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Hydrogen gas bubbles up into the tube on top of this microbial electrolysis cell. Behind is the power source used to boost the process. ((Shaoan Cheng/Penn State University))

Two U.S. research papers have advanced the potential of hydrogen as a fuel.

In one study, scientists from Pennsylvania State University have developed a method to convert cellulose — the main component in plant fibre — and other biodegradable organic materials into hydrogenusing microbial fuel cells.

"The energy focus is currently on ethanol as a fuel, but economical ethanol from cellulose is 10 years down the road," environmental engineering professor Bruce Logan said Mondayin a news release. The method he developed with research associate Shaoan Cheng has been successful experimentally, he said.

The project placed naturally occurring bacteria in an electrolysis cell with acetic acid,found in vinegar. It's also themain acid produced by fermenting cellulose.

The bacteria consumed the acid, releasingelectrons and protons.The addition ofelectricity sent hydrogen gas bubbling up from the liquid.

Splitting water molecules (water hydrolysis) isa standard method for producing hydrogen, but is only about half asefficient, the researchers said.

Hydrogen fuel cells are one of the great hopes for production of clean energy. The cellscombine hydrogen and oxygen to produce electricity, water and heat, but are years from being practical.

Logan suggested hydrogen produced from cellulose could be used in natural-gas vehicles.

"We drive a lot of vehicles on natural gas already," Logan said. "Methane burns fairly cleanly, but if we add hydrogen, it burns even more cleanly and works fine in existing natural gas combustion vehicles."

In unrelated research, University of Virginia scientists Bellave Shivaram and Adam Phillips reported that they had developed a material that made it much easier to store and transport hydrogen in fuel cells.

The material could address problems with handling hydrogen at a much lower cost than current technology, further advancing the fuel's potential, the scientistssaid Tuesday in a news release.

Logan and Cheng's research was published in the online edition of Proceedings of the National Academy of Sciences.Bellave and Phillips presented their findings at the International Symposium on Materials Issues in a Hydrogen Economyon Monday.