Airbus eyes hydrogen power for airliner in next decade
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UAV compressed hydrogen tank systems with fuel cells in the 800-1600W range, the full system with tank, fuel cell and a small buffer battery works out to between 800-1200Wh/kg depending on size. Some guys in south Korea recently hovered a large hexacopter for 10.5 hours. The systems I've seen are typically configured for an output voltage equivalent to the float voltage of a 12S lipo.
Diesel fuel, jet a, avgas and other fuels are a whole magnitude more dense in Wh/kg stored than the above-mentioned hydrogen system.
Hydrogen is challenging/expensive to store/contain. Kind of the direct result of it being the smallest atom we have. Even more important: when it reacts uncontrolled, in particular with oxygen, it does so at a truly frightening speed. Once it goes, good luck doing anything about it.
The fact that this is almost never mentioned in every yet-another-hydrogen-is-going-to-be-our-future-next-year piece, always makes me wonder if that's the result of not-so-honest entrepreneurs trying to lure investors, or that none of these jokers ever talked to any experienced chemist.
This is no attempt to spread FUD regarding hydrogen. It sincerely worries (if not frightens) me, how so many initiatives appear to completely ignore that any volume of hydrogen that is sufficient to power something that can transport humans or cargo, is pretty much inherently a catastrophic disaster in the making. That is, if such a system would ever fail in a way that makes the stored hydrogen react uncontrolled.
Every widely utilized technology is bound to fails, even if only in edge cases, and of course: extra safety margins/features can be added to limit the effects of failures. But with hydrogen that might be a hell of a lot more expensive and/or difficult than most would realize.
So, the way I see this is that we either end up very cost ineffective solutions, or ones that will be far more dangerous than many would ever realize. That is, until something goes terribly wrong, and everyone realizes they have been ignorant and maybe even intentionally fooled by people trying to make money. Reminds me a bit of self-driving cars.
Hydrogen is a great rocket fuel because its specific impulse is second to none, so why isn't it universally used? Because even by rocket fuel standards it's a bugger to work with.
There are lots of things that react poorly to being set on fire. That doesn't make them all equally dangerous.
I think you are overestimating the difficulty of dealing with embrittlement. Many materials don't suffer from embrittlement at all, and others (like aluminum) only suffer at high temperatures.
Edit: I also wanted to add to the person who made the claim "kerosene burns, hydrogen explodes" that kerosone can explode too, and it obviously is possible to handle hydrogen in a way that explosion is unlikely or it wouldn't be used as rocket fuel (where it is literally combusted with oxygen... combusted, not exploded). I agree that hydrogen is more dangerous than kerosene, but it's not like kerosene is that safe either and the question is whether you can create good enough processes around the storage and handling of hydrogen to offset the risk.
Isn't it also in contact with everything around the tank on account on there being basically nothing which is completely impermeable to hydrogen?
It's exactly this difference that makes them relatively safe to use and even still relatively controllable once something goes wrong. With hydrogen, you simply won't get that change. It will be all over in a blink. A very hot and bright one, I might add.
Feel free to believe whatever you want, you have every right. But I'm rather sure that your optimism regarding hydrogen is more rooted in ignorance than in knowledge.
You have made some great points about hydrogen. But personal insults like that don't help you get your message across.
I'm actually not as much of an optimist on hydrogen as you seem to think. I think it is unlikely to be used in aviation in any real sense, for a variety of reasons, some having to do with safety, others with performance. However, I think it is worth investigating, and I do not think the problems around it are insurmountable from an engineering perspective.
Thought then I'm sincerely even more surprised you would say that any fuel tank on fire is a (relatively) equal problem.
As for hydrogen rapidly escaping and going straight up because of its low density, those properties I would only consider positive in scenarios where the hydrogen isn't reacting (being on fire, to be more precise). When on fire, quite the opposite. Buildup of heat on the ground might still be less of a problem than with heavier fuels (which indeed is a very real problem with those), but not much advantage of that once everything within a certain radius is reduced to the size of matchsticks by a powerful explosion.
