8 ms·

Hydrogen Fuel-Cell Powered Electric Aviation Powertrain

42 points by hootbootscoot 7y ago

otterley 7y ago
I smell a scam. If they've got something that works, surely they would have at least applied for a patent by now, yet my searches so far have turned up nothing. (Please correct me if I'm mistaken.)
- geggam 7y ago
  ICE burns hydrogen and emits water, is that zero emissions ?
  - avmich 7y ago
    Using fuel cells, the resulting water can be brought back, without releasing water in any form at the altitude.
    - nradov 7y ago
      They aren't going to bring back any water. It's too heavy.
      - avmich 7y ago
        Agree :) that would be logical.
- avmich 7y ago
  LinkedIn profile smells differently. https://www.linkedin.com/in/vmiftakhov https://www.linkedin.com/in/vmiftakhov Patents MODULAR, CUSTOMIZABLE AND SCALABLE MECHANICAL DESIGN FOR THE ELECTRIC CAR ASSEMBLY BASED ON THE EXISTING VEHICLE CHASSIS Issued November 1, 2014United States
  - otterley 7y ago
    This patent has nothing to do with a hydrogen-powered engine.
- foobarian 7y ago
  There was at least a test flight: https://www.youtube.com/watch?v=du1TBWuyKi4 https://www.youtube.com/watch?v=du1TBWuyKi4 Range and scaling up to be seen though.
  - otterley 7y ago
    They never showed the engine in this video, though. It could be an ordinary gas-powered one.
avmich 7y ago
I wonder how similar the technology is to that used by Toyota Mirai. Having enough power density (fuel cell) and energy density (compressed H2), the aircraft application seem logical... but there surely are lots of details.
- greglindahl 7y ago
  The Mirai seems to have had a huge cost problem that the fuel cell cost a lot more than Toyota thought it would be by the time the car shipped. So they used a small one with poor peak performance, and it's a much less exciting car than an electric car, but still costs extra and has annoying refueling. Planes need a lot of peak power for takeoff.
  - rad_gruchalski 7y ago
    There is a new Mirai planned for 2021. Also, Bosch and BMW seem to be recently looking into fuel cell technology.
danans 7y ago
Hydrogen fuel cells make sense for electric flight scenarios primarily because they have 1/200 the specific weight of lithium ion batteries and 10x the specific energy, which means a lot less weight to pick up of the ground. The challenge of course is safely carrying that volume of compressed hydrogen, and producing it at scale without fossil fuels. For making the hydrogen, if fossil fuels are being used, the process has to be more efficient than the propulsive efficiency of current aircraft engines: https://en.wikipedia.org/wiki/Fuel_economy_in_aircraft#/media/File:Gas_turbine_efficiency.png https://en.wikipedia.org/wiki/Fuel_economy_in_aircraft#/medi... Electrolysis itself is 80% efficient, and a combined cycle gas plant is 60% efficient, so that production efficiency is only 48%, which doesn't beat the 80% peak propulsive efficiency of a fuel powered turboprop. Steam reforming of natural gas to make hydrogen is only 75% efficient. Therefore renewable electricity based hydrogen production is essential for this to work.
- yalok 7y ago
  Re safety, when I talked to the founder, he mentioned that they are building really strong tanks for compressed hydrogen with walls way thicker than normally needed for that kind of pressure, so that these tanks could survive high impact. Basically, they are bullet proof. And they weigh more than the fuel itself, iirc Love the idea. Great guys.
  - danans 7y ago
    As a happy user of an eMotorWorks EV charger (it seems to be a lot of folks from that firm), I'm also confident that they are doing real stuff. However, I would think that they would want to engineer the tanks to minimize slow creeping failures. I would imagine a more likely dangerous situation than impact would be a sudden H2 containment failure that occurs without any impact at all, but due to stress cracks, etc, in the H2 vessel.
- danans 7y ago
  Correction: I meant 10x the specific volume, not the specific energy.
- Iv 7y ago
joshuaheard 7y ago
This would work for cars.
- danans 7y ago
  All fuel cell cars are also electric cars in that they use batteries and electric drivetrains in addition to the hydrogen fuel cell itself. The result is more complexity and hence cost, which is one big reason fuel cell cars haven't taken off. The other reason is the lack of sufficient hydrogen distribution infrastructure. Cars need a dense network of refueling points for convenience. For EVs, this already exists in the form of the existing electric grid and local distribution network (yes, I know it's harder for apartment dwellers right now). A similarly dense hydrogen distribution network doesn't exist, and would have to built from scratch. Airplanes, on the other hand, have far fewer refueling points (they're all at airports), so it's a lot easier to build those. In the future, as the cost and size of fuel cell tech drops, one can maybe see them being use for range extending applications for rapid refueling in long distance drives, but then again, rapid charging and high range EVs are making even that advantage somewhat moot.
  - bobthepanda 7y ago
    IMO fuel cells could also be better for freighters, which can’t use batteries for weight reasons as well.
  - BerislavLopac 7y ago
    > A similarly dense hydrogen distribution network doesn't exist, and would have to built from scratch. Or we can add hydrogen to the existing fuels on traditional petrol stations.
    - danans 7y ago
      Sure, but those stations would still need a invasive and expensive retrofit, adding new underground tanks. You'd also need a new fleet of hydrogen delivery tankers to parallel existing fleet of fuel delivery tankers. And remember that compressed hydrogen's energy density is 5x lower than gasoline [1], so to store the same amount of energy as gasoline, you need 5x the amount of storage volume on site to store the same amount of energy. Fuel cell drivetrains are about double the efficiency of typical gas engines, so that might bring the storage needs down to 2.5x the storage needs for gasoline, but then you also need special equipment to keep the hydrogen contained (it's harder to contain than liquid fuel). You also need 2.5x the number of hydrogen tankers to move that fuel to the stations, or 2.5x the frequency of tanker trips. Compare that to the relatively minimal cost of attaching an EV charging station to an existing building's power supply, and there's not much comparison. At most, you need to upgrade transformers and the local power substations to handle potentially higher demand at peak charging hours, but even that can be done incrementally based on demand profile changes, and mitigated substantially with smart coordinated charging during off-peak hours. 1. https://en.wikipedia.org/wiki/Energy_density#/media/File:Energy_density.svg https://en.wikipedia.org/wiki/Energy_density#/media/File:Ene...
soperj 7y ago
Don't know why they can't just drop an empty battery w/ a parachute once the plane gets to a high enough altitude.
- newnewpdro 7y ago
  Does jettisoning that weight have a tremendous impact on cruising efficiency? My impression is that the main advantage of dumping a take-off battery is reduced landing weight, which is certainly an issue with existing commercial jet airframes. They can't land with a full fuel load without damaging the plane. But I'm not clear on what affect it has on range/efficiency.
- ginko 7y ago
  At this point they could as well use an electric cable that detaches once the plane has reached a certain altitude/distance from the airport.
- nradov 7y ago
  Batteries don't handle impacts well. People living near airports don't appreciate battery packs crashing through their roofs when the parachute fails to open. It's expensive to have someone drive around with a truck and pick up the dead batteries. When weather conditions get a little rough, real airplanes can still fly but parachutes get blown all over the place.
ncmncm 7y ago
Hydrogen can be generated by dissociation powered directly by sunlight, with no side trip through electricity, yielding much higher efficiency. Nobody has found a use for the oxygen that would be released at the same time, although it might be usable for purification, if it could be delivered as h2o2. Then again, concentrated h2o2 is usable directly as rocket fuel.

