ATLANTA, Ga. –Since 2002, fuel has crept up from 9% of a fleet’s cost of operating a long-haul truck to a staggering 35%. It has reached the point where fleet managers get giddy over an opportunity to improve fuel mileage by as little as 1%.

But what if there was a way to improve fuel economy by 30% or more in stop-and-go applications or 8% over-the-road, all the while reducing idling and extending brake and engine life? Early users of hybrid trucks say it is possible.

Hybrid-electric drive trucks have been trickling into the marketplace, and are now providing real-world results that have many fleet managers taking notice.

With real-world testing substantiating claims of major fuel mileage improvements, two-fold extensions in brake life and significant idle-time reductions -it looks like hybrids are here to stay.

By now, all the OEMs have at least experimented with hybrid-drive vehicles, and most now have hybrid models in full production. The truck makers have favoured the Eaton hybrid system, which uses regenerative braking to harness kinetic energy produced during braking and then stores it in a battery pack. That energy is then used to help propel the vehicle via an electric motor which works on its own at low speeds and in conjunction with a traditional diesel engine at higher RPMs. It’s a parallel hybrid system, meaning a driver can continue to operate the vehicle via the diesel engine alone should the hybrid system become disabled.

With hundreds of hybrid trucks now in service across North America, the reviews are trickling in: and they’re overwhelmingly positive.

Bill VanAmburg, senior vice-president, WestStart-CALSTART, administrator of the Hybrid Truck Users Forum (HTUF), has been overseeing the use of hybrid work trucks over the past six years. The agency’s goal was to “speed the development and introduction” of hybrids, with its sights ultimately set on reducing the industry’s use of petroleum by 20% by 2020.

Under the HTUF program, 24 hybrid-electric trucks have been put on the road over 18 months. So far, 14 of those vehicles are delivering fuel economy improvements of 54% or more.

“The more work-site time, the better the miles per gallon,” explained VanAmburg, noting the best results were achieved with trucks that run auxiliary equipment such as man-lifts off the electric motor. Perhaps more impressive than the fuel savings, however, was the fact the HTUF trucks have averaged just one mechanical issue per truck every two years.

OEMs have been field-testing hybrid trucks as well, and they are telling similar success stories. At the National Truck Equipment Association’s Work Truck Show, officials from International, Freightliner and Kenworth all touted fuel economy improvements of 30-40%. But there are other advantages as well. In stop-and- go applications, where the greatest fuel economy improvements are achieved, some fleets have doubled, or even tripled, their brake life. This is because as part of the regenerative braking process, the electric motor acts almost like an engine brake, slowing the vehicle down when the driver lets off the throttle.

Jeff Mudget, senior technical engineer with Eaton Corp., says FedEx is running 24,000 to 28,000 miles between brake jobs on its hybrid delivery trucks -that’s double the life of the brakes on its traditional-drive vehicles.

The most impressive results have occurred with vehicles that combine stop-and-go driving with the need for an electronic power take-off (ePTO), such as utility trucks. A traditional-drive truck must idle to power devices such as a man-lift or boom.

The ePTO, however, shuts down the truck’s engine and powers the device almost soundlessly via the electric motor and batteries. When the batteries are nearly depleted, the truck automatically starts up to re-charge the battery pack. This generally takes about four minutes.

Once they’ve been recharged, the diesel engine again shuts down and allows the electric motor and batteries to do the work.

Utility fleets have reported idle-time reductions of up to 87% at job-sites, according to David Bryant, Freightliner’s vocational sales manager, hybrids. Not all applications are suited for hybrid-electric vehicles, however. For instance, an ePTO will not be of much use if the auxiliary device continuously draws more than 15 horsepower, admitted Bryant. And aerial devices taller than 50 feet may also draw too much power to achieve a significant fuel savings. The key is to talk to your dealer to determine whether your application lends itself to the use of hybrid trucks.

Components and packaging

One of the biggest challenges facing OEMs has been simply finding a home for all the additional components that hybrids require. Hybrid systems include several sizeable parts, including: a Power Electronics Carrier (PEC) which houses the lithium-ion batteries and related electronics; a hybrid drive unit which includes the electric motor, automatic transmission, clutch and other components; a motor inverter/controller; and a liquid cooling system, to name a few.

There are other optional devices that may be required for certain applications, such as an auxiliary power generator (APG) and electronic- PTO. The PEC poses the biggest challenge. It houses two high-voltage lithium-ion batteries, harnessing 340 volts of electricity.