But if you claim to be (some sort of) an expert, I'll believe you. I certainly am not, that much I admit.
I only based my opinion on what I've been told by chemists that I personally trust. They told me rather invariably that the engineering challenges for storing/operating hydrogen are such a bitch, that they are ultimately only a good for when you want something closely resembling a bomb, without actually being one (or just hoping it won't explode before it served its purpose). Like e.g. rocket engines.
The engineering problems obviously aren't large enough to prevent something like the Tu-155 from using liquid hydrogen. Whether it can ultimately made as safe as conventional aircraft, I don't know. Maybe not. Either way, I don't think the economics are favorable for hydrogen.
However, proof of their existence isn't proof of their safety. I have no doubt that they are (mostly) safe, even in almost every imaginable accident. However, it's the (unforeseen) edge cases that worry me. Not because of how often they might happen, but because of how bad the consequences could be when things go wrong.
It's a real bummer when whole a housing block gets wiped of the map, because one eccentric/rich guy just had to do something "for the environment" (#sarcasm).
From what I read, this car has storage capacity of 5 kg of pressurized hydrogen. I've seen similar storage tanks, and I have been amazed about how resistant they are to puncturing and tearing forces. Unlikely that any direct impact collusion would destroy one of these. But then there is always some corner case that it wasn't designed for. I certainly would not like to be even remotely around it, when 5 kg of pressurized hydrogen goes up in flames.
As hopefully every engineer knows, catastrophic failure is almost always a cascade of smaller compounding failures. Disrupt that chain-reaction and a catastrophe is usually averted.
However, with hydrogen the opportunity/window for that is often extremely short, with extreme consequences as a result. Not quite what you might call an optimal combination of factors.
Technically we could drive cars on nuclear reactors.
I am not sure I want to see the average untrained person handling a precision refueling apparatus that connects to a tank at 250 to 700 bar pressure. It's a lot more complicated and technical of an interconnect to refuel compared to just sticking a petrol station nozzle into a tank and pumping.
I don't think a system that requires a professional refueler staff person at every hydrogen fueling station is a good idea either.
For comparison 7 bar is about the same as 100 psi for Americans.
Also, if you're thinking of pressurized gaseous hydrogen instead of liquid hydrogen, then the tanks get really heavy because high pressure tanks don't scale well (unlike low pressure liquid tanks which do). Hoop stress is proportional to diameter, which means tank wall thickness needs to grow with diameter too. https://www.engineersedge.com/material_science/hoop-stress.h...
https://en.wikipedia.org/wiki/Delta_IV_Heavy
It is a very expensive vehicle though.
They didn't say how they would be using the hydrogen. I haven't been able to find it again, I did read about an article about a long endurance (days), high flying plane. It was powered by hydrogen. It burnt it. As I recall it was in an ICE, but at 50% efficiency using it as jet engine fuel isn't such a bad idea. It has an energy density of 120 MJ/kg, 3 times as much as normal fuels so it makes sense either way, if you can contain it.
In other news, the country where I live (Australia, 6th largest exporter in 2019) is contemplating exporting hydrogen. Why? Because if renewable power continues on its current price trend it will be cheaper to produce hydrogen than it is to mine the natural gas we currently export. Again, I presume no fancy technology - it will be burnt just like the natural gas is.
https://www.youtube.com/c/DoosanMobilityInnovation
There is more than one south Korean company working on combined packages of lightweight hydrogen tanks and fuel cell power systems. And several American companies.
There is an ongoing project [1] by US NAVY to turn seawater into jet fuel. This way we would not need to burn fossil fuels and would not need to throw away much of existing aviation technology.
[1] https://www.eurekalert.org/pub_releases/2020-07/uor-lch07152...
H2O, CO2, energy -> fuel
Water is free [1], Carbon Dioxide is free [2]. Energy is never free.
