General Motors has taken the wraps off a new diesel hybrid military pickup truck equipped with a fuel cell auxiliary power unit (APU) that could become the model for the Army’s new fleet of 30,000 light tactical vehicles by the end of the decade.
The quiet fuel cell APU is used in place of the loud engine- and battery-based stationary generators the Army now uses for field power.
The vehicle itself was designed and engineered by GM Military Truck Operations, based in Troy, MI, and incorporates technologies from Allison Transmission Division of General Motors, GM’s Fuel Cell Activities organization, and GM’s strategic fuel cell alliance partner, Hydrogenics, based in Mississauga, Ontario.
The US Army will evaluate the prototype before establishing performance and procurement criteria and opening a bidding process. The Army is expected to require 30,000 hybrids by the end of the decade.
The heavy-duty, four-door pickup is powered by a 6.6-litre Duramax Diesel V-8 engine, which generates 210 horsepower and 545 lbs.-ft. of torque.
The engine is mated to a parallel hybrid electric system for improving urban engine emissions and fuel economy. The system itself can increase fuel economy 25% to 40% over conventional gasoline trucks, according to GM.
The hybrid system, under early development by GM for commercial applications, uses a patented split power continuously variable transmission (CVT) with integral electric motors and an energy storage system, to deliver power to the wheels. The nickel-metal hydride-based energy storage system weighs a third less and is half the size of lead-acid battery storage systems.
In addition, the diesel-electric hybrid powertrain can operate as a self-contained generator, with the capability of providing up to 30kW ‘exportable’ DC and AC electricity for troop operations in the field. This eliminates the need for separate, less efficient, bulky motor-generator sets typically used.
The fuel cell APU, designed and built by Hydrogenics, is a 5-kilowatt proton exchange membrane (PEM) regenerative fuel cell system. When the vehicle is driven, the PEM electrolyzer uses diesel engine provided electricity to break down water into hydrogen and oxygen, with the hydrogen stored for future use. Later, with the engine off, the stored hydrogen, together with oxygen from the air, is fed to the fuel cell to produce electricity, returning the pure water as a byproduct, which is stored to repeat the cycle.
The regenerative APU thus produces its own hydrogen. Any additional water is not a problem since water is already provided to the troops; in a difficult situation, the fuel cell-produced water is drinkable.
The diesel hybrid truck is one of eight different militarised prototypes based on the Silverado that GM Defense will deliver to the Army later this year as part of the US Commercially Based Tactical Truck (COMBATT) program.