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Jerry Woodall, a professor at Purdue University invented the new alloy production process, promising affordable, easy hydrogen.  (Source: Purdue University)

Pictures of the alloy in water, reacting to produce hydrogen, as evidenced by bubbling.  (Source: Purdue University)

The byproduct of the process is a recyclable mix of aluminum and gallium-indium-tin ores.  (Source: Purdue University)

Here a Purdue researcher uses the hydrogen produced by the process to power an internal combustion engine.  (Source: Purdue University)
While some hydrogen research focuses on simulating nature, a new metal reagent developed by Purdue University promises economic viability

Jerry Woodall, a distinguished professor of electrical and computer engineering at Purdue University, is firmly ground in the world of commercial production.  When he began researching ways to improve hydrogen production using aluminum reagents, his goal was simple -- if it wasn't commercially viable, it wasn't a success.

While recent researchers have reported significant breakthroughs in fields such as synthetic photosynthesis and microbial hydrogen production, these methods currently are too inefficient to currently be feasible as a non-subsidized fuel alternative.  While these methods are exciting in that they may one day lead to cleaner and more effective energy production, many agree that the time for hydrogen is now, and waiting for theoretical methods is simply impractical.

Fortunately Purdue's Woodall developed a more down to Earth method of hydrogen production that promises a feasible infrastructure and short term commercial viability.  Woodall states, "We now have an economically viable process for producing hydrogen on-demand for vehicles, electrical generating stations and other applications."

The key to the method is a new aluminum reagent, which Woodall invented.  The new reagent is composed of 95 percent aluminum and then a critical 5 percent mixture of gallium, indium and tin to improve its reactive character.  Previous similar alloys used far more gallium, which is very expensive.  By cutting down the gallium, Woodall greatly reduced the costs of hydrogen production.

When the new alloy is exposed to water, it reacts to create hydrogen gas and oxygen.  The oxygen then bonds to the aluminum to form aluminum oxide, also known as alumina.  It is cheaper to recycle alumina back to aluminum than it is to refine aluminum from bauxite ore, which is another element contributing to its efficiency.  Woodall illuminates, "After recycling both the aluminum oxide back to aluminum and the inert gallium-indium-tin alloy only 60 times, the cost of producing energy both as hydrogen and heat using the technology would be reduced to 10 cents per kilowatt hour, making it competitive with other energy technologies."

Control of the microscopic structure of the solid aluminum and the gallium-indium-tin alloy mixture is critical to the technology's success.   The mixture is a "two-phase" mixture, meaning that it features abrupt changes in composition between one constituent to another.  Woodall explains this challenge stating, "This is because the mixture tends to resist forming entirely as a homogeneous solid due to the different crystal structures of the elements in the alloy and the low   melting point of the gallium-indium-tin alloy.  I can form a one-phase melt of liquid aluminum and the gallium-indium-tin alloy by heating it. But when I cool it down, most of the gallium-indium-tin alloy is not homogeneously incorporated into the solid aluminum, but remains a separate phase of liquid.  The constituents separate into two phases just like ice and liquid water."

Researchers had two options -- fast cooling to leave separate alloys or slow cooling to yield a single solid alloy brick.  At first they tried fast cooling, which required a puddle of gallium-indium-tin to initiate the reaction.  However, when they turned to the slow-cooled alloy, they were impressed to discover that it reacted just as well, or better, eliminating the need for the liquid gallium-indium-tin alloy.  Woodall adds, "That was a fantastic discovery.  What used to be a curiosity is now a real alternative energy technology."

The Purdue team is currently completing work on developing a production method to produce briquettes of the alloy.  These briquettes could be dropped into a tank of water, producing pure hydrogen.  This would eliminate both the need for hydrogen storage and hydrogen transportation, two critical obstacles for the hydrogen industry. 

