A hydrogen-powered air taxi flew 523 miles emitting only water vapor | Hacker News Reader

A hydrogen-powered air taxi flew 523 miles emitting only water vapor

popsci.com

72 pointsgeox87 comments

This is pretty cool. They built the taxi to do battery operated flights, with the longest flight so far was 150 miles at a top speed of around 200 mph.

For reference, 500 miles is the distance between San Diego and San Francisco. That’s a 90 minute flight that would take closer to 2 1/2 hours with this air taxi. So I suspect that this demonstration is less about any sort of aspiration to replace batteries and fossil fuels with hydrogen, and more a demonstration of an operationally clean burning fuel.

The criticisms that hydrogen is environmentally expensive are valid, but what’s interesting is that the operational use of the vehicle, whether it’s battery or fuel cell, is effectively emissions-free. When the operational fuel is clean, emissions improvements can be centralized. That’s a really big deal.

https://www.jobyaviation.com/news/joby-progresses-next-phase...

If it's a taxi service, is there a chance that +90 minutes for security and baggage could be avoided to make the door to door time more comparable?

You still need to make sure that no one except the pilot can take over the controls and that nobody is secretly loading up the VTOL with bombs in their luggage with the intention to crash it into the side of a glass skyscraper.

Then there is the safety of the passengers. If you and the pilot are the only ones in the aircraft, there is not much risk to yourself, but if the pilot dies, then the aircraft must land autonomously. If there is a group of passengers, then a terrorist could take the passengers hostage. So you still need to check for weapons and explosives.

The only case where you could get rid of security is with a fully autonomous aircraft that carries no luggage and only a single person.

This is a weird assumption, see my comment above - there already exist a bunch of airplanes operating in the US with no TSA. Also, what’s the point of bombing small airplanes? Why not to bomb a bus instead? The impact would be larger.

Americans have a massive blind spot to anything that happens as a result of driving a vehicle.

40k+ deaths/year and unlike the rest of the developed world, its increasing, and you can barely even start a conversation about better managing the size of the cars that are sold these days.

you're kidding, right? everyone I know both online and IRL complains constantly about how big cars have gotten as a result of the CAFE regulations

It’s not too expensive to buy your own small aircraft

This is already the case with a bunch of small plane airlines. They are also reasonably priced (compared to chartering). I personally love JetSuiteX (JSX) and the experience is truly incredible, with just 5 minutes to board the plane from entering the hangar. No TSA, no BS. There are a few more with similar service, but as far as I know, JSX was the one that found the loophole in the regulations that allowed them to run their operations this way legally. Proliferation of small aircraft cheap to operate will make this model ubiquitous.

Edit: typos

> is there a chance that +90 minutes for security and baggage could be avoided to make the door to door time more comparable?

Blade in New York flies through high-security corridors. Check-in is like a minute. (Counterpoint: I regularly show up to my small-town airport fifteen minutes before boarding is scheduled to start, although that precludes being able to check a bag.)

That said: you can’t easily take out a building with a helicopter. That may not be true with a tankful of 700-bar hydrogen.

I'm betting the hydrogen is actually a lot safer than a tank full of jet A. (not to defend using hydrogen, which in these applications seems to be a meme perpetuated by politicians/oil companies)

Since you are already betting, how much will you bet with me?

Define the bet and how we're going to test it, but I'll stand by my statement. Jet A is probably worse for buildings than high pressure hydrogen in an impact.

Jet A probably is worse for buildings, but compressed hydrogen gas seems a lot worse for the people on the plane and people near the plane when it is on the ground. Methane, ethane or propane also seems worse for the same reason, namely, they need to be at very high pressures for the tank to be small enough to be economical on an airplane.

Liquid Hydrogen is not a lot of fun. Anything with an 700:1 expansion ratio is a stored energy hazard in and of itself, but because it's cryogenic it also means the cumulative daily loses in tanks where cooling is not actively maintained will be a constant annoyance.

They seem intentionally coy about how the 523 miles where flown, seemingly just above Marina, CA. They have requested that flight tracking not be publicly shown on flight aware.

You might be able to find them on ADS-B Exchange, either live or in the historical data sets. They are somewhat famous for only using citizen-sourced ADS-B data and refusing all requests to delist or hide data (allegedly anyway).

It looks like their tail number is N542B but I'm not sure how to translate that to the ICAO hex codes that they use to archive their data nor exactly what date and location the flight took place. Some more sleuthing would be required.

https://www.adsbexchange.com/products/historical-data/

N542BJ is the tail number (not N542B,) flightradar24 has the Mode S code listed even though the flight data is locked there. https://www.flightradar24.com/data/aircraft/n542bj#

Some test flights around 6/23 - 6/27. Looks like a pretty boring way to get 523 miles. They should fly the loops over the Indianapolis Speedway instead.

https://globe.adsbexchange.com/?icao=a6df7c&lat=36.689&lon=-...

