The National Renewable Energy Laboratory (NREL)
, which is part of the US Department of Energy, has been monitoring the performance of three types of buses in New York City for the past year and now has some results to share. They looked at buses powered by conventional diesel
drive-trains, compressed natural gas
and diesel-hybrids built by DaimlerChrysler.
buses won out by a huge margin. They had 34 percent better fuel efficiency
than the diesels and 60-120 percent better than the CNG buses. The average maintenance cost of the hybrid buses was also 5 percent less than the CNG buses.
The Orion VII buses used a series hybrid design where the diesel engine basically powers a generator as needed and the primary motive force comes from the batteries powering the electric motor. The improved efficiency of the hybrid buses would mean savings of 20,000 gallons of diesel fuel per bus over the 12 year service life of a bus. The stop and go driving pattern of an urban bus is the ideal environment for a hybrid allowing lots of opportunity for regenerative braking to provide maximum efficiency.
[Source: The Auto Channel]