Collectively, the hybrid components weigh about 400 lbs, and they take up a lot of space. Fortunately, the electric motor provides 60 hp and 200 ft.-lb. of torque, so operators can spec’ a smaller diesel engine, recovering much of the 400 lbs that’s added by the hybrid system, said Bryant.

Freightliner, for instance, recommends the Cummins ISB, which offers a 490-lb weight savings over its heftier cousin, the ISC.

One of the pleasures of observing the emergence of hybrid systems has been watching the OEMs find clever ways of packaging the extra components while trying to maintain a tidy back-of- cab (BoC) for equipment upfitters.

For its part, Freightliner shortened the fuel tanks on its M2e so the hybrid cooling system could fit neatly behind the tank. With the increase in fuel mileage offered by hybrids, Bryant said most operators won’t be impacted by the 16% reduction in fuel capacity -the truck can still be operated just as long between fill-ups.

The company maintains a clear back-of-cab thanks to its step-mounted diesel particulate filter and muffler with vertical tailpipe. Well almost…the company has placed the motor inverter/controller on the back of the cab, which extends the BoC by four inches, but provides easy access for service.

On Freightliner’s new M2e hybrid beverage truck, the bulky PEC was mounted inside the body along the ceiling where it doesn’t impede payload. Bryant said the PEC can be mounted up to nine feet away from the other hybrid components, without suffering a decrease in voltage.

Mounting the PEC inside the body isn’t yet an option on refrigerated boxes, Freightliner officials told Truck News, and it may interfere with loading if it’s mounted on the ceiling of certain types of bodies.

Peterbilt has taken a different approach. The truck maker placed most of the hybrid components in the 12-volt battery box behind the cab steps, and mounted the PEC on the frame rail for an equally tidy approach.

“We found the body-builders wanted everything consolidated in the battery box,” explained Chris Wehrwein, senior design engineer with Peterbilt. The components can be mounted in various locations, depending on the need of the operator. The PEC comes with a nine-foot leash, which offers some flexibility.

Greg Loew, market manager, hybrid vehicles with Altec Industries, a manufacturer of aerial devices, said upfitting equipment to hybrids has not been without its challenges. First, the company had to ensure there were no operational differences for utility workers.

“It’s critical the operator doesn’t notice a lot of difference,” said Loew. “There needs to be a smooth transition fr
om one to another. We needed to add new things so when a guy grabs the pistol grip he’s been grabbing for the last 20 years, it functions exactly the same way.”

Installing equipment onto a hybrid chassis took some getting used to, and Loew said the company had to dedicate a special bay for upfitting equipment onto hybrids -trying to do it on the assembly line was causing too many slowdowns. Another challenge has been educating customers that not all applications are suited to hybrid trucks.

Digger derricks, for instance, use so much battery power that Loew said “batteries are going to last 30 seconds to a minute, and you’re not going to get the engine-off time that you need.”

Cost

With fuel savings often exceeding 50% and idle-time reductions of 80% in some applications, one may wonder what’s holding the industry back from the more widespread adoption of hybrid vehicles?

That can be summed up in one word: Cost. OEMs offering hybrid vehicles were surprisingly candid about the price, when asked recently at the Work Truck Show in Atlanta. Eaton’s hybrid system adds between US$40,000-$45,000 to the price of a chassis. If you require ePTO capabilities, you can tack on another $15,000.

“Cost is not a show stopper, they’re still ordering our trucks,” said Judy McTigue, medium-duty marketing manager, Kenworth Truck Company.

“We’re all fighting the same battle,” admitted Freightliner’s Bryant, when asked about the cost. “Right now, it’s a bugger.”

In the US, it’s a little easier to swallow a $60,000 up-charge, thanks to government incentives. Up to $12,000 in federal tax incentives are available for Class 7 hybrid purchases, and that can be topped off with state or local funding in at least nine states. Some US carriers have been able to cover the entire cost premium through government incentives, enabling them to enjoy an immediate payback.

Here in Canada, no such government grants or tax breaks currently exist specifically for hybrid commercial vehicles. Peterbilt’s Wehrwein said even without government help, a payback can be achieved in the right application. Utilities for instance, which benefit not only from improved fuel mileage and brake wear, but also from an 80% idle-time reduction while operating their truck-mounted boom, are perfect candidates for hybrids. Peterbilt projects a return-on-investment within three years in utility applications -not bad, consider ing the typical life-cycle of a utility truck is five to seven years. But customers are demanding even faster paybacks, according to Kenworth’s McTigue.

