“Think of it as a battery that runs on mud,” says the U.S. Office of Naval Research, and there in a nutshell is the concept behind the Navy’s new microbial fuel cell. The Navy has been using small lightweight microbial fuel cells to power sensors (to track sea turtles, for example) and now its goal is to develop one that is powerful enough to steer a small robotic watercraft.
In a microbial fuel cell, organisms feed on available nutrients and generate an electric current as they metabolize the food. The Navy is working with researchers at the University of Massachusetts on a microbe called Geobacter, which is the most promising in terms of its efficiency at generating electricity. Strains found in the wild have demonstrated a knack for converting nutrients in mud and wastewater into electrical current, and researchers have developed a new strain that is eight times more efficient than others.
The U.S. Navy and Mud-Loving Microbes
The Navy is so enthusiastic about the Geobacter-based fuel cell that it plans on showcasing it at the Pentagon’s Earth Day event this year, calling it “a device with the potential to revolutionize naval energy.” On land the fuel cell would need to be positioned at a source of mud or wastewater but in the ocean a watercraft powered by microbial fuel cells could range far and wide, using the bodies of decomposed marine organisms as nutrients. Powering an aircraft carrier in such a manner is somewhere far off in the future; for now the Navy is exploring the use of microbial fuel cells on a four-foot long autonomous underwater vehicle that could rest on the ocean floor to recharge its batteries.
Fuel Cells and Microorganisms
Geobacter is just one path to a sustainable fuel cell based on microorganisms. Over at MIT, researchers are creating one based on microorganisms that mimics photosynthesis. They’ve modded a bacterial virus that transforms into a sort of nanowire that is highly efficient at splitting water molecules into hydrogen and oxygen. That’s your basic photosynthetic process, minus the solar energy that is ordinarily needed to split water molecules into fuel. Meanwhile on the liquid fuel side, researchers are developing strains of microbes that secrete diesel and other petroleum-like substances without any middle steps.
Image: Mud by Percita on flickr.com.