"If you have a cup full of concentrated plankton, and you let it degrade, that would be equal to about a c-cell battery," she says. That's the size battery used in a medium flashlight, and it's powerful enough to run a number of small sensors.
Sensors Swim Like Fish
The researchers have designed several mobile prototypes, and they look a little familiar.
"Some of them look a lot like a fish," Reimers says. "They are torpedo-shaped, but with fins, and they can glide through the water. The idea is they could scoop up what's in their path and just let it decompose internally. You could draw energy from that, just like a fish gets energy from it."
Think of a shark, ripping along with it's mouth wide open, collecting plankton and whatever tiny delicacies that might find themselves in its way. Convert all of that into electricity, and you've got an autonomous robot that can go just about anywhere without ever needing new batteries.
The researchers think they've shown that's at least theoretically possible. Now all they have to do is make a few that really work.
Lee Dye’s column appears weekly on ABCNEWS.com. A former science writer for the Los Angeles Times, he now lives in Juneau, Alaska.