Hybrid propulsion is a future technology that is quickly becoming today’s reality. Just a few years ago in our King County fleet we had only a handful of hybrid cars. Now, we operate dozens of cars, more than 200 hybrid buses, and will soon expand our green technology to include these new hybrid trucks. Working together with our regional partners and the EPA, we are bringing this cutting-edge technology into the mainstream here in the Pacific Northwest.

—King County Executive Ron Sims

The Consortium is working with CALSTART-WestStart which has developed a hybrid truck commercialization strategy with the US Army Tank Automotive Research Development and Engineering Center, truck manufacturers, technology companies and fleet users. (Earlier post.)

The drive system in the International-Eaton utility trucks developed with the CALSTART-WestStart Hybrid Truck Users Forum Utility working group is a parallel hybrid configuration, with a 44 kW permanent magnet motor mounted directly in front of the transmission, behind the engine and clutch.

Power from the engine is used to drive the conventional drive-train directly or converted into electrical energy and stored for use as needed. Electric torque can be blended with engine torque to improve vehicle performance and to operate the engine in the most fuel-efficient range for a given speed or to operate the vehicle with electric power only. The system recovers kinetic energy during braking, charging the batteries while the truck is slowing down which provides additional power for acceleration. This truck is also able to operate the utility bucket in electric-only mode, with the engine-off, significantly contributing to the improvement in fuel economy.

Compared to conventional utility vehicles, the diesel-electric utility trucks will produce nearly 40% fewer greenhouse gas emissions, as well as up to a third fewer emissions that contribute to soot and smog. The new hybrid technology could also add up to 60% in fuel economy.

Roughly one-third of the fuel economy improvements come from the driving part of the duty cycle, with the other two-thirds coming from the on-site work component of the duty cycle (shutting the engine off at the work site).

King County formed the Northwest Hybrid Truck Consortium in November 2005, which includes King, Pierce, Snohomish and Thurston Counties; the cities of Bellevue, Renton, Tacoma, Seattle, Kent, Richland, Bremerton and Everett; Seattle Public Utilities and the Washington Department of Natural Resources.