Sunday, May 27, 2007

More on the Aluminum to Hydrogen Process

New process generates hydrogen from aluminum alloy to run engines, fuel cells

A Purdue University engineer has developed a method that uses an aluminum alloy to extract hydrogen from water for running fuel cells or internal combustion engines, and the technique could be used to replace gasoline.

The method makes it unnecessary to store or transport hydrogen - two major challenges in creating a hydrogen economy, said Jerry Woodall, a distinguished professor of electrical and computer engineering at Purdue, [and 2001 National Medal of Technology awardee], who invented the process.

"The hydrogen is generated on demand, so you only produce as much as you need when you need it," said Woodall, who presented research findings detailing how the system works during a recent energy symposium at Purdue. [...]

"When water is added to the pellets, the aluminum in the solid alloy reacts because it has a strong attraction to the oxygen in the water," Woodall said.

This reaction splits the oxygen and hydrogen contained in water, releasing hydrogen in the process.

The gallium is critical to the process because it hinders the formation of a skin normally created on aluminum's surface after oxidation. This skin usually prevents oxygen from reacting with aluminum, acting as a barrier. Preventing the skin's formation allows the reaction to continue until all of the aluminum is used.

The Purdue Research Foundation holds title to the primary patent, which has been filed with the U.S. Patent and Trademark Office and is pending. An Indiana startup company, AlGalCo LLC., has received a license for the exclusive right to commercialize the process. [...]

"Gallium is critical because it melts at low temperature and readily dissolves aluminum, and it renders the aluminum in the solid pellets reactive with water. This was a totally surprising discovery, since it is well known that pure solid aluminum does not readily react with water," [explains Woodall].

The waste products are gallium and aluminum oxide, also called alumina. Combusting hydrogen in an engine produces only water as waste.

"No toxic fumes are produced," Woodall said. "It's important to note that the gallium doesn't react, so it doesn't get used up and can be recycled over and over again. The reason this is so important is because gallium is currently a lot more expensive than aluminum. Hopefully, if this process is widely adopted, the gallium industry will respond by producing large quantities of the low-grade gallium required for our process. Currently, nearly all gallium is of high purity and used almost exclusively by the semiconductor industry."

Woodall said that because the technology makes it possible to use hydrogen instead of gasoline to run internal combustion engines it could be used for cars and trucks. In order for the technology to be economically competitive with gasoline, however, the cost of recycling aluminum oxide must be reduced, he said.

"Right now it costs more than $1 a pound to buy aluminum, and, at that price, you can't deliver a product at the equivalent of $3 per gallon of gasoline," Woodall said.

However, the cost of aluminum could be reduced by recycling it from the alumina using a process called fused salt electrolysis. The aluminum could be produced at competitive prices if the recycling process were carried out with electricity generated by a nuclear power plant or windmills. Because the electricity would not need to be distributed on the power grid, it would be less costly than power produced by plants connected to the grid, and the generators could be located in remote locations, which would be particularly important for a nuclear reactor to ease political and social concerns, Woodall said.

"The cost of making on-site electricity is much lower if you don't have to distribute it," Woodall said.

The approach could enable the United States to replace gasoline for transportation purposes, reducing pollution and the nation's dependence on foreign oil. If hydrogen fuel cells are perfected for cars and trucks in the future, the same hydrogen-producing method could be used to power them, he said.

"We call this the aluminum-enabling hydrogen economy," Woodall said. "It's a simple matter to convert ordinary internal combustion engines to run on hydrogen. All you have to do is replace the gasoline fuel injector with a hydrogen injector."

Even at the current cost of aluminum, however, the method would be economically competitive with gasoline if the hydrogen were used to run future fuel cells.

"Using pure hydrogen, fuel cell systems run at an overall efficiency of 75 percent, compared to 40 percent using hydrogen extracted from fossil fuels and with 25 percent for internal combustion engines," Woodall said. "Therefore, when and if fuel cells become economically viable, our method would compete with gasoline at $3 per gallon even if aluminum costs more than a dollar per pound."

The hydrogen-generating technology paired with advanced fuel cells also represents a potential future method for replacing lead-acid batteries in applications such as golf carts, electric wheel chairs and hybrid cars, he said. [...]

The concept could eliminate major hurdles related to developing a hydrogen economy. Replacing gasoline with hydrogen for transportation purposes would require the production of huge quantities of hydrogen, and the hydrogen gas would then have to be transported to filling stations. Transporting hydrogen is expensive because it is a "non-ideal gas," meaning storage tanks contain less hydrogen than other gases.

"If I can economically make hydrogen on demand, however, I don't have to store and transport it, which solves a significant problem," Woodall said.

Source: Purdue University

3 Comments:

Blogger Harry Eagar said...

'when and if fuel cells become economically viable'

They have been going to be ready day after tomorrow since before I was old enough to vote, so I ain't holdin' my breath on that.

No aluminum oxide skin forms? Hmmm. And what happens when you scrape one of those pellets along the pavement?

May 27, 2007 1:58 PM  
Blogger Duck said...

We're still talking about energy conversion technology and not energy production. The energy to convert the aluminum oxide to aluminum requires a source of energy. You also have the problem of aluminum oxide collection. Each time you fill up your tank with gallium-aluminum pellets you have to empty your holding tank of the by-products. You need a transportation network to truck those waste products to the reprocessing plant. Not the most ideal relpacement source for gasoline so far.

I think this technology holds a lot more promise. All you need to refill it is an air compressor.

May 28, 2007 6:57 AM  
Blogger Oroborous said...

Yeah, that's a cool little in-town runabout.

If you lived in a place with a lot of sun or wind, you could even generate the electricity needed to run the compressor at home, fill up a holding tank throughout the day or night, and just transfer the compressed air to the vehicle when you get home.

May 28, 2007 1:41 PM  

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