Could Airports Make Hydrogen Work As Fuel? (bbc.com) 168
"On a typical day 1,300 planes take off and land at Heathrow Airport, and keeping that going requires around 20 million litres of jet fuel every day," reports the BBC. "That's the equivalent of filling up your car around 400,000 times.
"But, when it comes to fuel, airports around the world are having to have a major rethink..." To be of any use to the aviation industry, hydrogen needs to be in its liquid form, which involves chilling it to minus 253C. Handling a liquid at that kind of temperature is immensely challenging. Given the chance, liquid hydrogen will "boil-off" and escape as a gas — potentially becoming a hazard. So tanks, pipes and hoses all have to be extra-insulated to keep the liquid cold.
France's Air Liquide has a lot of experience in this area. For around 50 years it has been supplying cryogenic hydrogen to the Ariane rockets of the European Space Agency (ESA)... Over the past three years, in partnership with Airbus and France's biggest airport operator, Group ADP, Air Liquide has been investigating the potential of hydrogen in the aviation business. It is also part of the H2Fly consortium which this summer successfully flew an aircraft using liquid hydrogen. For Air Liquide, it was an opportunity to test systems for fuelling a hydrogen aircraft...
However, installing the equipment needed to store and distribute hydrogen at airports will not be cheap. The consultancy Bain & Company estimates it could cost as much as a billion dollars per airport. One start-up, Universal Hydrogen, says it has a solution... The company has developed special tanks to hold liquid hydrogen (UH calls them modules), which can then be trucked to the airport. The modules are designed to slot straight into the aircraft, where they can be plugged into the propulsion system. No need for pipes, hoses and pumps.
The modules are extremely well insulated and can keep the hydrogen in its liquid form for four days. Two modules would hold 360kg of hydrogen and would be able to fly an aircraft 500 miles, plus an extra 45 minutes of flight time in reserve.
"But, when it comes to fuel, airports around the world are having to have a major rethink..." To be of any use to the aviation industry, hydrogen needs to be in its liquid form, which involves chilling it to minus 253C. Handling a liquid at that kind of temperature is immensely challenging. Given the chance, liquid hydrogen will "boil-off" and escape as a gas — potentially becoming a hazard. So tanks, pipes and hoses all have to be extra-insulated to keep the liquid cold.
France's Air Liquide has a lot of experience in this area. For around 50 years it has been supplying cryogenic hydrogen to the Ariane rockets of the European Space Agency (ESA)... Over the past three years, in partnership with Airbus and France's biggest airport operator, Group ADP, Air Liquide has been investigating the potential of hydrogen in the aviation business. It is also part of the H2Fly consortium which this summer successfully flew an aircraft using liquid hydrogen. For Air Liquide, it was an opportunity to test systems for fuelling a hydrogen aircraft...
However, installing the equipment needed to store and distribute hydrogen at airports will not be cheap. The consultancy Bain & Company estimates it could cost as much as a billion dollars per airport. One start-up, Universal Hydrogen, says it has a solution... The company has developed special tanks to hold liquid hydrogen (UH calls them modules), which can then be trucked to the airport. The modules are designed to slot straight into the aircraft, where they can be plugged into the propulsion system. No need for pipes, hoses and pumps.
The modules are extremely well insulated and can keep the hydrogen in its liquid form for four days. Two modules would hold 360kg of hydrogen and would be able to fly an aircraft 500 miles, plus an extra 45 minutes of flight time in reserve.
A proper use for hydrogen (Score:3)
For airports lucky enough to be located near suitable land and that see reasonable sunlight and/or wind then the hydrogen could be cleanly created at the airport, getting around one of hydrogen's weak points, transportation. The same goes for ports servicing long haul shipping.
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When you consider the weight of the container, hydrogen gives you about the same W/kg as lithium ion batteries. Refuelling can be faster than batteries though, though I'm not sure that is necessarily a problem at an airport. If you connected the plane to a fast charger when it started to unload, I think it would be done by the time it was ready to take off again.
Re:A proper use for hydrogen (Score:4, Interesting)
Batteries are roughly 4 KG / KWh
H2 is about 36 KWh / KG. The FC stack is about 50% efficient (actually it is a little better), so 20 KWh / KG.
This is 80x the weight density of a battery.
The tank for 5 KG of gaseous H2 (at 700 bar) is about 100 KG. So 100 KWh in 105 KG is still 4x better than batteries.
The tank for LH2 is much lightly as it does not need to contain pressure. It is basically a "thermos bottle".
None of this means H2 is easy, or inexpensive. Just that the weight of batteries will make some existing Jet-A applications very hard to replace.
