High-pressure compound could be key to hydrogen-powered vehicles

May 11, 2009

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 . 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 .

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 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.

There is currently no material that satisfies all of the requirements for on-board fuel storage for hydrogen-powered vehicles, according to Lin, who is working with Wendy Mao, assistant professor of geological and environmental sciences at Stanford and a co-author of the paper.

"If the material can be stabilized at or near ambient conditions with a large amount of hydrogen content, then I think it will be very promising," Lin said.

There are potentially several ways to help stabilize the compound under normal temperature and pressure conditions. One idea is that there might be some "alternative chemical paths, like adding some catalyst to try to stabilize the system," Lin said.

If Lin and Mao succeed, ammonia borane could move one step closer to becoming an everyday storage material for hydrogen. Also closer to a reality would be scientists' and environmentalists' dream of powering cars with oxygen from the air and hydrogen from the fuel cell, while pumping out only water from the exhaust pipe.

Source: Stanford University (news : web)

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5 / 5 (3) May 11, 2009
How about a nanoscale Pez dispenser?
4 / 5 (2) May 11, 2009
The problem is getting H2 in the first place. While this report is interesting from a materials/chem POV hydrogen powered cars are still a dead duck. Electric seems to be the way forward, with huge strides being made in battery tech.
2.8 / 5 (4) May 11, 2009
BMW have a hydrogen-powered car they have a fuel tank the size of a brief case. Yes due to incredibly low storage temp required the cell loses 10% volume per month if the vehicle has not been driven, a minor concern....... the US is stalling because the dont have the hooks in the H2 industry to control it.
4.5 / 5 (2) May 11, 2009
I am researching the development of Hydrogen infrastructure with the key examples of same drawn from around the world. According to MIT Tech review reports, there are only 50 years supply of Lithium ore, and 50% of that remains in the ground in countries such as Bolivia. How long do you think these resources will last if everyone has a lithium battery in their cell phone, ipod, etc, if demand for Lithium is forecast to grow at an additional 2% per annum, and electric cars are still low volume items.

I see it as a shame for the US that they are reducing funding to Hydrogen research, because if this is true and continues, it will no doubt lead to a brain drain of your best researchers to countries where they have more enlightened funding policies. I agree with some of the posts here, and suggest that both Europe and Japan are light years ahead with the total Hydrogen roll out scenario.

The thing that gets me is that many developed countries are already producing large quantities of Hydrogen as part of the petroleum refining process, or for the manufacture of fertilisers. It is just going to waste, and the decision about funding appears to have been made because it's all about the quick fix or short term budget criteria.

Surely it would be better to consider where the US Hydrogen technologies are world class, [as described in this article] and be more careful in allocating funds to these research teams such that the competitive advantage is improved as a result.

not rated yet May 11, 2009

Lithium-ammonia electrocatalysts seem like a good fuelcontainment system.
1 / 5 (1) May 12, 2009
I have two comments: Finding a way to store the compound at near-ambient pressures and temperatures is a non-trivial task, and 2: A hydrogen car should be run using fuel cells to extract the energy, not by using an inherently inefficient internal combustion engine. Yes, the fuel cells of today are very expensive, which is why we need even more time for the technology to become mature. Internal-combustion engines can be used in a transition phase, but will be of little help for the carbon footprint. This news item is promising, but we need even more money for basic research!
not rated yet May 12, 2009
If high-pressure hydrogen is stored in your car, in a garage under the house, an explosion could put your house in orbit! Wear SPACE SUITS to bed!
1 / 5 (1) May 12, 2009
60,000 times ambient pressure? That's 882,000 psi.
not rated yet May 12, 2009
H2 reclamation via plasmafication in gas turbines sounds like the way forward for both electrical and H2 applications.
not rated yet May 17, 2009
BMW have a hydrogen-powered car they have a fuel tank the size of a brief case. Yes due to incredibly low storage temp required the cell loses 10% volume per month if the vehicle has not been driven, a minor concern.......

The energy consumption involved in liquifying hydrogen is non-trivial. You need complicated, multi-stage cooling that is very inefficient(the amount of energy needed to cool the hydrogen is equivalent to approximately 30% of the energy content in the hydrogen.)

Routinely boiling off hydrogen gas into any enclosed space, a garage or anything else, is a glaring safety hazzard.

When you say suit case you mean something entirely different then when I say suit case. A typical 10-20 litre suitcase would contain 0.7 to 1.4 kg of liquid hydrogen which is equivalent to a mere 1.5-3 US gallones of gasoline when you account for the efficiency of a fuel cell versus an ICE.
not rated yet May 17, 2009
How come so little mention is made of hydrogen on demand generators? It solves the hydrogen distribution problem along with the onboard storage issue.Existing petrol stations could be distribution points.See: http://tinyurl.com/2cyz3c

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