September 15, 2009
MERC Team Uses Bacteria to Tackle an Energy Challenge
One of the oldest life forms on the planet may be able to help solve some very modern problems. Certain strains of cyanobacteria are known to produce hydrogen, so staff in the Milton Eisenhower Research Center (MERC) are studying the bacteria to evaluate their potential as a clean source of hydrogen fuel.
“Using bacteria to produce hydrogen could create a portable power source for Department of Defense applications and provide an alternative fuel option, and one that would not increase greenhouse gases because cyanobacteria actually consume carbon dioxide,” says Richard Potember, co-investigator on a Science and Technology Business Area Independent Research and Development (IRAD) project studying the issue. “I thought it would be exciting to use an ancient life form—cyanobacteria have been around 3.7 billion years—to provide a new energy source.”
But before they can plug bacteria into fuel cells, team members must first determine the best way to maximize the organisms’ hydrogen output.
“Our major goal for this IRAD is to get the bacteria onto a film, which has been shown to increase the amount of hydrogen they produce,” says MERC chemist and co-investigator Jennifer Breidenich. “We’re basically taking something that nature has already done and we’re incorporating it into materials to increase the efficiency.”
Cyanobacteria obtain their energy through photosynthesis, so spreading them out on a film exposes each organism to more light than if the bacteria were suspended in liquid. In a jar full of bacteria, those in the middle of the container receive less light than those near the sides, and therefore make less hydrogen.
Bacteria-produced hydrogen is an attractive renewable resource because the bacteria require only water, sunlight, air and trace mineral salts. The process produces neither hazardous materials nor greenhouse gases.
This project is the first of its kind under a recently signed memorandum of agreement between APL and the Savannah River National Laboratory, a Department of Energy laboratory near Aiken, SC. Researchers at Savannah River are experts in cyanobacteria and storing and processing hydrogen, while APL brings materials science expertise to the project.
Scientists at North Carolina State University are also participating, developing a method to attach the bacteria to a latex film.
The MERC team is attaching the cyanobacteria to a polyvinyl-alcohol hydrogel. The hydrogel is a bit thicker than latex but still less than a millimeter deep. The advantage is that it can hold both water and the nutrients that cyanobacteria need to thrive so they can split hydrogen from the water’s oxygen molecules.
Hydrogen is not the only gas produced by the bacteria, so their output would need to be filtered before going into a fuel cell. Breidenich says the team will work with Savannah River scientists on different types of membranes to separate and filter the bacteria’s output.
It may even be possible to one day remove the cyanobacteria from the process entirely, says Potember. The MERC team is exploring the idea of recreating the chemical processes performed by the cyanobacteria so that they would not need to depend on the living cells to produce hydrogen, which might be more appealing for fuel cells in harsh environments.
"Fuel cells and advanced battery concepts are of extreme importance for Department of Defense energy applications," says Victor McCrary, APL's Science and Technology Business Area Executive. "We believe the niche for APL will be in the applications where we can produce energy and power storage for special-operation missions that increase mission persistence for small sensor platforms. In addition, several business areas have expressed interest in new and innovative concepts to reduce size and weight over current portable power sources. This IRAD project represents the business area’s interest in energy and power management, and builds on the MERC’s expertise in advanced materials and nanotechnology."