THE DAY COULD SOON come when autonomous robots roam the planet in search of raw biomass to consume for power. Such is the vision of the Energetically Autonomous Tactical Robot system, although you can call it EATR. “Imagine the robot in the movie WALL-E—but instead of just compacting trash, it's combusting trash for electrical energy,” says Robert Finkelstein, director of the Intelligent Systems Laboratory in the Clark School of Engineering at the University of Maryland and president of Robotic Technology, the company developing EATR. The robot uses intelligent software to visually distinguish its preferential “food”—wood chips, dried leaves and other vegetative biomass—from nonuseful materials such as rocks, animal matter and metal. Then, using a robotic arm guided by a close-range laser-based guidance system, EATR grabs the vegetation and places it into a hopper leading to an external-combustion engine, which charges an onboard battery.

Such self-directed power generators could revolutionize many military, civilian and even scientific operations, Finkelstein says. “In the next few years every U.S. soldier will use the equivalent of 120 AA batteries every day to power his communications and support equipment,” he says. “Using an EATR would greatly reduce the logistical burden of supplying that energy in remote locations, because [the robot] can be out consuming vegetation while the rest of the unit rests.” Funding for EATR comes from the Defense Advanced Research Projects Agency.

Veggie-eating robots could also be put in service of the environment. The U.S. Forestry Service wants an EATR mounted on legs, rather than on a Humvee. In that way, it can wander the countryside in search of invasive plant species without leaving treadmarks. “The legs would let it negotiate uneven terrain without damaging that terrain as much as tires or treads would,” Finkelstein says.

EATR is currently confined to a stationary test platform at the University of Maryland, but Finkelstein expects a fully mobile, foraging model to be operational sometime in 2012. The prospect sounds creepy, but he believes that a world in which robots are self-sufficient is not only desirable but inevitable. “We already have household robots that can plug themselves into an outlet to recharge without bothering us,” Finkelstein says. “This is just the same idea, taken to the next level.”