Electric and Hydrogen aeroplanes - feasibility and issues

yasotay

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CNH

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Electric aircraft are a fantasy.

If you doubt that, look at the energy density of jet fuel and lithium batteries.

I've just bought an electric car. Anywhere more than 50 miles away, I'll take my other car - petrol driven.
 

CNH

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I think you might be writing that somewhat tongue in cheek.

Hydrogen.

Boils at 20 K. Might be a bit difficult to handle in the liquid form. So let's look at using it in the gaseous form. To store any worthwhile amount, you're going to need to have it at very high pressure – which means an extremely heavy tank to withstand the necessary pressure.

Which is why I suspect that hydrogen will never take off (no pun intended) in aircraft, or indeed in cars.
 

Hood

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You would need to take the A380 out of mothballs and convert the upper deck to the fuel tank.
Don't think passengers would love sitting under a hydrogen tank. Though I see BMW is once again working hydrogen powered cars, Toyota, Honda and Hyundai have tinkered for years. I remember VW and Mercedes messing around with it at least 20 years ago. Always seems to be the fuel of the future that never comes and the technical side seems never to have been 100% sorted, let alone the infrastructure issues.

Electric aircraft are a fantasy.
Agreed 100%. Using a battery-powered DHC-2 for 17 minute sightseeing trips is one thing. Flying a battery-powered A320 from Gatwick to Malaga and back seems less likely, even in the next twenty years.
 

TomS

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You would need to take the A380 out of mothballs and convert the upper deck to the fuel tank.
Don't think passengers would love sitting under a hydrogen tank. Though I see BMW is once again working hydrogen powered cars, Toyota, Honda and Hyundai have tinkered for years. I remember VW and Mercedes messing around with it at least 20 years ago. Always seems to be the fuel of the future that never comes and the technical side seems never to have been 100% sorted, let alone the infrastructure issues.

All three are actually selling hydrogen fuel-cell cars commercially right now. So the tech has worked out to the point that they think they can trust it with consumers. Infrastructure is going to be the sticking point, for sure, though.
 

robunos

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I've seen a proposal online somewhere, for producing the hydrogen on-site at the filling station, by electrolysis. That way, it's easy to convert existing filling stations, electricity and water supplies are already available, only the electrolysis plant and storage tanks need be added. This way, there's no need to be transporting large quantities of hydrogen around, to stock the filling stations.
EDIT: Here's the LINK

cheers,
Robin.
 

Zoo Tycoon

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One of the as yet unsolved problems is diffusion leakage;- H2 is such a small molecule it slowly passes through the wall of any material you use to contain it, especially for pressurised systems. Leave your H2 powered pride and joy in the garage for a week, it’ll be empty when you need it (how will you get filled up again?) and maybe you’re garage won’t have a roof.
 

TomS

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Hmm. Of all the issues I've heard discussed with non-cryo gaseous hydrogen for vehicles, tank wall diffusion has never been raised as a serious concern. Liquid cryo hydrogen (which I think is what BMW has been using) has boil-off issues, but not anything that will reach explosive concentrations.
 

TomS

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That's a study on what happens with a leaking hydrogen tank after a collision. It has nothing to do with a vehicle sitting unused in a garage. And note that the conclusion is that such a leak is not particularly dangerous.
 

Hobbes

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I've seen a proposal online somewhere, for producing the hydrogen on-site at the filling station, by electrolysis. That way, it's easy to convert existing filling stations, electricity and water supplies are already available, only the electrolysis plant and storage tanks need be added. This way, there's no need to be transporting large quantities of hydrogen around, to stock the filling stations.
EDIT: Here's the LINK

The drawback of electrolysis is that it's very inefficient. This becomes viable only when we have a massive excess of electricity available.
 

Hobbes

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Hmm. Of all the issues I've heard discussed with non-cryo gaseous hydrogen for vehicles, tank wall diffusion has never been raised as a serious concern. Liquid cryo hydrogen (which I think is what BMW has been using) has boil-off issues, but not anything that will reach explosive concentrations.

IIRC it's more the result of hydrogen diffusion that is a problem: embrittlement.
 

Wyvern

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There was one crazy idea to create hydrogen from nuclear waste. In my opinion, once we have come up with an efficient way of producing hydrogen and coming up with an effective way to store it, I do believe hydrogen will become a fuel that we will use everyday, but that is just an opinion.
 

Zoo Tycoon

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That's a study on what happens with a leaking hydrogen tank after a collision. It has nothing to do with a vehicle sitting unused in a garage. And note that the conclusion is that such a leak is not particularly dangerous.

