So here is a proposal: hydrogen is very light but clumsy to store due to the cylindrical tanks. So what about a hydrogen flying wing?

- A triple passenger deck in the middle.
- A hydrogen cylinder tank on each side.
- Cargo on the outside of the hydrogen tanks.

Advantages:

- some bending relief from the tanks.
- passengers centred so less movement when in a roll.

First hydrogen must be made cheaper. It costs around 6US$ per KG (electrolysis sourced), while jet fuel is more than 10x cheaper for the same weight (and more than 5X cheaper for energy capacity).

rbretas wrote:

First hydrogen must be made cheaper. It costs around 6US$ per KG (electrolysis sourced), while jet fuel is more than 10x cheaper for the same weight (and more than 5X cheaper for energy capacity).

That's also a chicken and egg thing. Furtermore there's no tax on kerosine.


Electrolyses sourced hydrogen will likely take a huge leap as it is a way to use the future overcapacity of off-shore windfarms and cost of scale effects kick in.

Liquid hydrogen: Whatever heat passes through the isolation is used to steam hydrogen which is immediately burnt.

I guess pressure tanks are too heavy. Otherwise a sphere around the wing box? It's not flying wing, though.

evacuation issues first. no flying wing for pax


i think metane will be more useful

Taxi645 wrote:

rbretas wrote:

First hydrogen must be made cheaper. It costs around 6US$ per KG (electrolysis sourced), while jet fuel is more than 10x cheaper for the same weight (and more than 5X cheaper for energy capacity).

That's also a chicken and egg thing. Furtermore there's no tax on kerosine.


Electrolyses sourced hydrogen will likely take a huge leap as it is a way to use the future overcapacity of off-shore windfarms and cost of scale effects kick in.

This is a super-optimistic approach.
As for hydrogen as aviation fuel - it has some very nasty characteristics. Especially in case of emergency, where tank rupture can lead to massive destruction, nothing close to heavier Jet-A. ANd even for just compromized tank - hydrogen flame is almost invisible, and people can run into it. Safe way of walking around hydrogen installations is either checking the path with heat vision, or - on a cheap - wave a wooden stick in front of you as you walk. Stop if wood suddenly catches fire, you got a problem.
If anything, methane is a more feasible thing in forceeable future, and even then net benefit may be low, if not zero, due to tank weignt

IDK the storage pressure for nitrogen, but it would require a really heavy wing to contain it.

stratclub wrote:

IDK the storage pressure for nitrogen, but it would require a really heavy wing to contain it.

Thing is, hydrogen has pretty low per-volume energy density; and both cryogenic ang high pressure (250+ atm to make it practical) require spheric tanks.
So wing storage in a tube+ wing pretty much out of question anyway. BWB _may_ offer more room, but good luck doing TWO significantly new technologies in a single project.

If green hydrogen is 6-10x the price of Jet-A, then you're better off using any surplus wind power to synthesize hydrocarbon fuels or convert biomass into some drop-in fuels.

What about jet engines themselves? Is an engine, built for Jet A, capable of running on hydrogen as a "drop-in"?

https://en.wikipedia.org/wiki/Tupolev_Tu-155
at least it can be made for this.

Phosphorus wrote:

What about jet engines themselves? Is an engine, built for Jet A, capable of running on hydrogen as a "drop-in"?

Absolutely not.

Some aviation turbines can run petrol or other hydrocarbons, but hydrogen is an entirely different animal.

kalvado wrote:

stratclub wrote:

IDK the storage pressure for nitrogen, but it would require a really heavy wing to contain it.

Thing is, hydrogen has pretty low per-volume energy density; and both cryogenic ang high pressure (250+ atm to make it practical) require spheric tanks.
So wing storage in a tube+ wing pretty much out of question anyway. BWB _may_ offer more room, but good luck doing TWO significantly new technologies in a single project.

In the distant future maybe the aviation industry won't have a choice and they will be forced to doing two significantly new technologies in a single project.

Here is a rough sketch of what the lay-out could look like (span is a bit on the low side).

wish you be at desk 2 in case of accident

Armadillo1 wrote:

wish you be at desk 2 in case of accident

Because it's a blended wing body it would only be 3-deck for a short part of it's length due to the required wing profile. It would taper into 2-deck and then single deck. Because in a wing profile the widest point is quite close to the front, main exits (at least of the 2nd deck) could be at the front.

Maybe they could make it work as a two deck as well. I wouldn't be able to tell because I don't have the skills nor tools to do the numbers.