“Customers want a two to three year return on investment,” she said.

Then there are those companies that are motivated not by cost reductions, but by corporate-driven environmental values.

That’s the case with most early adopters of hybrid trucks, said Dan Kratz, truck operations manager for GE Capital Solutions. He said he fields calls every day from companies looking to ‘green’ their fleet operations as part of a corporate objective.

“The main push is corporate mandates,” he said. “That’s the major portion of what we’re doing. As far as the tax implications, they love it, but the real driver is the corporate mandate.”

Once a fleet has come to terms with the increased purchase price, there are other maintenance costs to consider as well.

The PEC contains a filter which must be changed twice a year. The filter costs about $15, said Josh Lepage, sales manager, product integration with International Truck and Engine. But beyond that, there’s not a lot to worry about. Synthetic transmission oil can last up to 500,000 miles and the batteries are designed to last six to eight years, depending on duty-cycle and weather.

But those lithium-ion batteries will lose power gradually, and when they do give up the ghost entirely, they cost about US$5,000 to replace.

Lepage said OEMs are looking at exchange programs as well as remanufacturing options for batteries. Batteries remain the weak link in the hybrid chain; they are expensive, heavy and offer a finite power supply.

Kratz pointed out fleets also have other concerns preventing them from leaping onto the hybrid bandwagon.

Parts and labour availability, for instance, could be an issue.

“Are dealers going to stock parts? For some of the units there may be a reluctance to,” Kratz suggested. He also pointed out many dealers remain uneducated about how to sell and service hybrid vehicles. And then there’s the question of resale value.

“Is there a demand for used hybrid trucks? We don’t know, they haven’t been in the market long enough,” Kratz said. He pointed out stripping a chassis of its costly hybrid components before resale is not ideal.

On the road

I had the opportunity recently to test drive several medium-duty hybrid trucks on Atlanta’s city streets. They included: a Freightliner M2e beverage truck; an International 4300 utility truck; and a Peterbilt 335 utility truck. All were Class 7 vehicles and each featured Eaton’s hybrid-electric system.

Hybrid-electric drive trucks certainly provide a unique driving experience. Although engineers urged me to drive each of the vehicles “just like any other truck,” the driving experience was vastly different. Not better or worse – just different.

Central to the Eaton hybrid system is its proprietary AutoShift transmission, which takes shifting out of the equation. I simply released the air brakes, pushed the ‘D’ button for drive and was ready to roll. The AutoShift routinely starts out in second gear, but you can over-ride this if need be by switching the transmission to manual mode and selecting first gear. I never found this to be necessary.

When I first let off the brake, the vehicle crept forward, powered solely by the electric motor, which emitted a soft whine.

The diesel engine remained at idle as I exited the garage. The beauty of the electric motor is that it offers full torque immediately upon depressing the throttle. Think of it as a light switch, when you ask for power, you receive it instantly.

International’s Lepage said a hybrid truck can reach 60 mph nine seconds faster than a traditional-drive vehicle. I wasn’t going to be hitting 60 mph on the short test route in downtown Atlanta, but I don’t have any reason to doubt him.

“You get that 60 hp (provided by the electric motor) immediately when touching the gas,” Lepage reasoned. Indeed, the electric motor was very responsive. This is a characteristic of hybrids which is undoubtedly welcomed by drivers who make frequent stops and starts, which most hybrid operators are likely to do.

As my speed crept up to 12 mph, the diesel engine was still at idle. But once I crossed a threshold (at about 600 RPM), the diesel engine roared to life, spooled up to match the speed of the electric motor and then the two worked in unison to power the vehicle. At that point it drove like any other medium-duty truck, until I let off the throttle, that is.

When I let off the gas, the electric motor immediately began bringing the vehicle to a halt. You can’t coast along like you would in a traditional-drive vehicle. It’s almost like someone threw a sail out behind the truck. This takes some getting used to, but it lends credence to the claim that brake life can be extended dramatically compared to traditional-drive trucks. I let the electric motor slow me down entirely when approaching stop signs and red lights – the only time I stepped on the brake pedal was to come to a complete stop and maintain my position.

As the motor slows the truck down, it harnesses power which is transferred to the batteries housed in the PEC. That power is then used to help launch the vehicle the next time the throttle is applied, saving fuel in the process, as well as wear and tear on the diesel engine.

Another impressive feature of the Eaton system is its “hill hold” capability. I stopped the vehicle on a steep incline and found that the truck did not try to roll back like you
‘d expect it to. No fancy footwork is required when you want to continue on your way.

