16 November 2011

The National Academies published a review of the 21st Century Truck Partnership, a US public-private R&D initiative aimed at reducing fuel consumption and emissions from heavy-duty engines and vehicles. The review was conducted by a committee appointed by the National Research Council (NRC) and chaired by professor John Johnson of the Michigan Technological University. This is a second (Phase 2) review report of the program, following a Phase 1 report completed in 2008.

The objectives of the 21st Century Truck Partnership (21CTP) include development of a truck engine of 50% brake thermal efficiency (BTE) by 2015 (re-scheduled from the original 2010 deadline) and 55% BTE by 2018 (originally by 2013). The current flagship program under the 21CTP umbrella—the SuperTruck Program—aims to achieve (1) a 50% increase in vehicle freight efficiency (ton-miles per gallon) which translates to a 33% reduction in load specific fuel consumption (gallon per ton-mile), (2) achieve at least 20% improvement through engine efficiency development and achieve 50% BTE under highway cruise condition, and (3) evaluate potential to achieve 55% BTE. Three SuperTruck projects (Cummins, Daimler, Navistar) will receive 21CTP funding over the period 2011-2014. Each of the projects will integrate a number of technologies (such as efficient engines, waste heat recovery, aerodynamics, rolling resistance and weight reduction) into a Class 8 long haul freight demonstration truck.

The 21CTP is a cooperative R&D partnership including four US federal agencies (DOE, DOT, DOD and EPA), and 15 industrial partners (Allison Transmission, ArvinMeritor, BAE Systems, Caterpillar, Cummins, Daimler Trucks North America, Detroit Diesel, Eaton, Honeywell, Navistar, Mack Trucks, NovaBUS, Oshkosh, PACCAR, and Volvo Trucks North America). The main leadership in the Partnership resides with the DOE’s Office of Vehicle Technologies.

During 2009 and 2010, the program received funding under the America Recovery and Reinvestment Act (ARRA). These ARRA funds have significantly enhanced the ability of the 21CTP to meet and demonstrate its goals in prototype vehicles—concludes the Phase 2 report—as the steady decline of funding levels from FY2003 through 2007 was threatening the attainment of program objectives. As an overall recommendation, the report finds that the 21CTP should be continued to help meet the nation’s goal of reduced fuel consumption in the transportation sector.

The report includes a number of specific findings and recommendations for the program’s major focus areas. Some of these conclusions include:

  • Engine Systems And Fuels
    • The 21CTP should continue to provide important enablers for the 55% BTE goal and the DOE should ensure that the engine R&D for the goal of 50% BTE at over-the-road cruise conditions and the goal of 55% BTE in an engine in a laboratory receive the appropriate share of the SuperTruck funding.
    • Petroleum will remain the primary source of vehicle fuel for many years to come. Whereas future US gasoline demand is expected to be flat for the next 20 years, diesel fuel demand is expected to grow (necessitating changes in refinery operations). Therefore, the DOE should reinstate its program for advanced petroleum-derived fuels with the objective of maximizing the efficiency of their use.
    • The aftertreatment program within the 21CTP should be continued, and DOE should continue to support the activities of CLEERS (the DOE Cross-cut Lean Exhaust Emissions Reductions Simulations program) that interface with the activities of the aftertreatment technical community at large.
  • Hybrid Vehicles
    • Although the recently adopted GHG emission standards contain test procedures for determining fuel consumption for heavy-duty hybrid trucks, a manufacturer still needs to certify the engine to the EPA criteria emission standards (a procedure that does not recognize hybrid heavy-duty trucks). As partners of the 21CTP, EPA and DOT’s NHTSA should work with California ARB to develop test procedures for the certification process for criteria emissions so that the emissions benefits of hybridization will be recognized.
  • Idle Reduction
    • Idle reduction technologies could provide 6% reduction in overall fuel consumption for Class 8 long-haul trucks with sleeper cabs. The 21CTP should review and potentially revise its idle reduction plans and goals in view of the fact that the proposed 2017 fuel efficiency standards provide an incentive for the adoption of idle reduction technologies.
    • The Delphi solid oxide fuel cell (SOFC) auxiliary power unit (APU) provides several advantages over diesel APUs, but it has significant issues in its current development status. The DOE should reassess the viability of the SOFC APU, particularly for application to the SuperTruck program, considering the following: (1) SOFC APU is still in the laboratory, (2) the low efficiency of 25% versus the DOE goal of 35%, (3) the low 1.5 kW output compared to the typical 5 kW diesel APUs, (4) the disadvantages associated with the requirement for continuous operation at 750°C, and (5) the expiration of funding from the DOE Office of Fossil Energy and EERE Fuel Cell Technologies Program of the DOE Office of Energy Efficiency and Renewable Energy after 10 years of development.
  • Efficient Operations
    • The 21CTP recently proposed “efficient operations” as a new focus area. Besides the many technologies available for reducing the fuel consumption of trucks, there are other ways of saving fuel that do not require any changes to vehicle or engine technologies―involving, for example, the ways that vehicles are operated and maintained, or the nature of regulations that may constrain or promote technology implementation and efficient operations.
    • The committee identified the following topics to consider in formulating goals in order to reduce fuel consumption:
      • Improved aerodynamic and rolling resistance performance for trailers,
      • Exploitation of the use of intelligent vehicle systems, and
      • Assessment of the potential impact of high-productivity vehicles and providing of leadership in getting them into trucking operations.
    • Specific goals for efficient operations should be developed, with strong consideration given to exploiting the potential for intelligent transportation systems (ITS) to reduce fuel consumption.

The report also includes findings and recommendations for the SuperTruck program. The SuperTruck projects go beyond the scope of previous 21CTP projects—instead of relying entirely on simulations and laboratory testing, each of the three projects will result in a drivable truck. However, the SuperTruck projects allow each team to design its own test cycle (within certain constraints), with the negative consequence that the three trucks may never be tested using a common cycle for comparison. The committee recommended that DOE and the SuperTruck contractors should agree on at least one common vehicle duty cycle that will be used to compare the performance of all three SuperTruck vehicles. In addition, fuel consumption improvements should be calculated on the basis of the EPA/NHTSA fuel consumption regulations.

Source: National Academies