by Michael Graham Richard via Treehugger.

The B5L Hybrid Double Deck is made by Volvo and uses the company's I-SAM (Integrated Starter, Alternator, Motor) technology, which was developed for use across the whole group's heavy vehicles. No specific figure yet on fuel economy, CO2, or NOx emissions, but a Volvo 7700 Hybrid Single Deck in Gothenburg has been showing better than expected fuel economy (around 30% improvement). London might show even better results since the stops are closer to each other.

Green Car Congress wrote this in 2007 about the Volvo hybrid tech: "The I-SAM (Integrated Starter, Alternator, Motor) parallel hybrid system comprises a starter motor, drive motor and alternator fit between the clutch and the I-Shift automatic transmission. It supports regenerative braking; electric launch and assist; electrification of power steering, air compressor and airconditioning; and idle avoidance."

The hybrid bus can move up to 12 MPH in all-electric mode, and over that the diesel engine kicks in. One of the main benefits of the hybrid system in an urban area will certainly be the reduced smog-forming emissions. We hope that Volvo will update us soon with those numbers.

How About Natural Gas Hybrid Buses?
But to go even farther in that direction - short of an all electric battery or fuel cell bus - would be to have a CNG (compressed natural gas) hybrid bus. Such a bus (they exist) would certainly have very low PM and NOx emissions compared to even diesel hybrids, which is crucial in urban areas. And if the natural gas could be sourced from methaned captured in a landfill, it would even be close to carbon neutral. Are you listening, Volvo?