You need some big solar panels or a nuclear reactor to get the energy. (Can you put a wind turbine in a ship?) (The usual trick of burning fuel to produce energy is not a good idea here.) So this kind of process should not be interpreted as "water -> fuel" but like "energy -> fuel".
It can be useful to store energy for a while, or producing fuel using a nuclear reactor in the carrier and using the fuel in the planes. (I'm not sure that this is economical or tactically a good idea.)
If the idea is to produce the fuel on land, it is much more efficient to sell the energy and buy fuel. The energy you sell will cause a electric plant that use carbon to close and the net effect will be bigger reduction of the CO2 level.
From the article:
> Laboratory team led by Heather Willauer announced it had used a catalytic converter to extract carbon dioxide and hydrogen from seawater and then converted the gases into liquid hydrocarbons at a 92 percent efficiency rate.
I really doubt this. Organic reactions have a horrible low efficiency, specially the ones that create complex molecules using simple ones. (Perhaps the 92% efficiency is counting how many of the CO2 are converted, but the most important part of this reaction is the energy. If it convert the 92% of the CO2, but it stores only the 1% of the energy, it is very wasteful.)
[1] Processing water to avoid the problems with salt and tartar may be a big problem, so it may not be so easy.
[2] But the concentration is usually low, that is generally bad for fast and efficient reactions.
The chemistry and chemical engineering problems you point out are the major hangups.
On the other hand, doesn't this incentivize carbon capture by making the cost of energy storage just energy?
More generally, either hydrogen or fuel synthesis requires energy to come from somewhere; In this regard it is no different than re-building airplanes to use hydrogen, as the original article suggests.
The point is that we might have better chances synthesising fuels usable in existing planes, versus re-building majority of aviation to use hydrogen.
Jet fuel is safe to handle, the infrastructure is there, it doesn’t go all Hindenburg in a crash, and it doesn’t require new engines.
What we need in the next decade is a better jet fuel.
If commercial flights all used 50/50 renewable fuel that would cut greenhouse emissions in half. Providing that much biofuel without disrupting food production or fresh water supply will require a moonshot effort but it still seems like a simple obstacle compared to replacing fleets with electric or hydrogen powered aircraft.
Airline emissions aren't that bad compared with everything else, but they aren't being decarbonised at the same rate like everything else, and on top of that they are growing dramatically.
In 2019 there were 4.5b passengers globally. In 2006 there were 2.25 passengers globally, so doubled in 13 years. Planes are slightly more efficient now, but there's a long tail of less efficient planes.
Moving to 50:50 biofuel may save a decade of growth, but it's not a silver bullet.
Production of LH2 from cheap solar- and wind-generated electric power and water, right at the airport, will make aviation the most practical place to start using hydrogen as a fuel. Maybe auxiliary LOX tankage could help reach cruise altitude more quickly, or enable flying higher, so as not to waste the oxygen by-product.
(a) H2 is energy-dense but not mass-dense,
(b) wing tanks are not a practical place to carry LH2,
(c) LH2 tankage would rely on recent improvements in insulation,
it makes me wonder what you think this comment adds to the discussion.
gasoline: 45.8 MJ/kg hydrogen: 120 MJ/kg
What about safety? I visited the Zeppelin museum in Friedrichshafen last week...
Wouldn't it be nice if turning CO2 into gasoline would enable us to re-use tall the existing infrastructure?
AFAIK liquid hydrogen tanks are orders of magnitude safer (as in “a totally different problem”).
- Liquid hydrogen is so cold that many metals weaken
- Exposure to hydrogen itself weakens many metals (hydrogen embrittlement)
- Liquid hydrogen expands rapidly if exposed to heat, so venting is needed
- Hydrogen leaks through the smallest of seams
Now imagine trying to build a tank that prevents all that from happening, and it has to be lightweight for usage on spacecraft / aircraft.
In french we differenciate "batterie" and "pile", "pile" are one use, but I thought due to the name that the hydrogen cell would store energy.
