Bacteria research explored as power source for Air Force systems

  • Published
  • By William J. Sharp
  • Air Force Office of Scientific Research
ARLINGTON, Va. --  The Air Force Office of Scientific Research recently awarded a five-year grant to
the University of Southern California (USC) valued at $4.5 million to lead a study on bioengineered fuel cells.

USC will collaborate on the multidiscipline university research initiative - or MURI - with Rice University in Houston, Texas.

Bioengineered fuel cells are bacteria capable of producing electrical energy simply through the process of consumption. Bacteria that serve as catalysts in the fuel cells can eat a variety of carbon based wastes and materials such as glucose, lactose and glycerol. In turn, the bioengineered fuel cells can convert food intake into electrical power.

Leading USC's effort is Dr. Ken Nealson, professor of geobiology, department of Earth sciences. Dr. Nealson believes that microbes and bacteria have a number of interesting properties that make them attractive for converting organic energy sources into electricity.

"The Air Force has long been interested in developments in compact power sources. Developments in these sources could enable certain systems, such as unmanned aerial vehicles, to operate for longer periods of time without the use of conventional engines and batteries," said Maj. Jennifer S. Gresham, AFOSR's program manager for biophysical mechanisms. "The bio-based fuel cells that could result from the efforts of Dr. Nealson and his team may help solve some of the challenges faced by these systems, including infrared signature detection, excessive noise and weight and slow
battery recharge. We believe his research may allow air vehicles to one day refuel themselves by using their surroundings."

"If this research works and we can manipulate these cells to be better at power production and increase their waste reduction capacity at the same time, then we will have achieved something very important to the Air Force," Dr. Nealson said.

"Microbes can eat a wide variety of things. Potentially, that makes them very versatile in how they can be used. Standard fuel cells typically consume only a single compound or element," Dr. Nelson said. "Since bacteria can eat dozens of things, you could have a fuel cell capable of turning a variety of organic energy sources into electricity."

Dr. Nelson believes that bacteria as catalysts for energy conversion offer other interesting qualities as well.

"In comparison to expensive platinum catalysts, bacteria are virtually free. One needs only to grow them up in the quantities needed," Dr. Nealson said. "And bacteria are self-repairing systems, too. If stressed, the colony simply reforms and fixes itself."

According to Dr. Nelson, the challenge is that no one has yet been able to get the systems to produce enough electrical current for the systems to be taken seriously.

"We have very good evidence now, as do a number of other labs, that these organisms have great energy production potential. Our goal is to learn the mechanism by how they turn organic compounds into useful electrical energy so we can exploit this capability and get the bacteria to produce even greater volumes of energy," he said.

"Shewanella oneidensis and geobactor are the current systems under investigation because researchers know a lot about these bacteria forms," Dr. Nelson said.

Like the human process of breathing in oxygen and exhaling carbon dioxide, Shewanella oneidensis has the ability to inhale certain metals and compounds, which may be toxic to humans, and exhale these metals in an altered, non-toxic state. Researchers believe Shewanella oneidensis and other closely related microbes have a number of potential uses, including environmental clean-up because they can grow under a wide variety of conditions. Additionally, the bacteria could be used almost anywhere and do not cause disease in humans or other organisms.

"I consider these two to be model systems. We plan to learn from them as much as possible. Then, based on the model systems, we will explore how to build upon nature."
Dr. Nealson's research consists of a number of thrust areas. The microbiology thrust area involves identifying components of the fuel cells to better learn how the energy transfer occurs. The second thrust area involves understanding how the fuel cells might be better engineered to maximize their interactions with the microbes. Genetic improvement of the microbes is the goal of the third thrust area to increase power production. The fourth thrust area is an examination of the communities of organisms working together. In this effort, researchers are looking to identify communities that show the greatest power production potential.

"I believe it is within reach in the very near future to begin understanding the basic mechanisms involved in electricity generation. We can then exploit this knowledge to increase the power production of the cells under study by many orders of
magnitude," Dr. Nealson said. "With time and a little luck, we may be able to increase power enough to accomplish a number of laudable goals, but only if we understand the mechanisms involved."