Re:A proper use for hydrogen (Score:4, Interesting)
I think the main competitor is hydrocarbon fuels, not batteries. Methane's weight density isn't quite as good as hydrogen's, but it's not bad, and it's so much easier to work with. It's easy to store. You don't need super-refrigeration or very high pressure. It also is easy to make from renewable energy, and the efficiency is only slightly lower [wikipedia.org] than making hydrogen.
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That doesn't help. At best, this offsets a tiny part of flight operations for very small planes carrying fewer than 10 people or small cargo. For major use, the energy capacity needs to get a lot higher. Jet A1 (used in turboprops and jet engines) has a specific energy of 43.1 MJ/kg, or about 12 kWh/kg. NMC lithium batteries seem to max out right now at around 300 Wh/kg. Figuring out the energy efficiency of an aircraft is complicated for a number of reasons, but even with a presumed much higher efficiency
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This is not a show stopper, but you do have to account for it in your math.
It actually could be a show stopper. The max landing weight of a 777-300ER is 100 tons less than its max takeoff weight, which suggests that a similarly sized and ranged aircraft would simply be infeasible if it had to be battery powered.
Re: A proper use for hydrogen (Score:2)
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I guess we're going to fly those planes to the destination and just leave them there? Or is Air Liquide going to drive H2 to every airport so these airplanes can fly back?
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To start off you can support a significant fraction of regional flights which go from a hub to an outlier airport and back again, with a single fuel load. Do not succumb to the Slashdot disease of arguing that the entire system and all limitations must be overcome at once.
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Yes? Kind of like we currently drive jet fuel to all the airports?
Re: A proper use for hydrogen (Score:2)
Itâ(TM)s never going to happen. Hydrogen needs big heavy tanks to store it, which uses up a bunch of the planeâ(TM)s payload. More so, it canâ(TM)t be stored in thin structures like wings, so you will end up losing a bunch of fuselage space.
It just isnâ(TM)t the right fuel for airliners.
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In addition, one also needs to take into account hydrogen embrittlement. Hydrogen embrittlement, also known as hydrogen-assisted cracking or hydrogen-induced cracking, is a reduction in the ductility of a metal due to absorbed hydrogen, which while also an issue with hydrogen powered rockets -- as those currently flying are all expendable, its impact is greatly minimized. While hydrogen embrittlement does not affect all metallic materials equally, the most vulnerable are high-strength steels, titanium alloy
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Actually, it is fairly common that jet engines are not made of plastic, as well as other materials that currently make up the processing and management of cryogenic hydrogen. Can these problems be solved, certainly. The question to be answered though is at what cost. In addition, what do they plan on using as feedstock for the hydrogen -- as this will also impact the cost structure. There is a lot of "risk" to be paid down before we live in future world.
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The idea of hydrogen ICE for cars just feels wrong as your taking a complex system, an ICE, and making it more complicated. In that sense fuel cells are probably a better option where viable. In the case of aircraft, where weight and space an issue, then burning the hydrogen may well be a better option than a fuel cell. Some development in concepts in that area wo
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This isn't a "what if", it is happening. I read about the problems of BEVs sitting on dealer lots unsold on a website called "Slashdot", perhaps you've heard of it?
Yeah, for example here in Europe, because European EVs are bad and very expensive at the same time. You can get a much better Tesla at a significantly lower price (e.g. -25%) or you can get a Chinese EV at half the price.
So right now you can hear car manufacturers complaining about bad EV sales, making excuses that the market isn't there, but what they forget to tell is that they lag 10 years behind competition.
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You can get a Tesla at a significantly higher price in Europe. Yes, they are better, but they are also much more expensive than the bad European EVs. Tesla Model 3 starts at 42k, a new Peugeot e208, Renault Zoe or a Fiat 500e are about 30k, a new VW e-Up or a Renault Twingo start at around 25k and you can get a new Dacia Spring for less than 18k.
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You cannot compare the cars you mentioned to Tesla in any way - Tesla 3 is a relatively large luxury car whereas Fiat 500e or e-UP are toy vehicles.
Look at VW ID.3, ID.7, Skoda Enyaq etc.
Re: A proper use for hydrogen (Score:2)
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The market has spoken on BEVs and batteries, so I not going to debate something that is being sold in the millions with 'what if' arguments.
This isn't a "what if", it is happening. I read about the problems of BEVs sitting on dealer lots unsold on a website called "Slashdot", perhaps you've heard of it?
Killer statistic and source. You've read about some dealers currently having trouble selling some BEVs. You don't link to a survey of the actual market [pwc.com] because it would anhillate the argument you are trying to push.
From the article I linked to: "BEV sales in all twenty analyzed markets increased by 26% in the third quarter of 2023 in comparison with the same period last year."
Only double digit annual percentage increases? OMG! The BEV market is tanking! Its a fad that is all over! (/s).