Oop’s Try this one;-

“Permeation from compressed gaseous hydrogen storage systems is a current hydrogen safety topic relevant to regulatory and standardisation activities at both global and regional levels.”

“Permeation in the context of CGH2storage systems may be defined as “molecular diffusion through the walls or interstices of a container vessel, piping or interface material”
 
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robunos

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TomS

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That's a study on what happens with a leaking hydrogen tank after a collision. It has nothing to do with a vehicle sitting unused in a garage. And note that the conclusion is that such a leak is not particularly dangerous.

Oop’s Try this one;-

“Permeation from compressed gaseous hydrogen storage systems is a current hydrogen safety topic relevant to regulatory and standardisation activities at both global and regional levels.”

“Permeation in the context of CGH2storage systems may be defined as “molecular diffusion through the walls or interstices of a container vessel, piping or interface material”

Ok. But reading through it, it sounds like known materials achieve permeation rates below the threshold considered safe under the terms of the study. And those levels are certainly not of the scale to empty a vehicle's hydrogen tank in a week or blow up a garage.
 

Richard N

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This video was made in 2018. Electric car range and installed infrastructure have increased considerably since then. Can any hydrogen proponent point you to the location of the nearest hydrogen fillup station? I've never seen one hydrogen station but electric charging stations are everywhere. Much electric infrastructure already exists and it is much cheaper to move and store electricity than will ever be for hydrogen.

Electric powered planes are in their infancy and are practical for short duration flights like Harbour Air's air taxi service.


 

CJGibson

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I have spawned a monster...

Ironically, Aberdeen has two H2 filling stations.

JCB (who bought Boris' favourite bus maker) hope to develop H2 powered buses, trucks and trains.

Chris
 

Schneiderman

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25 years ago Iceland was looking at the possibility of becoming the world's first hydrogen economy. A small population and an abundance of geothermal/hydro electricity generating capacity made H2 manufacture as cheap as feasible. They were exploring a possible partnership with a car manufacturer and oil company, maybe others. No idea when that initiative faded away.
 

nuuumannn

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Errare humanum est, sed perseverare diabolicum"

The one thing that has always raised my curiosity is how they found out that goldbeater's skin was impermeable to hydrogen.

Out of interest, airship gas cells used to be made of sheets of goldbeater's skin, which was the lining of the stomach of an ox, named the caecum (and used by book binders for making gold leaf, hence it's name). It also had a habit of continuing to 'grow' once stitched together in sheets to form the cells. A single rigid airship, taking the dimensions of a typical wartime German Zeppelin, an 'r' Class like L 33 for example of around 690 ft, with a 92ft diameter contained around 19 gas cells within, made of goldbeater's skins stitched together and lined with rubberised cotton.

Airship manufacturers had their own farms, primarily because to build a single rigid airship, in this example I'm quoting the British airship R.34 that was the same dimensions as L 33, the Beardmore airship works at Inchinnan required the skins from some 600,000 animals. Hydrogen was manufactured at the point of operation; the major airship bases all had hydrogen processing plants, with piping that led from the storage tanks directly to the hangars so the airships could be topped up in situ.
 

Hobbes

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Regarding hydrogen diffusion, this may offer a solution . .


That article calls it a 'breakthrough'. This class of material is called a 'metal hydride', and metal hydrides have been known for a long time. Mercedes had a car running on hydrogen that used a MH tank in the early 1980s. The problem was, the tank cost $100k. It looks like they've found a new material that will function as a metal hydride.
 

CNH

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Are hydrogen cars likely to blow up your garage?

Probably not. Very many years ago, I spent my fourth year at university working on a project which involved cooling an infrared transparent window to 20 K. This was done by means of hydrogen: a day's experiment involves the use of quite a large cylinder (about 5 foot tall) filled with hydrogen at some rather high pressure. The hydrogen would first be pre-cooled with liquid nitrogen before being allowed to expand and therefore cool further. After about an hour of this, the infrared window would reach 20 K.

What did we do with the hydrogen once it had been expanded and cooled? There was a tube which ran out to the window. That was it. During the course of the day's experiment, a full cylinder of hydrogen would be vented to the air outside. I looked at this, and asked, what's the chance of this blowing up? The answer I was given is that concentration of hydrogen in the air had to be greater than 4% in order for it to ignite. There's an article about it here:
https://en.wikipedia.org/wiki/Hydrogen_safety

The other problem is that if the system springs a leak, and the hydrogen is ignited, the flame is totally colourless (no incandescent articles of carbon). This can also be a hazard since you can't see it.

