Sugar could power hydrogen fuel cars says VTU researcher
Sugar could power hydrogen fuel cars says VTU researcher
mongabay.com
May 22, 2007
Sugary carbohydrates could be used to produce low-cost hydrogen to power fuel cells report researchers writing in the May 23 issue of PLoS ONE, the online, open-access journal from the Public Library of Science ( www.plosone.org).
A team of researchers, led by Y.-H. Percival Zhang of Virginia Tech University say that a combination of 13 enzymes can convert polysaccharides (i.e. sugary carbohydrates) and water into hydrogen. The new process would be significant because it is cost efficient and “clean” relative to producing hydrogen gas from natural gas, as most hydrogen is currently produced.
“Polysaccharides like starch and cellulose are used by plants for energy storage and building blocks and are very stable until exposed to enzymes,” states a news release from Virginia Tech (VTU). “Just add enzymes to a mixture of starch and water and ‘the enzymes use the energy in the starch to break up water into only carbon dioxide and hydrogen.'”
A membrane separates off the carbon dioxide and the hydrogen is used by the fuel cell to generate electricity. The process takes place at low temperature — about 86 degrees F — and atmospheric pressure.
The researchers say the technology could someday be used to power fuel cell cars.
“A car with an approximately 12-gallon tank could hold 27 kilograms (kg) of starch, which is the equivalent of 4 kg of hydrogen,” explains VTU. “The range would be more than 300 miles… [with] one kg of starch will produce the same energy output as 1.12 kg (0.38 gallons) of gasoline.”
The researchers say the process yields greater hydrogen storage than long-term targets set by the Department of Energy.
“Using polysaccharides as the hydrogen storage carrier, the research team achieved hydrogen storage capacity as high as 14.8 mass percent,” report the researchers.
“It is environmentally friendly, energy efficient, requires no special infrastructure, and is extremely safe. We have killed three birds with one stone,” said Zhang. “We have hydrogen production with a mild reaction and low cost. We have hydrogen storage and transport in the form of starch or syrups. And no special infrastructure is needed.”
“The next R&D step will be to increase reaction rates and reduce enzyme costs,” Zhang said. “We envision that in the future we will drive vehicles powered by carbohydrate, or energy stored in solid carbohydrate form, with hydrogen production from carbohydrate and water, and electricity production via hydrogen-fuel cells.
“What is more important, the energy conversion efficiency from the sugar-hydrogen-fuel cell system is extremely high — greater than three times higher than a sugar-ethanol-internal combustion engine,”Zhang said. “It means that if about 30 percent of transportation fuel can be replaced by ethanol from biomass as the DOE proposed, the same amount of biomass will be sufficient to provide 100 percent of vehicle transportation fuel through this technology.”
Related
Cell phone batteries could be powered by OJ. Researchers at Saint Louis University in Missouri have developed a fuel cell battery that can run on virtually any sugar source — from orange juice to tree sap — and may last three to four times longer than conventional lithium ion batteries.