Powering vehicles with aluminum

Pop a few aluminum bits into this little RC racer and you’ll have power for around forty minutes. This concept, which has been patented, is the result of a college research project. It uses a chemical reaction between aqueous Sodium Hydroxide and aluminum. The result of that reaction is hydrogen, which is gathered and directed to a fuel cell that drives the car.

Novel? Yes. Interesting? Absolutely. But you should be raising an eyebrow at the dubious choice of fuel that is aluminum.

If you don’t know what we’re talking about let us paint you a picture. Aluminum is a metal that is refined from bauxite ore. It takes an immense amount of electricity to smelt the metal. This is usually justified because aluminum is one of the most recyclable substances on earth, capable of being melted down and reformed countless times. But dissolving it in drain cleaner breaks it down and then it’s gone. So what we have here simply must be the least efficient disposable battery so far developed. It’d probably use less resources to grow and harvest lemons as a power source.

[via Engadget]

83 thoughts on “Powering vehicles with aluminum

  1. I bet that they could get a million dollar grant to “research” making it more efficient…with the same result when the aluminum is gone its gone.Flippin’ greenies are destroying the planet!

  2. I would actually use magnesium as opposed to aluminum; it’s much easier to extract and the effect would be the same. Plus this would make a good two-stage cell: first, add sodium to water and use up the resulting hydrogen. The NaOH is actually produced in situ as a byproduct. Then add magnesium. When the cell is totally spent, return swap out the case for a new one, the sodium metal is recovered and the MgO is sent off for reprocessing/recovery.

  3. @Hacksaw: Matter doesn’t disappear. It simply reverses what they do at the aluminium smelter – dropping the oxygen off. Add the oxygen again and you get the energy stored by that back.
    You can do it again and again.
    It’s simply not efficient.


  4. @Dougle: NaOH is made from brine – concentrated NaCl solution. The reactions are: 2 Na⁺ + 2 H₂O + 2 e⁻ → H₂ + 2 NaOH
    2 Cl⁻ → 2 e⁻ + Cl₂
    Sodium is hazardous material, has to be stored in mineral oil, etc.
    Magnesium is a very expensive metal – on the other hand, alumina is practically free relative to the costs of turning it into aluminium.
    The sodium hydroxide doesn’t need any replacing with the hydrogen, it’s simply a matter of collecting the aluminium hydroxide.
    Pass the solution through a heat exchanger, extracting the heat. The aluminium hydroxide will quickly crystallise from the solution and can be recycled.
    Perhaps the sodium hydroxide will need replacing every once in a while, like engine oil.

    Aluminium is cheap, easy to transport.
    No other metal seems to be more suitable.
    It’s cheap, non-flammable (unlike magnesium) and safe to handle (unlike sodium).
    The extra step with sodium would only add more inefficiency, more danger and more cost.


  5. some people here are in desperate need of a chemistry lesson as far as im concerned dougie is the only one who got it right.
    @nathan zadocks sorry mate but most of your equations dont really make sense
    most likely the aluminium gets hydrated forming aluminium hydroxide and hydrogen (either directly by reacting with water or indirectly by reducing the sodium wich then reacts with water) the in the fuel cell the hydrogen reacts with oxygent to produce energy.
    overall its really nothing new. its really similar to an aluminium air battery except the charges are not used right away but rather used to create hydrogen wich is then “burned” in the fuel cell.it sounds more like a workaround to the storage problems aluminium air batteries have.

    the point many people are missing is that aluminium packs a punch energywise making aluminium a premium component for high energy to weight ration batteries (even better than lithium batteries). unfortunately rechargable aluminium batteries are only lab prototypes at this stage and years away from mass production.

  6. A couple issues with the summary here.

    Lemons are not the power source, they are the electrolyte. The power in a lemon battery comes from the oxidation of the zinc cathode. In fact, the pure zinc plays a very similar role to the aluminum needed in this case.

