Although it can be tricky to save fuel using hybrid technology, government fleet managers are finding other ways the vehicles can contribute to the bottom line. Utilities and transit agencies are using hybrids to reduce emissions, noise and maintenance costs.
Hybrid vehicles are designed to reduce the fuel consumption of cars, trucks and buses by mating a gasoline or diesel engine to an electric motor and battery pack. However, hybrids only save fuel in stop-and-go driving, when the electric motor powers the vehicle at a low speed and then helps with acceleration.
“The critical focus is on this technology’s economic viability,” says George Survant, director of fleet services for Miami-based Florida Power & Light (FP&L). The utility is purchasing 20 hybrid utility boom trucks — diesel-electric hybrid vehicles combining a six-cylinder diesel engine — from Warrenville, Ill.-based International Truck & Engine with a hybrid-electric drivetrain developed by Cleveland-based Eaton.
Fuel economy was the rationale when FP&L first considered purchasing hybrids, but the utility saw other advantages in reducing vehicle noise and emissions. “Most emission solutions add cost, whereas the hybrid option can reduce cost by burning less fuel, benefiting our shareholders and customers alike,” Survant says. “The wear-and-tear savings are going to be one of the pleasant surprises from hybrid technology, right up there with noise reduction. We get a real good reception in residential neighborhoods when we arrive to restore power — and they’re going to be even more delighted when we do that without waking the babies.”
Allen Schaeffer, executive director of the Frederick, Md.-based Diesel Forum, sees advantages beyond fuel economy. “There’s a real sea change going on where diesels are concerned,” he says. “A typical diesel-only city bus averages a road call every 1,700 to 2,000 miles of operation. With these diesel-hybrids, the average jumps to 7,000 miles.”
Transit buses are one area where hybrid technology is taking off, even though the anticipated fuel savings do not always materialize. For example, King County Metro has purchased 235 buses from Winnepeg, Canada-based New Flyer Industries to serve routes in the Seattle area. The buses’ diesel-hybrid system was expected to improve fuel economy by 60 percent, saving the county an estimated 750,000 gallons of fuel per year.
The Seattle Post Intelligencer reported slightly poorer fuel economy — 3.6 miles per gallon (mpg) versus 4 mpg from diesel-only units. That is largely because the hybrids were placed on longer-haul suburban express routes that are the antithesis of the stop-and-go environment where hybrid technology saves the most fuel, according to Jim Boon, Metro vehicle maintenance manager.
At a cost of $645,000 each — approximately $200,000 more than a new diesel bus — hybrids might not seem like a wise investment. However, Michael Voris, the agency’s procurement supervisor notes that the electric engine is especially valuable during acceleration from zero to 12 miles per hour, when a diesel engine would otherwise be burning the most fuel and getting the most wear and tear on its components.
Boon says that Metro’s hybrid fleet is saving $3 million a year in maintenance cost over the older diesel-only buses they are replacing. He also says they produce far less noise than diesel buses and accelerate much better on hills and highways because of the electric motor power.
Houston Metro Transit is adopting hybrids by buying four 40-foot hybrid diesel-electric buses from Detroit-based General Motors (GM) with a grant from the federal government’s Clean Cities/Clean Vehicles program. The city is a non-attainment area, meaning that its air quality is extremely poor, so the agency will use the buses to help reduce emissions. GM’s hybrid bus produces much lower hydrocarbon and carbon monoxide emissions than conventional buses, lowering particulates, hydrocarbon and carbon monoxide emissions by up to 90 percent and nitrogen oxides by up to 50 percent, the agency says.
The Capital Metropolitan Transportation Authority of Austin, Texas, also is testing GM’s hybrid buses. “The key is that these [hybrid] buses are quieter, more efficient and have much lower emissions than their diesel counterparts, without losing any performance,” says Fred Gilliam, president and CEO of Capital Metro.
The diesel engine on Capital Metro’s hybrid buses powers an electrical generator, which, in turn, charges a battery pack on the roof. The batteries then power an electric motor that turns the wheels with the bus switching automatically between battery power and diesel power depending on speed and torque. The vehicle moves on battery power alone from zero to 20 miles per hour, and the batteries recharge when the vehicle is not accelerating.
“The hybrid’s clean diesel engine is significantly smaller than traditional buses, closer to the size of a large pickup truck,” Gilliam says. “Any vehicle emits the most pollution when it accelerates from a stop or goes up hill. The hybrid bus uses electric power from its batteries when it accelerates, eliminating the excessive dark cloud that an accelerating vehicle typically emits.”
Cutting fuel costs are a top priority for New York City Transit, which recently ordered 325 hybrid buses from Mississauga, Canada-based Orion Bus Industries. The buses are equipped with a HybriDrive propulsion system from United Kingdom-based BAE Systems. The fleet operates 4,373 buses traveling more than 107 million miles using 38 million gallons of gasoline per year.
