http://seattlepi.nwsource.com/transportation/203509_metro13.html?source=mypi
***$47 MILLION MORE THAN WE NEEDED TO PAY*** 235 BUSES X $200K MORE THAN THE OLD BUSES
Monday, December 13, 2004
Hybrid buses' fuel economy promises don't materialize
Older models have gotten better mpg
By JANE HADLEY
SEATTLE POST-INTELLIGENCER REPORTER
Expensive new hybrid diesel-electric buses that were portrayed by King County Metro as "green" heroes that would use up to 40 percent less fuel than existing buses have fallen far short of that promise.
In fact, at times, the New Flyer hybrid articulated buses have gotten worse mileage than the often-maligned 1989 dual-mode Breda buses they are replacing. Yet the hybrid buses cost $200,000 more each than a conventional articulated diesel bus.
The disappointing results are a far cry from the rosy predictions made by officials.
In May of this year, when Metro held a public event to herald the arrival of the first of the new hybrid buses, County Executive Ron Sims said they would save 750,000 gallons of fuel a year over the Bredas.
Metro was the first agency in the country to buy a 60-foot articulated bus with a hybrid diesel-electric technology. It ordered 235 of them, 213 for itself for $152 million and 22 for Sound Transit. Metro now has the largest fleet of hybrid buses in the world.
Hybrid diesel-electric buses use a battery-powered electric engine to assist a diesel engine. The batteries, carried on top of the bus, are charged both by the diesel engine and by capturing energy from braking action. The electric engine is especially valuable during acceleration from 0 to 12 mph, when a diesel engine would otherwise be gulping fuel, said Michael Voris Metro's procurement supervisor.
Of Metro's active fleet of nearly 1,400 buses, 1,005 are conventional diesel buses, 210 are hybrid diesel-electric, 144 are trolley buses and 28 are Bredas.
Despite the significantly higher cost and the underwhelming fuel efficiency of its hybrid buses, Metro had little choice but to get them, said Jim Boon, Metro's vehicle maintenance manager. That's because they are the only feasible bus Metro can use when it begins sharing the downtown bus tunnel with Sound Transit's light rail line in 2009.
Besides, the hybrids have their good points, Boon said. The hybrid fleet as a whole is saving $3 million a year in maintenance costs over the Bredas. And they're quieter than regular diesel buses and faster than the Bredas on hills and the highway.
They also have very low emissions -- as do all the new buses Metro is buying these days, hybrid or not.
But the expected fuel efficiency has not been there.
[snip]
Sounds like a design problem.
You mention that these are faster than the old buses on hills and the highway.
This would indicate that these buses are optimized for improved performance with the same horsepower and fuel economy. Specify a smaller engine next time, and performance will drop to the level of the old buses, but fuel economy will increase.
Some of the new hybrid SUVs are being designed that way on purpose- to get more performance for the same fuel usage.
If you spec an engine large enough to maintain highway speeds on steep grades, then you have too much engine to really get the best advantage of the hybrid system. In fact, due to the added weight of the hybrid system, the vehicles will most likely get worse mileage running up and down hills at highway speeds.
And you noted that the maintenance savings are $3 million per year. That buys a LOT of diesel.