A Hydrogen Fuel Cell Drone

When we think about hydrogen and flying machines, it’s quite common to imagine Zeppelins, weather balloons and similar uses of hydrogen in lighter-than-air craft to lift stuff of the ground. But with smaller and more efficient fuel cells, hydrogen is gaining its place in the drone field. Project RACHEL is a hydrogen powered drone project that involves multiple companies and has now surpassed the 60 minutes of flight milestone.

The initial target of the project was to achieve 60 minutes of continuous flight while carrying a 5 kg payload. The Lithium Polymer battery-powered UAVs flown by BATCAM allow around 12 minutes of useable flight. The recent test of the purpose-built fuel cell powered UAV saw it fly for an uninterrupted 70 minutes carrying a 5 kg payload.  This was achieved on a UAV with below 20 kg maximum take-off mass, using a 6-litre cylinder containing hydrogen gas compressed to 300 bar.

While this is not world record for drones and it’s not exactly clear if there will be a commercial product nor the price tag, it is still an impressive feat for a fuel cell powered flying device. You can watch the footage of one of their tests bellow:

Drones are definitely getting more diverse and innovative as they play a more relevant role in our everyday life.

As a side note, It would be interesting to know how much hydrogen is there in a 6-litre / 300bar deposit and how much weight you could lift with that…

Thanks for the tip [Itay]

36 thoughts on “A Hydrogen Fuel Cell Drone

        1. This is a more accurate number.
          It would be awesome though if we could get even a kilogram of hydrogen on board. That would equate to 9 hours of flight time

  1. “As a side note, It would be interesting to know how much hydrogen is there in a 6-litre / 300psi deposit and how much weight you could lift with that…”

    300 bar is a lot more than 300 psi (~14 times).

    6 litres at 300 bar is 1800 litres at 1 bar. That’s a lot of balloons :)
    A mole of hydrogen takes up 24 dm^3 at 20 degrees C. So the amount of hydrogen is 1800 / 24 = 75 moles.

  2. “As a side note, It would be interesting to know how much hydrogen is there in a 6-litre / 300psi deposit and how much weight you could lift with that…”

    …300 bar, not 300 PSI ;-)

  3. 6 litres at 300 bar is approximately 6*300 = 1800 litres at 1 bar. That’s about 0.16 kg of hydrogen, and it would displace 2.2 kg of air, providing about 2 kg lift capacity if the balloon skin weighted nothing.

    1. Not true, the air it displaces is at atmospheric pressure and not 300 bar, so it displaces about 7.5 grams of air. It is actually heavier when filled with hydrogen at 300 bar than with air at 1 bar.

      1. Vacuum has a greater lifting force than hydrogen, but nobody has yet been able to make a vacuum container able to withstand atmospheric pressure *and* be lighter than the air it displaces.

  4. 6 litres at 300 bar is 1800 L (1.8 m3) at atmospheric pressure. Hydrogen has a density of 0.08988 g/L (from Wikipedia), which works out to 0.16 kg. Air has a density of slightly over 1.2 g/L, so 1.8 m3 of air weighs about 2.2 kg. The air is therefore about 2 kg heavier than the expanded hydrogen would be, so that gives about 2 kg of lift.

  5. A little step toward proliferation of fuel cells. Does anybody know the current price tag for fuel cells or any commercial applications? Methanol-powered ones would be especially interesting for common hacker.

    1. Eons ago I saw a documentary on fuel cells and they presented these methanol fuel cells as the future. I’m still waiting for that future… Nevertheless, they are utterly fascinating!

    2. Bloom Energy… Silicon Valley company has industrial size system that are currently being used by Google, Yahoo, ebay, & more…. Natural Gas in h2o & electricity out… quite a low-carbon thing… unfortunately there are still the issues of fracking, & methane seepage to consider…

      1. A equivalent 3.3 horsepower engine could weigh as much as 13kg.

        Fuel: 0.148 kg of hydrogen
        Fuel tank: 3.2kg 7lb 6L Carbon Fiber Tank (4500psi)
        Fuelcell: 7.7kg 17lb 2.4kW stack by Intelligent Energy in the UK.
        With gasoline you would also save about 3.2kg by not having 6 electric motors (DJI E5000). But you would still need the six 28×8 inch (711×203 mm) propellers, and also additional weight of a complex drive shaft configuration, balanced to handle 6000 rpm.

        But the main problems with gasoline would be vibration (not very good for a film shoot) and high decibel noise.

        I was thinking the same until I watched the full video in the link above from stephen arsenault.

        1. The “generator” weight should be 4 – 5 Kg and should produce 1.8 – 2.4 kW.

          “But the main problems with gasoline would be vibration (not very good for a film shoot) and high decibel noise.”
          Agreed on the vibration, maybe it can be solved with a more robust anti-vibration system for the gimbal.
          About the noise… 6-8 big props make a lot of noise.
          The audio is normally done in post-production.

  6. Hydrogen is a weak fuel and stands to flood rivers if “hydrogen fuels” are ramped up. You can use H2 and CO2 to make methane. Methane is CH4, and generates far more energy than just hydrogen. Ignoring all of that, hydrogen fuels are produced purely using electricity, and thus offer another route for inefficiency in comparison to electrics.

    1. I once thought that abandoned quarries, filled with ground water would be prime for covering with solar panels and windmills, solely for the electrolytic production of Hydrogen and Oxygen, and organic methane to boot.
      I am now somewhat disillusioned with our rabid, modern day alchemical quest, to swap electrons for greater and greater energy gains, ignoring the fact that every common form of energy we use today alters our environment in ways which we fail to foresee.
      We are forced to seek the greatest potential that nature can provide us, but we need to seek a form which does not rely on trading electrons or splitting nuclei in it’s process. Hopefully, the unimaginable amounts of conventional energy we expend in the super colliders and space missions in the name of science will in time get us to an understanding of gravity, quantum physics, dark energy/matter, and antimatter before we tip the scales in an unrecoverable fashion. That is, if we haven’t already.
      Given our history, I’m also apprehensive about the potential outcome of exploiting these new discoveries.

      Perhaps we should just revert to mandatory treadmill service as an energy tax.

      1. That would be one of the most inefficient energy sources. Food is a quite expensive energy source and the human body has no better energy efficiency (calories to mechanical work) than a small gasoline engine. And even in your body electrons (and ions) are “traded” to – at first – produce ATP which can later be converted to work.

  7. “As a side note, It would be interesting to know how much hydrogen is there in a 6-litre / 300bar deposit and how much weight you could lift with that…”
    I’m more interested in how much potential energy there is in 6 litres of hydrogen at 300bar compared to how much energy was consumed compressing the hydrogen to fill the container, assuming the hydrogen already exists at 1bar,so yes, just the energy squashing it.

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