How to incorporate a Hydrogen fuel cell into an electric aircraft for Homebuilders?

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Aesquire

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Pedant! ;)

The point is that Airships allow low pressure storage & dual use of the fuel cell fuel. A H2 Cessna 152 would have heavy tanks and limited endurance. A transcontinental H2 727 would have no room for passengers. But an Electric Macon? Home built hot air balloon & blimps exist, they just need a specialized skill set. So does steel welded frames and composites.

Any bleeding edge marginal technology like electric planes is going to initially manifest with unusual high efficiency craft, like motor gliders, first. ( simply because of the power density ) A semi rigid airship is similarly both efficient, fringe, and useful for a small minority.

Note that several people here are fringe enough that we'd be happy with electric motorgliders, even if I can't afford one. Even fewer can afford the airship hanger, so the notion is mostly tongue in cheek, but still an e!egant engineering solution.

Make it a fuel cell electric Delta Pumpkin Seed and you've got flying wings, Low AR, electric, and historical threads all rolled into one. :)
 

dog

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There are a bunch of fuel cells that run on amonia,which is a liquid fuel with a similar energy density to gasoline.
The downside of amonia is that its exremely dangerous to spill,and any leak is bad news.
Farmers use it all the time so it can be done.
Another interesting bit is that there are regenerative fuel cells that can make the hydrogen that they can later use for power,
with theses bieng suggested for distributed production of hydrogen and providing electric
viehicle recharging from one unit,or power for
other purposes.
 

Topaz

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Airships are NOT hydrogen powered. The use the hydrogen for buoyancy. The engines are regular gas powered aircraft engines.
I'll jump on the pedant bandwagon. ;)

Early German airships indeed used Diesel engines for propulsion, but later they switched to "blau gas", which had the advantage of not changing the weight of the airship as it was burned (weighs roughly the same as air). American airships tended to use gasoline engines and had to compensate by releasing helium as they burned fuel although, in the Akron and Macon, there was an attempt to recover water vapor from the exhaust and store the condensed liquid onboard to compensate for some of the lost fuel weight.

We now return you to your regularly scheduled discussion.
 

BBerson

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Petrol and hydrogen or hydrogen mix fuels were used for German airships to advantage:

Graf Zeppelin was the only rigid airship to burn Blau gas;[39][40] the engines were started on petrol[nb 6] and could then switch fuel.[24] A liquid-fuelled airship loses weight as it burns fuel, requiring the release of lifting gas, or the capture of water from exhaust gas or rainfall, to avoid the vessel climbing. Blau gas was only slightly heavier than air, so burning it had little effect on buoyancy.[42][43] On a typical transatlantic journey Graf Zeppelin used Blau gas 90% of the time, only burning petrol if the ship was too heavy, and used ten times less hydrogen per day than the smaller L 59 did on its Khartoum journey.[44][nb 7]
 

Rhino

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Airships also offer a storage solution that only requires a really big hanger and a willingness to limit flying to low wind days. And money, lots of that.

I spent a very entertaining 45 minutes watching the Goodyear Blimp go about a mile against a headwind to land at the Rochester Airport. We were on the Barge Canal bike path directly below and could easily see the control surfaces moving as it struggled in the turbulence. Great pilots, working Hard.
Maybe they worked by the hour.
 

BFE_Duke

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The 17 cents per km was for the expensive onsite production by electrolysis. Industrial production is cheaper.
At the end he said hydrogen makes sense for aviation. It works regardless of the fuel cost.
The real solution will be reforming liquid hydrocarbon fuels into hydrogen for the fuel cell.
Isn't the entire purpose of hydrogen to get off fossil fuels? If you're reforming liquid hydrocarbon fuels into hydrogen, why not just burn the liquid hydrocarbon fuels?

Hydrogen component weights in a Toyota Mirai:
Fuel cell stack: 123 lbs
Hydrogen tank (1" thick carbon fiber): 193 lbs
Battery: 98 lbs
Electric motor & controller: Not sure, but the weight of electric motors is generally well understood.

Comparing the system weight minus the motor/controller, it's ~414 lbs, compared to ~1000 lbs in a tesla battery pack for similar range. There's definitely weight savings, but the complexity and cost of refilling is not as attractive as a pure battery-electric system, especially when using electrolysis, which is renewable and the entire point of hydrogen.
 