I wonder if the the high-pressure, non-cryogenic hydrogen tanks used in some cars and buses would work. That technology seems to have solved the major issues, although I suppose aircraft crashes could introduce some additional problems.

Toyota has some detail about their system, which is similar to systems used by Honda and Hyundai, at: https://www.toyota-europe.com/news/2015/hydrogen-is-that-saf...

The Hydrogen in our supply chain also comes from petroleum so it’s more dangerous, more expensive and less green than any other alternative. Its would literally be more green to burn coal.

Cost to produce H2 from water, 50-55 kWh/kg Cost to liquefy H2 is 10-13 kWh/kg 1 Kg of H2 stores about 33 kWh of energy. More than 50% of the energy is wasted before transport, storage, boil off etc are concerned.

H2 does not make any sense whatever.

Well, the article actually admits that 95% of hydrogen produced in the US is from hydrocarbons, and thus produces lots of CO2.

And if you think about it for a minute: Do CO2 emissions that occur miles away from where I'm standing right now really even exist?

Just give me an electric train for that distance...

It makes better sense than curtailing solar or wind production. 50% is better than zero.

That being said, hydrogen is usually the worst option, but I don't think that's true for every scenario.

If you had all of that H2, what is the additional cost to just fix some CO2 into hydrocarbons?

It feels like that would be a much simpler way to get to net zero than having to reinvent all of the infrastructure.

So much simpler that I wonder why anyone would keep trying on hydrogen. Which makes me darkly suspect that the goal is to take our attention off the solution that's already being deployed, i.e. wind and solar.

Regardless of net efficiency, that still entails collecting CO2 at a central facility (where it could have been dealt with in other ways, such as injection underground) and sprinkling it through the air as you fly over delicate ecosystems. I'm sure bankers see both as net zero, but condors might have more issues with your simpler workaround.

> sprinkling it through the air as you fly over delicate ecosystems

I wouldn’t be so sure spraying water vapour is innocuous. As long as it’s atmospheric CO2, the environmental impact of synthetic fuels is much less than rebuilding the world’s air fleet and fuelling infrastructure to accommodate hydrogen.

It takes a lot of energy to pull CO2 from the air since it is only 400ppm. It also takes energy to make hydrocarbons. This means they will be really expensive. They might be used for classic cars but can’t replace fossil fuels.

Hydrogen or ammonia have advantages that can be made from water and nitrogen. Ammonia may be good for ships and planes since can be liquid at cold temps. But can’t substitute in cars.

>1 Kg of H2 stores about 33 kWh of energy

as horrible as Hydrogen is, isnt that still ~two orders of magnitude better than li-ion? Pressure vessel will probably bring that down to one order of magnitude.

In cars where weight doesnt matter that much Toyota, leader when it comes to pushing BS hydrogen, is only able to get Hydrogen Yaris to do 10-14 Fuji laps https://www.youtube.com/watch?v=DGL5g91KwLA thats 45-60km of range on Hydrogen.

That gravimetric energy density is about 2 orders of magnitude higher than lithium ion batteries.

The difference in volumetric energy density is not that big though, and hydrogen is not as flexible as jet fuel or even batteries when it comes to how you can store it in the vehicle.

To be fair, high gravimetric density is a fairly large advantage for an air plane. But the bad volumetric energy density does present some serious challenges.

So why it’s not used in rockets?

It was used in the Space Shuttle and SLS uses the same engine as the shuttle.

Also nobody launches to orbit using lithium ion batteries as main propulsion.

> Also nobody launches to orbit using lithium ion batteries as main propulsion.

It can be part of the main propulsion.

https://en.wikipedia.org/wiki/Rutherford_(rocket_engine)

https://en.wikipedia.org/wiki/Electric-pump-fed_engine

That's why I phrased it that way.

Most internal combustion engine cars have a lead acid battery to start it up and run the spark plugs (or preheat the glow plugs if diesel). They don't get called "hybrid" or "battery powered" because the batteries aren't the propulsive power themselves.

This is akin to that: the batteries run the pumps, they're not the propulsive system itself.

Ion drives can be run off battery, but you can't launch with those.

Unlike a car battery though, these batteries provide a not-insignificant part of the energy that is generated by the engine. Each Rutherford engine generates around 37 mega-watts of power at sea-level (24900 N and 3.05 km/s exhaust velocity, Power = 1/2 * Thrust * v_e) and there are nine in the first stage. The first stage battery provides around one megawatt [1].