Furthermore, the flames seen in the film were from kerosine fuel. All the hydrogen released went up, up, up. It is quite difficult to ignite hydrogen at atmospheric pressure; it requires oxygen mixed in a narrow range of partial pressures.
So, no, safety of H2 fuel is not a problem.
Aviation accounts for just 2% of CO2 emissions. While it’s good that Airbus is considering alternative, greener fuels, because aviation will continue to grow, there are larger determinants of GHG emissions and warming.
Also, how you even certify use of hydrogen on an aircraft will be a challenge. The current design for fuel has been well-understood for seventy-five years now, and like the rest of aviation some improvements have unfortunately but unavoidably come from tragedy (see TWA 800). You can throw a match into Jet-A and it won’t catch fire. Throw a match into a flask of hydrogen and you have a fire or explosion.
In addition, it seems to me that the discussion around nation level changes has become focused on a developed nations vs developing nations issue, when in reality it's all of our issues.
This 'attention shift', it's similar to the way the plastic/oil industry successfully instilled recycling as a way to get us thinking we're doing something useful, while the larger goal was to keep plastic bans at bay [1]
This trick plays itself out in other spheres; recently in the UK we would have people "clapping for the NHS". They would stand outside their doors and clap or bang pots/pans together. Very few of us wrote to our MPs asking for better working conditions and better pay. Anyway, just last week, our government voted against protecting the NHS from a post-Brexit trade deal.
1: https://www.npr.org/2020/03/31/822597631/plastic-wars-three-...
This is based on the blindingly obvious maxim that if you want more of something, subsidize it. If you want less, tax it.
And by taxing pollution instead of regulating it, you generate revenue for the government.
People in the us accept that the price of fuel goes up and down but they are the only ones. In other countries people riot when the cost of fuel goes up.
Many people have a lot of fear that tradable emission permits are an Enron-style scam that will suck money out of our pockets into somebody's pocket who will recycle 1% of profits back to politicians to maintain their privilege.
What we need to is either ban certain uses of fossil fuels or introduce an energy source that is so superior that people don't want to use fossil fuels. The latter is hard but doesn't violate the laws of physics, but any other kind of Collective action on climate violates the laws of social physics which are absolute for N > 10^9.
When it comes to industrial stuff, that's what you just work with industry to generate mandates that everyone has to follow. Manufacturing managers I talk to say they don't mind mandates. They just don't want to the be the sucker. As in Gallant installs $5 worth of emissions controls. Gooffus ships the factory to Indonesia and bribes government officials to look the other way.
https://www.europarl.europa.eu/news/en/headlines/society/201...
Only source of CO2 that has relatively grown for the past two decades.
> they do, but the substantiality of that depends on where you live
This is true but misleading: yes if your electricity is produced by coal plants electric cars are just slightly better CO2-wise (but cleaner on NOx and other sources of pollution), but the idea is to move away from coal so that running your EV become cleaner over time. (1)
A striking example is the UK, this chart tells the story of coal to renewables:
https://www.theguardian.com/business/2020/jun/09/great-brita...
(1) and as a consumer in most countries you can vote with your money by choosing to buy electricity coming from renewables.
However, I totally agree that the focus should be on those heavy polluting industries. I don't believe it's evil for humans to want to live the lives they do, with the technology we've created, and I also don't think we can change enough people to ever make a dent in those consumption requirements. Better to fix the issue more efficiently, at the source of the pollution, by switching heavily polluting industry out for greener alternatives, as the input into the consumption machine.
The size of needed changes and consumers limited agency makes anything but coordinated society wide action a worthless endeavor.
Perhaps you could come to some sort of conclusion about why we should start the switch to EV’s now?
When it comes to environmental consequences aviation is a growth business, the most important thing we can do is address the 737-class airplanes that people ride in, not the widebody airplanes that are advertised in magazines. Too often ideas like blended wing body, hybrid, and hydrogen are used as excuses to delay a 737 replacement. We've been watching this movie for decades but these is enough $$$ going to the media and politicians and nothing will replace the 737 until the Chinese do it with to the C919 and then all the people who brought you this disaster will say they were blindsided. They get blindsided every time because that's what they do.
