13 ms·

ZEROe: Hydrogen-hybrid aircraft concept

95 points by based2 6y ago

jeffreyrogers 6y ago
Interesting that this doesn't primarily use fuel cells[0] (which is what hydrogen-electric aviation usually proposes to use), but directly combusts the hydrogen to run a traditional jet engine. There was a Soviet Union airliner that did this, so it definitely works, although I'm skeptical that hydrogen makes sense as an aviation fuel because jet fuel is much more convenient (easier to transport, store, and handle, and cheaper). [0]: It uses fuel cells too, but looks like most of the propulsion comes from the turbines.
- Hypx 6y ago
  Fuel cells are too heavy, at least for the time being. Other than biofuels or synfuels, there's basically no alternatives. Aviation companies will have to pick one of those fuels.
  - Robotbeat 6y ago
    Fuel cells are better because they don't emit directly. Turns out high altitude water vapor is itself a powerful greenhouse gas. At least with fuel cells, you could collect the water and dispense it periodically as a liquid at lower altitudes. https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2002JD002623 https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/200... But actually, batteries are better than people think. 1000km battery-electric range is feasible with current chemistries, and ~3000-5000km is feasible with metal-anode, maybe lithium-sulfur or other advanced chemistries plus extremely high performance structures and aerodynamics. Lithium-air batteries with these improvements could enable >10,000km flights.
    - DesiLurker 6y ago
      but wont this just create another problem, the mass for the 'spent' hydrogen would be 9 times more than original because of Oxygen being much weightier (atomic mass: 16). so your fuel tank would basically get 9 times heavier. that will negate any benefit you get from higher energy density. also it may create storage problems because now you have to provision another tank for water storage. I think they'll just handwave it and release it periodically.
      - Hypx 6y ago
        Metal-air cells have the same problem. That’s why they were briefly considered for airplanes, and then abandoned once they realized that problem.
      - Robotbeat 6y ago
        Releasing it periodically can be done at a slightly lower altitude and in a liquid phase, both of which should significantly reduce impact.
    - Hypx 6y ago
      H2O as an emission lasts for days, not centuries. It shouldn’t be that big of a deal. You do realize a fuel cell is a hydrogen-air battery? If you’re going to bring up metal-air batteries, you might as well skip to the end and try to figure out fuel cells.
      - Robotbeat 6y ago
        It lasts for days in the lower troposphere but years in the stratosphere. And kg for kg, H2O is a much stronger Greenhouse gas than CO2, so the long-term averaged effect is on the same order as CO2 (maybe higher, depending on conditions). And sure, I guess you could argue lithium-air is a type of fuel cell (or that hydrogen fuel cells are a kind of inefficient battery), however lithium-air is much more energy dense (volumetrically) than hydrogen-air and both the "fuel" and the "exhaust" are solid and stay in the battery, which has operational advantages. (Although to be completely fair, hydrogen fuel cells are high TRL whereas lithium-air is still lab scale at best.)
        Hypx 6y ago
        > It lasts for days in the lower troposphere but years in the stratosphere I addressed this in my other reply. Table 1 of the study you cited stated that the residence time of stratospheric water vapor is measured in days. I'm not seeing a lifetime of years in that study. > however lithium-air is much more energy dense (volumetrically) Maybe. Lithium-air absorbs oxygen when it is operating. Not sure how to calculated this though.
    - ncmncm 6y ago
      Batteries are way, way, way worse than you imagine. Their energy density would need to get >10x better, when 2x is a miracle. Furthermore, without internal combustion, you are limited to ~350 knots.
      - Robotbeat 6y ago
        i study this professonally. batteries are sufficient if we make other improvements as well. and not true about combustion being essential.
        aero-glide 6y ago
        Do you have any links where I can read more about this?
    - Someone 6y ago
      But are batteries more efficient for long distance planes? Conversion losses may be lower, but a battery-powered plane doesn’t lose weight during flight. That makes the impact on landing harder, so planes will have to be made stronger and, thus, heavier. And yes, that should make quite a difference. Reading https://en.wikipedia.org/wiki/Fuel_fraction https://en.wikipedia.org/wiki/Fuel_fraction, 40% of the take-off weight of long-haul flights is fuel. Not all of that will be gone at landing, but if 10% of fuel is reserve, such an airliner still will be a third lighter at landing time. Also, commercial planes have turnaround times of about an hour, sometimes half of that (https://simpleflying.com/turnaround-time-importance/ https://simpleflying.com/turnaround-time-importance/). I would think pumping in hydrogen would be easier to do in that time than charging batteries. Batteries could be replaceable, but that would add more weight.
xoa 6y ago
