Hydrogen could provide an alternative to battery power
Tomohiro Ohsumi/Getty
By David Hambling
The accidental discovery of a novel aluminium alloy that reacts with water in a highly unusual way may be the first step to reviving the struggling hydrogen economy. It could offer a convenient and portable source of hydrogen for fuel cells and other applications, potentially transforming the energy market and providing an alternative to batteries and liquid fuels.
“The important aspect of the approach is that it lets you make very compact systems,” says Anthony Kucernak, who studies fuel cells at Imperial College London and wasn’t involved with the research. “That would be very useful for systems which need to be very light or operate for long periods on hydrogen, where the use of hydrogen stored in a cylinder is prohibitive.”
The discovery came in January, when researchers at the US Army Research Laboratory at Aberdeen Proving Ground, Maryland, were working on a new, high-strength alloy, says physicist Anit Giri. When they poured water on it during routine testing, it started bubbling as it gave off hydrogen.
That doesn’t normally happen to aluminium. Usually, when exposed to water, it quickly oxidises, forming a protective barrier that puts a stop to any further reaction. But this alloy just kept reacting. The team had stumbled across the solution to a decades-old problem.
Hydrogen has long been touted as a clean, green fuel, but it is difficult to store and move around because of its bulk. “The problem with hydrogen is always transportation and pressurisation,” says Giri.
Slow reaction
If aluminium could be made to effectively react with water, it would mean hydrogen on demand. Unlike hydrogen, aluminium and water are easy to carry – and both are stable. But previous attempts to drive the reaction required high temperatures or catalysts, and were slow: obtaining the hydrogen took hours and was around 50 per cent efficient.
The new alloy, which the team is in the process of patenting, is made of a dense powder of micron-scale grains of aluminum and one or more other metals arranged in a particular nanostructure. Adding water to the mix produces aluminium oxide or hydroxide and hydrogen – lots of it. “Ours does it to nearly 100 per cent efficiency in less than 3 minutes,” says team leader Scott Grendahl. Moreover, the new material offers at least an order of magnitude more energy than lithium batteries of the same weight. And unlike batteries, it can remain stable and ready for use indefinitely.
Full-size, hydrogen-powered tanks might also be an option
U.S. Army photo by David McNally
HT/Macusn
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No, the Al is not consumed in the process, it’s a conversion. But not to worry – it can easily be converted back using energy from the H that was produced in the process, and then you can do it all over again. An endless supply of H, the only drawback is that you never get to use it for anything else. But best to check first just how much Al the H would be able to covert back. Maybe it’s not quite endless.
It bugged me that Willis’ figures were a bit low….
From very first principles of a Coulomb being x number of electrons, a kilo of Al being y number of atoms and each atom needs 3 electrons, you need to run just under 30,000 amps for an hour to get a kilo of Ally.
Does a cell work at 2 Volts – so that gives 60 kWh per kilo. Says I.
Then I goes check and surprise, I got it right, ish –
lowtechmagazine tells us…
From here: http://www.lowtechmagazine.com/what-is-the-embodied-energy-of-materials.html
Is this between six and nine times the energy density of gasoline?
Promising stuff.
Very energy dense and it burns *very* hot (do they still weld railway tracks with it, certainly launch rockets) so it could make an exceptionally ‘Carnot efficient’ engine.
The exhaust ‘gas’ (carborundum basically) would be rather abrasive tho.
But and and, an aluminium electrolysing cell uses about the same amount of graphite as the aluminium it produces – they need to get the oxygen out the way as fast as fooking possible before it re-reacts with the aluminium they’ve just made.
So how much energy comes from (= is required to make) a kilo of graphite? Gotta add that in.
“burns *very* hot”
Not a useful characteristic. The main problem with all heat engines is that it isn’t practical to run them at optimum efficiency because the materials used won’t take it. Jet fuel for example has a adiabatic combustion temperature of 2,900 K, but no turbine material yet invented can take more than about 2,000 K.
If it generates a lot of heat, then that heat could be used to drive a steam turbine generating electricity at an efficiency about of 35-40%. Add that to the 33% calculated above and it is about 70% efficient overall, providing H2 and electricity.
It would take a pretty big tank to make room for a boiler, a steam turbine, a generator, a condenser and a cooling tower.
The ‘New Scientist’ could easily be renamed ‘New Witchcraft’….it really has become a fringe publication.
