from the the-Hindenberg-steam-engine-crossbreed dept.
‘They said we were eccentrics’: the UK team developing clean aviation fuel:
“Anyone passing would have wondered why these people were staring at a pipe and whooping and laughing,” says Bobby Sethi, associate professor of gas turbine combustion at Cranfield University. “But we were almost certainly the only people in the world right then burning anything without producing CO2.”
[...] “We were able to demonstrate successful ignition and safe combustion of pure hydrogen and air at high temperature and pressure – producing no carbon emissions,” he says. Even if, he adds, the passing layperson would have only seen a pipe and some steam.
[...] Sethi recalls the scepticism of even five years ago, when he was pursuing funding for the hydrogen research project, known as Enable H2: “They said we were eccentrics. Now they’re queueing up to be on our advisory board.”
There are broadly three strands of work that the aviation industry is frantically investigating for an environmentally acceptable future. One is to create greener fuels for the large aircraft currently in service. A second is electric flight, which appears feasible for smaller aircraft and short-haul hops. And a third is hydrogen.
Two projects pioneered at Cranfield are using hydrogen in the form of fuel cells to power electric motors and propel planes: ZeroAvia flew a six-seater from here last September, and hopes to scale up the technology for commercial short-haul flights in the coming decades. Another, Project Fresson, is planning to use fuel cells for a green, short-hop passenger service around the Orkney islands as soon as 2023.
But the ambitions for direct combustion of hydrogen are on a bigger scale; whether a radically different plane and propulsion system could replace the modern, paraffin-fuelled passenger jet. Which is where Sethi’s research comes in.
Nothing yet in the sheds looks anything like a plane. The rig here is a unique facility, Sethi says, assembled to show that hydrogen can be clean, safe and efficient for aviation, and produce data showing the optimum temperature and pressure to minimise other harmful emissions such as nitrogen oxides or NOx, a family of highly poisonous gases.
Not the only scientists looking for controlled ignition of hydrogen. What's described still seems a long way away from something that produces thrust, which is the ultimate need. However, technology usually advances in small steps, and that's fine as long as there's an ultimately reachable goal.
(Score: 1, Informative) by Anonymous Coward on Thursday August 19 2021, @09:25PM (9 children)
Not great to fly any real load anywhere.
While energy per unit MASS is high, energy per unit VOLUME is the opposite. The need to lug around a huge cryogenic tank obviates all theoretical advantages.
https://en.wikipedia.org/wiki/Hydrogen_fuel#Drawbacks [wikipedia.org]
(Score: 3, Informative) by SparkyGSX on Thursday August 19 2021, @09:55PM (5 children)
It's even worse than that; cryogenic storage doesn't work for hydrogen, so you need large, heavy tanks with insane pressures (up to 1200 bar) to store a disappointing amount of hydrogen.
Combustion of hydrogen isn't exactly new, the university I used to work at did that 8 years ago in a slightly modified car.
Also where would this "green" hydrogen come from? There is no such thing as "excess renewable energy". Industrial hydrogen is made from natural gas, which produces more CO2 than burning the gas directly, since the energy in the carbon is lost, and the hydrogen needs to be compressed to thosr
If you do what you did, you'll get what you got
(Score: 2, Insightful) by Anonymous Coward on Thursday August 19 2021, @10:11PM
Yes there is. It can exceed demand and storage. So they use it for hydrogen electrolysis.
(Score: 1, Insightful) by Anonymous Coward on Thursday August 19 2021, @10:12PM (3 children)
Cryogenic storage works just fine for hydrogen, it just needs to be kept at around 20°K, colder than any other cryogen but helium. Keeping it that cold simply requires venting the excess gas, which is a highly flammable, explosive pollutant that is cold enough to freeze nitrogen. Everything else you've said is true.
(Score: 2) by FatPhil on Friday August 20 2021, @05:40AM (2 children)
Your credibility absolutely just plummetted below zero.
Great minds discuss ideas; average minds discuss events; small minds discuss people; the smallest discuss themselves
(Score: 0) by Anonymous Coward on Friday August 20 2021, @06:33AM (1 child)
I made a typographical mistake. Did I commit any factual errors?