Yeah, well, we all know jet fuel burns very well and that's why it's so useful. Fire is the worst crisis on an airliner.
https://www.youtube.com/watch?v=7nL10C7FSbE
It takes a spray nozzle atomizing it for him to actually meaningfully burn it with a blowtorch.
Not because of jet fuel.
Agreed. This is why, despite being an active member in the sustainable movement for nearly 18 years now, I've never once felt 'ashamed' due to my travels all over the World and will continue to do so. The model shows that unsustainable living habits, particularly those of waste and uncaptured value due to loss in these network,s are the real glut of not just CO2 emissions, but also of CH4 and other more harmful GH gasses.
If anything Travel, not to be mistaken with tourism, can open your eyes to seeing your Fellow Human as you see yourself as you interact and briefly and live as he does and in turn walk away with a Global sense of Community and an understanding that cannot be conveyed in books, TV or movies. I think it's why despite my 'radical thinking' I sincerely feel that the ICE based model for airplanes, and rockets will likely always remain. We should strive for constant refinement, not scrapping it since it accounts for so little of total GH emissions and can have a high ROI.
> These are pervasive beliefs among environmentalists. Meanwhile very little attention is paid to corporate and nation level changes.
No, its just not enforced up on by Nation States, as they often have strong incentives to keep things as they are, the environmentalists (I'm one) have been pushing for corporations to be held accountable for eco-cide [1], and be held accountable for all the costs it has and will incur, which in turn could help fund the remediation of those sites.
> The best thing you can do for the environment is vote. This feels counterproductive but it's entirely true.
No, entirely false, for the reasons listed above. The best you can do is think Globally and act locally about the problem. That is begin to get active in these matters in your community and share your ideas and build a collective of people driven to see these goals get accomplished in real-time; the State will not do it for you, and waiting and relying on them to do so is how we got to this point and why its so wide spread. People are still surprised when they're expected to use their corrupt Legal system and expect another result?! Your diffusion of PERSONAL responsibility to this apparatus is the real problem, not what specious reasoning or beliefs some 'environmentalists' may or may not have or use.
Voting gives you the illusion you're doing something, when you really aren't and are only really validating a flawed concept with your continual participation, and the idea of it ever really making any difference is where you see the divide between people who actually do, and those that only talk about it. The former being where most people remain to this day on the matter(s) even as the problems continue to compound.
What matters is whether hydrogen tanks can be a cheaper or better approach to storing and transporting lots of energy than competing technologies.
Proponents of using hydrogen say existing electricity infrastructure has way too little capacity making hydrogen, which can be pumped through existing gas lines, an attractive approach alongside electricity for transporting power. That makes it more attractive for storage, too.
Hydrogen is too much of a trouble fuel with no infrastructure in place to handle.
The problem is of course where to get the CO2 from. It should be gotten from some kind of carbon capture setup. Ideally from biomass power plants.
[1] https://www.edf.org/climate/methane-other-important-greenhou...
What this whole thread boils down to is we need a huge amount of nuclear power, after which rather than worrying about all 3 of "safe", "dense", "efficient", we can just worry about the first 2.
Seriously, if it takes 1000x the energy from nuclear power to fix enough C02 to make conventional jet fuel from the air, that is fine. That's something we can optimize on a leisurely basis when we are not worrying about global warming.
Hydrogen is awful to store and has no existing infrastructure around it, and you only get efficiency gains if you use fuel cells, otherwise it's back to Carnot's law.
Compare this to synthetic biofuels. They are already the market, as an example I can go fill up my diesel car right now with it, certified to work by the manufacturer, and can be transported and used by existing infrastructure.
Why isn't this talked about more? Are the land usage requirements making it unfeasible for a global switchover in the aviation and maritime industries requiring converting CO2 from the air making it much more expensive? Or is it simply not flashy enough?
Fuel cells can also use synthetic fuels, including hydrocarbons, and ammonia.
