I clipped the entire article, it is kinda long.
Hybrid vehicle saves fuel, pollutes less
by Gerry J. Gilmore
WASHINGTON (Army News Service, April 23, 1999) - Army automotive
engineers, in partnership with the private-sector, are developing
fuel-efficient, low-emissions vehicles to meet 21st-century transportation
needs.
Technicians at the National Automotive Center, part of the U.S. Army
Tank-automotive and Armaments Command in Warren, Mich., are testing a
modified, Family of Medium Tactical Vehicles-based, five-ton truck that
uses both a diesel engine/electric generator and batteries to provide power
for propulsion.
Dual-power-source, also known as hybrid, vehicles most likely will provide
the bulk of land transport needs for the Army After Next, the force
envisioned for the year 2020 and beyond, according to Robert Crow III, the
Army program manager for the hybrid vehicle project.
"The goals of Army After Next require a 75-percent reduction of fuel
[usage] by the year 2020," Crow said. "Using hybrid electric propulsion can
reduce [individual] vehicle fuel consumption by 25 to 30 percent.
"If a vehicle gets better fuel economy, you can eliminate some of the
logistics 'tail' -- fuel haulers, ships -- used to move the fuel forward
[to combat line units].
"It is predictable that this fuel reduction can translate into a
75-percent reduction, overall, meeting the Army After Next goal," he said.
The prototype hybrid vehicle will undergo some limited testing at Aberdeen
Proving Ground, Md., this fall, Crow said. First fielding of the system, he
said, may occur "in five or six years."
The hybrid truck uses a commercial diesel truck engine, which is connected
to a 120-kilowatt generator, Crow said. Two computerized power control
units channel the generator's electrical energy to the hybrid's two
alternating current electric motors, with each motor connected to a
driveshaft -- one front, one rear - thereby maintaining the six-wheel-drive
capability of the original truck.
"The hybrid vehicle propels itself with its diesel engine/generator, the
on board battery pack, or both - depending on how much acceleration is
required," Crow said. "When operating on batteries alone, it is very quiet
... think about the new and novel tactical capabilities of such a system.
"Since this truck has a massive amount of surplus electrical energy on
board, you can power on board weapon systems, ground-based radar, or even
missile systems with the vehicle itself. You won't have to tow generators
for such applications anymore."
The power control units "constantly monitor the batteries to assess their
state of charge," Crow said. When the batteries are discharged to a certain
level, the generator recharges them.
"Batteries are a challenge, but not a 'showstopper,'" Crow said. "We wish
we had lighter, more powerful and less costly energy storage options, which
would result in a better overall system. However, even if the state of
battery technology does not change significantly over the next five years,
we believe we could still field an effective hybrid system."
The Army's prototype hybrid truck is hefty at 22,000 pounds, about 2,000
more than a conventionally powered truck, Crow said. Continuing development
efforts, he said, should trim around 1,500 pounds from the hybrid's overall
weight.
The battery pack itself, Crow said, currently weighs 2,000 pounds.
"But, that [weight] will shrink as we examine other battery types and
manufacturers," he said.
"Regarding other sources of energy, it takes a lot of power to move a
vehicle this big, and solar cells are too 'wimpy.' Fuel cells, on the other
hand, could one day replace the diesel engine/generator combination.
Fielding fuel cell-powered military vehicles is probably over 20 years
away," Crow said.
The NAC was chartered in 1992 to combine military and commercial research
and development efforts whenever practical, Crow said. The Army's prototype
hybrid vehicle uses the same private-sector developed components used by
six hybrid-powered buses now being evaluated by the New York City transit
authority, Crow said.
Crow said the hybrid truck project "is a near ideal example of a dual-use
technology development partnership" between the military and the private
sector.
"Historically, military and commercial research and development have been
conducted separately; this is obviously duplicative and wasteful," Crow
said. "[Through military/civilian collaboration] money is saved up front
because the research and development costs are shared [and] duplication of
effort is eliminated.
"Economies of scale are realized in manufacturing because the military
product is the same as the commercial," he added.
Hybrid systems also provide benefits for the environment, Crow said. The
diesel engine in the hybrid is tuned to run at near constant speed, he
said. This saves fuel and reduces pollution.
"Hybrid propulsion has very low [exhaust] emissions," Crow said. "Some
prototypes we've been watching are showing an 80-percent reduction in
particulate emissions and significant reductions in all other categories."
Even the Army hybrid vehicle's regenerative braking system is energy
efficient, Crow said.
"When decelerating, the electric motors that are normally used to
accelerate the vehicle become generators ... [that] then produce electric
energy that is sent back to the batteries - thereby recovering otherwise
lost energy normally dispersed as heat in a normal brake system," he said.
"The normal air brake system is still retained for sudden stop conditions,
but brake wear will be dramatically reduced because of regenerative
braking."
Most future commercial truck designs will be hybrids "as truck and bus
manufacturers are starting to realize that the dramatic fuel economy
improvements and low emissions of hybrid propulsion are too attractive to
ignore," Crow said.
"When commercial industry goes hybrid so will the Army - there won't be
anything else to buy," he said. "It is our intent to get involved and
influence these commercial designs up front to make sure that whatever is
produced is a true dual-use product that can meet the military need."
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