Air Force Supports Sugar-to-Hydrogen Research

  • Published
  • By Maria Callier
  • Air Force Office of Scientific Research
ARLINGTON, Va. --  An AFOSR-funded scientist at Virginia Tech in Blacksburg, Va. is conducting research that will lead to creating low cost hydrogen gas from sugars.

Dr. Percival Zhang of the Biofuels Laboratory at Virginia Tech and his team have developed a new technology enabling them to produce hydrogen by mixing enzymes together with sugar in what is becoming known as "in vitro synthetic biology." Synthetic biology combines science and basic engineering in order to synthesize novel biological functions and systems. In vitro synthetic biology has greater engineering flexibility than in vivo counterparts. The team uses the chemical energy stored in sugar, along with ambient-temperature heat, to split water and release hydrogen. By adding other enzymes to the cocktail, the team can even transform cellulose, a major constituent of wood that is composed of sugar links, to hydrogen as well. Essentially, Zhang and his team will overcome the disadvantages typically associated with using low-cost hydrogen as a transportation fuel, including the lack of high-density storage, costly infrastructure and safety concerns.

If Zhang and his team are successful with their research, they will help decrease greenhouse gas emissions by producing hydrogen from biomass sugar and at the same time increase energy utilization efficiency.

"If we can transform this technology to application, we would achieve the transportation fuel independence without any reliance on fossil fuels," he said.

In the meantime, the scientists are busy stabilizing enzymes and increasing reaction rates.

If an enzyme is not stable, the scientists must frequently produce many enzymes to replace them. As a result, the costs for commercial hydrogen production using this developing technology are still too great. Nonetheless, Zhang believes the researchers will reach their goals gradually and hydrogen generation rates will become fast enough to power vehicles.

"Because of the funding we've received from AFOSR for our research, we've been able to prolong the reaction time of the enzymes to 150 hours. Of course, we need to go further and increase the reaction rates 1,000-fold by using stabilized enzymes," he said.

Zhang believes that in the future, sugar-powered vehicles will drive more than 300 miles per refill. 'A number of stabilized enzyme cocktails will convert sugar syrup (or perhaps even a cellulose slurry as a cheaper alternative) to hydrogen, which will quickly be converted to electricity with very high energy efficiency and high power density via the fuel cell,' he said.

Looking ahead, Zhang predicts that sugary hydrogen will be more advantageous than electrical energy stored in rechargeable batteries (which will replace internal combustion engines after the technology has been improved) because sugar has a much higher energy storage density than does electricity stored in batteries.