The M2e beverage truck that I drove had already accumulated 50,000 miles, yet the inside of the smokestack was a real testament to cleanliness of the vehicle. The inside of the stainless steel stack still gleamed – maybe it’s time we reconsider the term “smoke” stack.

Unlike the Freightliner, both the International and Peterbilt utility trucks featured an ePTO and auxiliary power generator (APG).The ePTO is used to power equipment such as a man-lift while the APG provides AC power for other devices. (If the hybrid system is too quiet for your liking, you can plug a stereo in there).

Both the ePTO and APG can be activated by pressing a button on the shifter inside the cab. Eaton engineers allowed me to play with the ePTO to demonstrate how quiet it is. The outriggers and lift could be operated by the electric motor alone, which made for nearly soundless operation.

I’m told this is appreciated by work crews, who can now communicate with each other in a normal tone of voice rather than via walkie-talkie.

Depending on how much strain you put on the batteries, the electric motor could power truckmounted equipment for minutes or hours. Typically, after about 30 minutes of use, the truck’s engine restarts and juices up the batteries.

Of the trucks I drove, only the Pete 335 had a dash display to show exactly how the hybrid system was working. The truck I drove had a rudimentary screen, but Wehrwein said production models will come with full-colour screens and snazzier graphics.

The display featured power graphs that indicated the amount of energy being driven into the batteries as well as the remaining battery power. They also displayed throttle pressure and fuel efficiency, providing the driver with real-time advice on how to maximize fuel mileage.

What’s next?

As medium-duty hybrids continue their trickle into the marketplace, truck makers have already fixed their sights on bigger things – such as Class 8 hybrids.

McTigue said Kenworth has already started producing heavyduty hybrids based on the T660 platform. While heavy-duty trucks typically don’t undergo rigorous start/stop applications, there are still fuel savings to be had, she insisted.

In fact, McTigue said Kenworth’s heavy-duty hybrid will deliver 10-15% fuel savings in line-haul applications. Meanwhile, the trucks can provide a reduction in idle-time and eliminate the need for an auxiliary power unit (APU) to provide heating, cooling and hotel load power.

Just five minutes of engine idling is required to charge the hybrid system’s batteries, meaning Class 8 tractors can comply with strict antiidling rules in places such as California.

Class 8 hybrid systems are comprised of the same basic components as the medium-duty vehicles, McTigue explained. Peterbilt has designed a heavyduty hybrid based on its Model 386, which has been undergoing real-world testing with Wal-Mart.

The truck was expected to deliver fuel savings of 5-7% as well as a 90% reduction in idle-time when the truck is parked.

Meanwhile, Volvo Group has developed its own hybrid system for Volvo and Mack Class 8 trucks, as part of a partnership with the US Air Force.

The proprietary system utilizes an electric turbo-compound to generate electricity which can be used to power devices such as pumps, fans, air compressors and even power steering and air conditioning, explained Anthony Greszler, vice-president, advanced engineering with Volvo Powertrain North America. This takes strain off the diesel engine, saving fuel in the process. It also eliminates the need for an APU and can reduce idling almost entirely, even while stuck in stop-and- go traffic, Greszler added.

Volvo officials claim their heavy-duty hybrid system will achieve fuel savings of 5-8% in long-haul applications.

Another development that could be on the horizon is the more widespread use of hydraulic hybrids.

The systems offer the same benefits of hybrid-electric trucks while doing away with the burdensome batteries, instead generating power hydraulically.

“Hybrid hydraulics are moving forward,” said WestStart- CALSTART’s VanAmburg. “In the heavy segment, with heavy stop-and-go, hydraulic hybrids are going to be very competitive.”

For now, however, it’s hybrid-electric vehicles that are receiving most of the attention, with the expectation that higher volume orders will help drive down production costs and by extension, purchase price.

“We need production numbers in the thousands,” said VanAmburg. “A self-sufficient marketplace is the goal, but we’re not yet at the tipping point.”

That tipping point may be near, however. Just last month, Eaton announced that Coca-Cola had placed an order for 120 hybrid beverage trucks -the single biggest order of hybrid systems in Eaton’s history.

A few more orders like that, and economies of scale will help eliminate the cost factor entirely. Steve Guillaume, general manager, medium truck group with International, predicted the cost of hybrid systems will decrease 50% by 2010.

If his prediction rings true, the value proposition driving hybrid truck sales will become much stronger, with or without government incentives. •