(Score: 2) by kazzie on Saturday August 21 2021, @01:20PM
In absolute terms, no.
(Score: 4, Informative) by Immerman on Thursday August 19 2021, @10:04PM (1 child)
True, but there are plenty of people working on alternative storage methods. You only need high pressure and/or cryogenics if you're trying to store it as a dense gas or liquid. If it's dissolved in a solid or liquid carrier instead, then you reduce mass density, but may greatly increase volumetric density.
Most recently I just heard about Plasma Kinetics in a Sandy Monroe video. The name doesn't seem to have anything obvious to do with the technology, which is a thin hydrogen-absorbing film wound into a continuous loop cartridge sort of like a giant 8-track cartridge.
If I understand correctly it will absorb hydrogen even from low-concentration sources like sewer-gas, and release it when it spools past a laser light "reader head". It sounds like the energy density of the cartridges (by mass or volume) is currently a bit better than cutting edge lithium-ion batteries, though as an added benefit it's non-flammable. But it sounds like they've just reached the point of being ready to bring the technology to market, and who knows what future advances in the technology might hold.
And of course they're hardly the only ones pursuing such alternative methods of hydrogen-storage.
Still, it seems like biofuels, syngas, etc. would offer a much more immediate solution for long-haul vehicles like airplanes, trains, and ships. Such fuel could be used in existing vehciles, and so long as it's synthesized from atmospheric CO2 it's carbon neutral, which is all that really matters. Well aside from all the "normal" toxic pollution from hydrocarbon engines.
(Score: 0) by Anonymous Coward on Friday August 20 2021, @05:16AM
So you're saying one day I'll carry my phone in my back pocket and pass gas to recharge it?
(Score: 0) by Anonymous Coward on Friday August 20 2021, @12:47AM
(Score: 1, Touché) by Anonymous Coward on Thursday August 19 2021, @09:51PM (12 children)
"...nitrogen oxides or NOx, a family of highly poisonous gases."
"highly poisonous gases"
"highly poisonous"
Wow.
(Score: 2) by Immerman on Thursday August 19 2021, @10:10PM (11 children)
And your point is?
NOx gasses are a result of heating nitrogen to high temperature in the presence of oxygen - it's a problem with practically every form of combustion. Gasoline engines produce them, I think diesels tend to produce even more (higher operating temperature), heck even your kitchen stove produces them, assuming it's not electric.
(Score: 0) by Anonymous Coward on Thursday August 19 2021, @10:19PM
It's a wonder any of us still live!
(Score: 2) by tizan on Thursday August 19 2021, @10:39PM (3 children)
That is what catalytic converters are for ...otherwise we would be killing ourselves with acid rain.
(Score: 3, Informative) by Immerman on Thursday August 19 2021, @11:29PM (2 children)
I'm pretty sure a typical catalytic converter is designed to oxidize the incompletely burned hydrocarbons left over from the fuel, dramatically reducing the emission of organic pollutants and carbon monoxide. NOx has already been oxidized, that's the problem. Oxidizing it more wouldn't help anything.
They do make NOx catalytic converters, but it doesn't sound like those are what's included in a typical car. Rather it's the conditions within the combustion chamber that are optimized to reduce NOx production in the first place.
(Score: 4, Informative) by Beryllium Sphere (r) on Friday August 20 2021, @12:39AM
These days, I think "three way" converters are typical:
https://en.wikipedia.org/wiki/Catalytic_converter [wikipedia.org]
They include a function of breaking nitrogen oxides into nitrogen and oxygen.
(Score: 2) by tizan on Tuesday August 24 2021, @10:13PM
these things are de-rigueur on diesel vehicles (remember VW dieselgate)
Nox is converted to N2 and water vapor
https://www.sae.org/publications/technical-papers/content/2019-01-0047/ [sae.org]
(Score: 0) by Anonymous Coward on Friday August 20 2021, @12:34AM (5 children)
I think his point was that nitrogen oxides wash out of the air as nitrates and nitrites, which are basically fertilizer. In other words "what plants crave".
Trace levels are harmless or beneficial. Calling them highly poisonous is disingenuous. Yes, they are poisonous in high concentrations, but that is not what "highly poisonous" means.
