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New Material for Low-Temperature Storage and Release of Hydrogen as Adjunct to Hydride Storage

4 December 2006

Bath
Calculated structure for
[Rh6(PH3)6H14]+. Click to enlarge.

Different mechanisms for storing hydrogen using metal lattices are under development, but metal hydrides only work at temperatures above 300° C and metal organic framework materials only work at liquid nitrogen temperatures (-198°C).

Scientists at the University of Bath (UK) have developed a material which stores and releases hydrogen at room temperature, at the flick of a switch. Although its gravimetric hydrogen storage density is insufficient to make an entire hydrogen tank from it, the material could be used in combination with metal hydride sources to store and release energy instantaneously while the main tank reaches sufficient temperature, 300°C, to work.

They hope to have the fully-working prototype ready within two to three years.

Our new material works at room temperature and at atmospheric pressure at the flick of a switch. Because it is made from a heavy metal (Rhodium), its weight to fuel ratio is low, 0.1 per cent, but it could certainly fill the time lag between a driver putting their foot on the accelerator and a metal hydride fuel tank getting up to temperature.

The new material absorbs the hydrogen into its structure and literally bristles with molecules of the gas. At the flick of a switch it rejects the hydrogen, allowing us to turn the supply of the gas on and off as we wish.

The fact that we discovered the material by chance is a fantastic advertisement for the benefits of curiosity driven research.

—Dr Andrew Weller, from the Department of Chemistry at the University of Bath

The University of Bath researchers made the discovery while investigating the effect that hydrogen has on metals. Having constructed an organo-metallic compound containing six rhodium atoms and 12 hydrogen atoms, they began studying the chemical properties of the complex with researchers in Oxford (UK) and Victoria (Canada).

The material absorbs two molecules of hydrogen at room temperature and atmospheric pressure and releases the molecules when a small electric current is applied to the material.

The researchers are now looking at ways of printing the material onto sheets that could be stacked together and encased to form a storage tank.

Potentially this tank could sit alongside a metal hydride tank and would kick into action as soon as the driver put his or her foot on the accelerator, giving the metal hydride store the time to heat up to 300°C.

The research was initially funded by the Engineering & Physical Sciences Research Council.

The researchers are now working on the first stages of the prototype, which involves printing the material onto a glass substrate. A further £500,000 grant to the Department of Chemistry has enabled Weller along with other researchers in the Department to buy two mass spectrometers which allows them to examine the molecular structure of the material.

Resources:

  • Storing and Releasing Hydrogen with a Redox Switch”; Simon K. Brayshaw, Dr., Jennifer C. Green, Prof., Nilay Hazari, J. Scott McIndoe, Prof., Frank Marken, Dr., Paul R. Raithby, Prof. , Andrew S. Weller, Dr.; Angewandte Chemie International Edition, Volume 45, Issue 36 , Pages 6005 - 6008

December 4, 2006 in Hydrogen Storage | Permalink | Comments (5) | TrackBack (0)

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Comments

Great! Rhodium is only 4900 $ per ounce, just about four times more expensive than platinum and 8 times than gold.

Wouldn't it be easier just to have a small tank of compressed H2 handy for the purpose of immediate availability?

I like this hydrogen storage patent application much better than the one in the story. Check it out.

United States Patent Application 20060266441

Mg-Ni hydrogen storage composite having high storage capacity and excellent room temperature kinetics

Abstract

A hydrogen storage alloy having an atomically engineered microstructure that both physically and chemically absorbs hydrogen. The atomically engineered microstructure has a predominant volume of a first microstructure which provides for chemically absorbed hydrogen and a volume of a second microstructure which provides for physically absorbed hydrogen. The volume of the second microstructure may be at least 5 volume % of atomically engineered microstructure. The atomically engineered microstructure may include porous micro-tubes in which the porosity of the micro-tubes physically absorbs hydrogen. The micro-tubes may be at least 5 volume % of the atomically engineered microstructure. The micro-tubes may provide proton conduction channels within the bulk of the hydrogen storage alloy and the proton conduction channels may be at least 5 volume % of the atomically engineered microstructure.

FILED OF THE INVENTION

[0001] The instant invention relates generally to hydrogen storage materials and more specifically to a new composite hydrogen storage material having heretofore unheard of properties. Specifically the instant hydrogen storage material provides for a storage capacity of up to 4.86 weight percent hydrogen with a high adsorption rate at temperatures as low as 30.degree. C. and an absorption pressure of less than about 150 PSI. The composite materials are light weight and absorb at least 3 weight percent in less than two minutes at 30.degree. C. More remarkably, the composite materials also have the ability to fully desorb the stored hydrogen at temperatures as low as 250.degree. C., an ability not heretofore seen in materials with such a high total storage capacity. Even more amazingly the same material can desorb 2.51 weight percent of the stored hydrogen at 90.degree. C. and 1.2 weight percent at 30.degree. C. In addition these material are relatively inexpensive and easy to produce.

http://appft1.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&p=1&u=%2Fnetahtml%2FPTO%2Fsearch-bool.html&r=2&f=G&l=50&co1=AND&d=PG01&s1=%22energy+conversion+devices%22&OS=%22energy+conversion+devices%22&RS=%22energy+conversion+devices%22

This is interesting science, but the cost of rhodium being so high it makes the concern about the weight (gravimetric density) of enough rhodium to serve as primary hydrogen storage seem kind of, uh, moot. Incidentally, if you were to come up with an inexpensive source of rhodium (asteroids, say, or transmutation) it could be better applied in the making of catalytic convertors that can eat NOX, where it would allow regular (bio)diesels to run at high temperatures and high efficiencies. In other words if rhodium hadn't been so precious we might well not be reaching for hydrogen in the first place.

Having to make H2 is the daftest way of storing energy...posts like this are starting to show it. Utter madness.

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