Army Lab Aims to Lighten Soldiers' Load

By Ian Graham
Special to American Forces Press Service

Oct. 23, 2009 - Soldiers carry a heavy load, with basic body armor alone weighing about 45 pounds, not to mention firearms, ammunition, radio equipment, food and other tools they may need for a mission. The Army Research Laboratory's Electrochemistry Branch in the Sensors and Electron Devices Directorate is working to lighten their load by creating fuel cells that are lighter and more efficient and durable than existing batteries.

Cynthia Lundgren, chief of the directorate at Aberdeen Proving Ground, Md., described the benefits of fuel cell technology during an Oct. 21 webcast of "Armed with Science: Research and Applications for the Modern Military" on Pentagon Web radio.

The new fuel cells will help soldiers by lessening the number of batteries they carry for missions lasting longer than 24 hours, Lundgren explained.

Depending on their role in the battalion, some soldiers may carry up to 35 pounds of batteries with them for a 72-hour mission, she said. She'd like to see that weight reduced to 12 pounds.

"We'd like to reduce the weight a soldier carries by a third to a half," she said.

Fuel cells use a chemical reaction between air and a fuel to create energy, which in turn is harnessed as electricity. Hydrogen is the most commonly used chemical fuel, but because it's very reactive, it can be dangerous to carry around. It's also difficult to create and make available for soldiers' use.

"Hydrogen is a pretty energy-dense fuel, but it's a gas, so it has to be condensed ... and it's not very convenient," Lundgren said. "Logistically, it's not a very friendly fuel. And carrying hydrogen-gas bottles around isn't exactly something soldiers want to do."

Lundgren is trying to find fuel chemicals that will have an efficient electrochemical reaction with as few safety issues as possible for its carriers.

"If a lithium-ion battery is punctured, lithium is incredibly reactive and will react with moisture in the air," she said. "Anybody who's seen or heard of battery fires from laptops will appreciate that. We're trying to make those batteries last longer, be lighter and be safer."

Lundgren's team has been testing fuel cells using propane and simple alcohols like methanol to act as power sources for mobile, portable equipment. Fuel cells are being built and designed to handle power usage as high as megawatts -- the kind of power needed for a large vehicle like a submarine or aircraft carrier -- and as low as microwatts.

Their primary focus with higher wattage cells right now is allowing for "silent watch," when a vehicle can be turned off but the electronics can still run at full power. Fuel cells providing this capability generally run from 10 to 40 kilowatts, but the Army requires JP8, a jet fuel, to be used to reduce the logistics burden to supply the fuel.

"Small, portable fuel cells ... run pretty much like a battery [the fuel is prepackaged and can be exchanged like a battery]," she said. "But once you get over a kilowatt, it becomes harder to sustain logistically.

"Part of our reformation research is how to convert JP8 into a fuel that a fuel cell can use," she continued. "This is mostly geared for auxiliary power units .... The efficiency of [a fuel cell] is much higher than the vehicle using its own fuel in an internal combustion engine, and it allows for silent watch."

Soldiers and researchers are testing new ideas, ideally giving warfighters a lighter load to carry and greater operational capacity in the field, whether it's powering a small navigational tool or allowing them to silently run unmanned vehicles.