Slashdot Mirror
EasyJet May Trial Hydrogen Fuel Cells For Taxiing (thestack.com)
An anonymous reader writes: Low-cost airline easyJet is discussing plans to install hydrogen batteries as part of a proposed zero emission fuel system, which would power its aircraft during taxiing. The budget service revealed designs for a hybrid plane this week, and said that it would begin trialling the technology later this year. The system will involve embedding a hydrogen fuel cell on board the aeroplanes, with the energy captured from the brakes on landing able to power the jet on the ground. As the only waste product from a hydrogen cell would be fresh, clean water, Ian Davies, head of engineering at easyJet, also suggested that this could be used to refill the planes' water systems during the flight, providing a water source for passengers to drink and for flushing toilets.
Nix the plan, Joe. You need special tubing. I heard it on the Internet.
This sounds suspiciously like a perpetual motion machine.
Only if you ignore the fact that the energy they're re-capturing was generated by the plane's jet engines during flight, rather than by this fuel cell. It's just a form of regenerative braking, no different than the flywheels commonly in use in automobiles today. And they said they'd be using the energy to power the plane on the ground. Water is a natural byproduct of the energy production, rather than the goal.
Five comments in, and the signal-to-LUDD ratio from the Luddites has already dragged the conversation so far below the noise floor that it's not even a conversation anymore, just LUDD LUDD LUDD.
Guess what? Internal combustion engines of any kind will, at some point in the future, become non-viable. We'll have to come up with alternatives or lose much of our transporation capabilities. What they're doing here doesn't have anything to do with propulsion during flight, but at least someone is trying to think outside the proverbial box.
The system will involve embedding a hydrogen fuel cell on board the aeroplanes, with the energy captured from the brakes on landing able to power the jet on the ground. This technique is similar to the high-end kinetic energy recovery systems (KERS) used in Formula One cars, which store recovered energy to later use for acceleration.
TFA mentions harvesting the braking energy as being similar to KERS used in Formula 1. But no mention is made of the additional mass or equipment (unsprung at that) that would be needed to be added to the landing gear in order to harvest that energy. Such equipment needing to be robust and large enough to capture a worthwhile amount of energy in the 10 seconds of braking that a plane experiences when landing. For the rest of the 99.9999% of the flight this is dead weight that the plane has to burn fuel in order to carry it around.
So color me surprised if anyone really thinks that is practical. (let alone the bizarre notion that the recovered energy could somehow be funneled into a hydrogen based fuel cell - super cap yes! fuel cell ? are you kidding me?)
It would probably make more sense to assign a tractor to drag each aircraft from the gate to the start of the runway rather than use the planes fuel to taxi around.
I am Slashdot. Are you Slashdot as well?
Hydrogen in aircraft? What could possibly go wrong? https://en.wikipedia.org/wiki/...
We should ban that jet fuel stuff too while we're at it! Have you seen how dangerous it is?! https://www.youtube.com/result...
Pure H20 is so corrosive you need special tubing for it. You sure this is a great idea?
You'd also need special humans for it. Pure H20 cannot be consumed by humans . It is however good for lead acid batteries. The solution is of course is a re-mineralization process.
Ah yes, I think of that every time I see people exploding after they drink distilled water.
If only there was some way to carry a tank of brine solution on board an aircraft...
W..w..W - Willy Waterloo washes Warren Wiggins who is washing Waldo Woo.
Distilled water will kill you if you drink too much of it.
putting the 'B' in LGBTQ+
Not mentioned in the blurb is that this also includes putting motors in the plane's wheels and adding controller hardware. That's going to add on weight to the plane, as I can imagine a set of electric motors (and associated gear trains, etc) that can move a plane that weighs something like 100,000-150,000 lbs are exactly "light". Plus there is the difficulty of packing it all into the landing gear, where there's not exactly a lot of room. You could do a hydraulic drive of some sort, but then you have the pump and motor sitting somewhere, too, plus the weight of the hydraulic fluid.
Less sexy would be to develop a tug that could not only push the plane back, but also perform taxi duties. You could have that thing run on batteries, fuel cells, etc -- and you don't have to fly it everywhere with you.
You're a loon if you believe for even a second that drinking distilled water cannot be drank by humans. The amount you'd have to drink to have any ill effects in insanely high. So keep telling yourself that distilled water is bad as you keep swilling mountain dew and cheetos.
Any water will kill you if you drink enough of it.
Oh no... it's the future.
You'd also need special humans for it. Pure H20 cannot be consumed by humans [...]
Life Hack: Pure H2O becomes safe to drink by adding a sticker that says; "Gluten Free".
I tried it and it totally works!
Bought into the bottled water mafia hey? I grew up drinking distilled water. Many people in my home town had distillers.
