Submitted by Hypx t3_10mdti7 in Futurology
Angry_Washing_Bear t1_j62k22j wrote
And what happens if this is exposed to a fire, collision or similar?
Issue with hydrogen is and always will be the potential magnitude of consequences linked to failures and/or accidents.
An electric or fossil fuel vehicle is just going to burn down in a rather controlled manner. Not so with a vehicle running compressed gas.
The potential damage this can cause, especially in traffic, near housing and similar is massive. And if you have multiple of these vehicles then what is the potential for chain reactions?
ttystikk t1_j62pqwm wrote
I've seen explosion events in propane powered cars in video, and those were just a barbeque tank or so in size.
There are a lot of reasons why hydrogen isn't a good transportation fuel and we can throw this one on the pile.
Angry_Washing_Bear t1_j62qal8 wrote
I can see its use in shipping since any accident on a ship, while catastrophic, is at least somewhat isolated and contained as opposed to vehicles in dense traffic, parking garages, near residential homes etc.
ttystikk t1_j62r6ry wrote
Electric cars are just better and they are still improving rapidly.
IGetNakedAtParties t1_j62x1dp wrote
That's kind of the missed point when comparisons are made, batteries are advancing according to their own (lower) version of Moore's law, energy density has tripled over the last decade. And more importantly the prices are obliging Wright's Law, coming down in relation to production volume. The physical limits of known technology are still 3x away.
Hydrogen is limited by physics already, with only small improvements in efficiency available.
Hypx OP t1_j6360qt wrote
Except that hydrogen just gained 80% more energy density right now. You should read the article.
In fact, it has already exceeded the theoretical limits of any conventional battery chemistry. So in some sense the war is already over on this subject.
IGetNakedAtParties t1_j63arkg wrote
In the case of cars and road haulage it's not necessary as current energy density of batteries is already practically sufficient. The total system energy efficiency of batteries is significantly better they hydrogen can ever be, and higher compression actually makes this worse source
This technology does have practical applications for ocean shipping, and possibly flights down the line (as the article points out) but often the focus is on personal vehicles as the article mainly focuses on. And this is my main criticism: most of the narrative around hydrogen is used to support the argument that "we should keep using petroleum for now as hydrogen is just around the corner" whilst ignoring the fact that BEV is already better than gas from a total cost of ownership perspective.
I can't claim that this article is connected with the oil industry or traditional auto, but as BMW have their majority of their profits from ICE and the publishing house is based in Detroit I can't help but question the intention of the publicity, independent of the value of the technology.
Basically, all research like this is valuable, but the narrative is often used against BEVs which I am suspicious and critical of.
Hypx OP t1_j63b76d wrote
Then why mention energy density if you ultimately don't think it matters? It will mean much lighter cars and more range. You should be suspicious of those who don't want those options.
IGetNakedAtParties t1_j63cm63 wrote
As I said, "more importantly costs are falling under Wright's Law" meaning energy density isn't much of a concern, but even if you believe it to be important it is still improving in BEVs.
The article is exclusively about energy density and doesn't mention the financial or energy costs of the cryogenics, energy density is important for practicality but cost is what will drive adoption.
Lighter and/or better range BEVs at better prices are inevitable: hydrogen lost this competition. My criticism is against the article's narrative that hydrogen is "just around the corner" for personal cars and road haulage, it cannot compete on price based on the physics involved.
Don't get me wrong, I'm happy that the technology is improving, hydrogen will likely have it's place in ocean shipping because of technology like this increasing energy density to practical levels. I'm not against hydrogen, I'm against hydrogen (stories) being used against BEVs by oil and ICE companies.
Hypx OP t1_j63csvv wrote
Cost would be a different subject. No one brought that up until you did just now.
Also, you should expect cost to come down for any technology. Especially one that is radically superior to what came before it.
IGetNakedAtParties t1_j63dm81 wrote
For sure costs will decline for both, but the physics of the supply chain will always give a cost benefit to batteries where they are practical. And we should not be waiting for anything as TCO of BEVs is already on par to ICE.
It's that which makes me critical of all "hydrogen cars" articles, I've yet to read one without a connection to the oil or ICE industry.
Hypx OP t1_j63f2ho wrote
Even after just now, after a 80% increase in energy density? You do realize that at this density, a few tanks the size of scuba tanks will easily get you 300 miles of range in a hydrogen car? Volume wise, it's basically the same as a gasoline tank in a conventional car. So pretty vast amounts of cost is coming out of that hydrogen car.