LH707330 wrote:

If green hydrogen is 6-10x the price of Jet-A, then you're better off using any surplus wind power to synthesize hydrocarbon fuels or convert biomass into some drop-in fuels.

Once enough money is thrown at it, price will come down. Solar electricity, batteries, mobiles, planes and everything else has/ had a learning curve.

Sokes wrote:

LH707330 wrote:

If green hydrogen is 6-10x the price of Jet-A, then you're better off using any surplus wind power to synthesize hydrocarbon fuels or convert biomass into some drop-in fuels.

Once enough money is thrown at it, price will come down. Solar electricity, batteries, mobiles, planes and everything else has/ had a learning curve.

Not denying that, just questioning if that's the right approach. If you had a billion to spend on green hydrogen or SAF, which would get you further? My guess is SAF, based on the fact that you're using existing infrastructure already and the properties of it are nicer than hydrogen.

LH707330 wrote:

If you had a billion to spend on green hydrogen or SAF, which would get you further? My guess is SAF, based on the fact that you're using existing infrastructure already and the properties of it are nicer than hydrogen.

Personally I believe that fuels based on sugarcane might be the future for aviation. Either alcohol processed further or synthetic fuel from CO2 from burning the cane after juice is extracted.

I doubt electric and I doubt hydrogen.
But I also doubted solar, so quite likely I will be wrong again.

With one billion one doesn't reach anywhere.
Tens or hundreds of billions have to be spent along the value chain.
But then what else to do with all the wealth capitalism generates?

What is SAF? Natural gas?

Sokes wrote:

LH707330 wrote:

If you had a billion to spend on green hydrogen or SAF, which would get you further? My guess is SAF, based on the fact that you're using existing infrastructure already and the properties of it are nicer than hydrogen.

Personally I believe that fuels based on sugarcane might be the future for aviation. Either alcohol processed further or synthetic fuel from CO2 from burning the cane after juice is extracted.

I doubt electric and I doubt hydrogen.
But I also doubted solar, so quite likely I will be wrong again.

With one billion one doesn't reach anywhere.
Tens or hundreds of billions have to be spent along the value chain.
But then what else to do with all the wealth capitalism generates?

What is SAF? Natural gas?

My bad, SAF=sustainable aviation fuels. It's an umbrella term for any fuels made in a CO2-neutral way that don't compete with food as gen-1 biofuels did. I wrote an article about the adoption of it: https://www.merlins-corner.net/whysaf.html

Regarding electric, I think it could come in useful for GA and air taxi on <500 nm legs, but longer distances will be best off sticking with hydrocarbons due to their superior energy density, and as lightsaber points out, handling qualities.

lightsaber wrote:

Hydrogen and a flying wing is a lot of new technology. You will not see both together until both prove themselves.

Lightsaber

Germany and Spain have shown with solar what is possible if enough money is thrown at it.
Wind turbine development was a joint effort.
China takes/ took care of HVDC transmission development.
Smartphones, China, France, Tesla, California, Norway and others took care of battery development.
Now hydrogen is missing.

Japan leads the way with hydrogen. I believe the US also has more hydrogen cars than others.
Merkel has killed most of renewable additions in Germany, but now (one year before elections, but then her party and its supporters are divided over renewables and consumers pay for solar development over twenty years from installment) she wants to join the hydrogen trendsetters. Good. Germany has hardly sun and wind, but good potential in research. I hope more countries will join.

I assume once 100 billion $ are spent collectively on hydrogen technology development over the next years, we will see light at the end of the tunnel how to "green" aviation.
I assume CO2 from burning sugar cane fiber and hydrogen will make liquid fuels for long range flights.
No idea what will succeed short to medium range.

A long journey starts with a single step.

Sokes wrote:

Now hydrogen is missing.

and there a reason for this

Armadillo1 wrote:

Sokes wrote:

Now hydrogen is missing.

and there a reason for this

While the gist of it is correct, that is a lot of "convenient theory daily" in that picture, that is valid now, but isn´t in a 100% renewable sourced grid.

