A by-product of biofuel manufacture can power microbial fuel cells to
generate electricity cheaply and efficiently, according to scientists
presenting their work at the Society for General Microbiology's Autumn
Conference. The work could help develop self-powered devices that would
depollute waste water and create a model for other applications.
Distillers Dried Grain with Solubles (DDGS) is a waste product from
bioethanol production that is commonly used as a low-cost animal feed. Researchers
from the University of Surrey incorporated DDGS together with
bacteria-inoculated sludge from a waste water treatment plant in their
microbial fuel cell.
The design of the fuel cell meant that the bacteria, which used the DDGS for
growth, were physically separated from their oxygen supply. This meant that the
bacteria were forced into sending electrons around a circuit leading to a
supply of oxygen. By tapping into this electron flow, electricity could be
generated from the waste.
Microbial fuel cells offer the ability to convert a wide range of complex
organic waste products into electrical energy, making it an attractive target
technology for renewable energy. Finding cost-efficient starting products is
necessary to help commercialize the process, explained Lisa Buddrus who is
carrying out the research. "DDGS is potentially one of the most abundant
waste products in the UK. As the biofuel industry expands the supply of DDGS
will become more abundant," she says.
As well as being low-cost, microbial fuel cells that use DDGS are very
environmentally friendly. The waste that is left following electricity
extraction is of greater value, as it is less reactive with oxygen, making it
less polluting. "We've found something really useful from a waste product
without affecting its value as animal feed and at the same time improving its
environmental status. This is something we place great importance on and within
our group we have a team solely dedicated to reducing polluting potential,"
says Professor Mike Bushell, leader of the group.
A lot of microbial fuel cell research focuses on developing environmental
sensors in remote locations. "Self-powered sensors in remote places such
as deserts or oceans can be used to provide important data for monitoring
weather or pollution. Other applications in focus for microbial fuel cells
include treating waste water to produce green electricity and clean up the water
at the same time," explains Bushell.