42 points by hootbootscoot 7y ago

I smell a scam. If they've got something that works, surely they would have at least applied for a patent by now, yet my searches so far have turned up nothing. (Please correct me if I'm mistaken.)

geggam 7y ago
ICE burns hydrogen and emits water, is that zero emissions ?
- avmich 7y ago
  Using fuel cells, the resulting water can be brought back, without releasing water in any form at the altitude.
  - nradov 7y ago
    They aren't going to bring back any water. It's too heavy.
    - avmich 7y ago
      Agree :) that would be logical.
avmich 7y ago
LinkedIn profile smells differently. https://www.linkedin.com/in/vmiftakhov https://www.linkedin.com/in/vmiftakhov Patents MODULAR, CUSTOMIZABLE AND SCALABLE MECHANICAL DESIGN FOR THE ELECTRIC CAR ASSEMBLY BASED ON THE EXISTING VEHICLE CHASSIS Issued November 1, 2014United States
- otterley 7y ago
  This patent has nothing to do with a hydrogen-powered engine.
foobarian 7y ago
There was at least a test flight: https://www.youtube.com/watch?v=du1TBWuyKi4 https://www.youtube.com/watch?v=du1TBWuyKi4 Range and scaling up to be seen though.
- otterley 7y ago
  They never showed the engine in this video, though. It could be an ordinary gas-powered one.

avmich 7y ago

I wonder how similar the technology is to that used by Toyota Mirai. Having enough power density (fuel cell) and energy density (compressed H2), the aircraft application seem logical... but there surely are lots of details.

greglindahl 7y ago
The Mirai seems to have had a huge cost problem that the fuel cell cost a lot more than Toyota thought it would be by the time the car shipped. So they used a small one with poor peak performance, and it's a much less exciting car than an electric car, but still costs extra and has annoying refueling. Planes need a lot of peak power for takeoff.
- rad_gruchalski 7y ago
  There is a new Mirai planned for 2021. Also, Bosch and BMW seem to be recently looking into fuel cell technology.

