Rather than stressing over the prospect of global warming and where to find cleaner, cheaper energy, maybe we should just kick back and enjoy a beer. Perhaps by doing so, we can even contribute in some small way to solving the energy crisis with a side benefit of helping to clean up the environment.
One technology that has been emerging over the past decade, involving microbial fuel cells, is quickly becoming an economically viable source of energy. By adding the right kind of bacteria to biomass, including industrial waste, we can generate electricity. Maybe not a lot of electricity right now, but that could change as the technology develops and applications diversify.
What’s in a Name
The term “fuel cell” has become quite common over the past few years. One type of fuel cell that is generating millions of investment dollars from both industry and government is the microbial fuel cell, or MFC. Microbial fuel cells, also called biological fuel cells, are cells that use bacteria to generate electricity or hydrogen, which can power fuel cells. The MFC uses biomass, often from waste streams, as the fuel source, with most deploying two electrodes and specialized bacteria that consume the sugars and other organic material and release electrons as a byproduct. These electrons travel to the anode and flow in a wire to the cathode, producing an electrical current. The water in the fuel cell donates positive hydrogen atoms that combine with the electrons and oxygen to form pure water.
While the knowledge to create fuel cells that use bacteria to convert waste products to electricity has been around for over a decade, MFCs have garnered a lot of interest in recent years due to breakthroughs in process design and efficiency. This field is maturing rapidly as the best organisms for each application are identified, efficiency is increased, and functioning prototypes are built.
Working with Waste
Organic waste, including animal manures and corn stover, accounts for over 300 million tons, more than one third of the solid waste generated in the United States each year. Because they contain sugars and other organic materials that bacteria can consume, these wastes, along with many industrial wastewaters, can be easily converted to fuel for microbial fuel cells, and in the process produce electricity, hydrogen or pure water.
Several universities around the world have formed research centers to explore the commercial use of microbial fuel cells. Recently, a team from the Biodesign Institute at the University of Arizona has overcome a key problem of MFCs-predicting efficiency. Researchers there have come up with a novel concept involving the electrical potential on the biofilm anode. Through this they can now extrapolate more information about the state of the electrons in the wastewater. In particular, the team has shown that the biofilm should be neither too thick nor too thin to optimize power output and performance. Through its partnerships with companies such as OpenCEL and NZ Legacy, this group is actively pursuing the commercialization of this technology.
Drink Beer, Save the Planet
Two different operations, half a world apart, are scaling up to full commercial use of microbial fuel cells. After a successful three-month prototype demonstration, Foster’s of Australia, working with University of Queensland researchers, is currently working on installing a 660-gallon MFC at one of its breweries near Canberra. While the primary use of this fuel cell will be for the treatment of the brewery’s wastewater, it will also have the added benefit of generating approximately two kilowatts of power. While the amount of electricity generated will not be huge, the recycling aspect could potentially be even more useful in drought stricken areas like Australia.
Another brewery, New Belgium in Colorado, has also incorporated MFCs to treat its wastewater and generate methane, which is subsequently used to provide up to 10 percent of the brewery’s energy needs. A logical extension of this scenario and perhaps the quintessential utilization for this technology is in wastewater treatment plants themselves.
Small Could Turn out Big
In the near future, microbial fuel cells could be used in a wide variety of applications from medical to automotive to military. For example, in remote locations MFCs could run low-power antennae, thus eliminating the need to replace batteries by placing a colony of bacteria, along with the electrode, at the bottom of a pile of waste.
Further off there is the prospect of installing micro-MFCs being in the body and using naturally occurring blood glucose as a fuel source. These could then power devices such as pacemakers, again obviating the need to replace batteries, in this case through repeated surgeries.
As alternative fuels increasingly move center stage in our energy landscape, what stands out is their variety, from wind power to solar to bio-based fuels. And while biofuels might replace our larger energy need for automotive fuel, microbial fuel cells will operate on a smaller, but potentially more diverse scale, powering everything from breweries to biosensors inside our bodies.
Tags: electricity, fuel cell, hydrogen, microbes