(Score: 3, Insightful) by Beryllium Sphere (r) on Friday August 20 2021, @12:42AM (4 children)
They wash out as acid rain.
I'm OK calling something highly toxic if it has to be kept in the parts per million range:
https://www.google.com/search?q=nitrogen+dioxide+danger+level&rlz=1CATTSD_enUS821&oq=nitrogen+dioxide+danger+&aqs=chrome.1.69i57j0i512j0i22i30l8.26326j1j7&sourceid=chrome&ie=UTF-8 [google.com]
(Score: 2, Informative) by Anonymous Coward on Friday August 20 2021, @01:29AM (3 children)
Once again, doomsayers conflating things. Nitrate acid rain washes out quickly and is basically fertilizer. It is also far below the ppm level you talk about, even with heavy air traffic. Heavy ground traffic in cities might produce damaging levels.
Sulphate acid rain is the stuff that caused all the damage. Dirty coal-fired power stations were stationary sources that produced huge quantities that killed forests and dissolved marble buildings down wind from them.
(Score: 2) by KilroySmith on Friday August 20 2021, @03:52AM (2 children)
As a kid who grew up East of Los Angeles, in its air sewer, we routinely had to deal with smog alerts caused by NOx. No playing, stay indoors, etc. Doesn't sound like it "washed out quickly" enough to keep from being a hazard to children and adults at the concentrations found in the atmosphere, now does it? And I'm not sure what you mean by "washes out" - are you implying that there might be rain in the LA basin in the summertime, often enough to impact air quality?
(Score: 0) by Anonymous Coward on Friday August 20 2021, @04:53AM
Did you often get jet airliners flying along the streets of LA?
(Score: 0) by Anonymous Coward on Friday August 20 2021, @05:00AM
Smog alerts weren't due solely to the NOx from traffic, but to the interactions with unburnt hydrocarbons from shitty engines and diesel particulates, and industries that just dumped their shit in the atmosphere. Pollution controls have mostly made that go away, and electric cars will finish the job.
The level of NOx that you would get from even ten times the current level of jet aircraft is so widely dispersed and disappears so quickly that it is not a problem.
(Score: 0) by Anonymous Coward on Thursday August 19 2021, @11:11PM (9 children)
Is there a market for blimps to come back?
Nice big surface area to put solar cells on.
(Score: 5, Interesting) by Immerman on Thursday August 19 2021, @11:52PM (8 children)
Lots of people trying, but the idiocy around the Hindenburg disaster really spoiled the idea in the public perception (they used cheaper hydrogen lift-gas in a cheaper helium-designed airship lacking all the fire mitigation systems hydrogen airships had).
Plus... there's the more practical considerations. Airships with a useful payload are by necessity big, expensive, slow, and really difficulty to moor gracefully. With the invention of commercial airplanes they were rendered mostly obsolete. For passenger applications they're like a limited-capacity cruise ship, which could be a cool way for the upper crust to take a holiday where they could literally look down at the little people beneath them, but it's not a very practical form of transportation.
The one place they do have potential is deliveries to undeveloped destinations, which is what most of the current development work is targeting. Seems like the most promising designs actually include vertical thrust, allowing them to perform powered VTOL landings where they actively push themselves against the ground while loading and unloading so that they don't get tossed around by the wind. Of course, there's very limited demand for large deliveries to undeveloped locations, mostly military.
Though actually there is one other potential application - drone "motherships". An Amazon airship with a host of delivery drones to handle the "last mile" deliveries to the ground might have potential. Whether it could be more cost-effective than a number of delivery-van based "mini-motherships" remains to be seen.
(Score: 0) by Anonymous Coward on Friday August 20 2021, @01:24AM (1 child)
(Score: 2) by FatPhil on Friday August 20 2021, @05:48AM
>> limited-capacity cruise ship, which could be a cool way for the upper crust to take a holiday where they could literally look down at the little people beneath them
will benefit from being told to:
> think "sky super-yachts" for the over-privileged.
?
