Adding to Existing Fleet of 235
According to the King Country Metro website, the public transit authority that covers Seattle already had 235 diesel-hybrid buses in operation. That number if about to go up significantly; Daimler has just announced that King County Metro placed an order for 500 new Orion VII diesel-electric buses. 93 are to be delivered next year, and the metro took options for 200 more.
Reduction in Emissions
This will make the bus fleet significantly more fuel efficient, reducing CO2 emissions, but the biggest difference will probably be in air quality. Buses, by definition, operate in populated areas, and they drive around the city almost non-stop. A hybrid system is particularly effective in that context and tailpipe emissions of smog-forming compounds can be reduced pretty significantly.
Another benefit is that hybrid buses are more reliable (Daimler doesn't say exactly why, but I suppose it's because there's less wear on the brakes and the engine tends to rev at a more constant speed). Daimler claims that in New York City's fleet, its diesel-hybrid buses were 2.6x more reliable than the regular diesel buses.
Fuel economy goes from about 3.5 MPG for a standard diesel bus to 5 MPG for an Orion VII diesel-electric. This might now sound like much, but that's about 40% better! the lifetime NOx emissions go down by about 20% compared to a regular diesel.
Via Daimler, Autobloggreen
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