A New York City Transit hybrid bus study determined that the vehicles would help cut fuel costs. In the study, diesel buses averaged 2.42 mpg, while the hybrid buses averaged 2.65 mpg. That translates into 45 cents worth of diesel per mile for regular buses, while the hybrid buses used 39 cents of diesel per mile, for a savings of about $6.4 million dollars per year. Hybrid buses are expected to consume slightly higher amounts of oil — between 0.72 and 0.22 quarts per thousand miles — adding about $15,000 to $50,000 more per year in oil costs.
The buses feature a regenerative braking system, which uses the drive motor to slow the bus, effectively turning the motor into a generator to help recharge the energy storage system. That feature saves energy and also lessens brake wear — thus reducing the frequency and cost of brake maintenance.
Indeed, as the cost of crude oil reaches new highs, fuel savings may once again become the main reason for purchasing hybrids. But unlike fluctuating fuel prices, lowering emissions, decreasing maintenance cost and quieter operation provide buyers all the reasons they need to consider hybrids for the long run.
Sean Kilcarr is senior editor at American City & County’s sister publication, Fleet Owner.
Hybrid truck systems: Who makes what
There are several different kinds of hybrid truck systems, covering everything from sport utility vehicles (SUV) to transit buses. Following is a sample of the different chassis, systems and manufacturing companies.
Oshkosh, Wis.-based Oshkosh Truck is producing a 66,000-pound, heavy diesel-electric hybrid chassis designed for refuse applications, powered by a 300 horsepower (hp) Cummins ISB engine connected to the company’s ProPulse electric drivetrain.
Detroit-based Ford Motor plans to produce a diesel-electric hybrid version of its super-size SUV, the Excursion. The company currently builds a hybrid version of its Escape mid-sized SUV, which operates in electric-only mode when the vehicles travel at low speeds or are idling at a stop.
Warrenville Ill.-based International Truck & Engine is building two medium-duty diesel-hybrid trucks: a four-door crew cab 4700 model truck equipped with a dry van freight body for pickup and delivery operations, and a utility boom truck. The Class 6 crew cab truck uses a 175-hp three-liter inline four cylinder married to a parallel hybrid drivetrain. International’s 4000 Series also provides the base platform for its diesel-electric hybrid utility truck, which couples a DT 466 in-line six-cylinder diesel engine with an Eaton hybrid-electric drivetrain — comprised of a transmission, batteries and permanent magnet motor. The system recovers kinetic energy during braking, charging the batteries while the truck is slowing down and also provides additional power for acceleration.
Detroit-based General Motors is building a 40-foot hybrid transit bus combining a diesel engine with an Electric Drives EP System, developed by its Allison Transmission subsidiary, designed to produce lower hydrocarbon and carbon monoxide emissions. GM also is building hybrid pickups and plans to roll out hybrid versions of its Chevy Tahoe SUV in 2007 using a new dual mode system developed with Stuttgart, Germany-based DaimlerChrysler, which plans to roll out a gasoline-electric hybrid version of its Dodge Durango SUV in 2008.
Toyota is offering a diesel-electric hybrid truck chassis through its Hino Motors subsidiary — the Hino 165 conventional Class 4, a chassis rated at 16,000 pound gross vehicle weight powered by the company’s standard four-cylinder, five-liter diesel. The system includes a proprietary flywheel generator/starter that captures braking force when the vehicle slows, storing it as electrical power in a battery array. The electrical power is then used to augment the diesel on startup, as well as cruising.
Winnepeg, Canada-based New Flyer Industries is building gasoline-electric hybrid 40-foot urban transit buses based on a propulsion system designed by ISE Corporation of San Diego. ISE offers a gasoline-fueled variant of the ThunderVolt drive system, which combines a Ford ultra-low emission V10 gasoline engine, Siemens drive motors and generator, batteries and other hybrid-electric drive components. Benefits include the reduction of nitrous oxides and particulate matter emissions.
Mississauga, Canada-based Orion Bus Industries, a division of Greensboro, N.C.-based DaimlerChrysler Commercial Buses North America, offers a hybrid version of its Orion VII 40-foot bus that uses the HybriDrive diesel-electric propulsion system developed by British aerospace engineering firm BAE Systems to reduce particulate emissions, NOx and greenhouse gases.
DaimlerChrysler also is testing a plug-in hybrid version of its Dodge Sprinter vans that can be connected to an electric outlet at night to recharge the vehicle’s battery pack in addition to the recharging that occurs when the vehicle runs its gasoline or diesel engine. One diesel-electric and two gasoline-electric Sprinters are being tested this year.
— Sean Kilcarr