And yet you're so certain that this can't be cheaper...
IGetNakedAtParties t1_j63fcu1 wrote
Unless cryogenically liquifying hydrogen has a negative energy cost, yes. The physics doesn't make sense.
Hypx OP t1_j63fugu wrote
Are the batteries in your EV free in this example? We're talking about a hypothetical hydrogen car that is effectively identical to a conventional car in basic material needs.
Also, this is not liquid hydrogen. You should read the article.
IGetNakedAtParties t1_j63plkb wrote
OK, I'm interested in making this calculation, I'm happy to have my assumptions challenged.
As per my link, the efficiency of BEVs from source to wheel is 76%, the current same for hydrogen is 30%. This technology will likely make this worse for H2 in exchange for better practical applications, range, weight, etc.
If you want to compare a hypothetical H2 car against a real world BEV lets compare a Tesla Model Y against the best case H2.
Assumptions:
12 year vehicle lifetime
14 000 miles per year
0.0456 $ per mile (typical home charging)
0.1155 $ per mile (assuming the above relationship, this accounts for inflation in the comparison)
These numbers give us the cost of energy difference at $11 743 in favour of the BEV. Given that a replacement MY batters is $15 000 you are correct that the H2 is better economy than the BEV, however the BEV exists now, with a charging infrastructure, but the H2 vehicle does not. Also whilst H2 costs aren't likely to change much with economy of scale, this definitely isn't true of battery technology.
Basically my previous points stand, H2 is going to be important for some uses, but there is a danger that stories about it give the illusion that we don't need to stop using ICE now and switch to BEVs for personal vehicles for both environmental and economic reasons.
One can be pro BEV and pro H2 at the same time.
Hypx OP t1_j65d048 wrote
But no talked about what is better right now.
You're just making a big fuss while basically accepting my point.
IGetNakedAtParties t1_j65e6c0 wrote
Please don't manipulate what I say for your gain.
Hypx OP t1_j65efnj wrote
This is futurology. You're just being a jerk while missing the point.
maldobar4711 t1_j638ci3 wrote
You forget the potential of terroristic attacks..
I always shiver thinking about LNG ships now imagine hydrogen ships
TheAnonFeels t1_j63wjcx wrote
Years ago, and I thought this was hilarious. I watched a segment on hydrogen fuel for cars.. I'm talking 12 years + ago.
but they claimed it was 100% safe and unlike gasoline, a fire would just vent out of the hydrogen tank.. They demonstrated this on a open vehicle frame.. They talked about how it's safe since hydrogen fires burn straight up. So in their demonstration... the tank was UNDER THE DRIVER'S SEAT burning straight up.
Epic! o.o
Not sure if any of that was just a marketing claims, investment demo, etc but i found it funny.
Angry_Washing_Bear t1_j644e13 wrote
Bigger issue is when you have no vent and heat just builds up around the entire tank.
E.g. parking house fire, a fire on a packed ferry and similar.
TheAnonFeels t1_j645doc wrote
Definitely, just found it comical how even that was 'safe'
Even with a vent, its a serious issue.. where will the hydrogen go. But yes, without a vent you're gonna get a large over pressure event
Hypx OP t1_j62l7wj wrote
It will likely just vent out quickly. Any fire would be brief. Hydrogen is safer than gasoline in a fire because it does not stay in place very long.
Angry_Washing_Bear t1_j62ltst wrote
That’s the point.
It explodes rather than burn off.
Which makes the consequences much higher even if the risk is the same or lower.
Throughout the entire article not a word was mentioned about consequence and risk in the case of unforeseen failure or accidents. To me this seems deliberate because the consequences are massive.
Hypx OP t1_j62mb9n wrote
An explosion is unlikely. You need a very thorough mix of air and hydrogen for there to be an explosion. It is not likely to happen in a conventional accident.
Angry_Washing_Bear t1_j62pxc4 wrote
With the thousands of accidents happening on roads every year something can and will happen with hydrogen based vehicles whether as fuel, transported or both.
To not even offer a word about risk and consequences in an article seems disingenuous. Even if the risk is low the consequences are major.
What happens if there is a fire in a parking garage and you have multiple hydrogen vehicles now being exposed to extreme heat over a long time?
Instead of burning off you now have a risk of a major explosion causing far more damage than burnout from liquid fuels or batteries.
