Two Boston research groups say bacteria-powered fuel cells can fulfill energy needs in the developing world.

Jennifer Cutraro

Around the world, 1.6 billion people lack access to affordable, reliable electricity. Two Boston-area research teams believe they have technology that can solve the problem. They are developing low-cost fuel cells that generate electricity by harnessing the electrons produced by bacteria as they metabolize biomass–compost, animal dung, even sheets of paper.

While still in the early stages of development, these microbial fuel cells could one day provide electricity to charge cell phones and other small electronics in off-grid locations around the world, according to the researchers.

Bucket power

When he began developing his fuel cell technology, Harvard University microbiologist Peter Girguis kept a lamp in a bucket of dirt in his basement. The lamp glowed as brightly as a 40-watt bulb for a few hours every night for a year, even though it wasn’t plugged into a wall socket. This prototype fuel cell was plugged into the dirt.

Girguis is founder and chief scientist of Living Power Systems, a new company created to commercialize his technology. Living Power recently received funding from the Charles A. and Anne Morrow Lindbergh Foundation to test its prototype in India and Mexico.

Girguis says the device is designed to attract naturally occurring, electron-producing microbes in the environment. The fuel cell consists of a pair of electrodes connected to a circuit board about the size of an iPod. One electrode is placed into any oxygen-deprived environment where bacteria thrive, such as soil, compost, or sediments. This electrode collects the electrons the bacteria kick out as they digest organic matter. These electrons flow through a wire to the circuit board and then to the second electrode, generating electricity.

The fuel cell offers a cleaner way to provide light in rural areas far removed from the grid, Girguis says. “In many parts of the world, organic matter, such as compost and animal dung, is burned for its light in open pits or open stoves in the home,” he says. “That animal dung or compost would be a perfectly good fuel for a microbial fuel cell.”

Team BioVolt

Last fall, a team of MIT students placed first in the MIT and Dow Materials Engineering Contest with a microbial fuel cell called BioVolt. Unlike the Living Powers System device, theirs relies on cultures of specific strains of bacteria to produce electricity from cellulosic biomass such as crop waste. The team also developed a membrane in the middle of the fuel cell that facilitates the movement of ions from one side of the fuel cell to the other, eliminating the need for costly platinum catalysts used in a traditional fuel cell.

Andrew Hoy, MIT sophomore and member of the BioVolt team, says the motivation for their project came from a market analysis of sub-Saharan African nations, where it’s common for people in rural areas to walk many miles to cell-phone charging stations in cities. “It’s expensive and time-consuming for people to do this,” Hoy says. “We’d like people to be able to charge their cell phones on the dinner table using food scraps,” he says.

Need more juice

A major challenge facing microbial fuel-cell projects is power output. The BioVolt prototype produces only a milliamp of current, Hoy says. At that level, it would take about six months for one of their devices to charge a cell phone.

This spring, members of the MIT team will work on ways to improve the efficiency of the device by redesigning the membrane to boost the rate of ion transfer and thus overall electricity production. They will also test other combinations of bacterial species to find the one that can pump out the most electrons. Coupling several devices together may also increase power input, says Hoy.

Girguis points out that with his system, power production is directly proportional to the surface area of the electrodes. While he wouldn’t give any precise numbers on the power output of his current prototype, he says that his soil-powered device could charge a cell phone at the same rate or faster than a conventional charger.