Utility Trucks
Later this year, hybrid-powertrain units will be fielded to test a promising concept for the nation's utility fleets.
Tomorrow's hybrid utility trucks may not look much different from today's, but will make less noise and fumes, and use 40% to 50% less fuel.
Tom Berg
Equipment Editor
Big change is afoot for the nation's public utility fleets. The engine-driven PTO configuration used on utility trucks for many years will soon begin a transformation to an engine-electric layout, saving considerable fuel and reducing noise and exhaust emissions. It's part of a drive to introduce hybrid powertrains to various segments of trucking.
About 25 of the country's top public utility fleets are cooperating in the effort to design a hybrid electric powertrain that would run digger booms, aerial man-buckets and other tools commonly used by utility crews, according to George Survant, director of fleet services for Florida Power & Light Co. He is leading a "specialty trucks" effort within the Hybrid Truck Users Forum, an information exchange and advocacy group whose members have met three times to hear each other's stories of progress.
The specialty category also includes heavy trash removal trucks. Other categories include beverage delivery trucks, package delivery vans and military vehicles. Two basic types of hybrids — engine-hydraulic and engine-electric — are being developed, and each has advantages. The electric type seems better suited for utility trucks.
Utility fleets are interested in hybrids because of their economic promise and public relations value, says Doug Bailey, staff principal engineer at Alabama Power Co., one of the participants. Engines in hybrid trucks would not have to run as often, which would save fuel and reduce noise. Noise from working trucks is one of the major complaints made by neighbors, even though they want crews working to restore their electrical power as soon as possible. And utility companies expect to be caught up in anti-engine-idling regulations aimed primarily at over-the-road sleeper trucks, Bailey and his colleagues believe.
The first type of hybrid utility vehicle is will be the "27,500 trouble truck," used by crews to repair downed lines and other infrastructure damaged by accidents and storms, and to perform scheduled maintenance work, often in urban settings. The truck usually has a man bucket on a 32- to 45-foot boom, as well as other tools. It's a Class 7 chassis rated at 27,500 pounds, typically runs 100 to 150 miles a day, often pulls a heavily loaded trailer, and spends the majority of a working day at repair sites. There are also Class 8 and Class 5 versions of utility trouble trucks.
In the present mechanical layout, the fast-idling engine turns a power take-off gearbox, which runs a hydraulic pump, which pressurizes fluid to operate the boom and other equipment. With a hybrid electric powertrain, the engine will run a generator to store current in batteries. Electric current will then turn electric motors to run one or more hydraulic pumps, which would run hydraulic gear as now. Stored power would allow the engine to be shut down much of the time, and participants hope this would result in fuel savings of 40 to 50%, Bailey says.
Electric power could also be produced by regenerative braking during a truck's on-street running and stored in the batteries. Some of the power could help launch the truck from stops — the main benefit of hybrids in other trucking applications. Because utility trouble trucks run low miles, this benefit would be limited. Launch-assist might allow a hybrid truck's engine to be smaller than the 200- to 250-horsepower diesel now used in this class of truck, though that hasn't been decided yet.
Participants in the project want the hybrid powertain to produce 25 kilowatts of power, which is enough to run the on-board equipment and perhaps light up a blacked-out neighborhood while crews work to restore grid power, Bailey says.
Shutting off the main engine while working with stored electric power brings up a safety concern: If stored power unexpectedly runs down and the engine won't restart, anyone up in a bucket is stuck there. Today's trucks cover the engine-off scenario by reserving one battery for cranking the engine. A hybrid truck might use the same fail-safe scenario.
The specialty trucks group is refining a request for proposals that will be sent to suppliers. The RFP should be done by early spring. It expects bids soon thereafter, and plans to order 12 to 15 hybrid utility trucks by mid-summer, Bailey says. These will be spread around the country for use by participating companies. If the trucks prove out, more orders will be placed in 2005 and later.
The group will list what it wants the trucks to do, and leave exact specifications up to suppliers. Among other things, the trucks must perform the same work that today's utility trucks do, be easy for crews to drive and operate, and perform the same on the road. It's likely that hybrid components can be bolted onto standard Class 7 truck chassis, which can then be sent to an upfitter for installation of bodies and equipment.
The resulting truck will likely be a "parallel hybrid," which can run on either engine or electric power or both. Most electric parts are proven, off-the-shelf items; the electronic controls will be the most complex component. Users want the truck to be able to operate with the engine alone if the "new technology" fails, Bailey explains.
Because of considerable information sharing between users and suppliers through the Hybrid Truck Users Forum, the group expects definite bids from at least two suppliers. Both have built prototypes and working chassis for civilian and military customers.
Thanks to the forum, the specialty trucks group is piggybacking on development done by suppliers for the U.S. Army, which is spearheading the move to hybrid trucks for all military branches. Army participants have told civilian members of the forum that they should take advantage of the military's investment in the technology.
Civilian orders will in turn help military proponents sell skeptical Pentagon brass on the hybrid truck concept. The specialty truck group's members say they have the commitment of top company executives — a must if this or any other new technology is to succeed.