Why are these concerns always omitted when it comes to articles and discussions surrounding the commercialized use of hydrogen?
Hypx OP t1_j62u350 wrote
Liquid fuels are also pretty explosive. So are li-ion batteries. We are not in any more danger.
BoredCop t1_j63cgpz wrote
Liquid fuels are nowhere near as explosive as compressed hydrogen gas.
For one thing, hydrogen has much wider explosion limits than gasoline so explosions can happen in a wider range of fuel/air mixtures.
The main difference, however, is that liquids are liquid while compressed gasses are compressed gases. By which I mean, if you spill gasoline on the ground it merely forms a very non-explosive puddle and slowly evaporates. It's the mix of vapour and air that is potentially explosive. If you get a hydrogen leak, the pressure makes it rapidly expand and mix with air so you get nearly complete mixing with air almost instantly. A liquid leak just drips down under gravity. A compressed gas leak jets out at high velocity and turbulently mixes with air. Big, big difference in explosion hazard.
Hypx OP t1_j63d0et wrote
Liquid fuels are considered more dangerous because they burn in place. It is not just a "non-explosive puddle." It is a carpet of flames if it ignites. This is a very dangerous situation since it can trap someone in a car during a fire.
A gas, especially one that is much lighter than air, will quickly dissipate. It will have a much lower chance of fire and any fire that does happen will not stay in place. The danger is only during the moments when gas is leaking.
BoredCop t1_j63ejdy wrote
Tell me you've never responded to a fire, without telling me you've never responded to a fire.
I'm a cop, I have seen the immediate aftermath of many fires including ones that involve flammable liquids and gases. And I've been around many a wrecked car with gasoline leaking out. The only times on my watch that we've had real ka-Boom explosive fires involved pressurised gases, such as propane. Conversely, we've had arsonists intentionally starting fires with gasoline only to have the fire self extinguish after using up the available oxygen in a room.
A gas that completely mixes with air in a second or two is much more likely to ignite than a puddle of fuel on the ground. Especially so when the gas in question has a very wide range of ignitable fuel-air mixtures, as is the case for hydrogen.
Sure, the hydrogen fire will "not stay in place". Nice euphemism for "blow up the whole garage".
Hypx OP t1_j63g264 wrote
Hydrogen isn't propane FYI. It is a lighter than air gas. Propane is heavier than air.
BoredCop t1_j63k2ed wrote
I'm fully aware of that. Makes no difference to degree of risk, only to wether it will accumulate along the floor or along the ceiling in a garage or a tunnel.
There are reasons why an old name for hydrogen in some languages is "knallgass" or variants of same, it translates as "bang gas" and refers to its explosive tendencies.
There are reasons for why you're supposed to connect and disconnect the charger or jumper cables in a certain order when dealing with a car that has a flat lead-acid battery, and make the final connection to chassis ground away from the battery. Such batteries can create and leak hydrogen via electrolysis, and explosions are a known hazard. The act of connecting jumper cables can create enough of a spark to set it off, as many people have experienced.
Basically, the explosive hazard of hydrogen gas is well known and has been for over a century. Your claiming otherwise cannot change the facts.
Hypx OP t1_j63kvb5 wrote
And yet it is fact that it is safer than gasoline. This is not actually a debate here. People have set both on fire and gasoline is a lot more dangerous:
BoredCop t1_j63nx60 wrote
That first one is laughable, it is from a biased source and is intentionally rigged to produce the desired result. They present it as if the overpressure relief valve is the only probable leak point, and set it up to immediately ignite before any real volume of gas has time to mix with air. It's like lighting a gas range in a kitchen immediately after opening the valve, and claiming this proves it would be safe to let gas leak out for half an hour and then light a match in the same kitchen. Of course you get no explosion when you carefully make sure the conditions needed for an explosion don't occur, by igniting immediately at the leakage site.
The second one is more interesting. Here, they do in fact allow the gas to mix with air for a few seconds before ignition. However, these tests used liquid hydrogen at a much lower temperature than the gaseous phase cold compressed hydrogen we are discussing here. Liquid hydrogen is seriously cold, and only boils off to gas phase at a slow rate depending on how much heat energy it can absorb from the surroundings. In that sense liquid hydrogen it is rather similar to liquid gasoline; it's the gas that burns not the liquid. You'll note none of the spill experiments in that video involved pressure vessels rupturing or pressurised fuel lines breaking, it was all liquid hydrogen at atmospheric pressure. That makes a huge difference in how rapidly it mixes with air. The very low temperature also slows down the reaction when it is ignited, compared to igniting gas that's a hundred degrees warmer.