Yes, I know there is already a lot of explosive stuff on the average plane, including the door bolts (tell that to the next nervous seatmate you need to avoid). But hydrogen is so memorable in the storied history of aviation. Customers will freak. For economizing on ground time, so much cheaper and simpler to have more and better tugs.
Not sure I want any part of the plane, including landing gear, to be any more complex than absolutely necessary.
pr0n - keeping monitor glass spotless since 1981.
The cycle from electricity to H2 generation, storage and burning in a fuel cell is only about 22% efficient.
This seems like a lot of trouble to go to on a very inefficient process.
Might be better to use batteries to capture the electricity (and these can be supplemented on the ground by plugging it into the grid). Electricity to battery round trip can be better than 90% efficient.
I don't read your sig. Why are you reading mine?
So how often do people request their water intravenously on a flight?
That link has to do with over drinking water related deaths such as water drinking contests.
It has nothing to do with pure/distilled water.
There are tons of companies selling distilled water systems for home use. My sister and her husband have one and have been using it for almost 20 years and they have not even once died of water intoxication.
How many hundreds of pound will this add?
It's not clear to me how having a battery on board is going to move the plane from the terminal to runway the and back again without embedding some sort of drive mechanism in the wheels. Unless a fuel cell produces thrust? WTF.
Me thinks the technical details have been utterly muddled by the original FA.
When Fascism comes to America, it will call itself Anti-Fascism, and tell you to give up your guns.
You would need so little salt to treat the water that the tank would be insignificant in mass compared to the fuel cell equipment, or even the other food service equipment on board.
This idea has many, many problems with it - but "pure H2O" is not one of them.
W..w..W - Willy Waterloo washes Warren Wiggins who is washing Waldo Woo.
And just to give you some numbers to play with... MAXIMUM recommended dissolved solids in drinking water is 500mg/L. An Airbus A380 carries 1700 L onboard. Thus the weight of the water is 1700kg and if all of that water was grossly overtreated to the maximum limit, you would need to carry 0.85kg in solids with you.
W..w..W - Willy Waterloo washes Warren Wiggins who is washing Waldo Woo.
Any major changes to critical flight systems ( landing gear is one I imagine ) would require some serious FAA and manufacturer test and approval program.
Brilliant idea though.
Pure H20 is so corrosive you need special tubing for it. You sure this is a great idea?
Yet another reason this is a really BAD idea...
1. Hydrogen is an explosive risk when stored
2. Storing quantities of hydrogen sufficient to power anything requires either pressurization, very cold temperatures or both and the equipment to do this is pretty heavy if you wish to avoid the problem #1
3. Industrial sources of Hydrogen cause a LOT of CO2 emissions or are environmentally very unfriendly.
4. Fuel cells are pretty inefficient, so it takes a lot of fuel and oxidizer to obtain a specific amount of work.
5. Utilizing electric power to taxi an aircraft with will require the redesign of a number of aircraft systems, many of which are critical to safety and are subject to very specific regulations. If you use electric motors in the wheels, they will need to not impact the success of the abort takeoff at max weight with no fire test, which I find unlikely. Plus these systems will add a lot of weight in wiring and control electronics, which is the absolute opposite direction you go for designing an efficient aircraft.
6. It will be expensive to operate. You will have multiple fuel types to load, more complex systems to maintain, a heaver aircraft and less useful load. Complexity breeds inefficiency and cost, weight just makes you burn more fuel.
7. H2O is corrosive...
"File to fit, pound to insert, paint to match" - Aircraft Maintenance 101
Distilled water is not isotonic. Go tell hospitals they are loons for using 5% isotonic solution for their IVs.
https://en.wikipedia.org/wiki/Water_intoxication
Osmosis, they taught me that in high school. You?
Did you read the article you linked?
Water is considered the least toxic chemical compound, with an LD50 of over 90 ml/kg in rats
hyponatremia was just as likely to occur in runners who chose sports drinks as those who chose water
So.. yep, it is toxic if you drink too much. So is isotonic solution. The article you linked even cites court cases where hospitals have been sued for causing water intoxication via IV...
Then you need to compress it to a liquid.
Why? High pressure gas might be sufficient.
Have gnu, will travel.
The Internet tubes have already been pre-treated with filth.
Have gnu, will travel.
Pure H20 cannot be consumed by humans.
Flint Michigan public utilities, plz go.
Have gnu, will travel.
BIG difference... As a liquid Jet A is pretty nearly inert, you have to vaporize it to make it burn well, either by spraying it into air or heating it until it boils. It doesn't explode as a liquid sitting in a tank, even if you throw in burning objects. It is REALLY hard to keep hydrogen in a liquid state because of the pressures and temperatures involved in it's storage. Hydrogen gas is highly explosive when mixed with some oxidizer and it's really hard to keep it from doing that. Jet A can be safely stored in vented tanks, where hydrogen is not easily kept from explosive forms and must be stored in closed systems.
