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Researchers discovered ideal particles size for catalyst inside a fuel cell

Researchers are working hard to develop hydrogen fuel cells as a viable method of powering automobiles. The problem with this type of fuel cell at this point is that the storage of hydrogen is difficult and the fuel cells don’t last as long as manufacturers would like.

Two scientists from the University of Wisconsin-Madison have made an important stride in making hydrogen fuel cell vehicles more viable. The two scientists -- Professor Dane Morgan and PhD student Edward Holby -- have designed a computational model that can optimize one of the most important components of a fuel cell, possibly leading to a longer usable life.

The computational model is being used to investigate how the particle size of a material relates to the overall stability of the material. The researchers are using the model to look at the most efficient and effective particle size for the catalyst inside the fuel cell.

The fuel cell catalyst is typically made from platinum or platinum alloy. The catalyst is used to aid the reaction between the protons, electronics, and oxygen at the cathode inside the cell. Platinum is able to withstand the corrosive fuel cell environment but is costly and not available in abundance.

Platinum particles used inside current fuel cell catalysts are as small as two nanometers across. The tiny particles offer enough surface area for the reaction, but are quickly destroyed and degrade rapidly. The degradation of the catalyst means that the fuel cell doesn't last long. The Department of Energy figures that a fuel cell needs to last for 7 months of continuous use for automotive needs.

The computational model developed by the pair has shown that the ideal particle size for the catalyst is about 20 atoms across, roughly twice as large as the particles inside fuel cells today. At the 20-atom size, the particles degrade much slower and allow the fuel cell to function significantly longer.

Morgan likens the stability of larger particles to cheese, "When you leave a large chunk of cheese out and the edges get crusty, the surface is destroyed, but you can cut that off and there is still a lot of cheese inside that is good. But if you crumble the cheese into tiny pieces and leave it out, you destroy all of your cheese because a larger fraction of the cheese is at the surface."

Another group of researchers made a breakthrough in July with the potential to make storing hydrogen for fuel cells more efficient.



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RE: Shows some promise
By drmo on 9/18/2009 5:36:46 PM , Rating: 2
I'm not sure the cost issue is as much a problem anymore. I thought the GM Volt battery was around 100 kW and cost about $10,000. Now, according to this: http://en.wikipedia.org/wiki/Fuel_cell
fuel cells are down to $73 per kW, which would mean a 100 kW fuel cell would be $7300 to produce. But you also have to make the hydrogen, so the fuel is more expensive for now. If home reformers (from natural gas) become cheap, then that will help, because NG is cheaper than electricity.

As far as the other poster, I think the point was that a battery loses much less energy in its energy sequence than a fuel cell:
Electric: charge-discharge-motor sequence (93%+ electric line efficiency; 90% efficiency charge-discharge; then about 89%+ efficiency in battery to propulsion).
Fuel cell: (up to 50% for electric hydrolysis efficiency, up to 80% for natural gas to hydrogen conversion efficiency; then 40-60% fuel cell to motor efficiency).

Note, an internal combustion engine gets about a maximum of 30% efficiency. So a fuel cell is better than combustion anyway, but not more efficient than an EV.


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