5 ms·

As a private pilot I am SO looking forward to finally be able to do away with piston engines and fly electric...

by geff82 4y ago

api 4y ago
Has anyone experimented with hydrogen or natural gas fuel cells? They're cumbersome for cars but for planes the reduced weight would make sense. Weight doesn't matter as much for land transport. I know hybrids don't make as much sense for planes because the throttle range is typically 50-100% through a flight vs cars where you spend tons of time down at 10-15% throttle and need only bursts of power.
- Full_Clark 4y ago
  Universal Hydrogen is outfitting a Dash-8 with one hydrogen fuel cell engine for a test flight in March (leaving the other engine unchanged as a Jet-A powered turboprop). If all goes well they'll convert the other engine to hydrogen fuel cell as well, and they hope to be operating it in passenger service by 2025. https://hydrogen.aero/product/ https://hydrogen.aero/product/ Seems promising because they don't have to fully design a new aircraft, they just have to get the new powertrain certified. Though the same end-customer airline (Air New Zealand) is also eyeing off some new-build battery-electric aircraft with 250nm range and 30 min recharge times. https://simpleflying.com/eviation-alice-first-flight/ https://simpleflying.com/eviation-alice-first-flight/
- rgmerk 4y ago
  Airbus is experimenting with fuel cells for airliners; I believe the idea is to use the fuel cells for cruising and use gas turbines when more power is required.[0] Joby Aviation (the air taxi developer) also bought a company that's been working on a hydrogen fuel cell light aircraft. The power density of fuel cells density would make VTOL air taxis a whole lot more plausible (though you've still got a distinctly nontrivial hydrogen storage problem). [1] There's another startup called HyPoint working on fuel cells specifically for aircraft [2], though they haven't announced a whole lot recently. [0] https://edition.cnn.com/travel/article/airbus-fuel-cell-engine-rolls-royce-easyjet-engine-c2e-spc-intl/index.html https://edition.cnn.com/travel/article/airbus-fuel-cell-engi... [1] https://evtolinsights.com/2022/07/hydrogen-fuel-cell-company-secretly-bought-by-joby-accelerates-progress-towards-zero-emission-commercial-flight/ https://evtolinsights.com/2022/07/hydrogen-fuel-cell-company... [2] https://hypoint.com/ https://hypoint.com/
- jillesvangurp 4y ago
  The problem with hydrogen is the volume, not the weight. It's 3x that of methane, which in turn is worse than aviation fuel. And that's in liquid form. Chilling hydrogen to near absolute zero to get it in liquid form requires some really heavy duty equipment. And keeping it there takes energy. Most hydrogen trucks use compressed gas instead. At around 200 bars, the energy density by volume is about 18x that of diesel. So, you need a huge tank for the same amount of energy. And also 200 bar means it needs to be a really strong tank. Hydrogen trucks aren't really competitive with battery electric trucks for this reason. You need a lot of infrastructure and you add a lot of weight and complexity to the trucks. The handful of hydrogen trucks driving around have in common that they are expensive, don't have a lot of range, and need to be supplied via an as of yet non existent distribution network for hydrogen. If you truck the stuff around, you need 18 trucks for every diesel truck to move the equivalent in energy. All that volume is a show stopper on planes. We're talking about huge planes that are mostly hydrogen storage tanks with not a lot of room for useful load. Or alternatively really heavy tanks that can keep hydrogen at close to absolute zero. A more likely use for hydrogen in aviation is to use it to produce synthetic fuels that are more dense and easier to handle. Huydrogen really sucks as a fuel. And it's not a particularly efficient battery either. Storing it is problematic. Transporting it is problematic. The vast majority of hydrogen today is produced and consumed in the same place for this reason. It's main role is as a raw material to produce other things (fertilizers, steel, etc.).
  - dgroshev 4y ago
    It might have its niche as season scale energy storage. It's pretty easy and cheap to store it in underground cavities, they are good enough for helium [1] which leaks even easier than hydrogen. [1]: https://en.wikipedia.org/wiki/National_Helium_Reserve https://en.wikipedia.org/wiki/National_Helium_Reserve
earleybird 4y ago
For context, a gallon of gas carries about 33.4 Kwh, a Cessna 172 has a fuel capacity of 56 gallons. Topped up at take-off it's carrying the equivalent of 1.87 Mwh. That will take you about 1,200 km. I expect short range electric commuters will come first - similar to cars.
- wyldfire 4y ago
  For the mass of 56 gallons of gas (~200kg) you could carry 240kwh of Li-air battery? Feel free to check my math, could've gotten it wrong.
- tjmc 4y ago
  What's the conversion efficiency with a Cessna 172's ancient engine though? Batteries don't have to get that much better for electrics to dominate the training GA market. There's a Pipistril Velis Electro[1] that shares a hanger with my flight school. It can only fly for about 30 minutes + 30 mins reserve with 2 relatively light pilots. If it had a battery which allowed for 2 hours of flight you've now tripled your range - 1.5hours + 30 mins reserve. That would cover all ab-initio training. A battery like the one in the article would expand the range further to cross country capability and/or higher useful load, with the complete reconstruction of a piston engine every 2000 hours gone from the equation. Can't wait. 1. https://www.pipistrel-aircraft.com/products/general-aviation/velis-electro/#tab-id-2 https://www.pipistrel-aircraft.com/products/general-aviation...
- cameldrv 4y ago
  The math is quite a bit better than those numbers would suggest. An aircraft piston engine is roughly 25% efficient, but an electric motor can be over 90%. A gallon of gas weighs about 2.7 kg, so the gas is about 12.3 kWh/kg. If we adjust this type of battery to account for the difference in efficiency, it is about 4.3 (equivalent) kW/kg. Ok, so that's still a factor of 3 worse. However, all the gas in the Cessna weighs about 336 lbs. The engine weighs about 250 lbs. A comparable electric motor is about 70 lbs. That gives you another 180 lbs, or over 50% more weight to fill with batteries. Now we're at about 50% of the useful energy of the Cessna. You can also factor in a little bit of gain from "regenerative braking" since the electric airplane can charge the batteries while descending. This may not make a huge difference in range for just point to point flying, but it does add some extra for flight training with lots of landings, and also provides some extra reserve in the case of a missed approach for example. All of that is to say that this doesn't bring the small electric airplane to parity with gasoline, but it's starting to much more credibly inch in on its turf.
taneq 4y ago
There's an electric trainer plane flying out of our local light airport, it's very cool.