Great minds discuss ideas; average minds discuss events; small minds discuss people; the smallest discuss themselves
(Score: 3, Informative) by PinkyGigglebrain on Friday August 20 2021, @02:12AM (5 children)
helium was not cheap by any stretch of imagination in 1936-37. At the time the USA was the major source of Heilium in the world but due to how rare and expensive it was and the desire of the USA to use it in their own air ships exporting it was banned in 1927 [wikipedia.org], which resulted in many other countries at the time to use Hydrogen in their airships as well. At the time Germany had hoped to get the USA to give them special treatment and sell Germany the Helium it needed [wikipedia.org]. When that didn't happen they had to use Hydrogen, which was very cheap at he time. It wasn't just for lack of concern for safety that caused the choice, it was also in part because the USA was protecting it's own interests as usual.
"Beware those who would deny you Knowledge, For in their hearts they dream themselves your Master."
(Score: 3, Interesting) by Immerman on Friday August 20 2021, @04:19AM (4 children)
Helium definitely was not - hence "cheaper helium"
Helium *airships* however were much cheaper than their hydrogen cousins. Just the cost to build the ship, not the gas to lift it. Hydrogen ships included lots of fire-mitigation systems because, well, hydrogen. And those systems added construction costs.
The Hindenburg was a helium ship, had it been filled with the helium it was designed for it wouldn't have had a problem. There are no doubt several reasons it was using hydrogen instead, without being properly refitted to do so... but the end result was the death of airships.
Heck, as I recall it wasn't even the first ship to have such a disaster - but it was the first to be caught on TV and provided a truly horrifying visual spectacle.
(Score: 0) by Anonymous Coward on Friday August 20 2021, @06:52AM (3 children)
The US was the only supplier of helium in the world at the time and it was illegal to export it [wikipedia.org] since it was a strategic resource.
(Score: 2) by Immerman on Friday August 20 2021, @09:24PM (2 children)
And that explains why the Germans chose not to use hydrogen in their airships without first refitting them for it?
(Score: 1, Informative) by Anonymous Coward on Saturday August 21 2021, @06:05AM (1 child)
It was the singular reason why they wound up using hydrogen even though the Hindenburg was designed for helium: The only supplier in the world wouldn't sell to them. That they didn't retrofit to make it hydrogen safe was because it would have cost too much, the high cost of hydrogen safety being why they designed it for helium in the first place.
(Score: 2) by Immerman on Saturday August 21 2021, @09:30PM
Exactly. They *chose* to invite the disaster by operating a passenger airship in a manner they knew perfectly well was highly unsafe, for purely financial reasons. Idiocy. In a just world everyone involved in that decision would have been convicted of multiple counts of murder.
Though I suppose for some reason we consider willful criminal negligence to make it only manslaughter, despite that premeditation is supposed to make it murder. They didn't premeditate to kill those specific people, but they did to kill *someone*, whoever the dice finally landed against.
(Score: 1) by jman on Friday August 20 2021, @01:02PM (1 child)
Immerman is correct about public perception due to the awful events of 1937.
Even with safety protocols, though, not sure I'd be comfortable being around a big bag of element 1 while floating up where lightning starts.
Though we don't have the technology for this today, the ideal solution would seem to be generating the required hydrogen at runtime through ambient extraction, thus minimizing stored volume.
This of course follows for any energy source. Need a sun? Just turn it on! Done, turn it back off.
(Score: 2) by Immerman on Friday August 20 2021, @10:14PM
>Even with safety protocols, though, not sure I'd be comfortable being around a big bag of element 1 while floating up where lightning starts.
And that's the problem. Perception killed it despite the actual safety levels.
It's not like even a direct lightning strike could make a hydrogen airship explode. Hydrogen is only flammable in the presence of oxygen, which means you can only get fire when there's already a leak in the bag allowing the hydrogen to escape. And even then it will only be a relatively small fire hovering around the leak - unlike a balloon there's only a slight pressure difference caused by the weight of the ship, so you won't even get a significant jet of escaping gas forming a "hydrogen torch" - the flame can't enter the bag, and so long as the skin itself isn't flammable you'll get little more than a small "pool" of flame filling the hole. Which was one of the big problems with the Hindenburg - escaping helium would be it's own passive fire-suppression system, while escaping hydrogen instead accelerated the burning of the highly flammable skin.