I'll admit I really don't get the fascination with hydrogen as an energy storage medium. It has to be manufactured, so how green it is depends on whatever the power input is coming from. It's not any inherently greener then synthetic hydrocarbon production, which can be produced from atmospheric carbon for zero net carbon impact, and of course has no sulfur or aromatics. It also works fine with existing engineering. And hydrogen is an absolute total bitch to work with. It's got bad density, a really low/really high pressure liquidation point, escapes from everything, embrittles steel, and on and on. The infrastructure has no multiple use, unlike improvements to the grid. So why not just do full manufacture of regular fuel? I've never understood where hydrogen fits between improving batteries/capacitors and synthetic hydrocarbons. It always seemed like an answer without a question outside of rockets (and even there the economics and practicalities of methalox may be better).
- aeternum 6y ago
  It sounds futuristic though and the exhaust is water!
- Yetanfou 6y ago
  An advantage of hydrogen is that it can be used in fuel cells, producing only water as reaction product. Using hydrocarbons of any sort in existing engines leads to the production of nitrogen oxides due to the presence of nitrogen in the air.
  - xoa 6y ago
    Thanks for this reply as well. But batteries will cover most land use, and going by sources like the EIA [1] the primary source of anthropogenic N2O emissions is overwhelmingly agriculture, at 70+%. Other sources indicate that may have fallen somewhat since then, but even so everything I can find indicates fossil fuel combustion is still only around 10%. And of that air travel will be single digits. Not nothing, but I'm not sure it'd justify massive effort alone.
    - Yetanfou 6y ago
unchocked 6y ago
In a world where existing natural gas infrastructure transitions to hydrogen, securing sufficient hydrogen fuel at airports seems totally practical. Due to the fuel's low density, the conventional fuselage designs lose a lot of load capacity. The blended wing body looks practical, with plenty of interior volume. Hearing people complain about passengers not wanting to sit in a stadium, or that their inner ear will be unmitigatedly upset by roll changes remind me of historical folks who said cars would never take off because they'd scare the horses.
ebbflowgo 6y ago
It's good to see aviation companies looking for fuel alternatives. For those interested, use happen to keep track of the 2035 release of the Airbus ZEROe hydrogen aircraft https://www.usehappen.com/events/67517310 https://www.usehappen.com/events/67517310
Robotbeat 6y ago
Not as helpful for reducing effective emissions as you might think. High altitude water vapor is just as big of a problem as CO2 as the lifetime of water vapor in the stratosphere is measured in years, not days or hours like it is in the lower troposphere. Water vapor is, after all, a much stronger greenhouse gas than CO2, it's just that normally its lifetime in the atmosphere is so short so as not to matter. So unless we can be certain these planes will fly solely in the lower troposphere (unlikely, considering the aircraft presented), then hydrogen is not actually necessarily a silver bullet and in some situations (i.e. very high altitude flight, ala Concorde) could actually be worse than kerosene. https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2002JD002623 https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/200...
- skykooler 6y ago
  Keep in mind however that all hydrocarbon fuels, kerosene included, turn into both CO2 and water.
  - Robotbeat 6y ago
    In some ways, direct CO2 capture combined with carbon monoxide fuel (if burned super cleanly) might actually be better than either kerosene or hydrogen for super high altitude flight. The years-long lifetime of air in the stratosphere is small compared to the normal lifetime of CO2 in the atmosphere, so on net would be much better than hydrogen fuel.
    - ncmncm 6y ago
      How do you imagine capturing the CO2 coming out of a turbojet?
- Hypx 6y ago
  > High altitude water vapor is just as big of a problem as CO2 as the lifetime of water vapor in the stratosphere is measured in years, not days or hours like it is in the lower troposphere. On Table 1 of your study, it’s measuring residence time of stratospheric water vapor in days. How are you getting years from that?
neximo64 6y ago
Water vapour also has a greenhouse warming effect.
- neuronic 6y ago
  The stratosphere is cold. Will water vapor turn into ice crystals instead?
bfieidhbrjr 6y ago
Airbus has great marketing
ncmncm 6y ago
The real problem is that if these things don't fly before 2035, civilization is likely to collapse first.
codecamper 6y ago
Greenwashing should be illegal. These concept renderings omit the basic physical facts: that hydrogen is less energy dense and therefore you need more of it. Tanks will be bigger and distances will be shorter.
- bildung 6y ago
  Isn't the energy content per kg more important for planes than energy density (J/m³)? Energy per kg is much higher for liquid hydrogen (122.8 MJ/kg) than for kerosine (42.8 MJ/kg): https://www.fzt.haw-hamburg.de/pers/Scholz/GF/GF_Paper_DLRK_09-09-08.pdf https://www.fzt.haw-hamburg.de/pers/Scholz/GF/GF_Paper_DLRK_... So planes would look bulkier, but could actually be lighter than before.
- aero-glide 6y ago
  Yes, they clearly mentioned that in the 30mins video. That's why fuel will be stored in the aft of the fuselage instead of the wings.
hannob 6y ago
I find this announcement surprisingly scarce on details. It's basically a press release and some nice pictures. It lacks even basic information like the amount of hydrogen they'll need for a given flight.