"File to fit, pound to insert, paint to match" - Aircraft Maintenance 101
What's the efficiency of jet fuel from pumping to refining to shipping to burning in a jet engine? (Hint: Less than 22%.)
How dangerous can it be? It can't even melt steel beams.
I'm a good cook. I'm a fantastic eater. - Steven Brust
I don't think commercial jets have any internal combustion engines
Umm, what do you think propels the plane? Unicorn farts and pixie dust?
Planes are propelled by burning jet fuel (combustion) within a turbine (internal). You might consider learning what an internal combustion engine actually is before saying something so dumb publicly.
to put some perspective on this (i know this is /. but..)
the galley CURRENTLY has enough salt to "treat" any recovered water. (any in flight service folks pop quiz how many salt shakers are normally stored in the galley??)
Sigh yourself. Did you know that the Apollo astronauts all drink water that came from a fuel cell? Yes, long term you would develop an electrolyte imbalance drinking only ultra pure water (which is not what comes out of fuel cells) much as you would if you ate only food that had all salt removed from it. If you're concerned about it, eat a snack sized bag of chips when you land.
A plane traveling at 500 miles per hour, at an altitude of 40,000 feet, has to lose a huge amount of both kinetic and gravitational potential energy before it's stationary on the runway. If you can capture 1% of this, then you can taxi around the airport for quite an extended period.
Just add, "Calculate this extended period of time" and you'll have one of those math word problems I hated back in school. Will this be on future SATs :-)
It must have been something you assimilated. . . .
LOL, now you are stretching.
No, I'm still using a tank of brine solution - but it only needs to contain a kilogram of actual solids. That's a small tank compared to the 1700kg worth of water that you would otherwise be carrying.
But I'm happy to concede that you could solve this with other means besides a brine tank. Either way, it's a very solvable problem and would not hold up such a project.
W..w..W - Willy Waterloo washes Warren Wiggins who is washing Waldo Woo.
The motors would probably not be geared at all, but mounted right inside the wheels themselves, or on the axle. Large stator with many poles, capable of working well at low (for an electric motor) speeds. Reliable and lightweight motor/generator electronics already exist for electric cars.
Perhaps, but that nasty certification test where they run the aircraft fully loaded at take off speed then abort using only brakes is going to be a PITA to pass. Right now the biggest problem is the tires catching fire from all the heat from the brakes, now you want to add a bunch of wire, insulation, electronics and other junk to the wheel assembly which is already stuffed with brake rotors, pads, hubs and aircraft rubber? If you get the aircraft to actually stop during this test, you'd better bring a large fire extinguisher. (Oh wait, that's not allowed or you fail the test... )
"File to fit, pound to insert, paint to match" - Aircraft Maintenance 101
>> refill the planes' water systems
This is bullshit anyway.
If you drink the water, or flush it, where would you get the water from when you brake at landing ?
>> Hydrogen Fuel Cells For Taxiing
Fuel cells ? Inefficient.
https://www.youtube.com/watch?...
aaaaaaa
You don't need a brine tank. You just shake a salt shaker. Except distilled water will be fine for the glass or two that the average person gets on a plane, especially if they're eating pretty much any other prepared food.
But you can't capture any of the potential energy of elevation (certainly not without affecting flight characteristics - no windmills glued on the plane please). Mostly what you can get is the wheel spin from 200 mph maximum at landing. Well, maybe pop-out windmills to help the air-brakes on landing :-)
He seemed to be worried about the plane's plumbing, so I gave him a solution. The whole post is ridiculous and I'm not sure why I posted a reply. As if containing distilled water were not a solved engineering problem.
W..w..W - Willy Waterloo washes Warren Wiggins who is washing Waldo Woo.
AC...super-genius!
John McAfee 'It was like that time I hired that Bangkok prostitute; to do my taxes, while I fucked my accountant'
How much of that is carried on the airplane? Nobody ever said turbines are efficient. Just that they are capable of powering airplanes. Unlike fuel cells.
John McAfee 'It was like that time I hired that Bangkok prostitute; to do my taxes, while I fucked my accountant'
of course dosage matter. Strychnine in small doses is OK. But it will kill you faster than salt water.
putting the 'B' in LGBTQ+
If everything has already been developed, tested, proved cost effective and if they are ready to deploy it today and apply for FAA certificate, it would take 10 years before they get it. Plain documentation of what the system is, and FAA failure mode review and the maintenance and certification requirements, additional independent testing by FAA... no way they can get a hydrogen fuel cell into a passenger plane in less than 10 years.
sed -e 's/Chuck Norris/Rajnikant/g' joke > fact
Allegiant announced that will do the same thing, and charge passengers a Gee-Whiz Fee for the privilege of being on a plane with experimental technology.