Re:A proper use for hydrogen (Score:4, Informative)
The market has spoken on BEVs and batteries, so I not going to debate something that is being sold in the millions with 'what if' arguments.
This isn't a "what if", it is happening. I read about the problems of BEVs sitting on dealer lots unsold on a website called "Slashdot", perhaps you've heard of it?
FCVs sit on dealer lots, too. The problem isn't batteries. Teslas are selling faster than they can make them. The problem is that only Tesla has a real story for providing a nationwide charging network that is viable. The others all naïvely believed that the right approach was to put a couple of high-speed chargers near a bunch of locations where people might want to go for shopping or whatever, and although that might be useful for locals who for whatever reason cannot charge at home, it ignores the 95% use case, which is people traveling long distances.
There's nothing quite as problematic as getting to a charging station with only two chargers, finding out that they're full, one is nonfunctional, etc., and then having to drive for additional miles to find another station, which might be in use by the time you get to it, etc. Having banks of chargers in the same spot is just a much better approach for the most common use case, because you can see all of them, know when they become available, and know how many cars are waiting.
The idea of hydrogen ICE for cars just feels wrong as your taking a complex system, an ICE, and making it more complicated.
What is complicated is getting fuel cells to be durable enough at a low enough cost to be viable for use in cars that people will actually buy. Fuel cells aren't exactly simple, trying to shoehorn them into new applications will have complexities of its own.
The biggest problem isn't the cost of the fuel cells. Even if the fuel cells were literally free, hydrogen still wouldn't be viable for cars.
One major problem is that hydrogen embrittles pretty much anything it touches, including seals, etc., and because the molecules are so small, it seeps through everything. Leaks are a constant problem. Forty years after NASA first used hydrogen to launch the space shuttle, they still can't make hydrogen fueling work well [space.com]. So you can expect long-term maintenance problems for both the vehicle and the fueling infrastructure.
The other major problem is that dealing with hydrogen is inherently inefficient at multiple levels:
Multiply those together, and that means you get back 23% to 43% of the power you put in. Compare this with a battery, which gives back about 99% of the power you put in. That means you can operate anywhere from 2.5 to 4 EVs with the same amount of energy as one FCV.
Yes, you get more energy per pound than gasoline or whatever, but....
In the case of aircraft, where weight and space an issue, then burning the hydrogen may well be a better option than a fuel cell. Some development in concepts in that area would be worth exploring.
It would be nice to see some development and exploration of hydrogen as a fuel for jet en
Re:A proper use for hydrogen (Score:5, Informative)
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You're focusing on lithium chemistry while researchers are working on alternative chemistries. Swedish company Northvolt announced a sodium-ion battery last week [northvolt.com] that has no nickel or cobalt and has a specific energy of 160 Wh/kg, similar to some of the better LFP batteries (which also don't use Ni or Co but do, of course, use Li). They're primarily aimed at grid-level installations, but there's little stopping them from being used in vehicles or building batteries. Chinese battery company CATL has been pro
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And that should have been the GM Bolt line, of course, as the Volt was killed off a few years ago.
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One big question is the sourcing of cobalt. Right now much of this comes from Africa and Asia and things are getting a bit volatile in these places which could impact future trade. Use of LFP as an alternative to battery chemistry with cobalt can mitigate against this but that leaves lithium.
There are multiple alternatives to cobalt. The LFP is one, but nickel is proving to be not only a viable replacement for cobalt in current lithium batteries, but actually superior. So even in the medium term, much less the long one, there is no "cobalt" problem.
Lithium has it's own problems on producing enough now, and some of the places it comes from now have their own political volatility that could impact existing mining.
Could this argument be any vaguer? With any commodity with rapidly expanding demand there are always transient supply pinches, and so observing that we have seen some is not any sort of argument against the viability of lithium batteries, and is not
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For Toyota, it was worse than a distraction. The last family CEO, Akio Toyoda, put at serious risk Toyota's position as one of the biggest car manufacturers in the world with his insistence on hydrogen ICE and further hybrid development over BEVs. Toyota was responsible for proving that hybrids were workable and that batteries could be a critical part of a car, but he was willing to throw that away that tech and position lead because he was still stuck on ICE vehicles. Toyota is years behind its primary com
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Sodium-ion batteries are entering production. They have similar capacity to LFP while being less expensive (around $80/kWh compared to LFP's $100/kWh) and not relying on expensive or geo-constrained materials, and with growing production, manufacturers expect to cut the cost in half within a few years.
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We've been told about sodium ion batteries as long as we heard about fusion and flying cars.
Quite simply, no. (Score:2)
Because of all this: https://h2sciencecoalition.com... [h2sciencecoalition.com]
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No mention of the alternatives at net zero.