danans 7y ago

Hydrogen fuel cells make sense for electric flight scenarios primarily because they have 1/200 the specific weight of lithium ion batteries and 10x the specific energy, which means a lot less weight to pick up of the ground. The challenge of course is safely carrying that volume of compressed hydrogen, and producing it at scale without fossil fuels. For making the hydrogen, if fossil fuels are being used, the process has to be more efficient than the propulsive efficiency of current aircraft engines: https://en.wikipedia.org/wiki/Fuel_economy_in_aircraft#/media/File:Gas_turbine_efficiency.png https://en.wikipedia.org/wiki/Fuel_economy_in_aircraft#/medi... Electrolysis itself is 80% efficient, and a combined cycle gas plant is 60% efficient, so that production efficiency is only 48%, which doesn't beat the 80% peak propulsive efficiency of a fuel powered turboprop. Steam reforming of natural gas to make hydrogen is only 75% efficient. Therefore renewable electricity based hydrogen production is essential for this to work.

yalok 7y ago
Re safety, when I talked to the founder, he mentioned that they are building really strong tanks for compressed hydrogen with walls way thicker than normally needed for that kind of pressure, so that these tanks could survive high impact. Basically, they are bullet proof. And they weigh more than the fuel itself, iirc Love the idea. Great guys.
- danans 7y ago
  As a happy user of an eMotorWorks EV charger (it seems to be a lot of folks from that firm), I'm also confident that they are doing real stuff. However, I would think that they would want to engineer the tanks to minimize slow creeping failures. I would imagine a more likely dangerous situation than impact would be a sudden H2 containment failure that occurs without any impact at all, but due to stress cracks, etc, in the H2 vessel.
danans 7y ago
Correction: I meant 10x the specific volume, not the specific energy.
Iv 7y ago

joshuaheard 7y ago

This would work for cars.

danans 7y ago
All fuel cell cars are also electric cars in that they use batteries and electric drivetrains in addition to the hydrogen fuel cell itself. The result is more complexity and hence cost, which is one big reason fuel cell cars haven't taken off. The other reason is the lack of sufficient hydrogen distribution infrastructure. Cars need a dense network of refueling points for convenience. For EVs, this already exists in the form of the existing electric grid and local distribution network (yes, I know it's harder for apartment dwellers right now). A similarly dense hydrogen distribution network doesn't exist, and would have to built from scratch. Airplanes, on the other hand, have far fewer refueling points (they're all at airports), so it's a lot easier to build those. In the future, as the cost and size of fuel cell tech drops, one can maybe see them being use for range extending applications for rapid refueling in long distance drives, but then again, rapid charging and high range EVs are making even that advantage somewhat moot.
- bobthepanda 7y ago
  IMO fuel cells could also be better for freighters, which can’t use batteries for weight reasons as well.
- BerislavLopac 7y ago
  > A similarly dense hydrogen distribution network doesn't exist, and would have to built from scratch. Or we can add hydrogen to the existing fuels on traditional petrol stations.
  - danans 7y ago
    Sure, but those stations would still need a invasive and expensive retrofit, adding new underground tanks. You'd also need a new fleet of hydrogen delivery tankers to parallel existing fleet of fuel delivery tankers. And remember that compressed hydrogen's energy density is 5x lower than gasoline [1], so to store the same amount of energy as gasoline, you need 5x the amount of storage volume on site to store the same amount of energy. Fuel cell drivetrains are about double the efficiency of typical gas engines, so that might bring the storage needs down to 2.5x the storage needs for gasoline, but then you also need special equipment to keep the hydrogen contained (it's harder to contain than liquid fuel). You also need 2.5x the number of hydrogen tankers to move that fuel to the stations, or 2.5x the frequency of tanker trips. Compare that to the relatively minimal cost of attaching an EV charging station to an existing building's power supply, and there's not much comparison. At most, you need to upgrade transformers and the local power substations to handle potentially higher demand at peak charging hours, but even that can be done incrementally based on demand profile changes, and mitigated substantially with smart coordinated charging during off-peak hours. 1. https://en.wikipedia.org/wiki/Energy_density#/media/File:Energy_density.svg https://en.wikipedia.org/wiki/Energy_density#/media/File:Ene...

soperj 7y ago

Don't know why they can't just drop an empty battery w/ a parachute once the plane gets to a high enough altitude.

newnewpdro 7y ago
Does jettisoning that weight have a tremendous impact on cruising efficiency? My impression is that the main advantage of dumping a take-off battery is reduced landing weight, which is certainly an issue with existing commercial jet airframes. They can't land with a full fuel load without damaging the plane. But I'm not clear on what affect it has on range/efficiency.
ginko 7y ago
At this point they could as well use an electric cable that detaches once the plane has reached a certain altitude/distance from the airport.
nradov 7y ago
Batteries don't handle impacts well. People living near airports don't appreciate battery packs crashing through their roofs when the parachute fails to open. It's expensive to have someone drive around with a truck and pick up the dead batteries. When weather conditions get a little rough, real airplanes can still fly but parachutes get blown all over the place.

ncmncm 7y ago

Hydrogen can be generated by dissociation powered directly by sunlight, with no side trip through electricity, yielding much higher efficiency. Nobody has found a use for the oxygen that would be released at the same time, although it might be usable for purification, if it could be delivered as h2o2. Then again, concentrated h2o2 is usable directly as rocket fuel.