DonQuixBalls t1_j62xibj wrote
Bro. It's a no.
TheAnonFeels t1_j63xoe5 wrote
Sure, hydrogen can dissipate quickly..
It can also ignite faster. Fill the area around or in a car in under a second, it wont dissipate fast enough.. You could argue it would dissipate oxygen too, but it'll already get mixed with the air before that happens. All it takes is a ignition point before the gas can dissipate, and there would be no fire, because there would be no car left.
Hypx OP t1_j65ckam wrote
It's lighter than air. It won't stay very long. And no, that's not how a hydrogen flame would work.
TheAnonFeels t1_j65kgay wrote
Video 1: That's like one i commented earlier, where it burns straight up from under the driver seat, thanks for the laugh again.
Anyway, video 1: That's only if it's ignited as it vents, they didn't give the gas time to vent without a flame cause...explosion.
Video 2: Most of these are Liquid hydrogen which acts much more safe than gaseous hydrogen as countless people have pointed out.
If you can, point me to a segment that is gaseous hydrogen.
For clarity, yet again, liquid hydrogen stays liquid until i can get enough heat to vaporize. Also, because of that, it doesn't mix with air well.
We don't drive hydrogen cars with liquid hydrogen, its difficult to work with, being cryo.
Brings me to the part of Video 2 where they show what happens when hydrogen mixes with air: https://youtu.be/7bFJK5kU_UQ?t=443
TheAnonFeels t1_j65m1qt wrote
Here's a balloon full of hydrogen in a cardboard box, gaseous.
Hypx OP t1_j65mak5 wrote
It most likely won’t ignite at all even when vented. There needs to be an ignition source. In most cases, the hydrogen just dissipates completely.
You’re simply ignoring the other side of the video: What happens when a gasoline cars catches on fire. That is significantly more dangerous. And we already accept that danger. It’s pointless to fearmonger about something less dangerous.
TheAnonFeels t1_j65o4cp wrote
I'm not fear mongering but you're ignoring the other side too... I'm ignoring the gasoline cars because we're all accustomed to it.
What do you mean most likely wont ignite?????? Hydrogen is the single most dangerous gaseous atom we have.
Ignition source? crashes are full of them, what about the gasoline fire from the car that hit you? Or the time you open kick your door open and it scrapes the pavement making a spark? roads, garages, and crashes are full of ignition sources..
I just see us having a car sitting in a garage overnight, and a switch turns on, or a natural gas furnace kicks on and the building is gone.
I'm all for the attempt at hydrogen vehicles, but i don't see it as a fix all. I wouldn't drive one, hell i dislike my gasoline powered car. But you gotta accept that hydrogen can ignite after mixing. That balloon video ignited after mixing, how do you think a ruptured tank is going to look?
Hypx OP t1_j65ovnu wrote
You still need an ignition source for a fire. Not to mention how fast it leaves the vehicle. It also doesn’t explode. You are basically ignoring the videos and substituting your own imagination here.
A balloon isn’t a fuel tank. It is already premixed with air. Even sugar will explode in the right setting.
Again, it is safer than gasoline. This is not a debate anymore. The evidence already made this clear.
TheAnonFeels t1_j65q39q wrote
Did you not read my responses to those videos? about how they're all LIQUID hydrogen? Which is completely different...
We have 15k hydrogen vehicles on the road, yes. And their tanks can withstand the harshest impacts. I get this. I get their safer, but the catastrophic failures of gasoline vs hydrogen are completely different. And these will happen. Hydrogen is the leakiest material we have, and ever will have.
My only point through ALL of this, has been about how you keep talking about liquid nitrogen and don't understand the difference.
It doesn't explode?!
Hydrogen can explode.
Wanted to drop some stats before you stopped listening, but here they are anyway.
Gasoline flamability limits in sea level atmosphere: 1.4%-7.6% (cannot ignite outside that)
Hydrogen: 4%-75%
Detonability of hydrogen in air are 18.3% to 59% by volume.
Hypx OP t1_j65qi2x wrote
Again, you need an ignition source. And for an explosion you need a proper fuel mix. In reality, it will just float away immediately in most cases. A fire would hardly be dangerous compared to what a gasoline fire looks like. You're entirely ignoring actual data.