Dr Strangelove does a valuable calculation to provide a non-chemist with a useful comparison, but please cut the guys doing the work some slack as at least they are doing their best to provide a possible alternative to the insanity of current battery technology – which is doing the health of the poor kids digging the materials out of the ground no end of harm.
I wonder what the comparison to gas would be if you did the calaculation Dr Strangelove made for the full cost of running an electric car, from material extraction to processing plus producing the “magic” electricity which comes out of the plug into the battery stuffed into the car?
Any attempt to escape from the dead end battery technology and its social consequences seems worth considering.
“Any attempt to escape from the dead end battery technology”
Dead end battery technology? I bet you’ve never owned a cordless drill, or one of those $15 toy helicopters.
Moderately Cross of East Anglia
Well said, there’s more to all this than simply the numbers. And as this was discovered by accident, what’s to say it doesn’t lead to something else, or that something else isn’t discovered by accident.
It does demonstrate, however, that despite the human races conceit, we don’t know nearly as much as we think we do.
The urbanised greens are deliberately blind to the conditions where rare materials are mined, as long as it suits their EV objectives. Nor are these materials called ‘rare’ without reason, they’ll run out far quicker than fossil fuels.
And all this for a trace gas essential to life on earth that was naturally, but accidentally sequestered, quite possibly by catastrophic events.
And at the risk of boring everyone as I have said it before, it seems an extraordinary coincidence that man happened along just when CO2 was at (one of 2(?) periods) it’s lowest atmospheric concentration in the planets history and started liberating CO2 by burning fossil fuels. If I were religions, I might hail it a miracle. But I’m not, so perhaps it might be considered the most fortuitous coincidence the planet has ever witnessed.
I used to work for a hard drive disc manufacturer, substrate for disc was aluminum. Here’s the issue I see from my experience working there.
We would grind the aluminum disc down to the proper thickness, this left us with a lot of aluminum suspended in a slurry slowly converting to hydrogen and aluminum oxide. First of all this slurry had to be stored in tanks that were vented and monitored for H2 to ensure it did not reach an explosive levels. This is an issue that would probably be fairly easy to deal with in a hydrogen burning car.
Second issue is a bit more problematic, our aluminum slurry could not be allowed to dry out. Converting aluminum into hydrogen and aluminum oxide is an exothermic reaction, let it dry out slowly and that stuff will auto ignite. One of our engineers did an experiment, he put some in a dish with a temperature probe sitting in it. As the slurry dried out it slowly heated up to 130F at which point temperature increased rapidly and the sample started to burn. We disposed of the slurry by loading into a hazmat truck, hazmat driver was not allowed to stop until they reached their destination which was a waste burning facility ~4hrs away. That guy was driving a bomb with the detonator consisting of nothing but time. Before anyone says it’s not that bad, yes it is and we had a couple of very exciting events to prove it.
This can be a real serious issue in a car, can the car be designed to safely handle the “waste” fuel to the point a complete idiot can safely own and operate it? Can the gas stations “safely” handle the waste until it was picked? Are there enough hazmat certified truckers around to safely transport the waste? How far can a trucker go before the load is no longer safe to transport? Figure that last one out and you’ll know the maximum distance allowed between nonexistent reprocessing facilities that will have to be built.
There’s more cost associated with this fuel then just the conversion of Al-H2 and back to Al again. There’s going to be a large cost factor into safely designing a car to use this fuel and the cost of safely handling/transporting the waste for reprocessing.
Darrin and all,
Something that I haven’t seen mentioned so far is that hydrogen is notorious for embrittling metals (especially steel) and is prone to leaking because of its low molecular weight. Thus, even if the economics problems can be addressed, there are still a lot of engineering and materials science issues that need to be solved before the hydrogen technology can be applied commercially.
A detailed analysis of the Al + H2O reaction for hydrogen production was published in 2008, the summary of their conclusions were as follows:
“Aluminum Required: 9 kg Al per kg H2 assuming 100% yield
Gravimetric Hydrogen Capacity: 3.7 wt.% (materials only)
Volumetric Hydrogen Capacity: 36-46 kg H2/L (materials only)
Reaction Kinetics: 2 x 10-4 g H2/sec/g of Al – from published data to date
Cost: $7 per kg H2 (based on the cost of electricity for aluminum production considering only the reduction of alumina to aluminum step)
……..
The current DOE hydrogen storage system capacity targets are a hydrogen gravimetric capacity of 6 wt.% and a hydrogen volumetric capacity of 45 g H2/L (27). It is clear from the analysis presented in this White Paper that no aluminum-water reaction system can meet these targets. Additional negative factors are the high cost of hydrogen from this process, and the amount of aluminum required for large-scale vehicular applications.”