    The other thing is that pure aluminum is a great energy delivery mechanism. The aluminum power cell is a fairly well developed technology, it is just that there isn’t a good way to make them “refillable”. This technology solves that problem by going through an intermediate hydrogen step.

    Aluminum is a power delivery and storage mechanism here, not a power source. Just like hydrogen.

  7. I didn’t know that you could patent a simple chemical reaction like reacting aluminum with aqueous sodium hydroxide solution to produce hydrogen and sodium aluminate. Even the using the hydrogen for a fuel cell is very old technology. I guess the patent office was asleep again.

    (What’s next, a patent on the boiling point of water? Avoid the rush and get your application in now!)

  8. dude i can read wikipedia as well if i want “references” what i pointed out was that sodium aluminate is an IONIC compound and is therefore VERY unlikely to be found as such in aqueous solution. your equations assume pure compounds not solutions.
    as for NaOH you can make it by electrolysis of brine but also from reacting pure sodium with water. as for sodium getting reduced in solution yes it is very unlikeley but it still can happen

    furthermore your equation might be right BUT only what the “recyling” of sodium is concerend. the full reaction is more complex. in time sequence the aluminium is oxydised with water wich produces aluminium hydroxide and hydrogen(this reaction in only reversable with lots of energy=> recycling of the battery after use). the aluminium hydroxide can then react with the caustic soda to form sodium aluminate in SOLUTION. this reaction is reversible without any loss or gain of energy/hydrogen and will procede until equilibrium is reached. this is done so as to reduce the geling problems encoutered with aluminium hydroxide.
    i know my chemistry looks like yours could use some refreshing

  9. @snowdruid: In solution, the aluminate ion exists as the hydrated form [Al(OH)4]⁻. Aluminium isn’t stable in basic solution, however.
    NaAlO2 + 2 H2O → NaOH + Al(OH)3 happens quite easily. Whether the anion is hydrated matters little for the reaction mechanism – you could write it as NaAl(OH)4 → NaOH + Al(OH)3 too.
    Either way, aluminium hydroxide precipitates.
    For the non-armchair chemists, you can easily observe this with lye and aluminium foil.
    Solid aluminium hydroxide precipitates after it has cooled down. It will be reddish if you use tap water as it contains iron salts which react to form iron hydroxides.

    On the sodium reductions, it’s not simply ‘unlikely’ – it’s impossible. The first thing on the list to be reduced would be aluminium, if the hydrogen wasn’t there. No reaction would happen – the aluminium is already in elemental form.
    It also has been explained a zillion times above that it takes a crapload of energy to reverse it.


  10. Surprising no one has yet mentioned the version of this process where a bit of gallium is used instead of lye. The gallium just dissolves a bit of aluminum at any given moment, allowing it to freely react with the water without the interference of aluminum oxide; and is not consumed or involved in any chemical reaction.

  11. there is no point discussing this further since we more or less say the same thing the only points i wanted to make is:
    -your formula was right but overly simplified which made i look like a halftruth
    -sodium reduction might have been a poor choices of words on my part i was thinking more along the lines of temporary radical generation
    -the lye has no effect on hydrogen production what so ever it is only there to bind the not precipitated aluminium hydroxide (and more importantly move it away from the unreacted metalic aluminium) and therefore its not a catalyst but instead only facilitates the reaction (as opposed to speeding up the reaction by lowering activation energy)

  12. quote:”Basically, base-catalysed hydrolysis of aluminium.” and “It is base-catalysed hydrolysis.”
    i have no problem with the hydrolysis part because thats what this reaction is. my problem lies with the whole “catalysed by” thing. aluminium reacts with water without the need of any catalysts and is not “catalysed” by aluminium nor lye. if you reeeealy want to call it anything it should be called aluminium catalysed hydrolysis but even that is not really correct.

  13. @snowdruid: There’s a reason sealing anodised aluminium by forming aluminium hydroxie is done in *boiling* water. The reaction isn’t all that spontaneous. The more OH⁻, the faster it is.