ib84 6y ago
A side-question on the perspective of battery-driven electric-flights: when electric cars can recuperate power instead of breaking, why can't airplanes do the same on descent? Couldn't they build a propeller at the rear, which does propulsion and recuperation? Energy-wise, that would certainly be attractive...
- filleokus 6y ago
  My gut feeling is that it's probably not substantial amounts of energy to find there. Compared to a car in city traffic which might break to a standstill every other minute, an aircraft generally only "brakes" once when going down for landing. Further, since air resistance scales with the square of the velocity, the drag forces on an aircraft is so high that you typically never reduce thrust to zero until to just before touching down. An aircraft never idle-glide any substantial part of the flight. I.e, it's like trying to recuperate energy while driving slowly in a car up a very steep hill. Just releasing the throttle will make you stop quite rapidly...
  - ib84 6y ago
    I'm no expert, so this could be wrong but I have a gut feeling that during descent it could probably idle-glide by using the high-lift device sooner. If anybody was serious about flying with less emissions that could probably save lots of energy already today - it would just take longer to reach the target. It would be interesting to see numbers how the gravitational potential energy compares to the drag forces.
- jackdeansmith 6y ago
  You need battery mass to capture energy on decent, why lug that mass around when there's cheap energy available down on the ground where you're going?
jakozaur 6y ago
Would not be easier to produce synthetic kerosene fuel from captured CO2 and hydrogen. The process is straightforward: 1. A lot of cheap solar energy, from the best location. 2. Electrolyse to produce hydrogen. 3. Capture CO2. Either from air or from carbon intensive processes (e.g. producing cement). 4. Use Sabatier reaction to bond CO2 and hydrogen to produce carbohydrate fuel. 5. Since we use same amount of CO2 to produce as there will be burn this carbon neutral fuel. It's much easier to do it at scale, than redesign, get approved new planes, replace all existing fleets and the infrastructure. This could easily take 60-120 years, when we need to act much sooner to prevent worst consequences of global warming. Of course, today this would not work as individual steps are too expensive. Though all of the steps could be much cheaper as solar energy panel shows. It gives possibility for oil rich countries to transform to post carbon economy when they resources will be depleted and consumers would prefer carbon neutral fuels. I guess all of this sovereign funds would be much better of investing in this tech than pouring money in SoftBank to do WeWork style opportunities. Google crowd oil or solar kerosene for papers about it.
- Qwertious 6y ago
  "5. Since we use same amount of CO2 to produce as there will be burn this carbon neutral fuel." Not necessarily, it depends on the byproducts - hypothetically, suppose when you burned the fuel the emissions were SOMEHOW 100% methane. You're essentially turning CO2 into methane in this farcical hypothetical, which is probably worse than burning normal fossil-kerosene. Obviously the emissions won't be methane, but you'll need to track the CO2e of every type of emission it produces other than CO2.
- largolagrande 6y ago
  > A lot of cheap solar energy, from the best location. I recommend that you watch the "Planet of the Humans" documentary to understand why there is no cheap solar energy, no so-called "green" energies: https://www.youtube.com/watch?v=Zk11vI-7czE https://www.youtube.com/watch?v=Zk11vI-7czE So there will never be any "green" planes, no matter if they use hydrogen or kerosen. Since the minimum required amount of energy to fly from point A to point B with N passengers will always be the same.
largolagrande 6y ago
I recommend that you watch the "Planet of The Humans" documentary to understand why there is no cheap or green energy: https://www.youtube.com/watch?v=Zk11vI-7czE https://www.youtube.com/watch?v=Zk11vI-7czE
- Qwertious 6y ago
  I recommend that you watch a real documentary, because that doc is filled to the brim with misleading BS. https://en.wikipedia.org/wiki/Planet_of_the_Humans#Factual_accuracy https://en.wikipedia.org/wiki/Planet_of_the_Humans#Factual_a... https://votetosurvive.org/skepticism-is-healthy-but-planet-of-the-humans-is-toxic/ https://votetosurvive.org/skepticism-is-healthy-but-planet-o...
dathinab 6y ago
One problem with hydrogen powered air plannes (which I know from some older articles I had read airbus is aware of) is that emitting small water droplets in the higher atmosphere is actually problematic. I have no good sources but don't articles I have read said it's potentially worse then the CO2 emission of current air plainness. So additional care must be taken to not condense the water from the hydrogen burning into larger potions/prices before emitting it.
nmeofthestate 6y ago
Judging from the number of windows in the renders and comparing with existing aircraft, it looks like the rear third of the plane is fuel tank.
amai 6y ago
They plan to have these in 2035! That is shortly after we have nuclear fusion power plants.
GordonS 6y ago
The "Blended-Wing Body" design looks radically different that any plan I've ever seen. Anyone know if anything like that has existed before, and how the shape would affect take-off speeds, cruising speeds, handing etc?

