Elk Grove Struggles with Hybrid Buses on Freeways
10 August 2006
The Sacramento Bee reports on problems the city of Elk Grove—on the outskirts of Sacramento, California—is having with using its fleet of series hybrid buses for high-speed commuter transport on freeways.
Performance is not ideal, and the air conditioners in the buses are failing in the triple-digit temperatures baking the region this summer. As a result, e-tran, Elk Grove’s new transit agency, will be buying CNG buses for the freeway routes, and using the hybrids within Elk Grove.
“Hybrid may not be the way to go for commuter service,” said e-tran Transit Manager Carlos Tobar, who was hired to run e-tran more than a month after the start of the new service. ”Live and learn.“
So, what’s the problem with the hybrids? They perform best during stop-and-go traffic, Tobar said. The hybrid’s electric energy booster, an ultra capacitor, works in tandem with a 145-kilowatt generator. That booster is recharged every time a driver applies the brakes.
That’s great for intercity transit, but is troublesome on freeways where brakes are less often applied.“At highway speeds, many of the systems are stressed,” Tobar said.
Elk Grove’s hybrids are remanufactured by Complete Coach Works, using a gasoline series-hybrid powertrain from ISE Corp. The 17-bus e-tran fleet was to be the country’s first 100% hybrid commuter bus fleet.
The ISE powertrain uses a Ford ULEV 6.8-liter V-10 gasoline engine mated to a 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. (Earlier post.)
In the excessive heat this summer, the failure of the air conditioners is a particular problem. The transit agency’s maintenance team has installed new valves and compressors on most of e-tran’s buses and ISE and CCW are tackling reliability issues with the buses—especially the air conditioning.
On days when the temperature exceeds 105, e-tran now provides bottled ice water on each of the commuter routes.
(A hat-tip to Jim Gray!)
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