Fuel-Cell Researchers Look to Carbon

Researchers are making some progress in finding viable storage technologies for hydrogen fuel.

A group of researchers has developed a new method of layering graphite that could be used someday to efficiently and safely store hydrogen in a vehicle.

If their preliminary findings hold up under more experimentation, carbon-based storage may have the most potential, among several technologies now being considered, to make fuel-cell vehicles commercially viable.

Published in the July 26 issue of the Proceedings of the National Academy of Sciences, the study claims that earlier research underestimated the potential capacity of carbon materials to store hydrogen. According to John Tse, one of the authors of the study and a professor of physics at the University of Saskatchewan, graphite nanomaterial can be layered to adsorb hydrogen gas at higher volumes and densities than previously thought possible.

By controlling the spacing of layers of graphitic plates to maximize adsorption, Tse says a graphite storage system could meet the U.S. Department of Energy's milestones for both weight and volume of a hydrogen storage system. (The study did not consider the DOE's other two goals: cost and time of refueling.)

"[We think] it is possible store hydrogen at close to the highest theoretical concentration," Tse says.

The graphitic material is lighter than metal hydrides storage solutions currently being explored, and is relatively cheap to create. Furthermore, it's chemically inert and environmentally benign. Think of a pencil.

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The Bush Administration wants to reduce the use of fossil fuels, by helping the private sector domestically produce hydrogen that could be used in commercial fuel-cell vehicles by 2020. To that end, last year the DOE set increasingly stringent goals for 2005, 2010, and 2015, for the weight, volume, cost, and refueling time of hydrogen storage systems, which it believes should be met for hydrogen-powered vehicles to become commercially viable. (The department employs scientists who evaluate emerging technologies and oversee the progress of federal funding to university and laboratory researchers.)

According to DOE hydrogen program manager Steve Chalk, none of the three methods for absorbing gaseous hydrogen into other materials -- carbon, chemical, and metal hydride -- has yet achieved all four of the 2005 goals, although individual benchmarks have been met. Creating a viable hydrogen storage platform is "the most critical barrier to the hydrogen economy," Chalk says.