Biofuels Research Could Generate Alternative Energy Source

  • Published
  • By Molly Lachance AFRL/AFOSR PIP
  • Air Force Office of Scientific Research
ARLINGTON, Va. --  AFRL-funded biofuels researchers are investigating ways to produce sizable amounts of hydrogen gas using photosynthetic microbes, known more commonly as algae and cyanobacteria. If available in sufficiently large quantities, hydrogen gas could function as a clean, renewable, less expensive energy source for future military systems.

Princeton University's Dr. Charles Dismukes leads the program effort, which is carried out by a group of researchers from eight different colleges and universities--a group collectively known as the BioSolarH2 team. AFRL funds the BioSolarH2 team as part of the Multidisciplinary University Research Initiative, which focuses on research efforts that combine traditional science and engineering disciplines to address issues of importance to the Department of Defense.

The purpose of the BioSolarH2 team's research is to screen, study, and genetically engineer microbes capable of using light energy to split water molecules and produce hydrogen in the presence of oxygen. During screening, the BioSolarH2 team looks for naturally occurring, photosynthetic microbes having hydrogen-generating enzymes, or hydrogenases, that demonstrate a tolerance to oxygen. The team has identified several good candidate microbes in samples collected from the volcanic soda lakes of East Africa's Rift Valley, from Utah's Great Salt Lake, and from various locations throughout Yellowstone National Park.

The researchers' next step is to study the metabolic pathways, or series of chemical reactions, that take place in the microbes to produce hydrogen gas. To facilitate this activity, they developed powerful fluorescent and electrochemical tools and bioreactors for measuring the products and intermediate steps of these chemical reactions.

In addition to exploring the microbes' inherent properties and biochemical behavior, the BioSolarH2 team is employing a number of strategies to manipulate the microbes' naturally occurring chemical reactions and thereby increase their hydrogen production. One approach involves applying environmental stresses, such as osmotic shock via salt dilution, to accelerate the slow fermentation process so that it better matches the daily cycle of the sun. This strategy induces the microbes' production of hydrogen at a rate 20 times higher than normal.

Air Force officials anticipate that applications stemming from this research may eventually include biomimetic models for engineering synthetic generators. Capable of producing molecular hydrogen from water and light, these generators would enable the production of clean, renewable, lower-cost energy that could, in turn, lessen the dependence on fossil fuels.