That's about 0.3% of all energy generated by the engines, which is significantly more than what a spark plug does in an ICE.

[1] https://theaeroblog.com/the-rutherford-rocket-engine-the-fir...

This is the closest we have to electric power directly powering the ascent of a rocket from Earth.

Something like a HyperCurie engine (which is also electric pump-fed), could probably lift off from a planetary body like the moon. When they used it in orbit, they actually had to wait for the batteries to charge up from solar panels between each engine burn.

> not-insignificant

> 0.3%

> the closest we have

I don't understand why you're trying to paint the battery as a significant contribution here.

Like a car battery, although it's neat that they consider it as part of the engineering, it's none of the actual thrust unless it explodes.

It is about 1 megawatt (1341 HP) of the power pushing the rocket into the sky (directly translated into exhaust velocity and therefore thrust). That would be like a spark plug generating 1 HP in a 300 HP engine (Which would exhaust the typical car battery in about 1 second if it could even push that much power out).

It is all semantics anyway.

Correction: It won't drain in a second. But my point is the same. We don't really have 1 HP spark plugs out there :)

Rough estimates I've seen say the starter motor is about that, though. (Not that I can tell real pages from GenAI ad content farms, I'm not a petrolhead).

I'd agree "it's all semantics", but yours are confusing me :P

(And for energy content, like for like is comparing the size of the fuel tank with the capacity of the battery, but cars aren't 90% fuel by weight).

How many kg’s to orbit/year vs other fuels?

But according to HN armchair engineers, electricity will be free, nay, negatively priced in T+epsilon as exponential decrease in solar panel prices actually turns them negative. Or maybe even imaginary.

THEN it definitely makes sense.

Wholesome energy prices do in fact turn negative. But then you store it in batteries and use it when they flip positive again. No complicated, expensive, delicate, dangerous, cryogenic fuel systems required.

Storing it in batteries works for short periods of up to maybe a few days.

You don't think there will be seasonal mismatch between renewable generation and electricity demand?

Because if there _is_ a seasonal mismatch, hydrogen will be needed anyway.

Even 7 day storage will likely need hydrogen

https://energy.economictimes.indiatimes.com/news/oil-and-gas...

H2 doesn't make sense for a lot of things it's promoted for (see Michael Leibreich's Hydrogen Ladder for detail on this) but this is one area where it makes some kind of sense.

https://www.linkedin.com/pulse/hydrogen-ladder-version-50-mi...

There are times it makes sense - when you have a remote location you need power in that is more than batteries can provide for example. Say you need 300kW in a farm miles from the nearest supply for 3 months.

Why on earth would you want to maintain cryogenic fuel systems and delivery systems in a remote location?

Because you need power. And it’s not rocket science, it’s a shipping crate. The deliver system is a standard lorry, top it up with a can with some conpressed bottles in the back.

If you're delivering your electricity through hydrogen by lorry, you'll be cheaper just building out a transmission line. Or building 20x the number of solar panels so that you're good even on cloudy days.

For three months? Maybe not. Getting right of way to run power lines is no joke.

As someone who has done this with both diesel and green hydrogen, no it’s not cheaper to run power, nor provide multi-megawatt solar provision

From what I’ve read, liquid hydrogen isn’t a great option due to the energy required to create it. Where does that energy come from?

Commercially viable hydrogen production starts with methane, goes through a combination of "steam reforming" followed by "shift reaction." So far as I know, liquefaction involves essentially mainstream cryogenic refrigeration.

And the energy for that comes from where?

Probably more methane. As mentioned in the neighboring post, hydrogen is an energy storage mechanism, not an energy source. It's also a feedstock for some other chemical processes.

Unless we can tap into some sort of "too cheap to meter but too hard to transport" energy source in the future.

I recently learned there are natural hydrogen deposits: https://en.wikipedia.org/wiki/Natural_hydrogen

This isn't shocking, given that there's hydrogen in the atmosphere.

I naïvely would have expected that's entirely from chemical reactions like lightning strikes.

Ah good point, I hadn't thought about reactions above ground.

Hydrogen is just a “battery” for energy storage. The ultimate goal is to produce “green” hydrogen by cracking water using solar energy - either via photovoltaics or developing a way through bioengineering photosynthesis.

> ultimate goal is to produce “green” hydrogen by cracking water using solar energy

It’s miraculous how the gas industry succeeded where clean coal failed.

There will be no green hydrogen. It’s a veneer. That the same folks building LNG terminals are pushing hydrogen isn’t a coïncidence. Even if we get a green hydrogen economy, there will constantly be an incentive to adulterate the supply.

Can be from solar cells, the cheapest option today.