95 points by based2 6y ago

Interesting that this doesn't primarily use fuel cells[0] (which is what hydrogen-electric aviation usually proposes to use), but directly combusts the hydrogen to run a traditional jet engine. There was a Soviet Union airliner that did this, so it definitely works, although I'm skeptical that hydrogen makes sense as an aviation fuel because jet fuel is much more convenient (easier to transport, store, and handle, and cheaper). [0]: It uses fuel cells too, but looks like most of the propulsion comes from the turbines.

Hypx 6y ago
Fuel cells are too heavy, at least for the time being. Other than biofuels or synfuels, there's basically no alternatives. Aviation companies will have to pick one of those fuels.
- Robotbeat 6y ago
  Fuel cells are better because they don't emit directly. Turns out high altitude water vapor is itself a powerful greenhouse gas. At least with fuel cells, you could collect the water and dispense it periodically as a liquid at lower altitudes. https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2002JD002623 https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/200... But actually, batteries are better than people think. 1000km battery-electric range is feasible with current chemistries, and ~3000-5000km is feasible with metal-anode, maybe lithium-sulfur or other advanced chemistries plus extremely high performance structures and aerodynamics. Lithium-air batteries with these improvements could enable >10,000km flights.
  - DesiLurker 6y ago
    but wont this just create another problem, the mass for the 'spent' hydrogen would be 9 times more than original because of Oxygen being much weightier (atomic mass: 16). so your fuel tank would basically get 9 times heavier. that will negate any benefit you get from higher energy density. also it may create storage problems because now you have to provision another tank for water storage. I think they'll just handwave it and release it periodically.
    - Hypx 6y ago
      Metal-air cells have the same problem. That’s why they were briefly considered for airplanes, and then abandoned once they realized that problem.
    - Robotbeat 6y ago
      Releasing it periodically can be done at a slightly lower altitude and in a liquid phase, both of which should significantly reduce impact.
  - Hypx 6y ago
    H2O as an emission lasts for days, not centuries. It shouldn’t be that big of a deal. You do realize a fuel cell is a hydrogen-air battery? If you’re going to bring up metal-air batteries, you might as well skip to the end and try to figure out fuel cells.
    - Robotbeat 6y ago
      It lasts for days in the lower troposphere but years in the stratosphere. And kg for kg, H2O is a much stronger Greenhouse gas than CO2, so the long-term averaged effect is on the same order as CO2 (maybe higher, depending on conditions). And sure, I guess you could argue lithium-air is a type of fuel cell (or that hydrogen fuel cells are a kind of inefficient battery), however lithium-air is much more energy dense (volumetrically) than hydrogen-air and both the "fuel" and the "exhaust" are solid and stay in the battery, which has operational advantages. (Although to be completely fair, hydrogen fuel cells are high TRL whereas lithium-air is still lab scale at best.)
      - Hypx 6y ago
        > It lasts for days in the lower troposphere but years in the stratosphere I addressed this in my other reply. Table 1 of the study you cited stated that the residence time of stratospheric water vapor is measured in days. I'm not seeing a lifetime of years in that study. > however lithium-air is much more energy dense (volumetrically) Maybe. Lithium-air absorbs oxygen when it is operating. Not sure how to calculated this though.
  - ncmncm 6y ago