As a private pilot I am SO looking forward to finally be able to do away with piston engines and fly electric...

by geff82 4y ago

As a private pilot I am SO looking forward to finally be able to do away with piston engines and fly electric...

api 4y ago

Has anyone experimented with hydrogen or natural gas fuel cells? They're cumbersome for cars but for planes the reduced weight would make sense. Weight doesn't matter as much for land transport. I know hybrids don't make as much sense for planes because the throttle range is typically 50-100% through a flight vs cars where you spend tons of time down at 10-15% throttle and need only bursts of power.

Full_Clark 4y ago
Universal Hydrogen is outfitting a Dash-8 with one hydrogen fuel cell engine for a test flight in March (leaving the other engine unchanged as a Jet-A powered turboprop). If all goes well they'll convert the other engine to hydrogen fuel cell as well, and they hope to be operating it in passenger service by 2025. https://hydrogen.aero/product/ https://hydrogen.aero/product/ Seems promising because they don't have to fully design a new aircraft, they just have to get the new powertrain certified. Though the same end-customer airline (Air New Zealand) is also eyeing off some new-build battery-electric aircraft with 250nm range and 30 min recharge times. https://simpleflying.com/eviation-alice-first-flight/ https://simpleflying.com/eviation-alice-first-flight/
rgmerk 4y ago
Airbus is experimenting with fuel cells for airliners; I believe the idea is to use the fuel cells for cruising and use gas turbines when more power is required.[0] Joby Aviation (the air taxi developer) also bought a company that's been working on a hydrogen fuel cell light aircraft. The power density of fuel cells density would make VTOL air taxis a whole lot more plausible (though you've still got a distinctly nontrivial hydrogen storage problem). [1] There's another startup called HyPoint working on fuel cells specifically for aircraft [2], though they haven't announced a whole lot recently. [0] https://edition.cnn.com/travel/article/airbus-fuel-cell-engine-rolls-royce-easyjet-engine-c2e-spc-intl/index.html https://edition.cnn.com/travel/article/airbus-fuel-cell-engi... [1] https://evtolinsights.com/2022/07/hydrogen-fuel-cell-company-secretly-bought-by-joby-accelerates-progress-towards-zero-emission-commercial-flight/ https://evtolinsights.com/2022/07/hydrogen-fuel-cell-company... [2] https://hypoint.com/ https://hypoint.com/
jillesvangurp 4y ago
The problem with hydrogen is the volume, not the weight. It's 3x that of methane, which in turn is worse than aviation fuel. And that's in liquid form. Chilling hydrogen to near absolute zero to get it in liquid form requires some really heavy duty equipment. And keeping it there takes energy. Most hydrogen trucks use compressed gas instead. At around 200 bars, the energy density by volume is about 18x that of diesel. So, you need a huge tank for the same amount of energy. And also 200 bar means it needs to be a really strong tank. Hydrogen trucks aren't really competitive with battery electric trucks for this reason. You need a lot of infrastructure and you add a lot of weight and complexity to the trucks. The handful of hydrogen trucks driving around have in common that they are expensive, don't have a lot of range, and need to be supplied via an as of yet non existent distribution network for hydrogen. If you truck the stuff around, you need 18 trucks for every diesel truck to move the equivalent in energy. All that volume is a show stopper on planes. We're talking