Spirit announced that on each flight, straws will be drawn to determine which three passengers are fed into the fuel cells, generating power and saving weight at the same time. Next of kin will not get a refund on their tickets, however.
The AC I replied to apparently thinks they wouldn't but I suspect they would.
This is a lot of hype that the airline is using to get some publicity, and the idea is interesting, but will not take flight (hah). Taxiing is such a minimal part of the fuel burn, and of low relative cost, that the added complexity, not to mention certification hurdles, extra weight, etc. etc. of a new airworthy component will not be worth it.
You are carrying something with hydrogen (not a huge deal, but extra hurdles), heavy, and interacting with existing aircraft systems.I know of no example (or cannot easily think of one) where a fuel cell is currently certificated as an aircraft operating component (which I believe it would have to be, as described).
Richard Branson wanted to try something similar a decade ago for Virgin Atlantic, with a biofuel powered robotic mini-tugs that would clamp on to the wheels and tow aircraft to the runway. Even that idea went nowhere -- much less something that has to be a part of the airplane and fly. Funny how all the ideas get forgotten and tried again.
It depends, but electrolysis efficiency may be at least 0.70% without heat capture or 0.86% with. Fuel cell efficiency may be around 60%. Which leaves as with 0.42%. It is not perfect, but much better than just discarding all this energy as it is done now.
Only some delusional Musk cult member may suggest to use lithium batteries for any significant energy storage on an airliner. You would waste much more energy to carry them than they can store - airliners are not golf carts. To get 777 over Atlantic you need to burn something like 50 ton jet fuel.
You apparently do not know much about fuel cell technology. The hydrogen can be electrolyzed out of water using solar energy, and there's not much of it at any given time as it is then fed into the fuel cell and converted to electricity and water.
Oh I know enough about fuel cells to understand this, you need hydrogen to run them (Assuming you are using a hydrogen based cell). Hydrogen that has to come from someplace and that must be supplied in quantity with an oxidizer to the Fuel Cell to allow it to produce electrical energy.
Using electricity to split water is a pretty horrid energy waster. I takes quite a bit more to split than you can ever get back from the fuel cell. There are much more efficient, less energy consuming ways to get hydrogen that don't involve splitting water using electricity which are CHEAPER by an order of magnitude.
This idea of getting solar energy to do this is pretty stupid. Where it's possible, it's SUPER expensive to obtain electricity from solar, then if you just turn around and waste all that energy splitting hydrogen from water, you are going to just about double your costs, which where already high. And for what? To run your fuel cell so you can drive your airplane around on the ground?
Forgive me.. I'm just not able to stop laughing....
"File to fit, pound to insert, paint to match" - Aircraft Maintenance 101
Pure H20 cannot be consumed by humans
How pure are we talking, and why?
I got curious and tried to find sources, but I get anything ranging from "IT WILL KILL YOU DEAD BY LEECHING MINERALS OUT OF YOU" to "it's completely harmless due to the amount of minerals you get from eating food".
There are tons of people that have reverse osmosis water filtration in their home, who only drink from this filter. If this is true, then how are they not dead?
What about people that drink distilled water?
How is drinking distilled water different than R.O. water? Aren't they both mineral free from the filtration?
Google isn't much help since most of the results are people trying to sell me things or "NATURAL MEDICINE, CURE CANCER YOURSELF" type shit.
tl;dr I suck at biology
But we only want to get the airliner from the gate to the runway.
I don't read your sig. Why are you reading mine?
Pure H20 cannot be consumed by humans .
Of all the completely ridiculous asinine made-up bullshit I've read on /. over the past decade, this is the tops o' them all.
Pure H20 cannot be consumed by humans .
No problem.
As if containing distilled water were not a solved engineering problem.
Ah, but you're forgetting how utterly corrosive and powerfully toxic pure water is ;-)
Oh, the humanity!
Wow . That was fun.
It doesn't matter what you want, you still need to carry it all the way.
Seriously, the whole idea sounds like an April's Fool joke. Since when airlines do plane engineering? Boeing is working on LNG for airliners, but results are expected many decades in the future.
Looking at the original source now, it was some student thesis with some EasyJet funding, not real project.
no windmills glued on the plane please
What do you think those big things under the wings are? When the throttle is at idle, they're being pushed around by the airflow from forward momentum.
I am TheRaven on Soylent News
any in flight service folks pop quiz how many salt shakers are normally stored in the galley??)
Probably none - why would there be? Salt and pepper packets, sure, but shakers? How 'bout pepper grinders?
[Back when meals were still being served in steerage class, I used to travel with a mini pepper grinder and a sample size of hot sauce. Always improved matters.]