The U.S. Department of Energy Alternative Fuel Heavy-Duty Vehicle Program Update

Each year, DOE's Office of Alternative Fuels reviews heavy-duty engine research and development, alternative fuel truck demonstrations, heavy-duty emissions regulations, and the availability of information from ongoing and completed tests. The results of this survey are summarized in a report made available to the trucking industry and other interested parties. This year, the first third of this report was prepared. Steve Goguen, who heads DOE's Alternative Fuel Truck Application Program, presented it at DOE's Diesel Engine Emission Reduction Workshop in La Jolla, California, on July 24, 1995. The updated report will be presented in Dearborn, Michigan, at DOE's Contractors' Coordination Meeting October 23-27, 1995. Federal alternative fuel heavy-duty truck efforts grew out of Section 400 BB of the Alternative Motor Fuels Act of 1988 (AMFA). AMFA was intended to encourage the development and use of alternative fuels and to stimulate the production of alternative fuel engines. The Clean Air Act Amendments of 1990 (CAAA-90) reinforced AMFA's goals by requiring "clean fuel" fleets in the country's poorest air quality regions. The CAAA-90 also imposed stringent new emissions requirements on heavy-duty engines, making the adoption of alternative fuels an effective near-term compliance measure. Finally, the Energy Policy Act of 1992 (EPACT) provided incentives to fleet operators to purchase AFVs and refueling facilities.

This year's survey makes clear that engine manufacturers and fleet operators have made natural gas, of all the available alternative fuels, the focus of their efforts and interests. Detroit Diesel Corporation (DDC), which has had considerable success with its methanol- and ethanol-fueled 6V-92TA engines (there are 550 in service), reports it has no current orders for the 6V-92TA engine plant. DDC is marketing its Series 30G gas engine and its Series 50G bus engine, and developing the Series 50G and Series 60G natural gas engines for the truck market. Caterpillar has developed the G3306 and G3406 natural gas engine, derived from its diesels. Cummins is producing or developing four medium- and heavy-duty natural gas engines—the B5.9G and L10G are in production, the C8.3G is undergoing testing, and the M11G is slated for a 1998 introduction. Navistar International developed its 7.3-liter natural gas engine jointly with DDC and will also market it. Navistar may enter into a second joint venture with DDC to develop a natural gas engine based on Navistar's 8.7-liter diesel engine. Mack Trucks is field testing a natural gas derivative of its E7 engine and expects to offer it in two ratings. Hercules Engines' 5.6- and 3.7-liter natural gas engines have achieved wide acceptance in medium-duty applications, and Hercules is pursuing electronic feedback fuel metering. Tecogen (a division of Thermo Power Corporation) will provide 276 additional 4.3-liter V-6 natural gas engines to United Parcel Service and is developing a diesel-to-natural-gas conversion package for the Navistar DT466. Most of these companies' engines are represented in DOE or Trucking Research Institute demonstration fleets.

The availability and favorable pricing of natural gas are expected to make it the alternative fuel of choice for the immediate future. LNG's energy storage density will suit it best for line-haul trucks, and CNG will make inroads in the vocational markets and city fleets with central refueling facilities. In the future, an increasing degree of electronic engine control will be employed to protect medium- and heavy-duty natural gas engines from thermal stresses and from the effects of variable fuel composition.

Peter W. McCallum is a Systems Engineer with ANTARES Group, Inc., in Landover, Maryland. ANTARES provides consulting services on the technical, economic, regulatory, and policy issues affecting transportation and alternative fuels. For the past 2 years, ANTARES has been working with the National Renewable Energy Laboratory to support DOE's Alternative Fuels Program.

Cummins Engine Company natural-gas-powered L10- 300G photo courtesy of Cummins Engine Company

Detroit Diesel Series 50 natural-gas-powered engine photo courtesy of Detroit Diesel Corporation