“The November 2007 commodity price for aluminum is $2.36 per kg. At this price, hydrogen from an aluminum-water hydrogen generation approach would cost approximately $21 per kg H2. Even assuming high volume production, the DOE target range for hydrogen cost of $2-3 per kg H2 would not be met.”
Emphasis mine.
https://www1.eere.energy.gov/hydrogenandfuelcells/pdfs/aluminium_water_hydrogen.pdf
Hydrogen is a pain in the butt. Electricity is piped into everyplace, including your home and condo.
Recharging stations for electrics will be nowhere near as plentful as those required for a fleet of gasoline vehicles.
No one has (yet) mentioned the very high cost of producing those “micron-scale grains of aluminum”. Has anyone here ever purchased aluminum powder? The cost of reducing solid metal to powder is enormous.
That’s a major problem with all schemes proposed by economists, lawyers, sociologists, etc,, that they have no practical experience, the kind that a good engineer should have.
Ian
It would never be produced as a solid first. When the molten metal is ready, it would be sprayed vertically down into a nitrogen atmosphere cooling chamber producing the particles directly. That is similar to how lead shot is made (they use a screen for that).
Crispin,
Producing aluminum nitride?
You mean “the molten alloy”. Which is hard to make without any of the metals being a solid first.
Don’t tell Musk. He’ll turn it into another massive tax credit scheme.
Aluminium has merits, but the solid waste products, aluminium oxide or hydroxide, are messy and awkward to handle. This may seem trivial to some, but dealing with non-fluid compounds is hugely problematic for something that needs to be scaled up to a vast industrial scale. It won’t happen.
Nothing new under sun. Mercury catalysis brings hydrogen production from aluminium and water. Trace of mercury salt induces AL2O3 formation due to air humidity from aluminium surface- you may try it. Hydrogen formation from aluminium was used for balloon filling at start of 20. century. Nanno tricks are useless,
There is a very well known and massively researched principle in metallurgy which is called hydrogen in metals. It doesn’t sound very sexy, but about 28 years ago I had reason and opportunity to read up on it as much as I wanted to.
What is it? Hydrogen in metals is a phenomenon in which hydrogen atoms go into metal crystal lattices and keep on going in, and keep on going in, and keep on going in. The metal sort of absorbs the hydrogen but not chemically. The hydrogen eventually causes problems in the metals and causes metal parts to fail. These failures is the reason it has been studied so extensively, as scientists try to understand it and to learn how to prevent it.
What I am thinking here is that the nano state of the aluminum is possibly (probably?) allowing the water in some way to access the hydrogen that is INSIDE the aluminum already.
If this is the process that is bubbling the hydrogen out, then I can tell you that the wrong people to get involved is the physicists. This would be a metallurgical effect, a crystalline effect. Physicists will not have any experience with this at all.
——-
ALSO: They found this with aluminum, true. It may not be unique to aluminum, though. I’d suggest they nano-treat other metals the same way and see what happens. My bet is copper and silver might work, too. But for vehicles, if this is real, then aluminum would be best, due to weight factors.
——-
This kind of reminds me of the accidental discovery of white-light LEDs. Also the accidental discovery of graphene.
. , Crispin, you’ve got top raise the temp to over 2000C to extract aluminium that way -costing more energy again which is why electrolysis is used.
Try looking up thing’s… Aluminum melts at 1,200 F. High temp aluminum alloys usually under 1,500 F. Aluminum Hydroxide melts at around 540 F. As the vat of aluminum hydroxide melts by the use of a cathode and anode of carbon electric arc the Aluminum Hydroxide acts as a flux floating on top of the molten aluminum, as the molten aluminum pours out of the vat…more aluminum hydroxide is added in a contentious manner. To create an alloy other metals as oxides or hydroxides ot other compounds are added during the process and only slightly higher temperatures are required. This is from a 1933 updated in 1954 edition basic college chemistry book on my desk. What this takes in kwh I have no idea. We don’t know the alloy of the nanoparticles or the melting point to get it done to kwh. And you can melt aluminum and added metals in a microwave furnace in crucibles at lower temperatures than the temperature it takes to melt the alloy after its created. Making nanoparticles alloys is done in a different process from the conventional process.
http://pubs.acs.org/doi/abs/10.1021/acs.jpcc.6b04054#/doi/full/10.1021/acs.jpcc.6b04054