The Army has been testing a prototype hydrogen-fuel-cell system installed
within a conventional truck platform for about a year now, said Bill Haris,
a mechanical engineer at the Army's National Automotive Center (NAC),
which is part of the U.S. Army's Tank Automotive Research Development and
Engineering Center (TARDEC) at Warren, Michigan. The application is geared
toward nontactical vehicle usage.
The one-of-a-kind prototype is based on a Chevrolet Silverado, Haris said.
The truck's original engine, transmission and gas tank were removed and
replaced with two hydrogen fuel cells and two electric motors -- one motor
drives the front wheels and the other drives the rear wheels. "The
plumbing and the storage tanks for the hydrogen, as well as the brains to
control all the energy flow" are installed, Haris said. In comparison, a
hybrid vehicle uses two types of energy sources to provide motive power,
he explained.
At slower speeds the hybrid's electric motor moves the vehicle, Haris
said, while the gasoline engine is employed during faster highway travel
or to provide more acceleration. Hybrids are designed to provide better
fuel mileage and less pollution than a conventional gasoline-powered
internal-combustion-engine vehicle.
By comparison, a fuel-cell vehicle "is essentially a battery-driven
vehicle," Haris said. Hydrogen fuel-cell vehicles use "a totally different
technology than what you'd find under a conventional hood."
A conventional gasoline-powered automobile will achieve around 30 percent
energy efficiency, he said, while a fuel-cell unit will post about 50
percent efficiency. "That's where you gain your fuel efficiency," Haris
said, adding that no hydrocarbon-based fuels, like gasoline or diesel, are
used to power the Army's prototype hydrogen-fuel-cell vehicle.
Hydrogen fuel is available in both liquid and compressed gas form. The
industry is currently favoring compressed hydrogen gas for
fuel-cell-powered vehicle application. The Army's developmental hydrogen
fuel-cell truck is capable of reaching speeds of 95 mph, Haris said. But
its current range of 125 miles per fill-up is only about half of
hydrocarbon-fueled vehicles. "That's one of the areas that really need to
make a huge step forward," Haris acknowledged. One method under study to
solve the distance issue is using some type of solid-hydrogen storage
system.
Leveraging commercial research on hydrogen fuel cells dovetails with DoD's
desire to harness private-industry expertise, said Harold Sanborn, an
expert on alternative fuel sources who also works at NAC. "We need to look
at commercial technologies and find out if they are ready for military
applications," Sanborn said. The hydrogen fuel-cell-truck concept also "is
a good starting point for discussion about modernizing our bases and the
base infrastructure to make our bases more efficient and cleaner overall,"
Sanborn said.
Right now, fuel cells are from five to 10 times more expensive than
internal-combustion-engine-driven systems, Sanborn said. He also
acknowledged that using compressed hydrogen, a highly flammable element,
does present unique safety and storage concerns. However, those concerns
are being addressed with success, Sanborn said.
Some day military bases may replace their internal-combustion-engine truck
fleets with fuel cell or fuel cell/ hybrid vehicles, Sanborn said. "Then
they could use clean-burning hydrogen in that application and drive those
vehicles in their duty cycles."
News Archive, Gerry J. Gilmore, American Forces Press Service