Direct air capture for compensation : very expensive especially when the oil industry shrinks down.
Synthetic fuel from hydrogen and captured CO2 : very expensive and likely requiring more energy still
Biofuel : not enough arable land
Any argument not from a net zero perspective or which pretends biofuel can scale is dishonest, stupid or naive.
Re:Quite simply, no. (Score:5, Informative)
Ok, I (ShanghaiBill) wrote this. I have no idea why it posted anonymously.
But I freely admit that I am an idiot. Just after posting, I realized that Heathrow needs 20M liters per DAY, and 1190 liters/hectare is the production per YEAR.
So instead of 0.1%, biofuels would require 36.5% of all UK farmland just for Heathrow, which is obviously not feasible.
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It's the same problem with green hydrogen, incidentally. I forget the exact amount, but if we converted Heathrow to green hydrogen, it would take most of the current offshore wind capacity of the UK to produce (and we have a lot of offshore wind!).
However, we fuel it, it is difficult to get around the single biggest problem which is that jet travel takes a lot of energy.
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So you are arguing that electrification of all transportation, including cars is infeasible? Aviation only uses about 9% of the transportation consumed petroleum. If we can electrify cars, we and have enough electricity to produce fuel for planes.
Simply saying "it takes a lot" is a fatally weak argument.
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Which is just aviation, shipping has the same problem. You could in theory fast charge trucks at 10MW, but not a cargo ship on the ocean.
Hydrogen sucks compared to the status quo, as does everything at net zero.
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Wind powered ships are nothing new though, that's what we did before we had alternatives.
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How about: the aviation industry learned about hydrogen with the Hindenburg and a bunch of other hydrogen-related dirigable disasters.
A minor leak in the fuel tank and you've got an explosion. At least regular jet fuel doesn't explode without compression and a spark, hydrogen can be sparked by the static electric buildup on the fuselage.
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Some may label this as an 'attack' on the general population to prevent them from flying, but it is a privilege not a right
This is already the case. Only ~2-4% of the world population flew in an international flight in 2018 [sciencedirect.com]. ~10% of the world population took a flight, national or international.
More recent data from 2021 (but mainly from news article, I didn't check the actual study) seems to say that the numbers are still more or less the same.
People who believe that cutting down on flights and passengers is an attack on freedom are usually those who won't be able to fly themselves or have their children do so in the near futur
Re: Quite simply, no. (Score:2)
insane demand that drives a lot of airline fuel consumption today.
Quick math: 125,000 liters of fuel to transport 400 passengers for 15,000 km. That's the typical characteristics of a Boeing 787. That's... 0.02 liters per person and km traveled.
A typical car is in the 10 liters per 100 km range (or 5 liters of you take a Diesel - closer to kerosene). That's 0.1-0.2 liter per km for the driver only, or 0.04-0.02 liter per km per person. And a car doesn't even travel 800 km/h on average. More like 80.
Fuel consumption is not the issue - it's about the same as a very efficien
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Using tax policy to effect behavior has worked since the beginning of tax policy. The only reason we're even discussing EV's with the tiny market share they currently have is because of the massive tax breaks encouraging their adoption. The opposite works too, increasing the tax on something reduces its consumption.
The real reason it wouldn't work today is because there is a zero percent chance you will convince the 1% and their friends in world governments that they should be taxed into oblivion for frivolous bullshit that they now consider a vital part of their life. I think it would behoove us to consider a 300%+ tax on luxury fuel (private plane, private giant yacht), but I guarantee you they would manipulate the public into hating it before it could make it into any form of serious discussion. "Do you want to hav
Hydrogen is dead end... (Score:5, Insightful)
Once solar megafactories start operating in sunny countries - synthetised fuel should be much better option.
Hydrogen requires cooling and quite heavy tanks...
Synthetised fuel that takes CO2 from the air is carbon neutral...
Should be viable with mega solar farms in 20 years... no point going hydrogen...
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It will never work at scale though. To refuel all planes going out of just Heathrow, you would need ~40000 wind turbines. Solar is even less effective than wind for that, due to its lower capacity factor. Extend that to all flights worldwide, and you would neer to cover half of the earth arable land to produce as much efuel as you would need. Good luck with that.
Oh, and that would be just to allow ~6% of the world population to keep flying around. This is basically the amount of people that are currently ta
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No, you'd need a tiny part of North Africa and Australia's deserts.
Re:Hydrogen is dead end... (Score:5, Insightful)
Compared to for example the Middle East where we get most of our oil?
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Unsurprisingly, since the discovery of oil and the influence of capitalism, Saudi Arabia and UAE is a lot more stable than it was before. Read up on its history before you spout nonsense.
