US Army creates powder that recharges equipment in the field

Wednesday, August 30th, 2017

The US Army Research Laboratory has created an aluminum-based powder that produces a surprisingly high amount of energy when placed in water:

The unexpected discovery came when researchers mixed a nanogalvanic aluminum-based powder with water, and noticed that the water began bubbling away. On closer inspection, they soon realized the reaction was the product of hydrolysis, meaning the material was splitting the water into its composite molecules of oxygen and hydrogen.

Aluminum has been known to produce hydrogen in this manner, but it usually requires a catalyst in the form of heat, acid, electricity or other chemicals. But the new nanomaterial turns out to be an efficient mechanism for rapid and spontaneous hydrolysis of water.

“In our case, it does not need a catalyst,” says Anit Giri, a physicist on the team. “Also, it is very fast. For example, we have calculated that one kilogram (2.2 lb) of aluminum powder can produce 220 kilowatts of power in just three minutes. That’s a lot of power to run any electrical equipment. These rates are the fastest known without using catalysts such as an acid, base or elevated temperatures.”

For these initial tests, the team used the hydrogen created through the reaction to power a radio-controlled model tank around the lab. But in future, the team says the material’s energy potential can effectively be doubled if the heat given off is also harnessed.

“There are other researchers who have been searching their whole lives and their optimized product takes many hours to achieve, say 50 percent efficiency,” says Scott Grendahl, team leader on the project. “Ours does it to nearly 100 percent efficiency in less than three minutes.”


  1. Carl says:

    “220 kilowatts of power in just three minutes”

    Uhh. Power is instantaneous (time rate of change of energy) so the three minutes makes no sense. Unless it is supposed to say 220 kilowatt-hours of energy in three minutes.

  2. Wang Weilin says:

    220KW in 3 minutes! Sounds more like a slow motion explosion.

  3. Isegoria says:

    By comparison, a kilogram of gasoline stores 46 megajoules of energy, or 13 kilowatt-hours, and a kilogram of hydrogen stores three times that, or 39 kilowatt-hours.

    So, if one kilogram of this aluminum powder produces 220 kilowatt-hours of energy, that suggests that it frees 5.6 kilograms of hydrogen, in three minutes. Have a big balloon ready. (And have a ready supply of water.)

  4. Isegoria says:

    Another point of comparison is the energy density of most chemical batteries, which is on the order of one-tenth of one kilowatt-hour per kilogram.

  5. Candide III says:

    Burning aluminum in air yields 31 MJ/kg, that is 8.6 kWh/kg. There is just no way reacting it with water yields 220 kWh/kg. No chemical fuel yields that much. Hydrogen is the most energy-dense fuel per unit weight and it’s only 140 MJ/kg, that is 39 kWh/kg.

  6. Assuming they actually meant 220 kilojoules of energy being released over 3 minutes, and that we use the figure Candide gives for the energy density of hydrogen, I come up with a maximum of 0.93 grams (10.4 liters)per second of hydrogen being produced by the kilo of aluminum catalyst.

    Presumably it’s not 100% efficient and we also get some heat, but as a max figure that at least looks more physically plausible.

  7. Isegoria says:

    A New Scientist piece suggests that the powder yields aluminum oxide and hydrogen, with near 100-percent efficiency, so, if my rusty chemistry skills haven’t failed me, each kilogram of aluminum should release 0.1 kilograms of hydrogen, for 4 kilowatt-hours of energy, or 1,400 kilojoules.

  8. Ross says:

    Damn it you’re all making me want to look up the exothermic reactants and energy balance for cement now. Thanks a lot.

  9. Alrenous says:

    0.1 * 140 MJ = 14 MJ, 14,000 kJ. 40 kW-h is still far lower than 220.*

    Yes, that kW number makes no sense. It’s not supposed to be kilowatt-hours. It’s not 220 kW for three minutes; that’s 40,000 kJ. Either the researcher was black-out drunk or the journalist was.

    Also, what the hell is a ‘nanogalvanic.’ Sounds like they’ve nano-mixed the catalyst, essentially, as something is preventing the aluminum from oxidizing directly with the air. (Instead it needs to be stored in airtight containers or it will oxidize with ambient humidity. I wonder what happens if you touch it with a sweaty hand.)

    New Scientist confirms it’s an alloy. Notably, an alloy won’t release the full 0.11 kg of hydrogen per kilogram.

    While they’re at it, NS dives head-first into perpetual motion. Essentially this powder lets you store and release aluminum smelter energy. This is not useful for powering cars. It’s good for survivalist gear, including backup generators. Though recharging your phone by pouring water into it sounds…interesting.

    *(Incidentally, too much rounding. It’s 16 MJ to two sig figs. I mention it in case anyone else has numbers like these stick in their head forever. Or 13 MJ if you use the lower 120 MJ/kg number.)

  10. Something the powdered aluminum power system is very useful for is powering long-duration unmanned underwater vehicles.

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