    On a side note, I forgot to drop a pair of redundant water molecules on each side. The equation was still correct, however.
    6 H2O + 2 Al → 2 Al(OH)3 + 3 H2

    There are two reaction paths:
    6 H2O + 2 Al → 2 Al(OH)3 + 3 H2
    and the catalysed version
    2 Al + 2 NaOH + 2 H2O → 2 NaAlO2 + 3 H2
    followed by
    NaAlO2 + 2 H2O → NaOH + Al(OH)3
    It adds up to the same however, making it a lower activation energy path through the same overall reaction. Which is what a catalyst provides.


  14. yes agreed but
    2 Al + 2 NaOH + 2 H2O → 2 NaAlO2 + 3 H2
    is nothing else than
    6 H2O + 2 Al → 2 Al(OH)3 + 3 H2
    followed by
    2 NaOH + 2 Al(OH)3 → 2 NaAlO2 + 4 H2O
    which is reversible
    2 NaAlO2 + 4 H2O → 2 NaOH + 2 Al(OH)3

  15. i think a lot of people are missing the point. inefficient, sure. readily available, cheap, and powerful? yes! i will agree, with total energy spent being a factor, especially in today’s environmentally conscious culture, this is a pretty stupid way to obtain power. but, from an engineering standpoint, it is a basic yet awesome innovation on power storage systems.
    this battery was not made with the environment in mind. it was made with power storage, power output, and weight ratios in mind.
    on a different note, no, they should not have a patent on this type of battery. it was researched by nasa decades ago and turned down in favor of miniature nuclear reactors. i doubt that too much of that information was released due to confidentiality etc, but still should negate the effects of a stupid patent like this one.

  16. @Chris I am not sure, or rather do not know about, the reaction which replaces the lye with Gallium.

    However, I bought a little chunk of a Gallium-Aluminuium that is amusing to play with.

    Basiclly the Gallium is used to prevent the Aluminium from forming the protective oxide that it usually produces upon exposure to air/water. This oxide is like a suit armor that prevents further reaction – and further production of hydrogen. The gallium essentially keeps the Aluminium naked. So the Al produces Hydrogen when exposed to water, and continues to do so until the all is consumed.

    Last I got some it was about $1.50 a gram. Place called “Galium Source” online.

    I might have to get some more now and see if I can run one of my little nitro airplane motors. I have a pile of them, from the little cox .049 ones, on up to O.S. four stroke ones that I think are about 10cc or so. Wish I new more about how to convert one over! I might even trade an engine to someone that can show me a simple way to convert one of these to run on hydrogen, or propane or butane… compressed air…

  17. So, someone came up with a way to word a patent and was awarded it…good for them. Is what they are doing novel? Probably not. Is there something to be learned from what they have done and move it to the next step? I am sure there is.

    Reading through these posts, feel like I am watching fox news. It can’t be done, is a waste, how can I bash them so they look like fools! Perhaps the world really is flat!

    I have played with this chemical reaction and created a very nice pop raising a 1 gallon bottle of water 4 feet off the ground when adding a match to the end of bleed off hose. What I did learn though was there is a burnable gas coming out, there was a nice pressure created that could push a inline generator as the gas moved through the lines to create electricity which could be channeled to another reactor to produce move hydrogen through move conventional methods of electrical induction. Before someone points them out and discounts my observations, I am not saying this is the best way or that there are not other ways to do them…and if that is true, spend your energy learning from what is there and seen and move it to the next step instead of pointing out the problems to say it isn’t worth the effort.

    Oil prices are not going down and your all doing your part to keep us feeding the terrorist states to fuel our world. Ball is in your court to fix it, you can deflat it and say it doesn’t roll or you can make it more durable and kick it on to next team mate. Your choice.

  18. No aluminum is destroyed, simply transformed into aluminum hydroxide which can simply be recycled all over again by the aluminum industry. I don’t see where’s there any waste. Besides it makes use of a readily available resource in our society.

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