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Even were they as stable as the Middle East, solar farms cost dramatically more than drilling a hole in the ground. An oil well produces from 500 to 5,000 barrels per day, or 3 to 30 million MegaWatts. A 30 million MegaWatt solar farm would cost about 30 trillion dollars, to replace global oil production (90 million barrels per day), could cost 600 quadrillion dollars -- all at current prices. No way would the US put anything close to that anywhere but our own land.
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you would neer to cover half of the earth arable land
That makes no sense. Why would you build solar panels on arable land rather than in a desert?
Arable land is not only more expensive, but it is arable because it rains there, which means cloud cover.
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People live where arable land is, most people don't live in deserts. Transporting electricity from deserts to arable land is expensive. Let's say you need to transport solar power from the Sahara to the EU offices in Brussels, that's 3,531km over (at least) the Pyrenees and Alps, a quick calculation over 800kV 4/0 transmission wire shows 93.43% power drop besides the massive expense in building such a project. And that's just 1 small part of the city being powered (about 12 hours per day, as the sun doesn't
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It will never work at scale though.
Surface transportation uses about ten times the amount of energy as aviation. So you are arguing electric cars are impossible. That argument was lost many years ago. No one seriously questions that transportation can be electrified - it is a matter of discussion of which is the best way to produce the electricity. If you are arguing electrification of transportation is impossible you take yourself off the table as a serious commenter.
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Quebec for instance also uses NG [quebec.ca] (in small volume, but still). Even if we only consider hydro, there are emissions related to the lifecycle of electricity (including the transmission and distribution part), the GHG emissions are estimated by hydroquebec at 34.5g CO2eq/kWh [hydroquebec.com].
Add to that other stuffs, like tires manufacturing, brakes manufacturing, and the actual manufacturing of the car and battery.
All in all, in today's world, an EV still emits 30-40% of the CO2 emitted by an ICE vehicle, when looking at its
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Once solar megafactories start operating in sunny countries - synthetised fuel should be much better option.
You mean sunny countries like UAE? A country that already exports gobs of hydrocarbons and therefore has an existing infrastructure for moving synthesized hydrocarbons? The UAE is looking to expand their use of solar PV but they also build a nuclear fission power plant. https://en.wikipedia.org/wiki/... [wikipedia.org]
If UAE thought they could get the energy they needed from solar PV then they'd not likely provoke international outrage from building a nuclear power plant. I know people will make accusations that the nu
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Spent MOX fuel from PWR has plenty of plutonium and isn't recycled a second time AFAIK.
Fast reactors can burn most of it, but they are also very easy to repurpose to breed more of it. Every fast reactor is a proliferation risk. The non proliferation arguments always assume it's used as designed, but it's almost impossible to prevent a contained fertile fuel assembly being put in the core or blanket. The normal fuel being proliferation resistant is then irrelevant.
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Prevention of using a nuclear power plant to breed weapon grade material may be difficult but detecting it is trivial, it can be detected from space.
Breeding weapon grade material requires short fuel cycles, far shorter than any power plant could tolerate and still remain profitable. When a nuclear power plant shuts down a reactor to swap out fuel the heat output drops, and it is this heat that satellites in orbit can detect. This could be so blatantly obvious that it doesn't require some military grade h
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If UAE thought they could get the energy they needed from solar PV then they'd not likely provoke international outrage from building a nuclear power plant.
This is a very confused and weak argument.
There is no outrage from just acquiring a nuclear power plant using the existing world system of fuel management (buying enriched uranium from existing producers, and regular monitored spent fuel storage on-site).
And idly speculating that UAE doesn't think solar energy is feasible as a power source because they also are interested in an expensive nuclear plant is bizarre projection. You have argued that nuclear power provides ideal base load in combination with sola
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You mean this UAE?
https://u.ae/en/information-an... [u.ae]
Major rethink (Score:5, Insightful)
"But, when it comes to fuel, airports around the world are having to have a major rethink..."
No, aviation needs a major rethink. Remember when all these cheap flights started? It's because airlines don't pay taxes on fuel and are officially held out of the pollution records.
These cheap flights were not for people, they were for businesses to make a profit and let society clean up the mess.
It is time these companies are held accountable.
Re: Major rethink (Score:2)
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Some jurisdictions tax aviation fuel, but many others do not.
Removing taxes on aviation fuel is one way for countries to indirectly subsidize their national carrier.
This is a form of lemon socialism [wikipedia.org].
Re: Major rethink (Score:4, Informative)
EU Energy Taxation directive (2003/96/EG) prohibits taxation of commercial aviation fuel. The EU doesn't tax aviation kerosene at all.
Also the ICAO directive from 1944 prohibits taxation elsewhere than in the source country. However, there is a bunch of bilateral agreements that planes from country A are tax exempt in country B.
