Military Diesel Hybrid Truck Features a Fuel Cell Auxiliary Power
By Mike Hanlon
General Motors and the U.S. Army used the NAIAS to show an interesting diesel hybrid military vehicle 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 diesel hybrid improves Army fuel consumption by 20 percent over conventional diesels, reduces vehicle emissions and also provides troops with clean, reliable electrical power. These are crucial elements in helping to transform the Army into a lighter, more mobile military unit and with fuel transportation costs reaching up to $400 a gallon depending on training or battlefield operations, the savings could run into millions of dollars.
The fuel cell APU would replace the loud engine-and battery-based stationary generators the US Army currently uses for field power, thus enhancing the Army's "silent watch" capability, or the ability to operate undetected by the enemy. Fuel cells are much quieter than engine generators and do not give off as much heat, making them less likely to be picked up by enemy heat sensors. The fuel cell unit also familiarises the military with the next generation of commercially developed fuel cell technology, so that military vehicles could be powered by fuel cells within a decade.
GM unveiled the heavy-duty, militarised version of the commercial Chevrolet Silverado crew cab in a ceremony with Larry Burns, GM vice president of research and development and planning, and U.S. Army Major General N. Ross Thompson III, commanding officer of the Army's Tank-automotive and Armaments Command.
"Our prototype truck incorporates advanced diesel hybrid powertrain technology and introduces the military to the flexibility and security of fuel cell electric power," Burns said. "This defense project is a great opportunity to put large numbers of diesel hybrids and stationary fuel cell units in operation in the interest of national security.
"We also anticipate that it will accelerate cost-effective and durable civilian applications of hybrid-electric vehicles and fuel cells. As an early customer, the military will help drive down costs, increase our learnings, and spur the eventual development of a hydrogen-based economy."
The vehicle was designed and engineered by GM Military Truck Operations, based in Troy, Mich., 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 Corp., based in Mississauga, Ontario.
The Army will evaluate the prototype before establishing performance and procurement criteria and opening the bid process. The Army is expected to want 30,000 hybrids by the end of the decade.
"The potential for fuel cell and diesel hybrid technologies are of critical importance for the Army's next generation of tactical vehicles, and General Motors will play a key leadership role in the research and development efforts for transforming the Army's mobility," said Dennis J. Wend, director of the National Automotive Center, coordinator of the U.S. Army's collaborative vehicle research and development.
"In order for the Army to win today's and tomorrow's battles decisively, we must transform to a lighter, more mobile, more fuel-efficient Army, an Army that is rapidly deployed and sustainable anywhere in the world. The fuel cell auxiliary power unit's quiet operation and low heat signature also are vital elements in reducing the visibility of a deployed force."
GM has a long history of serving the U.S. Army's transportation needs. The automaker has produced about 80,000 military vehicles since the mid-1980s.
The truck's military features include Raytheon First Responder command and control equipment, infrared night vision camera and GM's "extreme mobility package" to meet the harshest off-road conditions and payload requirements.
"The Army owns a lot of trucks - nearly 250,000 of them, which makes it one of the largest fleets in the nation," said Wend. "Three of top four fuel users in the battlefield are trucks. That's why we need to bring the best and brightest from industry, academia and government to engage in significantly increasing the fuel efficiency of the our military and commercial fleets."
The heavy-duty, four-door pickup is powered by a 6.6-liter 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 percent to 40 percent over conventional gasoline trucks.
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 efficiently to the wheels. The lightweight 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 capable of producing electricity and hydrogen in remote areas. Today's Army uses extensive surveillance and communications electronics to accomplish its missions on tomorrow's battlefields. These electronics must be powered quietly for long periods of time in a manner that is undetectable by the enemy.
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 and the Army does not need to add a new logistics fuel. Any additional water is not a problem since water is already provided to the troops and, in a difficult situation, the fuel cell-produced water is drinkable.
The only sound produced is that of quiet air intake fans, making it perfect for use indoors, in confined spaces or where minimal noise is required. In addition, the fuel cell generates power at relatively low temperatures, removing the risk of enemy detection by heat monitoring devices.
"The fuel cell unit delivers the same amount of power as a conventional generator without broadcasting your presence," said Burns. "The energy density of hydrogen and the efficiency of the fuel cell gives the same capability of equal-sized batteries but with six to 10 times longer operation, particularly in adverse temperature conditions. The military recognizes these advantages as being key to its mission-critical operations."
Military applications require absolute reliability and durability, said Hydrogenics president and CEO Pierre Rivard.
"This is a valuable opportunity to demonstrate the capabilities of a fuel cell system in what are sure to be very demanding conditions," Rivard said. "We always derive significant learnings from opportunities like this and rapidly channel these learnings into our product development initiatives. In this way we ensure that when it's time to start producing this fuel cell technology in larger volume, it is in fact the current best available technology."
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 Commercially Based Tactical Truck (COMBATT) program. The program leverages commercial technology to reduce the cost of developing and acquiring a light tactical vehicle, and provides the Army with continuous technology improvement.
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