Hybrid buses fuse more than electricity, gasoline
Reduced emissions, increased fuel efficiency, less noise, a smoother ride, better brake life and lower operator fatigue combine to make hybrid buses the wave of mass transportation's future.
But are they really affordable?
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| Photo courtesy of Capital Area Transit Authority |
People might soon notice something a little different about buses in their city — a battery pack. How come? To supply electricity for its hybrid engine.
“Emissions, fuel economy, noise, improved performance, reliability, longevity of components, that’s a long shopping list, but it can be achieved with hybrids,” said Jim Boon, manager of vehicle maintenance at King County Metro, which services the greater Seattle area. KCM, like many other transportation authorities, has integrated hybrid electric buses into their fleets.
Hybrid buses operate on electricity at low speeds, diesel or gasoline at high speeds and a blend of the two in between. The electricity required to propel the vehicle is captured through regenerative braking, a process that captures the energy released during braking and stores it in battery packs atop the buses.
Hybrid technology increases fuel efficiency by 20-40 percent and reduces emissions by up to 90 percent, compared to conventional diesel buses.
KCM was a pioneer in introducing hybrid technology to mass transit. After receiving only positive results from testing the hybrid technology over a one-year period, they incorporated 236 hybrids into their fleet in 2004, the largest group in operation today.
Why the progressive move? Seattle has a tunnel running under its central business district that desperately needed newer buses running on it. The transportation authority saw hybrids as a way to lower emissions and noise in the tunnel.
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This new hybrid electric bus is the newest member of CEO Sandy Draggoo's fleet at Capital Area Transit Authority in Lansing, Mich. Photo courtesy of Capital Area Transit Authority |
Lowered emissions, better fuel economy and reduced noise pollution are not the only benefits that transit authorities see in hybrids. Capital Area Transit Authority, which services the greater Lansing, Mich., area, is expecting better brake life with the three new hybrids that use the EV Allison drive unit they introduced this fall.
According to Director of Maintenance Craig Allen, “This is due to the regenerative braking actually slowing the vehicle down versus the mechanical brakes application.” Allen said some owners are not expecting to replace the brakes in the 12- to 16-year operation of the vehicle, where a normal bus would need new brakes every 30,000 miles.
Besides scheduled maintenance, Allen said the hybrid buses have not been in the shop once. KCM is also seeing better reliability with they hybrid fleet. The hybrid technology is “just as reliable as a conventional diesel and over a long period of time will prove to be a lesser-cost vehicle to own,” Boon said.
He does not expect to rebuild the engine in the life of the vehicle. The electric drive unit is proving reliable because it replaces the transmission, which normally produces a lot of heat that causes wear and tear on the engine.
Boon also said: “This is good, solid technology. There are no gimmicks to keeping the bus running at a high level of availability. There are no impacts to shop infrastructure.”
Some disagree.
John Andoh, assistant transit manager with Elk Grove Transit outside Sacramento, said they have had some problems with their aluminum Ford V-10 engines. Unlike the New Flyer buses that KCM and CATA operate, which use CAT C9 and Cummins ISl engines, Elk Grove Transit experienced some part defects.
“Nobody has come out and said that the engine is the wrong type for [that model hybrid], but our best educated guess is that it is not,” Andoh said. Andoh also noted that the engine compartment is crowded and there are more parts, which makes routine maintenance difficult and time consuming.
Despite the problems, Elk Grove Transit has had great reactions from their passengers. The company posted a 77.6 percent increase in riders in the first quarter of 2006, compared to the same quarter a year earlier. According to Andoh, that’s the greatest quarterly increase in passengers among all public transit operators in the United States.
According to Andoh, the community has “been supportive, and it’s great to see so many residents attracted to [hybrid] transit as an alternative to auto trips.”
Boon said KCM has seen a lot of good will from the public. “They think we are real smart for doing such a timely thing,” he said. Passengers have also reported liking the reduction in noise and the smoother ride, since the bus does not shift.
Drivers are also pleased with the performance of the hybrid buses. Boon said they like the faster acceleration and regenerative braking. He suspects they are also experiencing less operator fatigue with dynamic braking. “We have one phase of the dynamics braking built into the throttle pedal so when they lift their foot off the throttle, it will actually slow the bus without having to depress the brake pedal,” Boon said. With this arrangement, operators may never have to touch the brake pedal.
During an all-driver training orientation for the hybrids, Allen told operators it is nothing different than driving an electric golf cart. He said that they have been well received by everyone who has driven them.
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Sen. Debbie Stabenow, D-Mich., left, and Capital Area Transit Authority CEO Sandy Draggoo speak about CATA's hybrid buses. Photo courtesy of Capital Area Transit Authority |
But there are some drawbacks to hybrid buses. A new hybrid will cost about $500,000, considerably more than a conventional diesel bus. When CATA added its first three hybrids this fall, federal grants paid for 80 percent of the cost.
“Finding the extra capital money is a challenge,” Boon said. “There is not much help from the federal government in that regard.”
But there are cost savings as well.
Boon also said the lower maintenance on the hybrids has led to cutting 24 mechanics, almost 10 percent of the staff.
“Diagnostics on hybrids is very computerized and trouble shooting and repairs are fast,” he said. “Some mechanics don’t like the bus cause they personally have not embraced the computer age.”
Whatever experience transit authorities have had, there seems to be a shift to alternative fuel technologies. Andoh said Elk Grove Transit is purchasing compressed natural gas buses for its commuter fleet, but will consider hybrids for its local service in the future despite their current troubles.
King County Metro is buying 600 buses for replacement and expansion, according to Boon. “If we can afford it, those will be hybrid,” he said. “This is not a test bus, or a bus where you need to buy on for a demo to see if it works; it’s the real deal.”
In 2003, the U.S. Department of Energy’s Energy Efficiency and Renewable Energy Division predicted that in mass transit “hybrids will provide low emission transportation with high fuel economy.”
Three years later, that prediction rings true.
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Karly Pence is a MSU senior double-majoring in journalism and geography. This is her first appearance in EJ. Reach her at pencekar@msu.edu.
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