The HVAC unit can be driven by the APU during rest periods
The truck can be plugged into shore-power electrical service, where fuel consumption to serve these loads can be cut significantly.
Another overall result was that the More Electric Trucks idled less than control vehicles (12.8 versus 26.5 percent) resulting in fuel savings.
The program has achieved some significant results but additional work is anticipated to further reduce fuel consumption. Example areas are mild hybrid storage using nickel metal hydride (NiMH) batteries; advanced cooling system components (electric thermostat valve and cooling fan, high efficiency after cooler); and decoupling the air compressor from the engine.
Finding 6-7. The More Electric Truck program demonstrated an integrated system to reduce idling emissions and fuel consumption. The test program showed significant progress toward achieving the objectives of Goal 2 in Chapter 5 (“Develop and demonstrate technologies that reduce essential auxiliary loads by 50 percent, from the current 20 hp to 10 hp, for class 8 tractor-trailers”) and Goal 6 (“Produce by 2012 a truck with a fully integrated idling-reduction system to reduce component duplication, weight, and cost”). By demonstrating 1 to 2 percent estimated reduction in fuel use including significant truck idling reductions. According to DOE, this translates into an overall annual fuel savings for the U.S. fleet of 710 to 824 million gallons of diesel fuel (about $2 billion per year at $2.75 per gallon).
Recommendation 6-7. Given the potential of this program to save fuel, the committee recommends that the 21CTP continue the R&D of the identified system components that will provide additional improvements in idle reduction and parasitic losses related to engine components that are more efficient and provide better control of energy use. The program should focus also on the cost-effectiveness of the technologies.
Based on the information provided by DOE in presentations, work under this goal is being performed by the DOD. The DOD has two fuel cell APU programs under way: the U.S. Army CERDEC (Communications-Electronics Research, Development, and Engineering Center) fuel cell APU programs focus on diesel and JP-8 fuel reforming coupled with fuel cells in the 500 W to 5 kW auxiliary power range. The U.S. Army TARDEC (Tank Automotive Research, Development and Engineering Center) fuel cell programs focus on combat vehicles and APUs in the range > 5 kW.
The DOD is supporting a variety of companies with various fuel reformers and fuel cells (solid oxide [SOFC] and polymer electrolyte membrane [PEM]). These studies are ongoing, and definitive results toward meeting goal 7 are not available.
Finding 6-8. The work on fuel cell APU is being carried out by the DOD and a number of contractors are being supported. There is no evidence that goal 7 has been met at this time.
Recommendation 6-8. The DOE’s 21CTP should continue to monitor and interact with the DOD program. As DOD reaches its goals, DOE should explore with major truck operators the possibility of bringing appropriate fuel cell APU technologies into commercial use.
Lloyd, Alan, and Thomas A. Cackette. 2001. Diesel Engines: Environmental Impact and Control. Journal of the Air and Waste Management Association 51:809-847.
SAE (Society of Automotive Engineers International). 2004. Primary Single Phase Nominal 120 VAC Wiring Distribution Assembly Design. Truck and Bus Standard No. J2698. Washington, D.C. September.