Green hydrogen (from renewables) is not the cheapest option to my knowledge. In fact it is not yet cost-competitive.

The electrolysis process is not still efficient today (but improving) and does not yet have scale, and the cost is several times SMR-produced hydrogen.

Most economical hydrogen is produced through SMR or as a byproduct.

That could be true, but the question was

> From what I’ve read, liquid hydrogen isn’t a great option due to the energy required to create it. Where does that energy come from?

and to get the cheapest energy, not the cheapest hydrogen, today one would surely consider solar.

Having said that, hydrogen could be interested as more ecology friendly fuel, which may rule out the commercially cheapest, but not clean enough, options.

To produce 640 tonnes of renewable hydrogen per annum takes: https://www.energy.gov.au/news-media/news/australias-first-l...

Current project status: https://arena.gov.au/projects/yuri-renewable-hydrogen-to-amm...

Related (Australian) hydrogen energy projects: https://arena.gov.au/projects/?technology=hydrogen

(and a few other largish projects with no government funding)

That's great. How horrible was the process of generating the fuel to only emit water by the final link in the energy chain?

You don't seem to realise that that process happened far away from where we are. Maybe even in a different country.

So when you think about it: Did it even really happen at all?

Greenwashed hydrogen?

The production and use of hydrogen in transportation requires 4x more energy from the electric grid than EVs - and there are people claiming the grid can't handle EVs (they're wrong - but that's another point). What the grid can't handle is hydrogen. Between Microsoft and Google battling over AI, the claim that the grid can handle EVs is being cast into doubt.

None of this is even getting into the consumer issues with hydrogen - of which there are plenty.

Hydrogen may find a use in long distance haulers and heavy-duty construction equipment (think replacing big diesel engines), but it's never going to get a strong foothold on personal transportation.

Note that they never say what the payload was. Was there just a pilot? Was it just remote-controlled? (I'm guessing just the pilot, but that's less than useful except as a personal transport, not a "taxi".)

Generation, transmission, storage and local consumption of energy, are separate problems. Hydrogen probably makes sense in the long term, it can be transported in pipes, can quickly refill a local users tank and is not going to create a monstrous waste recycling problem.

>it can be transported in pipes

how long do the pipes last before crumbing? and how long do the pumps last? Toyota cant even make a hydrogen car fuel pump last more than 7 hours.

We’re not even using hydrogen, the most dense fuel, in rockets. Why would you use anywhere else? Cars, trucks, EVTOLS and even planes are getting batteries which are superior in most aspects.

Apart from the SLS, Ariane 6, Japan's H3 Launch Vehicle, the Russian Angara's KVTK stage, the Saturn V 2nd and 3rd stages, and several others which do/did all use hydrogen.

How many kg’s to orbit/year vs other fuels? It’s close to 0. If hydrogen is too complex for space, don’t even dream using one for cars and planes.

% of kg to orbit doesn't tell you much about the complexity, especially given that SpaceX is approximately half of the global total mass to orbit all by itself… by doing things that everyone else thought were too complicated.

The fact that vehicles which were retired before I was born managed to use liquid hydrogen just fine, however, requires it to be relatively non-complex.

This doesn't necessarily mean it will win, just that you can't rule it out on that basis.

This is seriously impressive to me, if indeed as claimed. I'm no longer skeptical about the successful application of hydrogen for power in vehicles.

Buuut will we ever make it truly make sense for vehicles en masse?

Electric trains, people

But would falling passengers count as carbon emissions?

Impressive range! What's the CO2/mile?

It's reassuring to know that the CO2 that will be emitted in the end-to-end process of getting these planes airborne will be occurring somewhere far outside of my immediate vicinity.

"Emitting only water vapor"--which is a much worse greenhouse gas than CO2.

You might want to consider that 70% of the planet is covered with water which emits a lot of water vapor per day, everyday.

Water vapour condenses out of the atmosphere in a matter of minutes to hours. CO2 in the atmosphere has a half-life of 120 years.

Yes and no. Yes, water vapor is more effective at warming than CO2, and is responsible for over half of Earth's total greenhouse effect.

But humans have very little effect on the amount of water vapor in the atmosphere [1]. Emit a ton of CO2 and that CO2 remains in the atmosphere for hundreds of years.

Emit a ton of water vapor and it is gone from the atmosphere in weeks. The average emitted water vapor molecule only stays for two weeks.

So no, as far as emissions go emitting CO2 is much worse than emitting water vapor.

[1] https://climate.mit.edu/ask-mit/why-do-we-blame-climate-chan...

Don't worry, any excess water vapor quickly falls out of the atmosphere.

Literally. As rain.

We need to ban water as its existence makes water vapour possible. Do something.

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