Engine check: technology limitations stall military hybrids.

• Author: Axe, David
• Position: ENERGY CRUNCH - Cover story

THE U.S. MILITARY HAS LONG sought diesel-electric hybrids that would improve fuel economy, offer a reduced logistical burden and provide the ability to export power, among other advantages.

But after more than a decade of research and development, and despite much recent hype, military hybrids are still years away from mass production.

None of the current military hybrid engine efforts has any specific goals or timelines to deliver an operational vehicle. "Right now, we do not have a current hybrid program that targets fielding," says Gus Khalil, team leader of hybrid-electric research at the Army's Tank Automotive Research, Development and Engineering Center, or TARDEC.

TARDEC, a division of the Research, Development and Engineering Command, in Warren, Mich., is the military's main research center for vehicle technologies. Khalil and other TARDEC engineers have been developing hybrid-electric engines and testing vehicle demonstrators since 1992.

Across the Defense Department, there are around 30 hybrid-electric demonstrator vehicles in some form of testing. These demonstrators range from hybrid models of existing vehicles, such as Humvees, M-113 armored personnel carriers and M-2 Bradley infantry fighting systems, to new designs such as the Marine Corps' reconnaissance, surveillance and targeting vehicle, or RST-V.

Some of these demonstrators are more promising than others. Some even offer new niche capabilities. But all have failed to achieve the combination of performance, toughness, price and utility that the military demands of its vehicles.

"We found out way back when, that you cannot just take what is being developed out there for commercial cars and put it in military vehicles," Khalil says. "The space available on military vehicle platforms is extremely tight and the demand of the user is different than that of the average driver on the road."

"Hybrid technologies may seem like an easy undertaking, especially with the automotive industry making headway to reduce [gasoline] consumption by way of hybrid platforms," a TARDEC document says. "It is not so easy for the military. Our vehicles have larger electric- and use-loads than standard commercial vehicles, so adopting commercial technology for military use is not always possible. Additionally, our vehicles operate in conditions that most commercial vehicles do not."

"Generally speaking, size and weight are challenges for everything we do," Khalil says. "The weight is limited and...