Poo Power From New Fuel Cell
The microbial fuel cell captures electrons that are naturally released by
bacteria as they digest organic matter and then it converts the electrons into
electrical current. "We generated up to 72 watts per square meter, which is
2.8 times that generated in a larger device reported earlier this year in Environmental
Science & Technology," said Bruce Logan, co-author of the research
paper. Recently, Logan and his colleagues have tweaked microbial fuel cell
devices to produce up to 350 watts per square meter. "Two years ago we had
0.1... and now we're in the 100s," he said. "We'd like to get in the
range of 500-1000. We're looking for another order of magnitude increase."
Logan doesn't envision using his microbial fuel cell for the same type of
applications as hydrogen fuel cells, such as in automobiles or houses. "We
see using this any place where there's a high concentration of organic
matter," he said.
The most obvious application would be in wastewater treatment plants, which
essentially could power themselves as they treat water. Such a technology would
be particularly useful in developing countries, Logan suggests, because it would
produce a net amount of electricity, offering a reason to keep a treatment plant
running besides just treating wastewater. "Even if it's only powering a
cell phone tower, that would be a reason enough to keep it going," he said.
Other researchers have calculated that the energy potential in wastewater is
almost 10 times the cost to treat it. "If we could achieve just
one-twentieth of that power, we could break even," Logan said. "We're
confident we're going to be able to do more than that. In our system, the two
electrodes are separated by a proton exchange membrane, just like in a
conventional hydrogen fuel cell. It opens the door to using existing
hydrogen-gas based stack technologies with bacteria in water."
Logan said the device also could be used to treat waste from the food
processing industry and farms - especially hog farms, which have tremendous
problems with costs and odors. NASA scientists are even developing a similar
technology to be used in manned space missions, turning the astronauts' waste
into extra power. Logan plans to build a larger version of his microbial fuel
cell for demonstrations; he hopes to have the design completed in 2005.
A new fuel cell is being developed that can turn raw sewage into electrical
power says an article in the journal Environmental Science & Technology.
The microbial fuel cell not only treats wastewater, but also provides a clean
energy source with the potential for enormous financial savings, according to
scientists at Pennsylvania State University. While power output is still
relatively low, the scientists say the technology is improving rapidly and
eventually could be used to run wastewater treatment plants, which would be
especially attractive in developing countries. The device could be used to treat
waste from animal farms, food processing plants and even manned space missions.