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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.
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.
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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.
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!
So how often do people request their water intravenously on a flight?
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.
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
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.
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.
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?...
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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'
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.