The gallium-indium-tin alloy in the process is inert and is able to be recovered with almost 100 percent efficiency.  Woodall says even the less efficient aluminum recycling produces much less carbon emissions than traditional fuel.  He states, "The aluminum oxide is recycled back into aluminum using the currently preferred industrial process called the Hall-Héroult process, which produces one-third as much carbon dioxide as combusting gasoline in an engine."

In order to fully realize the technology on a national scale for fuel use, alumina recycling infrastructure would need to be dramatically expanded.  Additionally, gallium-indium-tin recycling would need to be added.  This infrastructure would be expensive, but according to Woodall "the economic risk is large, but the potential payoff is also large."

Woodall won the 2001 National Medal of Technology, the highest award for technological achievement in the U.S.  Woodall his fellow researchers will present their findings on Feb. 26, 2008 at the Materials Innovations in an Emerging Hydrogen Economy conference in Cocoa Beach, Fla.  The alloy production process's primary patent title is owned by the Purdue Research Foundation.  Purdue has licensed the technology to an Indiana startup company, AlGalCo LLC., which Purdue hopes will be the first company to implement the technology commercially.

Purdue's solution is similar to the University of Leeds' new method of producing hydrogen from biofuel waste sludge, in that both solutions are economically feasible, but require the development of production infrastructures.  However the new method from Purdue can make hydrogen from a far more plentiful source -- pure water.

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RE: unsure
By initialised on 2/22/2008 7:12:41 PM , Rating: 2
To get this started several small scale factories are set up to process recycled aluminium into pellets of reactant and to reprocess spent reactant. Ideal sites would be existing recycling facilities or, if it can be done small scale, existing filling stations.

These pellets are then loaded into small ~5-10kg canisters with an inlet for water and an outlet for hydrogen. The canisters could be made from a material with a sufficiently higher melting point than the fuel so that the canister could be used as a crucible in which the spent fuel is melted.

As you drive water is added to the canister to produce hydrogen. The hydrogen could either be used to top up a bank of capacitors and batteries via a fuel cell or burnt in an internal combustion process or both in a hybrid drive-train. Either way you would have a vehicle with a hydrogen fuel line supplied by the canisters output and a water tank whose size would be governed by the power-to-weight ratio of the vehicle. Since a canister would have a maximum output the minimum number of canister ports would be governed by the maximum hydrogen output required at peak load. The problem of filling up with water is much less of an issue as water is the output of both hydrogen combustion and fuel-cells. This 'waste' is simply recycled from the exhaust though occasional top ups would be necessary as it is unlikely that every water molecule successfully reacts to produce one alumina and two hydrogen atoms or that each hydrogen atom successfully binds to form a water molecule. However, it might be possible to minimise losses by using a liquid oxygen tank (hmmm... liquid oxygen direct injection internal combustion engine, could work underwater or in vacuum) but I digress.

When the reactant is depleted you simply replace the empty canister. Obviously any vehicle would have to have at least two of these replaceable fuel tanks. If peak output was more than a single can could provide then the minimum is three but range would be poor. Exceeding this max load +1 minimum would increase vehicle range. The +1 minimum exists because it is wasteful to dispense of a can before it is depleted and you cannot guarantee that you will run out of fuel at a filling station. In my twelve years on driving this has only happened to me once, I stopped at a diesel only pump in a petrol car and had to push it to the next one.

Used cans would be emptied, cleaned and refilled with pellets made from the waste product ideally in small automated micro-factory at filling stations.

As for the size of the tanks, well that would depend but keeping them under 10kg would help.

Once the infrastructure was in place there would be very little need for additional raw materials except to allow for surplus stock and cope with an expanding fleet and lost cans. Most of this could be obtained from recycled materials.

Whether this model is feasible depends on how far you can get in a typical car on this fuel, maybe it only scales up to portable electronics or down to heavy haulage. The inventors clearly believe it is commercially viable and I think this is an elegant and efficient way of doing it without the need for quarries or pipelines.

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