For battery electric vehicle future grids are all but guaranteed to include an HVDC line, and hence an extra AC-DC/DC-AC conversion step, and a grid side battery on top of that as well to match production and demand. If that is not part of the HVDC infrastructure, and i don´t know of any plans to do that, this grid battery comes with an AC-DC/DC-AC conversion step too. And that is if you are lucky, since many places on this planet have quite distinkt availability effects of seasons, so in a buch of places you may end up with grid side electrolysis-fuel cell storage stage, at which point the issue becomes not just mood, but is turned on its head, as that is where hydrogen fuel cell runs directly on stored hydrogen and is more efficient than batteries. Also doesn´t account for an Hydrogen Fuel cell car being a hell of a lot lighter than a BEV by some 300Kg. A hydrogen tank also essentially doesn´t have wear, a battery does.

Also, and most importantly: Since large scale direct long term electricity storage is impractical to boot, almost every place will have massive overcapacity on good days that can not be stored efficiently. At that point efficiency becomes irrelevant as hydrogen production can run on surplus electricity, or depending on the legal environment even charge money for providing load to the grid.

And once you have compressed your hydrogen transportation losses are more like 4%, not the ridiculous 20% ...
https://www.sciencedirect.com/topics/en ... 0be%20used.

There is a place for both, and that is why more and more places to have a hydrogen strategy in the mix these days. Compared to electricity hydrogen is really easy to store, and old natural gas infrastructure can already store it directly, or with minor modification, as the "city gas" they where build for was mostly H2 and CO.

best regards
Thomas

Taxi645 wrote:

Here is a rough sketch of what the lay-out could look like (span is a bit on the low side).

I would assume that (at least the first) implementations of hydrogen powered crafts would try to somehow "conventionally" burn the hydrogen, as large scale fuel cells are coming with a significant weight and - as already mentioned - further reduce the amount of usable energy during the conversion process. So for first generation hydrogen aircrafts I would expect some form of modified jet-engine or similar rather than an electric powered plane with fuel cells. ....but that's just my poorly informed opinion.

Armadillo1 wrote:

Sokes wrote:

Now hydrogen is missing.

and there a reason for this

Nice graphic, but source is missing.
Thanks for posting.

I do not doubt that batteries are three times as efficient as hydrogen, though this proportion may come a bit down.

However:
-Batteries are not good for transpacific flights.

-Europe once a year or so has dark doldrums. No wind and less sun for ten days or so.
Hydrogen storage in salt caverns is possible. It could be burnt in combined cycle gas turbines in district heating. I believe one needs CCGTs as backup anyway. Dark doldrums are in winter, waste heat will be useful.

-For steel manufacturing hydrogen can replace coke.

-In Qatar, Saudi Arabia and Portugal during auctions solar electricity prices of 1,6/ 1,7 cents were offered.
I shall assume that on the long run during midday electricity rates will be even lower.
One kg hydrogen contains 33,3 kWh which may require 67 kWh of electricity. Make that one Dollar for electricity. Or 50 cents? But all surrounding costs have to come down.

If one gets around 20 kWh/ kg H2 back in a CCGT the electricity cost may be something around 3-5 cents / kWh.
Other costs will dominate.

But no doubt, batteries are better for cars.
Pumped storage is also better, but then the required basins may interfere with a rare butterfly or snail.
Norway's existing dams would have enough energy potential to supply Europe with 200 GW for IIRC around 10 days. But how to manage the runoff downstream? One would have to build dedicated dams with upper and lower storage. That assumes Norway is interested to help.

Anyway we need to develop hydrogen technology.
Massive subsidies will be necessary. About efficiencies and uses we can think once the technology is mature. Now is not the time to think of efficiencies.

Would you have predicted 20 years back that solar will cost 1,6 cent/ kWh?

i dont want to disсuss any topic about current "green energy" prices, because too many interlocutors become liars

better lets return to hydrogen

New hydrogen-powered race series to launch in 2023

https://www.autosport.com/other/news/15 ... ch-in-2023

Armadillo1 wrote:

i dont want to disсuss any topic about current "green energy" prices, because too many interlocutors become liars

better lets return to hydrogen

New hydrogen-powered race series to launch in 2023

https://www.autosport.com/other/news/15 ... ch-in-2023

In case you refer to me:
I usually quote my source, but I am out of station and have to post from my mobile. Is there a copy/ paste function?

Great news about the hydrogen race series.
Somewhere I read that fuel cells dislike power peaks. I hope the series becomes successful. I believe research in peak power would be a priority.
But any research/ money spent in the field is welcome.

Actually, I always though that recent push for hydrogen energy happened when Bush II got briefed on fusion power development ("you know, same process which powers H-bomb. Hydrogen bomb") - and "hydrogen" somehow was the only word POTUS understood