So, hobbyist aviation fuel is taxed at the pump, probably yes. International flights : no.
Re: Major rethink (Score:5, Informative)
The ICAO directive prohibits taxation of fuel that is in the tanks on arrival, not on what is fuelled before the departure.
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That's what I tried to phrase, very clumsily...
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Yes, that is exactly what I'm telling you.
> Kerosene is indeed entirely tax exempt
https://www.uecna.eu/aviation-... [uecna.eu]
https://citizens-initiative-fo... [europa.eu]
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No it's not. No fuel is taxed at the pump in airports. It's taxed based on classification of flight, and international flights generally have aviation fuel completely tax exempt based on air-services agreements between nations (the same agreements that allow airlines to land at certain airports).
The closest anyone has come to taxing aviation fuel for international flights is for intra-EU flights but even the EU Energy Taxation Directive limits the ability to tax to private aircraft, and any fuel other than
Re:Major rethink (Score:4, Insightful)
These cheap flights were not for people
These cheap flights have directly lead to flying becoming a commodity. To say they "weren't for people" is just stupid, just because someone profits doesn't mean others don't benefit.
You can't solve global warming by telling someone to stop doing something completely. Human nature says that will get pushback, and this in a topic where any pushback is devastating to a project outcome.
Scenario: Your favourite political party makes flying too expensive for common people.
Result: Common people will vote for the other guy because they are sick of being disenfranchised by the rich. That other guy exists by the way. He is a real person. Every country has politicians who believe global warming is a myth (or say it is) just to get votes. The end result achieves nothing other than putting lunatics in power.
You need to think of a solution to flying, not an abandonment of it.
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The issue is that it's much harder to build a high speed rail link over land, than it is so set up a flight over it.
If we want to solve this, we need to get really good at building new high speed rail links. Ideally maglev, but wheeled can work too. It's possible, China did it, but maybe you need a dictatorial government that can just move people out of the way.
Unfortunately, we are beyond bad at infrastructure projects in many developed nations. The UK is a great example - it's planned northern high speed
Re:Major rethink (Score:5, Insightful)
Without the cheap flights and the conspiracy to destroy public transportation we'd have had the rail by now due to overwhelming demand.
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They are more convenient alternatives, but they are not superior. The emissions involved in transporting people by rail are much less than by air, and those emissions affect the quality (and amount!) of life for rich and poor alike.
After WWII Europe had a bunch of holes in it, and it was cheaper to build trains and small cars than a shitload of large cars. Today their per capita emissions are much lower than ours despite having a generally comparable lifestyle, and we're the ones who have to change most if
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After WWII Europe had a bunch of holes in it, and it was cheaper to build trains and small cars than a shitload of large cars.
There was a desire to do the American model of bulldoze everything nice and put cars in everywhere, but the lack of money (and in some cases such as London, massive concerted local opposition) put paid to that. Ironically, having lots of money freed America up to make the mistake everyone in power seemed to really want to make.
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Small cars were common in the US as well until the 70s when CAFE standards championed by environmentalists forced the US to buy bigger cars.
Before American cities 'bulldozed everything' for cars, light rail and bus was a thing (some cities still have them). However they weren't nearly as efficient (both in total cost and time) as a car.
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Cost is a significant reflection of total fuel consumption in a system, emissions are just a proxy for fuel consumption. If your train ticket is more expensive than a plane, it is because fuel costs and thus total emissions within the train system are likely equal if not higher (whether that is through the construction of the rail network, the steel in the rail and the woods in the girder or the cost of electric transport).
If you find a more efficient way of doing something, then your costs (in a competitiv
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Unfortunately, we are beyond bad at infrastructure projects in many developed nations. The UK is a great example - it's planned northern high speed rail link has now been reduced to a
We are not universally bad: it does depend on who's running it and the Tories are especially poor at it. I mean they do brag about being terrible at their job, and I guess in this instance they were actually telling the truth.
Crossrail opened recently (a bit over time and budget, but nothing out of the ordinary for a project o
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What is the cost of building rail (maglev, lol) networks to all major and minor cities. Right now TGV, with all its tax deductions and stolen land costs anywhere from 4-10M Euros per km just for the construction.
That's a Boeing 747 plane every 10km, or about 10 planes for every link you want to set up. You haven't included the cost of the actual railcars, the stations, the power lines and power consumption, the maintenance etc.
Trains work great if you have something heavy to move and you don't need it fast.
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We made the mistake of taking the cheapest option already, that's why we are in this mess.
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Yeah, because the political instability of countries taxing each other would be so much better. There is a reason airplanes and ships are not taxed except in their country of origin. Cheap flights started due to deregulation, nothing to do with taxation. You want cheaper trains, deregulate it, the problem is the full cost of high speed passenger trains is higher than that of flights and since passenger train networks are built by and for the government, they also don't really pay taxes, they are funded by t
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Cars aren't taxed on the fuel in their tanks when they enter a country either.
