“Alternative fuel source” talk is everywhere these days! So what’s the latest in alternative fuel sources you ask? Microbial fuel cells! A microbial fuel cell (MFC) is a specific type of biological fuel cell that converts chemical energy to electrical energy using microorganisms as the catalysts. Many different kinds of waste can be converted into useful energy to power our everyday needs.1 From sewage waste to animal manure, most types of biomass2 can be broken down by bacteria to release energy that we can harness into fuel.
Using bacteria to generate electrical current is a technique that has been known since the early 1900s.3 Fast-forward a century and we have Time Magazine selecting “the electric microbe’’ as one of the fifty best inventions of 2009.4 Although the concept of a microbial fuel cell is not new, a lab has now genetically engineered a microbe called Geobacter that is eight times more efficient than other bacteria when it comes to producing energy.5 An amazing develoment would be an efficient fuel cell with the Geobacter bacterial strain.
Here is a basic overview of how the fuel cell works: When bacteria are grown in the fuel cell they form a biofilm, which is a community of bacteria, on the electrode coated by a biofilm matrix, which is usually a mixture of sugar and protein. In the case where no oxygen is allowed into the fuel cell, the bacteria produce carbon dioxide, electrons, and hydrogen ions. These electrons are then transported to the electrode coated with the biofilm matrix, creating an anode generating current and creating electricity.6
The fuel cell simply takes advantage of how nature actually works. Say you have a pile of food scraps or manure; bacteria colonies will naturally form tiny colonies on your waste pile. The bacteria colonies then consume the waste and excrete electrons as well other byproducts. These electrons flow to some type of acceptor and this acceptor accumulates charge, becoming a sort of biological capacitor. The biological energy will be stored in that capacitor. A fuel cell basically short circuits this process and allows us to harness the energy produced for practical matters.
Some advantages of microbial fuel cells are that the catalysts—bacteria—are inexpensive. Bacteria are found everywhere, so the cost is essentially free. Because bacteria are found everywhere they can also survive anywhere, proving to be a strong and reliable energy source. Additionally, the bacteria are diverse, and we can select and cultivate colonies specific to our waste needs. Microbial fuel cells utilize waste that would otherwise be sent to landfills or pollute the earth and instead produce energy!
Wine is a popular and tasty adult beverage. Through the wine making process, there are many batches of grapes that fail to ferment and are thus wasted. Bruce Logan, an expert on microbial fuel cells, is currently conducting research at a Napa Valley winery aimed at turning the unused sugar and vinegar from failed fermentations into electricity and hydrogen.8 To do so, Logan installed a one thousand liter microbial electrolysis cell, which is about the size of a refrigerator, at the winery. Currently, Logan’s design is producing more methane than desired, although it is speculated that the hydrogen can be used to power a fuel cell and the methane can be burned for heat.9 Microbial fuel cells are also a cost effective way to process wastewater and turn it into energy needed to run the winery every month, which in turns means big electricity savings and hopefully less expensive bottles for wine aficionados to find at the store!10
The Future of Microbial Fuel Cells: Currently, microbial fuel cells are still in the developmental stage. Logan believes that it will take about three to five years before the microbial electrolysis cell could be economically feasible to use as an energy source.12 If these fuel cells are optimized for usage in the real world, an extraordinary amount of waste could be diverted from landfills to instead produce clean energy. About 5% of the electricity used in the United States is used for wastewater treatment, and there is almost ten times more energy in the wastewater than the amount currently being used to treat it!13 Not only will wastewater treatment be powered through the energy produced through its own treatment, but about 90% of the energy from the treatment process can be put directly onto the power grid as well.
If you are interested in experimenting with your own microbial fuel cell, it is quite easy to build your own using materials you have around the house! Check out this guide to build your own or you can purchase a ready-made cell from keegotech.com if you don’t feel like building one on your own☺