    Batteries are way, way, way worse than you imagine. Their energy density would need to get >10x better, when 2x is a miracle. Furthermore, without internal combustion, you are limited to ~350 knots.
    - Robotbeat 6y ago
      i study this professonally. batteries are sufficient if we make other improvements as well. and not true about combustion being essential.
      - aero-glide 6y ago
        Do you have any links where I can read more about this?
  - Someone 6y ago
    But are batteries more efficient for long distance planes? Conversion losses may be lower, but a battery-powered plane doesn’t lose weight during flight. That makes the impact on landing harder, so planes will have to be made stronger and, thus, heavier. And yes, that should make quite a difference. Reading https://en.wikipedia.org/wiki/Fuel_fraction https://en.wikipedia.org/wiki/Fuel_fraction, 40% of the take-off weight of long-haul flights is fuel. Not all of that will be gone at landing, but if 10% of fuel is reserve, such an airliner still will be a third lighter at landing time. Also, commercial planes have turnaround times of about an hour, sometimes half of that (https://simpleflying.com/turnaround-time-importance/ https://simpleflying.com/turnaround-time-importance/). I would think pumping in hydrogen would be easier to do in that time than charging batteries. Batteries could be replaceable, but that would add more weight.

xoa 6y ago

I'll admit I really don't get the fascination with hydrogen as an energy storage medium. It has to be manufactured, so how green it is depends on whatever the power input is coming from. It's not any inherently greener then synthetic hydrocarbon production, which can be produced from atmospheric carbon for zero net carbon impact, and of course has no sulfur or aromatics. It also works fine with existing engineering. And hydrogen is an absolute total bitch to work with. It's got bad density, a really low/really high pressure liquidation point, escapes from everything, embrittles steel, and on and on. The infrastructure has no multiple use, unlike improvements to the grid. So why not just do full manufacture of regular fuel? I've never understood where hydrogen fits between improving batteries/capacitors and synthetic hydrocarbons. It always seemed like an answer without a question outside of rockets (and even there the economics and practicalities of methalox may be better).

aeternum 6y ago
It sounds futuristic though and the exhaust is water!
Yetanfou 6y ago
An advantage of hydrogen is that it can be used in fuel cells, producing only water as reaction product. Using hydrocarbons of any sort in existing engines leads to the production of nitrogen oxides due to the presence of nitrogen in the air.
- xoa 6y ago
  Thanks for this reply as well. But batteries will cover most land use, and going by sources like the EIA [1] the primary source of anthropogenic N2O emissions is overwhelmingly agriculture, at 70+%. Other sources indicate that may have fallen somewhat since then, but even so everything I can find indicates fossil fuel combustion is still only around 10%. And of that air travel will be single digits. Not nothing, but I'm not sure it'd justify massive effort alone.
  - Yetanfou 6y ago

unchocked 6y ago

In a world where existing natural gas infrastructure transitions to hydrogen, securing sufficient hydrogen fuel at airports seems totally practical. Due to the fuel's low density, the conventional fuselage designs lose a lot of load capacity. The blended wing body looks practical, with plenty of interior volume. Hearing people complain about passengers not wanting to sit in a stadium, or that their inner ear will be unmitigatedly upset by roll changes remind me of historical folks who said cars would never take off because they'd scare the horses.