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Cheap flights happened because the expensive seats subsidized them.
The people in first and business class basically paid for the entire flight - economy class was just about extracting the last bit of pure profit. No one cared if the flights weren't full and that's why they could keep reducing prices - each additional seat filled was just profit.
Of course, that was pre-pandemic. These days, the business and first class travellers aren't paying full fare anymore as businesses decide they don't need to send e
No. Hydrogen will not work for aviation fuel. (Score:3)
Airplanes use the wings as fuel tanks because they are already hollow structures and can be easily adapted to hold liquid fuels. These wing tanks can't hold up to liquid or compressed hydrogen. Compressed hydrogen would just burst the tanks. Liquid hydrogen might also burst the tanks from boiling off but even if that was managed then the wings could easily ice over. Putting the tanks in the belly of the aircraft would add all kinds of complexity, decrease cargo volume, and generally create all kinds of a mess on getting the aircraft operational. This would take a lot of testing to get certified to fly even if starting with a well tested airframe. The rules are different for cargo and military so this is often where new things are tested, and that might shorten the testing and certification some but if anything crops up that could be a deal killer for passenger service then that could make the design a money pit than a profitable product.
What is even sillier than considering hydrogen as a fuel is thinking fuel cells are some improvement. Just burn the hydrogen in a jet engine and be done with it.
Consider what it would take to get a fuel cell powered airplane flying. One big problem is keeping the fuel cells cool. Maybe the fuel cells could be in the wings to give plenty of surface area and airflow to work with. That works when flying but on take-off power is at full with little airflow to speak of. Maybe the heat won't build up to levels to cause a problem if getting airborne soon enough but there is the matter of an aborted take-off. What then? Dump some liquid hydrogen to cool them off? Now you have a highly flammable gas to deal with, can't just dump that. Maybe flare it off? I'm sure an open flame out the top of the airplane as it taxis off the runway will be comforting to passengers and safety regulators alike.
Here's an idea... Put the fuel cells in a kind of tube hanging under the wing. Have a fan in front to blow cool outside air over the hot fuel cells. We don't want to waste that heat if it is possible to recover some energy from it. So maybe put a turbine fan of sorts on the exhaust on the back. To make this real simple mechanically just put the fan on the front on the same axle as the turbine on the back. For a bit of a bonus on energy conversion of this heat off the fuel cells maybe we could oversize that front fan a bit so it can provide some extra thrust on takeoff. Does anyone see a problem here? I do. At this point the fuel cells are largely redundant, just burn the hydrogen with fire and use the hot exhaust gases to spin a turbine, then use the power of that turbine to spin a big fan in a duct.
Maybe with hydrogen as a fuel there may be a use for fuel cells as some kind of auxiliary electrical power but this is also a solved problem on most aircraft that use kerosene as a fuel. What they do is have a small turbine in the tail of the jet to spin a generator, a bit of a bonus on this is that with a turbine already spinning this can run hydraulic pumps, perhaps some kind of air handler too for cabin HVAC and/or air to get the main engines spinning without some heavy electrical motor and wires. This small auxiliary power unit saves a lot on fuel consumption and wear of the large main engines when the jet is idle, it's also a nice safety redundancy in case of a main engine failure as the APU can take some load off the remaining engine so that power can be used for thrust than pumping hydraulic fluid and such. It would be interesting to get some specifics on how a fuel cell aircraft works to manage things like cooling the fuel cells, power management in case of some failure, protection of the passengers in case of a fuel leak, and so much more. The planning for hydrogen fuel cell aircraft has gone on long enough now that there should be some engineering plans to examine.
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The thermal leakage per m2 of tank surface is dwarfed by the power the engines consume, if you're worried about extra icing add some heating wires.
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The thermal leakage per m2 of tank surface is dwarfed by the power the engines consume, if you're worried about extra icing add some heating wires.
The tanks on aircraft are often the wings, so that makes the surface area quite large. When not flying the tanks will still be taking in heat to boil off fuel but there's not much engine power to consume this fuel that is boiling off. One solution is to vent fuel, and that introduces a lot of questions that need answers. Another solution is to have the tank heavy enough to take on the added pressure, and that introduces different questions. Heaters will certainly keep the icing away but then add to the
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The heaters will have little impact on the heat flux into the tank, ambient minus ten or ambient plus ten on the other side of the vacuum insulation isn't very relevant for liquid hydrogen temperatures.
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You make the plane longer. The fuel is now in the fuselage, but there is more space there. The wings are now proportionate much lighter because they have no fuel in them, with an added extra because hydrogen is more mass energy dense than aviation fuel so there is another saving.
