The search for a better battery is getting a push from the U.S. Defense Advanced Research Project Agency (DARPA), which has given Yale University’s engineering department $2.4 million to develop readily rechargeable microcombustion batteries.

The Yale research is part of DARPA’s Palm Power program, which addresses the military’s need for lighter and more compact electrical power sources. "DARPA is shooting for something that weighs as little as a few ounces to power the growing number of communications and weapons systems that tomorrow’s soldiers will carry," says Alessandro Gomez, director of the Yale Center for Combustion Studies and a professor of mechanical engineering.

Microcombustion technology generates heat by slowly burning tiny amounts of liquid hydrocarbons. The heat is then converted into electricity by other energy conversion schemes such as thermoelectric and thermophotovoltaic. By taking advantage of the abundant power densities offered by hydrocarbon fuels, a microcombustion battery with millimeter-level dimensions could provide the same power and operating time as a conventional battery up to 10 times its size. And microcombustion cells could be quickly refueled with an eyedropper.

The Department of Defense plans to use microcombustion batteries in everything from tactical bodyware computers to Micro Air Vehicles?six-inch-long unmanned reconnaissance aircraft. The technology, once perfected, should spill over quickly into business and consumer products, Gomez says. "Laptop computers, cell phones and a variety of other portable electronics products could all benefit."

During the next couple of years, Yale scientists will concentrate on developing the most effective combustion technology while researchers at other institutions will work on techniques for converting thermal energy into electrical energy. "Conventional battery technology has reached a dead end," says Gomez. "We’re looking to develop a power source that’s every bit as innovative as the latest military systems."