ebbflowgo 6y ago

It's good to see aviation companies looking for fuel alternatives. For those interested, use happen to keep track of the 2035 release of the Airbus ZEROe hydrogen aircraft https://www.usehappen.com/events/67517310 https://www.usehappen.com/events/67517310

Robotbeat 6y ago

Not as helpful for reducing effective emissions as you might think. High altitude water vapor is just as big of a problem as CO2 as the lifetime of water vapor in the stratosphere is measured in years, not days or hours like it is in the lower troposphere. Water vapor is, after all, a much stronger greenhouse gas than CO2, it's just that normally its lifetime in the atmosphere is so short so as not to matter. So unless we can be certain these planes will fly solely in the lower troposphere (unlikely, considering the aircraft presented), then hydrogen is not actually necessarily a silver bullet and in some situations (i.e. very high altitude flight, ala Concorde) could actually be worse than kerosene. https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2002JD002623 https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/200...

skykooler 6y ago
Keep in mind however that all hydrocarbon fuels, kerosene included, turn into both CO2 and water.
- Robotbeat 6y ago
  In some ways, direct CO2 capture combined with carbon monoxide fuel (if burned super cleanly) might actually be better than either kerosene or hydrogen for super high altitude flight. The years-long lifetime of air in the stratosphere is small compared to the normal lifetime of CO2 in the atmosphere, so on net would be much better than hydrogen fuel.
  - ncmncm 6y ago
    How do you imagine capturing the CO2 coming out of a turbojet?
Hypx 6y ago
> High altitude water vapor is just as big of a problem as CO2 as the lifetime of water vapor in the stratosphere is measured in years, not days or hours like it is in the lower troposphere. On Table 1 of your study, it’s measuring residence time of stratospheric water vapor in days. How are you getting years from that?

neximo64 6y ago

Water vapour also has a greenhouse warming effect.

neuronic 6y ago
The stratosphere is cold. Will water vapor turn into ice crystals instead?

bfieidhbrjr 6y ago

Airbus has great marketing

ncmncm 6y ago

The real problem is that if these things don't fly before 2035, civilization is likely to collapse first.

codecamper 6y ago

Greenwashing should be illegal. These concept renderings omit the basic physical facts: that hydrogen is less energy dense and therefore you need more of it. Tanks will be bigger and distances will be shorter.

bildung 6y ago
Isn't the energy content per kg more important for planes than energy density (J/m³)? Energy per kg is much higher for liquid hydrogen (122.8 MJ/kg) than for kerosine (42.8 MJ/kg): https://www.fzt.haw-hamburg.de/pers/Scholz/GF/GF_Paper_DLRK_09-09-08.pdf https://www.fzt.haw-hamburg.de/pers/Scholz/GF/GF_Paper_DLRK_... So planes would look bulkier, but could actually be lighter than before.
aero-glide 6y ago
Yes, they clearly mentioned that in the 30mins video. That's why fuel will be stored in the aft of the fuselage instead of the wings.

hannob 6y ago

I find this announcement surprisingly scarce on details. It's basically a press release and some nice pictures. It lacks even basic information like the amount of hydrogen they'll need for a given flight.

ib84 6y ago

A side-question on the perspective of battery-driven electric-flights: when electric cars can recuperate power instead of breaking, why can't airplanes do the same on descent? Couldn't they build a propeller at the rear, which does propulsion and recuperation? Energy-wise, that would certainly be attractive...