Vigilant1

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Isn't the entire purpose of hydrogen to get off fossil fuels?
I don't think so. If zero net atmospheric carbon were really the entire purpose, then it is much more attractive to just use hydrocarbon IC engines as part of a zero net carbon hydrocarbon fuel cycle (entirely renewable). This achieves zero net atmospheric carbon increase and acceptable onboard energy density at much lower cost (initial and operational costs) and all-up weight than hydrogen can.

I suspect the allure of hydrogen starts with the assumption that electric motors are inherently preferable to IC. Then, because it is impractical for present batteries to meet the energy requirements for most flight missions, proponents turn to hydrogen and hydrogen fuel cells as a work around.
 
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BFE_Duke

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I don't think so. If zero net atmospheric carbon were really the entire purpose, then it is much more attractive to just use hydrocarbon IC engines as part of a zero net carbon hydrocarbon fuel cycle (entirely renewable). This achieves zero net atmospheric carbon increase and acceptable onboard energy density at much lower cost (initial and operational costs) and all-up weight than hydrogen can.

I suspect the allure of hydrogen starts with the assumption that electric motors are inherently preferable to IC. Then, because it is impractical for present batteries to meet the energy requirements for most flight missions, proponents turn to hydrogen and hydrogen fuel cells as a work around.
Well it could mean something different for everyone, but every time someone mumbles hydrogen it is usually synonymous with unicorn farts, sustainability, and the color green.
 

Vigilant1

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Well it could mean something different for everyone, but every time someone mumbles hydrogen it is usually synonymous with unicorn farts, sustainability, and the color green.
Agreed. But, if "sustainability" is looked at from a whole system perspective, it can be achieved more quickly and at less expense using zero net carbon hydrocarbons ("biofuels") and IC engines than by using hydrogen. If, however, we start with the incorrect assumption that electric motors are the desired end state, then for airplanes we wind up with hydrogen as a means to an (inappropriate) end.
 

BFE_Duke

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I agree with that. We'd just have to get off corn ethanol here in the states, which uses as much energy (if not more) to produce than we get out of it.

On the topic of electric propulsion as a desired trait, the option of a range extender engine like in the greased lightning seems like a less finicky solution.
 

Aesquire

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Isn't the entire purpose of hydrogen to get off fossil fuels? If you're reforming liquid hydrocarbon fuels into hydrogen, why not just burn the liquid hydrocarbon fuels?
Yes, the Mission of the Hydrogen Economy from the beginning is to Replace Fossil fuels with a gaseous energy storage medium.

And, yep, using hydrocarbon fuels and wasting them (or accepting crud efficiency if you prefer ) to make hydrogen instead of using them directly defeats the purpose.

Any blather about Carbon or planetary salvation is from later con men who saw a chance to profit, and not just money.

Hydrogen isn't new. It was big argument fodder back at least in the 1970s and started long before that. And making Hydrogen from Fossil fuels is one small reason it just hasn't happened on big scale. That it takes far more energy to produce, store, and ship than you get out as an end user keeps it from being profitable without subsidies, so far.

There's a weird parallel with crypto-mining. Power to run your project has to be cheaper than you can sell the product. That's why there are storage sheds full of equipment in odd places where electricity is "super cheap or free" because the taxes pay for it. Or it's easy to steal.

I've already gone on about how your Reasons for using immature, expensive, limited, technology is important to make wise choices.

Don't bother to argue maturity and then claim next week's New Tech will solve the problems. Have some self awareness & self honesty, eh?

Expensive you can argue. If I assume 40 hours flying the pattern every week, then Electric rocks! If I assume 4-5 hours a week with a self launching hang glider/paraglider then not so much. And an Electric KC-135 replacement? How much is Gold per gram?

And, sure, the limits today are much better than a decade ago, and hopefully a decade from now it's an order of magnitude better. But compared to the mature tech of IC?



Otoh, if you're interested in multiple props and a chip controlling stability, that's not easy or often possible with motorcycle/car/snowmobile engines.
 
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BBerson

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The throttle response on giant scale gas RC models easily allows rock solid hovering in place by manual pilot control.
 
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