Freightliner LLC has introduced a heavy-duty truck that uses fuel cells to generate electrical power for on-board vehicle appliances. The demonstration truck - a Class 8 Freightliner Century Class S/T - offers an alternative for powering auxiliary devices on a parked heavy-duty truck in lieu of idling the engine. The truck was displayed at the Department of Transportation (DOT) National Intelligent Vehicle Initiative Meeting recently.
This truck uses a fuel cell auxiliary power unit (APU) developed by Freightliner and XCELLSIS, a joint venture company whose ownership includes Freightliner's parent, DaimlerChrysler AG. It includes two Ballard fuel cell "stacks" operating in series as an APU. Stacks are housed on the left side of the truck along the frame rails.
Proton exchange membrane fuel cells are used. Fuel cells are fed with hydrogen from a 52-gallon liquid tank on the left side of the truck. Within the fuel cell, hydrogen is split into positively charged protons and negatively charged electrons. Protons can pass through the membrane, but electrons cannot, so voltage builds up in the fuel cell. The only by-product of this process is pure liquid water.
The fuel cell APU produces more than 1.4 kilowatts, 120 volts AC, or 12 volts DC power. This APU is connected to the vehicle's electrical system through an 1,800-watt inverter, which takes electricity from the fuel cells, batteries, and alternator, and provides power to vehicle accessories/batteries in the required form (12-volt DC or 120-volt AC). The truck is outfitted with an 8,000-Btu/hour air-conditioning unit.
Freightliner is working to make fuel cell auxiliary power units commercially viable within three to five years.
