It's an HFCV (Hydrogen Fuel Cell "Vehicle")...but it's a plane

[ecarfan]

Although I think it is clear that hydrogen fuel cells don't make sense for passenger cars, perhaps a case can be made that they might make sense for some classes of airplanes. See The plane that runs on hydrogen and emits only water - CNN.com

Of course the plane described in that article is a 4 person modified sailplane (glider) but you have to start somewhere. It's an interesting idea. The goal is, quote: "The team aims to use fuel cells to power small and medium-sized passenger planes, which could change regional air travel and provide an alternative to carbon-emitting airplanes, buses and trains."

The energy density of batteries is well below -- I would guess by orders of magnitude -- what is needed to effectively power small commercial planes useful distances. Using a fuel cell to make electricity onboard you don't need to devote much weight to batteries. Yes you still need to expend energy creating the hydrogen, building fueling stations, etc. But likely it is better, in many ways, than refining oil into av gas or jet fuel.

 

[Yggdrasill]

Hydrogen isn't significantly better than batteries when used in aeroplanes.

- Jet A-1 can store approximately 4.3 kWh per liter and 5.4 kWh per kg (after ICE losses)
- Hydrogen at 700 bar can store approximately 0.65 kWh per liter and 0.85 kWh per kg (after FC/drivetrain losses)
- The best li-ion packs can store approximately 0.45 kWh per liter and 0.25 kWh per kg (after drivetrain losses)

When batteries become twice as good, they will be better than hydrogen. Hydrogen is limited by it's physical properties - it's unlikely to improve much.

 

[mrElbe]

Hey, it worked well for the Hindenburg airship.

 

[Kandiru]

First it is a twin-fuselage powered glider, the very low power requirements make me suspect that it could fare similarly with solar panels.

The high energy low light emitting hydrogen fire would certainly spare the occupants the agony of a lengthy recovery should it ever crash.

 

[Pollux]

Hydrogen isn't significantly better than batteries when used in aeroplanes.

- Jet A-1 can store approximately 4.3 kWh per liter and 5.4 kWh per kg (after ICE losses)
- Hydrogen at 700 bar can store approximately 0.65 kWh per liter and 0.85 kWh per kg (after FC/drivetrain losses)
- The best li-ion packs can store approximately 0.45 kWh per liter and 0.25 kWh per kg (after drivetrain losses)

When batteries become twice as good, they will be better than hydrogen. Hydrogen is limited by it's physical properties - it's unlikely to improve much.

So... 10X improvement in battery storage needed to make electric aircraft practical?

I also wonder whether you need still more improvement, because aircraft become more efficient as they burn their fuel, but battery weight never goes away.

Alan

 

[Electroman]

That's a great point. Effectively your take off weight cannot be more than the landing weight. And that is a huge negative for batteries and fuel cells, more so for batteries.

 

[swaltner]

That setup is very similar to the one-off Pipistrel Taurus G4 that was designed to compete in and succeeded at wining an efficiency contest put on by NASA. The Taurus G4 was a mashup of a pair of Taurus Electro fuselages , one standard set of wings mounted outboard of the fuselages and then a custom center section and motor pod to tie the two fuselages together.

Rereading the article, I guess they do mention this was done in partnership with Pipistrel, so they must have taken that same airframe and retrofitted it with the fuel cell for on-board electricity generation.