Recovery method makes hydrogen fuel cells feasible

Hydrogen can be used as a practical, widespread alternative fuel to gasoline, according to researchers from Los Alamos National Laboratory and The University of Alabama. The researchers have come up with a way to use a lightweight material called ammonia borane for storing hydrogen on vehicles, as reported in the March 18 issue of Science.

In the article, researchers describe an efficient method of adding hydrogen back into the material once the alternative fuel is spent.

"This is a critical step if we want to use hydrogen as a fuel for the transportation industry," said David Dixon, the Robert Ramsay chair of chemistry at The University of Alabama and one of the article's co-authors.

In the approach, ammonia borane in a fuel tank produces hydrogen. This combines with oxygen in the vehicle's fuel cell to release energy. The energy is then converted to electricity to power an electric motor. Water is the only emission.

After hydrogen is released from the ammonia borane, a residue, which the researchers refer to as "spent fuel," remains.

"The spent fuel stays in the car, and we need to add hydrogen back to it in order to use it again," Dixon says. "What this paper describes is an efficient way to add the hydrogen back to make the ammonia borane again. And it can be done in a single reactor."

This "fuel regeneration process," is a practical, efficient and affordable way to store hydrogen—a key challenge in making the powering of electrical motors via hydrogen fuel cells a realistic alternative to traditional gasoline powered engines.

Benefits of hydrogen fuel cell technology include cleaner air and less dependence on foreign oil.

However, while there has been much progress toward making the widespread use of hydrogen fuel cell technology practical, Dixon said other challenges remain.

"The basic three steps—the initial synthesis, the controlled release of hydrogen, and the regeneration of fuel—are actually in pretty good shape. The next piece is to get a cheap source of hydrogen that doesn't come from coal or fossil fuels," Dixon said.

"The biggest hurdle which we, and everybody else in the world, are looking at is 'how do I use solar energy efficiently to split water in order to make hydrogen and oxygen," Dixon added.

The experimental work was done at Los Alamos and the computer modeling work was done in Dixon's University of Alabama lab.

UA co-authors with Dixon are Edward Garner III, J. Pierce Robinson and Monica Vasiliu. The article's lead author is Andrew Sutton of Los Alamos National Laboratory. Other Los Alamos co-authors are Anthony Burrell, John Gordon, Tessui Nakagawa and Kevin Ott.

The research was funded by the U.S. Department of Energy through the DOE's Chemical Hydrogen Storage Center of Excellence. This entity, funded with $30 million, is a collaboration among multiple university and industrial partners across the country, including The University of Alabama, and with the Los Alamos National Laboratory in New Mexico and Pacific Northwest National Laboratory in Washington. Research for the project at UA, which was named a partner in the entity in 2004, is funded by some $2.2 million.