At the moment, hydrogen powered cars are something of a rarity:
https://en.wikipedia.org/wiki/Hydrogen_vehicle

PS – sorry Chris, for feeding your monster, but in this, the year of the plague, there's not a lot else to do.
 

Grey Havoc

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PS – sorry Chris, for feeding your monster, but in this, the year of the plague, there's not a lot else to do.

sometimes you gotta feed the beast


(Found here)
 

Hobbes

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Are hydrogen cars likely to blow up your garage?

Probably not. Very many years ago, I spent my fourth year at university working on a project which involved cooling an infrared transparent window to 20 K. This was done by means of hydrogen: a day's experiment involves the use of quite a large cylinder (about 5 foot tall) filled with hydrogen at some rather high pressure. The hydrogen would first be pre-cooled with liquid nitrogen before being allowed to expand and therefore cool further. After about an hour of this, the infrared window would reach 20 K.

What did we do with the hydrogen once it had been expanded and cooled? There was a tube which ran out to the window.

You see the difference, though? Venting hydrogen into open air vs. a leak in a closed garage?
 

Zoo Tycoon

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But you’re sure you’re garage is the same as every other that can contain a car?

A tank certified to SAE J2579: 01 2009 may leak 216 litres a day;- I reckon just few litres of H2 mixed at stoichiometric optimum will take a garage roof clean off.

This quarantine is getting tough....
 
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Arjen

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Consider the fire hazard posed by the comparatively flimsy gasoline tank in most conventionally powered cars.
 

TomS

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That's a study on what happens with a leaking hydrogen tank after a collision. It has nothing to do with a vehicle sitting unused in a garage. And note that the conclusion is that such a leak is not particularly dangerous.

Oop’s Try this one;-

“Permeation from compressed gaseous hydrogen storage systems is a current hydrogen safety topic relevant to regulatory and standardisation activities at both global and regional levels.”

“Permeation in the context of CGH2storage systems may be defined as “molecular diffusion through the walls or interstices of a container vessel, piping or interface material”

Right. I'm no denying that permeation is a thing that happens with hydrogen. It's a slippery little molecule, for sure. But the paper here walks through the methodology used by the HySafe organization to determine the maximum acceptable permeability of hydrogen tanks in vehicles and appears to conclude that those standards are reasonable, based on a really low rate of air change in residential garages. Given that commercial hydrogen vehicle makers like Toyota and Honda are members of HySafe, it seems certain that their vehicles comply with this standard. Do we think Toyota's legal department would allow Mirai (for example) on the roads if its hydrogen storage did not comply with the standards set out by HySafe?

It's worth noting that hydrogen embrittlement isn't an issue (in Mirai at least) because the tanks are not metallic -- the tank has a carbon-fiber resin overwrap and a polyamide (nylon) liner reported to have an order of magnitude less permeability than HDPE, the previous standard for non-metallic hydrogen tank liners.
 

riggerrob

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When you talk about "blowing up" an enclosed garage, are you talking about "inflating" or "exploding."

Most residential garages are deliberately "porous" to allow a variety of petro-chemical fumes to vent before they reach toxic levels.

OTOH One person sneaking into the garage for a quick "smoke" could ignite a hydrogen explosion.
 

martinbayer

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Can any hydrogen proponent point you to the location of the nearest hydrogen fillup station?

For my neck of the woods, a map of hydrogen stations (which, at least in case of the nearest one to our house [2.5 miles away, but of course your mileage may quite literally vary :)] that I visited out of curiosity, is colocated with a regular gas station) is for example provided at https://cafcp.org/stationmap.
 
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CNH

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Out of curiosity, what kind of range does the average hydrogen car have?
 

TomS

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Out of curiosity, what kind of range does the average hydrogen car have?

The Toyota Mirai, Honda Clarity, and Hyundai Nexo are offering ranges of 310, 360, and 380 miles, respectively. I know gasoline cars that won't go that far on a tank, but hydrogen clearly demands more attention to route planning at the moment, given the limited refill sites.
 

Desertfox

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A leaking gasoline tank is a lot more dangerous than a leaking hydrogen tank. Gasoline tends to pool underneath the car and vapors can easily mix with the air, which is why its used in the movie industry for all those nice Michael Bay explosions. Hydrogen being lighter than air will rise and tends to diffuse making it hard to reach the right concentrations to explode. Also a hydrogen fireball will rise as seen in the Hindenburg disaster (which saved a lot of the passengers and crew) while a gasoline fireball will stick close to the ground. As far as safety goes, I'll take a hydrogen car over a gasoline car any day.

BTW the Hydrogen disaster was primarily caused by its incredibly flammable skin (akin to thermite) more than its hydrogen filled bladders.
 

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