WILL THIS DOE PROGRAM REALLY RESULT IN BETTER FUEL ECONOMY?
Though the name evokes visions of futuristic vehicles straight out of a campy science fiction novel, the Dept. of Energy's (DOE) “SuperTruck” research program is far more grounded in reality than many may realize. It is expected that technology developed via its patronage will subtly start altering trucking equipment as it progresses.
“This program is really the extension of work we've been doing [on fuel efficiency] for a very long time now; it's not something we just started on,” explains Wayne Eckerle, vice president-research & development for engine maker Cummins Inc., one of the four “core” participants in the DOE's SuperTruck effort.
Cummins and direct partnerMotors Co. already constructed an engineering demonstration vehicle back in September and are now road-testing a range of new technologies and design enhancements geared to boost freight efficiency by 50%. Eckerle notes that this is based on a “ton-miles per gallon” metric.
“The real key to driving fuel economy improvements via this program is working with tractor-trailers as a complete, integrated unit — not just working on the engine, truck, and trailer in isolation from one another,” Scott Newhouse, one of Peterbilt's assistant chief engineers, points out.
Peterbilt is using a Model 587 tractor equipped with a modified Cummins engine to test a variety of new technologies, such as a waste heat recovery system.
“We're combining work on aerodynamics, lightweight materials, engine efficiency, and idle time management all at the same time within a single combination vehicle in order to maximize efficiency gains,” he says.
and Daimler Trucks North America (DTNA), the other two “core” program participants, are also at work putting similar test vehicles on the road.
Ramin Younessi,group vice president for product development & strategy, explains that his company is already hard at work on its second SuperTruck “prototype.” This model is based on a ProStar highway tractor attached to a Wabash trailer modified with a range of aerodynamic improvement systems.
“We built our first prototype about a year ago and are using the second one we're constructing now to refine some of the things we're testing,” he explains. “We're also splitting the things we're testing into two groups. The first one is made up of technologies and design enhancements we can start using now with our current products. The second one is made up of systems we should be able to see in production five or six years from now.”
Derek Rotz, DTNA's senior manager for advanced engineering-NAFTA region, says that his company initially conducted extensive testing on what it considers a “baseline” vehicle: aCascadia equipped with a DD15 engine. The company then measured its performance and energy usage of all relevant vehicle systems under defined test and drive cycles.
“We collected data from these tests and evaluated different SuperTruck scenarios via computer simulations to determine how aggressively each system has to improve in order to reach the overall 50% target,” he says. “This also provided engineers performance targets” to serve as goals during the development of each system.
Now, DTNA is moving into what Rotz calls the “preliminary system prototype” phase.
“We are still analyzing and developing designs using computer-aided engineering tools, and we are starting to build and test prototypes individually on ‘tinker trucks,’” he reveals. “In the optimization phase that will follow, our engineers will integrate all systems onto a single ‘SuperTruck’ and will ensure all technologies work in concert together, resolving any remaining technical trade-offs.”
Kicked off in early 2010, the SuperTruck program is funded under the American Recovery and Reinvestment Act and is administered by DOE's Office of Energy Efficiency and Renewable Energy.
In response to written questions, DOE tells Fleet Owner that total contract value for the SuperTruck is about $270 million, which includes agency funds as well as industry cost-sharing expenses. All of that money is being used specifically to spark significant fuel-efficiency gains for Class 8 long-haul trucks, the agency notes, as they are critical to the movement of the nation's freight, and therefore to economic activity. By DOE's calculation, Class 8 trucks haul about 69% of all freight tonnage and as much as 80% of the total quantity of goods transported, and 65% of all the fuel burned by commercial trucks.
“While Class 8 trucks represent just 6% of the total on-road vehicle fleet, they are 17% of the total fuel demand in the U.S.,” the agency says.
DOE adds that the SuperTruck project hopes to gain 40% of the total improvements in freight efficiency from engine efficiency gains, with the rest coming from other vehicle system improvements such as aerodynamics, light weighting, drivetrain friction reduction, and hybridization.
“To date, vehicle baselines have been established and the technical specifications developed,” the agency stresses. “We expect that at least one industry partner will have demonstrated a brake thermal efficiency of 50% at 65 mph for an engine on a dynamometer before the end of the first quarter of next year.”
Long term, DOE expects some of the technologies developed via the SuperTruck effort to begin entering the market in about four years. Over the next decade, it expects to see an estimated 80% of SuperTruck-related systems in the marketplace.
That dovetails with the timeline of Navistar's Younessi. “One of the technologies we're working on is a turbocharger powered electrically via a waste heat recovery system derived from the main engine's exhaust,” he says. “We see a system like that being production-ready in about five years.”
SUM OF MANY PARTS
Cummins is working on a related type of waste heat recovery system, one that also has a long lead time. This system extracts waste heat from the engine's exhaust via a refrigerant and turns it into energy that powers a turbine, explains David Koeberlein, Cummins' principle engineering investigator on the SuperTruck project.
This turbine does not function as a turbocharger, he explains. Instead, it provides power that relieves the main engine of parasitic loads. Koeberlein says Cummins is aiming to gain a 6% improvement in fuel efficiency from this technology.
Near term, however, Navistar's Younessi believes ongoing work with composite materials and new aluminum components will be more rapidly applied to current tractor designs, as well as aerodynamic advances.
