28 July 2009

Hydrogen fuel cells looking for boost

Hydrogen fuel-cell vehicles (FCVs) can be an important part of the solution to America’s energy crisis, but roadblocks continue to stand in the way of full time adoption.

There is now a plan under development researching lightweight materials to store hydrogen and release it, under control, as it expends energy, said Dr. Andrew Goudy, chairperson of Delaware State University’s Chemistry Department.

FCVs get their power from electric motors that derive energy from on-board fuel cells. The fuel cells convert pure hydrogen and oxygen into electricity.

Goudy defines several challenges:

• A car must be able to store enough hydrogen to travel 300 miles, the approximate equivalent of a tank of gasoline.
• The car must be able to refuel with hydrogen quickly. Some hydrogen storage materials may take up to 30 minutes to recharge, and few drivers are going to stand at the pump of a fuel station for a half-hour.
• The hydrogen storage unit must be sufficiently compact and lightweight to be practical.

One promising hydrogen-storage material is the complex hydride LiBH4. Its enthalpy, or thermodynamic properties, however, means it requires high temperatures to release hydrogen. Goudy is seeking ways to destabilize this material so it will release hydrogen at a practical temperature.

“Although just one of many scientific and engineering challenges, this one lies at the heart of the process,” Goudy said. “If you cannot store, release, and restore hydrogen with an ease and efficiency comparable to gasoline, you cannot have a practical hydrogen fuel cell vehicle.”

Scientific and engineering progress has enabled Toyota to make the 350-mile drive from Osaka to Tokyo, expending only 70% of the fuel supply of an FCV. Toyota Motors “is planning on releasing a fuel-cell car by 2015 in its attempt to retain its lead in the global race for green cars,” said Masatami Takimoto, a vice president with the company.

Along those lines, Honda’s FCX Clarity was the choice of 59 world jurors as the 2009 World Green Car. Its only emission is water, and its fuel efficiency is three times that of a conventional auto and double that of a gasoline-powered hybrid, Honda officials said. Volkswagen and General Motors are also moving forward with FCVs.

For related information, go to www.isa.org/manufacturing_automation.