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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.
Pure H20 is so corrosive you need special tubing for it. You sure this is a great idea?
This sounds suspiciously like a perpetual motion machine.
I understand there is a lot of energy which must be dissipated during braking, but enough to make water in flight?
Hydrogen in aircraft? What could possibly go wrong? https://en.wikipedia.org/wiki/Hindenburg_disaster
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.
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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.
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.
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.
Doesn't anyone remember the Hindenburg disaster?
Besides Hydrogen waste more energy than.
First you have to split water.
Then you need to compress it to a liquid.
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.
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.
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.
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
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.
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.
Nazi Germany made a Hydrogen fuel cell almost 80 years ago. Maybe you've heard about it.