Keeping and delivering the hydrogen cool is one problem; warming it up again in a controlled manner is another. But many of the pieces are getting there. Airbus have tanks, have a jet engine, an electric prop (for a different plane)
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The wings are now proportionate much lighter because they have no fuel in them
No, the wings are heavier because they have no fuel in them.
By putting the fuel in the wings the lifting force of the wings is now directly under the weight of the fuel. For many passenger jets the weight is roughly in three equal parts, airframe, passengers and cargo, fuel. You are taking 1/3rd of the weight that the wings have to carry off those wings and now putting it where there is already a large mass that needs to be lifted. To get the wing to hold up to this redistribution of weight means the win
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Nitrogen oxides cause 265x more warming effect than CO2. The big problem with jet aircraft is high altitude N2O emissions, and these are a direct result of trying to achieve higher thermodynamic efficiency by increasing the turbine inlet temperature. If you want to reduce them you have to reduce thermodynamic efficiency.
This is basically why they want to get fuel cells working, along with the potential to recover more energy from the fuel (though gas turbines at high altitudes are surprisingly efficient). I
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The real problem is preventing hydrogen from acting like fuel. It wants to burn. A fraction of a millijoule will set it off.
I worked around the stuff for too long to ever trust it.
Pipe dream (Score:2)
Even is that idea works, with the lifetime of airplanes and the complete absence of a compatible airplane design, it would take 30-50 years for anything to come from this.
Re: Pipe dream (Score:2)
Coincidentally, 30-50 years is the same timeframe that batteries should have sufficient energy density for airliners.
This isn't based on some massive breakthrough or lab experiment announcement that's never heard about again. Since the 1950s, batteries have increased in energy density (Wh/kg) by 3-5% per year when you average any 10 year span. There have been jumps and stagnation, but average any 10 year period and it's 3-5% per year. Simply assuming the plodding pace of industrial advancement continues as
Volumetric energy density (Score:2)
Not going to happen (Score:2)
Completely redesign and viable only for very short haul domestic flights.
Good luck with that.
Seems like an utter waste of time (Score:2)
For all the effort trying to get hydrogen to work in aircraft and the questionable benefits, it is probably better to manufacture e-kerosene, i.e. a synthetic fuel made from hydrogen produced by renewables and captured CO2. It's still nowhere close to as efficient as direct energy use via battery but for aviation battery energy density has some way to go before it's viable .
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Sure, that and unicorn farts. E-kerosene currently costs around $13.40 to produce (and production consumes about 4x as much carbon as it reduces) and the most optimistic takes is that this will reduce in cost to $6.70 per gallon by 2050.
Compare that to the current $2.80 cost of kerosene. Like the failed corn ethanol experiments and all other failed carbon reduction experiments, you can't just wish yourself to a better future.
Ticking Time "Modules" (Score:2)
Sure, let's load Heathrow and other airports up with these ticking 4-day timeb... oops, "modules". Nothing could possibly go wrong.
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Do you like handling LH2? (Score:2)
Because it takes a lot of insulation, embrittle metal, reacts to almost everything. Other than that, it's fine.
Very awkward to work with. (Score:2)
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I remember reading books from the 50s and 60s with designs for nuclear powered aircraft, cars, trucks etc. Once you have an unlimited energy source, you don't need to worry about the add-on weight as much. The energy density of a nuclear battery is 100 times higher than a chemical battery.
You can get micro-nuclear batteries for electronic applications sufficient to power microcontrollers for decades or even centuries, we have plenty of nuclear submarines with tiny reactors that can still deliver several MW
we're already doing this (Score:3)
It's inconvenient to fuel up on pure hydrogen, because it exists as a gas and must be compressed, requiring large, HEAVY storage. The answer to that of course is to convert it to a liquid or solid for storage.
And for that we have :"hydrocarbons" - ie jet fuel and gasoline. Storing hydrogen in liquid form.
So trying to run off gaseous hydrogen is probably the wrong approach. Instead, you need to come up with a better way to store it. Hydrocarbons do this really well, probably about as good as it's going to get. So the challenge moves on to how to produce it, and how to use it.
We're currently working on producing hydrocarbons from solar. So while that's being worked on, lets addres the other half of the problem: What to do with the waste product, rather than vent it into the atmosphere. Most of what's produced (besides water) is carbon dioxide and carbon monoxide. We're pulling oxygen from the air to combine with the hydrogen, and the waste is water which is fine, but it's the carbon that's the problem.
If you can find a way to get the carbon into solid form rather than combining it with two (or one) oxygen, you will be fabulously rich and we will all win. It'll lower the energy density a little bit, but that won't be a big deal in most cases. It's strange that I don't really see anyone working on this? You can be the first!