about huge planes that are mostly hydrogen storage tanks with not a lot of room for useful load. Or alternatively really heavy tanks that can keep hydrogen at close to absolute zero. A more likely use for hydrogen in aviation is to use it to produce synthetic fuels that are more dense and easier to handle. Huydrogen really sucks as a fuel. And it's not a particularly efficient battery either. Storing it is problematic. Transporting it is problematic. The vast majority of hydrogen today is produced and consumed in the same place for this reason. It's main role is as a raw material to produce other things (fertilizers, steel, etc.).
- dgroshev 4y ago
  It might have its niche as season scale energy storage. It's pretty easy and cheap to store it in underground cavities, they are good enough for helium [1] which leaks even easier than hydrogen. [1]: https://en.wikipedia.org/wiki/National_Helium_Reserve https://en.wikipedia.org/wiki/National_Helium_Reserve

earleybird 4y ago

For context, a gallon of gas carries about 33.4 Kwh, a Cessna 172 has a fuel capacity of 56 gallons. Topped up at take-off it's carrying the equivalent of 1.87 Mwh. That will take you about 1,200 km. I expect short range electric commuters will come first - similar to cars.

wyldfire 4y ago
For the mass of 56 gallons of gas (~200kg) you could carry 240kwh of Li-air battery? Feel free to check my math, could've gotten it wrong.
tjmc 4y ago
What's the conversion efficiency with a Cessna 172's ancient engine though? Batteries don't have to get that much better for electrics to dominate the training GA market. There's a Pipistril Velis Electro[1] that shares a hanger with my flight school. It can only fly for about 30 minutes + 30 mins reserve with 2 relatively light pilots. If it had a battery which allowed for 2 hours of flight you've now tripled your range - 1.5hours + 30 mins reserve. That would cover all ab-initio training. A battery like the one in the article would expand the range further to cross country capability and/or higher useful load, with the complete reconstruction of a piston engine every 2000 hours gone from the equation. Can't wait. 1. https://www.pipistrel-aircraft.com/products/general-aviation/velis-electro/#tab-id-2 https://www.pipistrel-aircraft.com/products/general-aviation...
cameldrv 4y ago
The math is quite a bit better than those numbers would suggest. An aircraft piston engine is roughly 25% efficient, but an electric motor can be over 90%. A gallon of gas weighs about 2.7 kg, so the gas is about 12.3 kWh/kg. If we adjust this type of battery to account for the difference in efficiency, it is about 4.3 (equivalent) kW/kg. Ok, so that's still a factor of 3 worse. However, all the gas in the Cessna weighs about 336 lbs. The engine weighs about 250 lbs. A comparable electric motor is about 70 lbs. That gives you another 180 lbs, or over 50% more weight to fill with batteries. Now we're at about 50% of the useful energy of the Cessna. You can also factor in a little bit of gain from "regenerative braking" since the electric airplane can charge the batteries while descending. This may not make a huge difference in range for just point to point flying, but it does add some extra for flight training with lots of landings, and also provides some extra reserve in the case of a missed approach for example. All of that is to say that this doesn't bring the small electric airplane to parity with gasoline, but it's starting to much more credibly inch in on its turf.

taneq 4y ago

There's an electric trainer plane flying out of our local light airport, it's very cool.