Like I said, you are just fearmongering. You already are in more danger driving a regular car.
TheAnonFeels t1_j65r41w wrote
dude, really.. Stop for a second.. A proper fuel mix?
Detonability of hydrogen in air are 18.3% to 59% by volume. There's the fuel mix for an detonation. Explosion is 4% to 75% ...
You're ignoring my entire comment.
Hypx OP t1_j65re8i wrote
And it's all just bullshit. Hydrogen is lighter than air. It doesn't have time to stay mixed. It's literally what they showed in the video.
Like I said, you are substituting reality with your own imagination here.
TheAnonFeels t1_j65s3op wrote
I've said multiple times that's liquid hydrogen.
My own imagination here is that i can convince you my only point here was telling you hydrogen COULD ignite...
Not saying hydrogen cars are more dangerous or less.
Not saying gasoline is safer.
I've only given you facts about hydrogen and how it could possibly ignite in a crash, you keep denying time and time again. Because of those videos, which again, were liquid nitrogen, the only gaseous hydrogen they showed was in a ball tank that..exploded.
Listen, i don't care what is safer, i feel its too early to tell, and so far they're doing great. I'm waiting for when the rare event happens that levels peoples homes comes up. Until this conversation i was under the impression that no way would people park these in garages but that opinion has changed.
Hypx OP t1_j65tes6 wrote
If you are admitting that gasoline is not safer, then what's the point of this conversation?
TheAnonFeels t1_j65tzxh wrote
Not admitting anything is safer...(Last paragraph of latest comment, if you forgot already)
The point?
- My own imagination here is that i can convince you my only point here was telling you hydrogen COULD ignite...
idek what to say anymore.. You literally aren't comprehending anything i type, even just conversational statements... This is so difficult to repeat myself and now I learn you still don't know my point...
I honestly wish, I wish so hard, my brain was like yours. Life would be easy.
Hypx OP t1_j65und1 wrote
Then your posts are total gibberish. You are trying to say something while admitting that you aren't trying to make a point at all.
There is nothing to comprehend in your posts. It's just word spam.
TheAnonFeels t1_j65ve6x wrote
>Then your posts are total gibberish.
Is it that hard to understand?
The comment I first made, was only talking about ignition, you keep telling me i'm against hydrogen cars.. I keep going back to informing you hydrogen can ignite, and dangerously.
I see where you got confused.. You thought i was conflicting with your world image.
Hypx OP t1_j65vug4 wrote
Which is stuff I admitted from the very first post. Yes, it can ignite. With an ignition source. Yes, it is dangerous, but less so than gasoline.
But of course you went off with multiple posts of pure spam and fearmongering before admitting that there is no real danger.
You're plainly trolling at this point. Time to stop and move on.
TheAnonFeels t1_j65xrbn wrote
Sorry we couldn't have an actual conversation but seems you don't know how.
BoredCop t1_j63bqup wrote
Explosions have already happened in hydrogen refueling stations.
Hypx OP t1_j63bua7 wrote
You mean fires, not explosions. Also, many things have exploded or caught on fire. Including existing gas stations.
BoredCop t1_j63ddkn wrote
Nope, I mean explosions. A chain of hydrogen stations in Norway got temporarily shut down for safety reasons after one exploded in 2019, that's the one I could find info on quickly.
Hypx OP t1_j63dwrf wrote
You one caught on fire? These things aren't report very accurately.
BoredCop t1_j63ivq7 wrote
Exploded. Pictures in media show parts of the station that got thrown some considerable distance by the blast. Investigative reports also call it an explosion.
Hypx OP t1_j63kn89 wrote
Fires can have pressure waves, but that is not an explosion. And if you do call it an explosion, than there are thousands of gasoline explosions all time.
BoredCop t1_j63l199 wrote
Are you conflating the terms explosion and detonation? Because you can absolutely have the former without the latter. When a mix of fuel and air between the lower and upper explosion limits for that fuel ignites, you get an explosion. Not all explosions are high order detonations.
Hypx OP t1_j63lfp9 wrote
Explosions technically imply detonation. But if you are going to call all big fires explosions, then gasoline explodes too. You cannot have it both ways.
Anyways, it's already proven that hydrogen is safer than gasoline because people have actually set them on fire before. You're just fearmongering on this.
BoredCop t1_j63oahs wrote
You might wish to read up on the definition of "explosion". And I've already commented on those videos.
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