> the ideal solution would seem to be generating the required hydrogen at runtime through ambient extraction
Umm...how would that work? Are you planning to deflate the ship when unused? Why bother? There's already at most only a skeleton crew on board, who can be evacuated relatively easily. It's not like an airship consumes hydrogen, aside from leakage losses. To be airborn, it has to be filled with hydrogen, and offhand I don't recall ever hearing about the supplemental/buoyancy-adjustmanttanks being a source of problems. They're already contain only a fraction of the hydrogen in the bags themselves.
Plus, do you have any idea how long it would take to extract that much hydrogen from the air? The atmosphere is only 0.00005% hydrogen gas, meaning that you'd have to process at least 2 million airship-volumes worth of air to fill one airship with hydrogen. Even if you split water vapor instead (with the huge energy requirements that implies), the atmosphere only averages about 4% water vapor, so you'd still have to process at least 25 airship-volumes worth of air.
(Score: 4, Insightful) by ElizabethGreene on Friday August 20 2021, @03:48PM (8 children)
Raise a skeptical eyebrow whenever someone calls hydrogen "green". 96% of hydrogen is manufactured by steam reformation of fossil fuel. It's critically important to understand what is greenwashing that makes people feel good vs. what actually has an impact. Without a sea change in hydrogen production it is firmly in the greenwashing camp.
It is possible to make it via electrolysis or photoelectrochemical processes and it's possible to get the energy to do those things from clean/renewable sources. Until that happens burning or fuel cell electricity from hydrogen will produce more CO2, not less.
(Score: 2) by Sourcery42 on Friday August 20 2021, @04:47PM (4 children)
You are absolutely right. There's no CO2 in the tailpipe of the mobile source, but there's an enormous tailpipe on the traditional SMR plant.
There is electrolysis, but it takes a tremendous amount of energy to convince water vapor to split apart. That's why we reform hydrocarbons into hydrogen rather than splitting water via electrolysis. Hydrogen has pretty terrible energy density per unit volume too. It is just hard to get excited about it as a transportation fuel. However, I can envision it serving a role as something more like a battery. Generate hydrogen with excess solar/wind/nuclear energy when there is a surplus. Burn it or put it through a fuel cell to generate electricity when the sun goes down or the wind stops blowing. Hydrogen takes on the role of the peaking plant today. It could be viable until we find a good way to make cheap, massive batteries.
One thing that becomes clear as you look into the details of green energy is that there is going to have to me truly massive investment to meet aggressive carbon goals with the tech we have now. Someone is going to bear that cost of capital. I grit my teeth when I read articles in business journals predicting energy is nearly free in the not too distant future because it is all green/renewable.
(Score: 2) by ElizabethGreene on Friday August 20 2021, @09:31PM (3 children)
I'm optimistic about a significant drop in energy prices IFF we can sort out and scale out orbital solar power.
There are two caveats to that.
1. I can be a Pollyanna about the rate of technical progress.
2. Only a blithering imbecile would believe that big energy, a multi-trillion dollar industry, is going to take that kind of innovation without fighting back. They have lots of experience doing it to discredit climate change. This will be that 2.0.
(Score: 2) by Immerman on Friday August 20 2021, @10:43PM
Sadly I smell a lot of "if" on this plan.
Currently we have no proposed way to build orbital solar plants that aren't far more expensive per kWh than ground-based alternatives. Even worse, despite decades of research we currently have no technology to get any such energy to the ground even from LEO without truly stupendous transmission losses.
We could sort of sidestep those issues with relatively cheap huge orbital mylar reflectors that simply keep ground-based solar fields illuminated 24/7. That also slightly mitigates the "orbital death ray" potential, since even from LEO the smallest bright spot that could be reflected onto the Earth would be about 3 miles across, up to about 200 miles across from geostationary.
Of course, if you presume that orbital solar becomes the primary source of energy you're still talking an average of around 465GW of total solar energy - focus all of that onto the same 3-mile circle and you're talking about 25kW/m^2, or roughly 25x the energy density of tropical noon sunlight. I'm not sure that's enough to burn down buildings, but I'm sure it would rapidly destroy crops.