filleokus 6y ago
My gut feeling is that it's probably not substantial amounts of energy to find there. Compared to a car in city traffic which might break to a standstill every other minute, an aircraft generally only "brakes" once when going down for landing. Further, since air resistance scales with the square of the velocity, the drag forces on an aircraft is so high that you typically never reduce thrust to zero until to just before touching down. An aircraft never idle-glide any substantial part of the flight. I.e, it's like trying to recuperate energy while driving slowly in a car up a very steep hill. Just releasing the throttle will make you stop quite rapidly...
- ib84 6y ago
  I'm no expert, so this could be wrong but I have a gut feeling that during descent it could probably idle-glide by using the high-lift device sooner. If anybody was serious about flying with less emissions that could probably save lots of energy already today - it would just take longer to reach the target. It would be interesting to see numbers how the gravitational potential energy compares to the drag forces.
jackdeansmith 6y ago
You need battery mass to capture energy on decent, why lug that mass around when there's cheap energy available down on the ground where you're going?

jakozaur 6y ago

Would not be easier to produce synthetic kerosene fuel from captured CO2 and hydrogen. The process is straightforward: 1. A lot of cheap solar energy, from the best location. 2. Electrolyse to produce hydrogen. 3. Capture CO2. Either from air or from carbon intensive processes (e.g. producing cement). 4. Use Sabatier reaction to bond CO2 and hydrogen to produce carbohydrate fuel. 5. Since we use same amount of CO2 to produce as there will be burn this carbon neutral fuel. It's much easier to do it at scale, than redesign, get approved new planes, replace all existing fleets and the infrastructure. This could easily take 60-120 years, when we need to act much sooner to prevent worst consequences of global warming. Of course, today this would not work as individual steps are too expensive. Though all of the steps could be much cheaper as solar energy panel shows. It gives possibility for oil rich countries to transform to post carbon economy when they resources will be depleted and consumers would prefer carbon neutral fuels. I guess all of this sovereign funds would be much better of investing in this tech than pouring money in SoftBank to do WeWork style opportunities. Google crowd oil or solar kerosene for papers about it.

Qwertious 6y ago
"5. Since we use same amount of CO2 to produce as there will be burn this carbon neutral fuel." Not necessarily, it depends on the byproducts - hypothetically, suppose when you burned the fuel the emissions were SOMEHOW 100% methane. You're essentially turning CO2 into methane in this farcical hypothetical, which is probably worse than burning normal fossil-kerosene. Obviously the emissions won't be methane, but you'll need to track the CO2e of every type of emission it produces other than CO2.
largolagrande 6y ago
> A lot of cheap solar energy, from the best location. I recommend that you watch the "Planet of the Humans" documentary to understand why there is no cheap solar energy, no so-called "green" energies: https://www.youtube.com/watch?v=Zk11vI-7czE https://www.youtube.com/watch?v=Zk11vI-7czE So there will never be any "green" planes, no matter if they use hydrogen or kerosen. Since the minimum required amount of energy to fly from point A to point B with N passengers will always be the same.

largolagrande 6y ago

I recommend that you watch the "Planet of The Humans" documentary to understand why there is no cheap or green energy: https://www.youtube.com/watch?v=Zk11vI-7czE https://www.youtube.com/watch?v=Zk11vI-7czE

Qwertious 6y ago
I recommend that you watch a real documentary, because that doc is filled to the brim with misleading BS. https://en.wikipedia.org/wiki/Planet_of_the_Humans#Factual_accuracy https://en.wikipedia.org/wiki/Planet_of_the_Humans#Factual_a... https://votetosurvive.org/skepticism-is-healthy-but-planet-of-the-humans-is-toxic/ https://votetosurvive.org/skepticism-is-healthy-but-planet-o...

dathinab 6y ago

One problem with hydrogen powered air plannes (which I know from some older articles I had read airbus is aware of) is that emitting small water droplets in the higher atmosphere is actually problematic. I have no good sources but don't articles I have read said it's potentially worse then the CO2 emission of current air plainness. So additional care must be taken to not condense the water from the hydrogen burning into larger potions/prices before emitting it.

nmeofthestate 6y ago

Judging from the number of windows in the renders and comparing with existing aircraft, it looks like the rear third of the plane is fuel tank.

amai 6y ago

They plan to have these in 2035! That is shortly after we have nuclear fusion power plants.

GordonS 6y ago

The "Blended-Wing Body" design looks radically different that any plan I've ever seen. Anyone know if anything like that has existed before, and how the shape would affect take-off speeds, cruising speeds, handing etc?