If you happen to be in Burbank, Calif., later this year you might see - but not hear - Kenworth's T800 waste hauler. To be used by Crown Disposal in Burbank as part of a pilot program, this will be the first Class 8 heavy-duty hybrid-electric truck, a Hybrid Electric Prototype Truck (HEPT) that is said to eliminate the roar of a diesel engine by replacing it with a battery pack for silent electronic operation.

Built by ISE Research Corp., San Diego, in cooperation with PACCAR, Seattle, the parent company of both Kenworth and Peterbilt trucks, the HEPT features a Kenworth T-800B chassis and ISE Research's ThunderVolt 801-H Hybrid-Electric Powertrain. Under the hood is a smaller GM 5.7 liter (350 cid) Vortec V8 converted to operate on compressed natural gas (CNG) rather than gasoline.

The drive motor - a ThunderVolt 400 kilowatt (kW), 536-horsepower (hp) peak/ 325 kW, 436-hp, continuous AC induction motor - receives power from the battery pack. When more power is needed, for highway driving or at a landfill, the motor receives electric energy from both batteries and a generator, which supplies electricity either to charge the battery pack or to the motor. The whole operation is managed by a ThunderVolt 500 KVA modular, variable frequency controller. Also, the ThunderVolt 801-H uses dozens of standard maintenance-free lead acid batteries.

About 75 percent of the time, less than 100 hp is required to operate the truck, so the internal combustion engine (ICE) is sized to provide the power level needed most of the time. Additional energy can be supplied as needed from batteries. When less power is needed from the ICE, the excess power recharges the batteries.

Additionally, the engine can operate essentially at a constant speed and output, which results in maximum fuel economy and minimum emissions. For example, testing of the HEPT showed a 50 percent reduction in fuel consumption and, depending on how it is driven, a 50 percent to 90 percent reduction in emissions compared to a normal truck of this size and capacity. Maintenance costs also were reduced by 10 percent to 20 percent.

There are additional differences between the HEPT and a normal Kenworth T-800. No shifting is required with the electric transmission; steering is done via the ThunderVolt high-efficiency electro-hydraulic system. Furthermore, the ThunderVolt high efficiency electro-pneumatic air brakes feature regenerative braking: Energy produced during deceleration and braking is recouped and used to keep the batteries charged. Electric motors replace belts and pulleys to power items such as the air compressor and hydraulic pumps.

Its top speed is 75 miles per hour (mph), and it can handle continuous grades of up to 15 percent and start on a 22 percent grade. Acceleration is 0 to 30 mph in 15 seconds and 0 to 60 mph in 50 seconds.

When operating in the pure electric mode, the ThunderVolt 801-H has a range of 50 miles in city driving and 35 miles on the highway. Battery recharging takes three to six hours using a 220/440 volt source. If operated in the hybrid mode, the travel range goes up to 300 miles.

Several options are available with the ThunderVolt 801-H, including NiMH (nickel metal hydride) and lithium batteries. Additionally, the ThunderVolt's internal combustion engine, called the auxiliary power unit (APU), can be ordered to operate on gasoline or propane. Or, fleet managers can opt for a Cummins 5.9 liter V8 direct injection diesel operating on diesel or CNG.

The California Air Resources Board (CARB), Sacramento; WestStart-CALSTART, Pasadena, Calif.; the Defense Advanced Research Projects Agency (DARPA), Arlington, Va.; California Office of Strategic Technology, Sacramento; South Coast Air Quality Management District (SCAQMD), Diamond Bar, Calif.; U.S. Army-TACOM, Warren, Mich.; San Diego Regional Technology Alliance; and the University of California, Riverside, all participated in the pilot, as they search for ways to reduce air and noise emissions in the thousands of trucks in operation.

While this pilot was configured for commercial waste hauling, the technology could be adapted to any Class 8 truck. A second prototype also is being built in collaboration with Peterbilt.