(Score: 0) by Anonymous Coward on Saturday August 21 2021, @06:16AM (1 child)
Orbital solar is already dead. [wordpress.com] Modern solar panels are more space and cost efficient than orbital power receivers. Even if the satellites were free, ground based solar would still be cheaper and take up less space. The only way space based power can compete now is to increase the flux density to dangerous levels, injuring or killing anything that gets too close to the ground stations.
(Score: 2) by Immerman on Saturday August 21 2021, @10:04PM
Orbital solar is more valuable for solving the storage problem - ground-solar generates near-zero power form most of the day (night), including those times when energy consumption is highest, and can be offline for weeks at a time if the weather is particularly uncooperative. The problem orbital solar really solves is eliminating the need for storage, since it can generate power 24/7, and clouds are transparent to properly tuned microwave power transmission. Even then though, there's a lot of storage systems far cheaper than an orbital solar array.
Orbital sunlight concentration might have interesting potential though - giant utra-thin mylar mirrors could be vastly cheaper than solar power stations, and refocus sunlight on ground-based solar plants throughout the night. By maintaining noon-time illumination levels 24 hours a day you'd be pushing 5x the daily energy production, without any "dead times". Assuming a large swarm in low orbit serving sites around the world, you could potentially even selectively re-target a protion of the redirected sunlight from areas passing through the low-demand part of the daily curve, to those currently experiencing high demand. You could probably even increase light levels to a few times natural noon-time levels without presenting an immediate survival hazard to anyone in the area. Though even just sustained noon-time levels would likely make the area unpleasant enough that almost nothing would live there. Though I suppose polar regions might flourish - you could create "islands" that never suffered the winter loss of sunlight, maybe even seeing an increase to compensate for the surrounding cold. Come to think of it, you could probably do something similar to create oases of optimal year-round growing seasons anywhere on Earth.
(Score: 2) by Immerman on Friday August 20 2021, @10:17PM (2 children)
Hydrogen is exactly as green an energy storage medium as batteries - which is to say it depends entirely on where the energy is coming from.
Steam reformation is currently the dominant way to produce hydrogen, just as fossil-fuel power plants are the dominant way to charge batteries. In and of themselves, neither technology does anything to combat climate change.
That said... you are absolutely right that much of the hydrogen push has been heavily backed by the fossil fuel industry as a way to remain relevant by greenwashing an inefficient derivative product. But you could make a similar argument that EVs greenwash the fact that your car is still powered by burning fossil fuels. Though at least the power plants tend to do so more cleanly and efficiently than car engines - though electric transmission losses eat a lot of those gains.
Ultimately, neither technology is inherently green. Instead they shift the dynamic from end-users generating CO2, to the infrastructure generating CO2, so that your 10 year old electric or hydrogen car will "magically" become greener as the infrastructure is updated.
It worth mentioning too that, whether you're generating hydrogen or electricity, the current production capacity is only just adequate to existing consumption, and we'll need to add new production to supply the demand for transportation. Electricity currently has a slight advantage, with solar electricity actually being slightly cheaper than coal-generated, but supposedly water-electrolysis hydrogen is already only very slightly more expensive per-unit than steam-reformed, though the electrolysis plants themselves are still more expensive.
(Score: 0) by Anonymous Coward on Saturday August 21 2021, @06:33AM (1 child)
Even ignoring distribution costs, internal combustion engines are only around 20% efficient. Even including distribution costs, BEVs are about 40% efficient. Assuming that all hydrogen is produced by electrolysis the BEVs would only need half the increase in electricity production of hydrogen powered cars. That is more than a slight advantage.
(Score: 2) by Immerman on Saturday August 21 2021, @09:18PM
There's also fuel cells, which can be considerably more efficienct than ICEs. But yes, it seems like hydrogen is going to be less energy efficient than batteries unless some other major advance comes along.
*However* it's much greater potential energy density that could make it a better option is specific cases. Probably not for passenger cars, assuming enough batteries can be made. Different compromises for different use cases. Existing batteries are physically incapable of storing energy densely enough for long-haul aircraft, shipping, trucking, etc., so it makes no sense to compare against them in those applications.
Existing batteries also still require a whole lot of elements whose production is going to be a major bottleneck in dramatically expanding the EV and solar/wind energy storage markets. Hydrogen doesn't share those resource bottlenecks, and can still be a huge improvement over fossils fuels.