Hydrogen Storage Breakthrough

Stanford researchers recently discovered a hydrogen-rich compound that may help overcome a major hurdle with hydrogen fuel storage...

A hydrogen-rich compound discovered by Stanford researchers is packed with promise of helping overcome one of the biggest hurdles to using hydrogen for fuel--namely, how do you stuff enough hydrogen into a volume that is small enough to be portable and practical for powering a car?

The newly discovered material is a high-pressure form of ammonia borane, a solid material which itself is already imbued with ample hydrogen. By working with the parent material at high pressure in an atmosphere artificially enriched with hydrogen, the scientists were able to ratchet up the hydrogen content of the material by roughly 50 percent.

"Including the hydrogen already stored in ammonia borane, this new material can store around 30 weight percent in total," said Yu Lin, lead author of a paper describing the work that was published this week in the online edition of Proceedings of the National Academy of Sciences.
The Department of Energy has set a target for hydrogen-powered vehicles of having an on-board storage system able to store 9 percent, by weight, of hydrogen in 2015. The new compound, called ammonia borane-hydrogen, contains more than triple that amount.But the fly in the hydrogen is that the sought-after storage system
must function at ambient pressure and temperature conditions. The process Lin
used to get the added hydrogen into the ammonia borane has to take place at a
minimum pressure that is approximately 60,000 times the usual pressure at the
surface of the Earth.

"For energy applications, we need to stabilize the material near ambient conditions," said Lin, a graduate student in geological and environmental sciences. Currently, most hydrogen-powered machines use either compressed hydrogen gas or liquid hydrogen, which needs to be maintained at high pressure or very low temperature, respectively, relative to ambient temperature and pressure. These methods have associated safety concerns in the case of compressed hydrogen and require significant energy for cooling in the case of liquid hydrogen.

- Brewskie

More Proof Why You Won't Need Platinum for Fuel Cells

(Editor's note: although blockquote works well for some bloggers, but its usage has proven finicky with Ghawar Guzzler. Excerpts from articles will be presented in italics until, otherwise noted.)

Researchers have grown arrays of carbon nanotubes which, under demonstration, may be capable of fulfilling the necessary role of catalyst with fuel cells - eliminating the need for exotic materials such as platinum; and they're cheaper and longer lasting, too boot.

Excerpts below include,

More than half the cost of fuel-cell stacks comes from platinum, according to the Department of Energy. "Fuel cells haven't been commercialized for larger-scale applications because platinum is too expensive," says Liming Dai, a materials-engineering professor at the University of Dayton, in Ohio, who led the work. "For electrodes, you need a cheaper material that still has a high performance."

Dai and his colleagues make electrodes by depositing the carbon-nanotube arrays on a composite film of polymer and carbon nanotubes. In a Science paper, the researchers show that using the material as a cathode gives four times higher current densities than do conventional platinum-coated electrodes. "There has been very limited success to finding a replacement for platinum, and [carbon nanotubes] could be one," says Prashant Kamat, a chemistry professor at the University of Notre Dame.

Carbon nanotubes, which are known to be electrically and mechanically robust, could overcome other issues that platinum faces. Carbon monoxide can stick to platinum's surface and make it less effective, Dai says. Also, platinum is not very durable, and its properties degrade over time. "Carbon nanotubes have long-term operational stability and do not suffer from carbon-monoxide poisoning," Dai says.

And...

To make the nanotube electrodes, Dai and his colleagues start with a compound containing carbon, nitrogen, and iron. They place this on a quartz substrate and heat it in the presence of ammonia, resulting in nitrogen-doped carbon nanotubes growing straight up from the surface. Then they oxidize the array to remove residual iron and transfer the array to a polymer film. Immersing the electrode in a potassium hydroxide electrolyte, the researchers found that it speeds up the cathode reaction of oxygen and electrons.

Meanwhile, others are working on different platinum substitutes. Kotaro Sasaki, who does fuel cell catalyst research at Brookhaven National Laboratory and his colleagues at Brookhaven are making atom-thick platinum films, which would use much less of the precious metal. Researchers at Monash University, in Australia, have made cathodes from a polymer called PEDOT. At Argonne National Laboratory, researchers have made nanotube arrays loaded with small quantities of platinum or iron.

- Brewskie