“Tractors are about as aerodynamically efficient as we can make them. The real gains are coming from aerodynamic improvements to the tractor-trailer as a single unit,” he explains. “That's really where it's at right now, especially in terms of managing the drag created by the gap between the tractor and trailer, as well as the trailer's shape itself.”
Navistar is working with trailer maker Wabash and ATDynamics on aerodynamic improvements to tractors and dry van trailers in unison to help drive fuel economy gains. Andrew Smith, founder & CEO of ATDynamics, says what's helping speed up the pace of improvement is the opportunity afforded by working in conjunction with engineers across the trucking spectrum alongside scientists in DOE research facilities.
“The SuperTruck program takes an overdue look at how to maximize fuel economy of the tractor-trailer combination as a single unit,” he explains. “We're also breaking down the ‘silos’ that exist in the industry, allowing engine, truck, trailer, and design engineers of all stripes to work together — an opportunity that really hasn't been there before. In a lot of ways, we're resurrecting [design] concepts constructed years ago, bringing them to reality because of the tools and facilities we have available through this program.”
DTNA's Rotz says it's the engineering work along with significant cross-category synergies that are occurring that really make the entire SuperTruck project the “sum of many parts.” He also notes that vehicle systems under investigation include but are not limited to external aerodynamics, lightweight materials and designs, powertrain and driveline efficiencies, low rolling resistance tires, hybridization, predictive technologies, vehicle auxiliary load, and idle reduction systems.
Engine systems under investigation for further improvement include the base engine's performance, engine parasitic losses, engine controls, aftertreatment, and the incorporation of a waste heat recovery system.
“The 50% freight efficiency improvement is, in itself, a very technically challenging target to reach,” says Rotz. “Each vehicle and engine system under development can be characterized as complex and entails a large degree of technical uncertainty and requires rigorous testing. Moreover, building multiple new technologies into a single prototype vehicle adds additional complexity. New integration challenges arise as trade-offs need to be understood and resolved to ensure everything functions and operates efficiently.”
Aerodynamics provides a good example, he points out. “Numerous devices can be attached to the tractor and trailer in order to reduce drag and hence improve fuel economy, but pose operational challenges without thoughtful design,” Rotz says.
For example, closing the tractor-trailer gap is an effective drag-reducing strategy but has implications regarding axle loading, back of cab access, and maneuverability — all of which need to be addressed simultaneously within the overall design.
“A boat-tail at the trailer door is also aerodynamically effective, but we need to consider ease of loading and unloading, and so on,” Rotz adds. “Ultimately, the adoption and acceptance of any of these [SuperTruck] technologies hinge on their impact to customer operations and maintenance practices, so it is essential for these aspects to be factored into any commercial product.”
To that end, many of the SuperTruck project's “core” participants are working closely with select customers to get ready for the next stage of prototype development.
Peterbilt, for example, is working closely with U.S. Xpress Enterprises to obtain feedback on how best to incorporate new technology and tractor-trailer design changes in order to maintain — or better yet, improve — ease of operation and maintenance.
“The plan for 2013 is to get the next stage of vehicle into their hands for real-world testing,” explains Peterbilt's Newhouse. “The requirement of this program is that these tractor-trailers spend 75% of their time in highway operation and that's what we'll get with our fleet partners.”
DTNA's Rotz adds that his company also intends to collaborate with customer partners in field operational tests as well, once SuperTruck technologies reach, in his words, “an adequate maturity level.”
“We're evaluating driver acceptance and maintenance requirements as part of the SuperTruck development process,” Rotz says. “Our customer partners provide valuable feedback on how vehicles are operated and maintained, and also weigh in on the technologies under development. The strategy is to incorporate these insights into the SuperTruck design to minimize any impact to their operations.”
“We're definitely taking maintenance needs into account,” adds Cummins' Eckerle. “The goal is to stay fairly consistent with current maintenance intervals and operating patterns. For example, if we add aerodynamic covers to a trailer's landing gear, we'll include a door or other ‘quick release’ method to give technicians easy access to that component for any required service or repair needs.”
The only changes he expects might be made are those that reduce maintenance intervals or service requirements.
“In many cases today, maintenance is conducted on a mileage basis,” Eckerle says. “If the power consumption of the engine is reduced by eliminating parasitic loads and improving aerodynamics, not only are you going to burn less fuel, you'll reduce wear and tear on components. Thus, one question we may need to ask for some systems will be, are mileage-based service intervals still going to be applicable?”
The key point to remember in all of this, however, is that none of what's being worked on should be considered “science fiction,” says Vinod Duggal, a research scientist working as a consultant with Cummins on the SuperTruck program.
“We've been working on aerodynamics and waste heat recovery strategies for years; this [SuperTruck] is not a science project,” he stresses. “This is an effort to develop commercially viable methods to improve Class 8 fuel efficiency.”
In the end, that could be the biggest challenge the participants in the SuperTruck project must surmount, says Cummins' Eckerle.
“Our biggest technical challenge is really getting the costs for any and all of the technologies and systems we're working on down to where the fleets will want to buy them,” he explains. “They need to be durable and reliable, of course, but in the end they must offer a way to reduce total cost of ownership in order for the customer to use them.”