and the energy storage is mounted on the roof of the coach. This is the same cradle configuration that ISE is using in its test of a hydrogen-fueled ICE version of this series hybrid. (Earlier post.)
The gasoline hybrid delivers approximately 4.5 mpg—about 30% better than the 3.5 mpg of a standard diesel—and substantially reduces emissions over a conventional diesel bus.
ISE also produces a diesel version of its series-hybrid system, using either a Cummins or Caterpillar diesel engine and the same hybrid control, electronics and drive system. The diesels deliver higher fuel economy (approximately 5.5 mpg in trials with New Jersey Transit), but also produce more emissions.
|ISE Bus Hybrid Systems (g/bhp-hr)|
|Emission||Diesel Bus (nat. average 2003)||ISE Gasoline Hybrid||ISE Diesel Hybrid|
|Fuel efficiency (mpg)||3.5||4.5||5.5|
Because it is a series hybrid system, the ISE hybrid is very different that the GM-Allison diesel parallel hybrid system. I’m looking for test data that would allow us to compare the results of the two approaches.