Plus the hydrogen production pipeline is mostly from hydrocarbon so it's no gain at all. AFAIK hydrolysis is currently rather expensive and mostly for situations where you need very pure hydrogen (e.g. scientific application).
The problem is the scale you'd need to make a dent. It's being proposed as a serious solution to road and rail transport hydrocarbon use, and the power requirements are bigger than anyone I've seen addressing. The last-mile distribution problem is also not inconsiderable, but it pales in comparison to having to copy and paste a chunk of our existing renewable energy fleet.
Hydrogen has a very high energy density per mass unit (the highest of the chemical reaction energy sources). But lower energy density per volume than Li.
The two figures matter for different use cases, cargo-ships and aviation want to optimize for energy density per mass, while small passenger transport (e.g. scooters, cars...) wants to optimize for energy density per volume.
Energy density per mass graph: https://en.wikipedia.org/wiki/Energy_density#/media/File:Ene...
Lithium-ion tops out around 2.4 MJ/L, LOH 8~10. Maybe one order of magnitude difference when you use less dense li-ion. Plus that energy density of LOH doesn't take in account the absolute hell that it is to keep stored. Fossil fuels are in the mid-30s by comparison.
What LOH does have compared to batteries and even fossil fuels is very high specific energy (energy per kg), it's about triple fossil fuels and a good 2 orders of magnitude better than li-ion. That's why it's been used a lot in rocketry, where mass is a much bigger concern than volume.
[1]https://www.zmescience.com/research/us-navy-synthetic-jet-fu...
Most of that stuff is engineering superstition at this point. Most problems regarding hydrogen were solved decades ago. BMW actually made a LH2 powered car and had no big problems (except limited range).
Frankly, you're just incredibly out of touch. We already are seeing H2 powered planes now, and a commercial jetliner powered by H2 should happen by 2030 or so. This very thread is about Airbus planning on building one.
Such as the horrific SST crash.
The idea that jet fuel is somehow safe is just a terrible misjudgment of the situation. What we have learned over time is how to handle it safely - but it is NEVER safe and it DOES burn. Another way to set it merrily burning is to scrape an airliner along the runway, or have the airliner hit any sort of obstacle, or for the fuel to leak onto hot engine parts, and on and on.
Surely if that's your benchmark then nothing is safe (with enough effort, few things don't burn), and the point is really rather the safety margin, which is significantly larger for fossil fuels than for LOH, therefore making them much safer than LOH? There's a reason why we prefer dynamite to liquid nitroglycerin, even though both do, in fact, explode.
As I said, jet fuel is NOT safe. What we do is try to safely handle it.
For example, nobody in the industry is going to allow a lit cigarette anywhere near an airplane.
We have a lot of experience with jet fuel fires and have learned how they burn, how they start, how to fight them, and how to prevent them. We have very little experience with hydrogen fires. They may be worse, they may be better. We don't know.
The US military has already proven a jet aircraft can be run on biofuels.
As opposed to digging it out of the ground where it's happy staying outside of our environmental system.
https://electrek.co/2019/06/11/hydrogen-station-explodes-toy...
Hydrogen needs to be treated with the proper respect at all times when it isn't safely bound to something else. It really doesn't take much to set it off. That the Hindenburg ever got off the ground is what is impressive about it, the amount of care that went into ensuring that a static charge could never reach the reservoir must have been massive.
Hydrogen plants have exploded in the past as well. Given aircrafts' tendency to build up static charges and to be hit by lightning I would not bet on that particular technology to work out.
The Hindenburg was - and that a pretty weird thing to write - about as good as it gets for an accident like that. Only about 1/3rd of the people on board died and it happened during a time when the aircraft was already fairly low (during the last stage of mooring). Had this happened at altitude likely all hands would have been lost.
Lots of weight in an aircraft was the deal breaker. I think the ruskies did end up with something flying but I'm not confident about that.
I don't think the author has a slimmest idea how gas turbines, and fuel cells work