[dehrmann]

> Hydrogen is such a terrible idea it was never getting off the ground.

It's coming from Toyota because Toyota can't wrap its head around not making engines. Ironically, the place hydrogen might work is airplanes where the energy density of batteries doesn't work.

[WalterBright]

> the place hydrogen might work is airplanes where the energy density of batteries doesn't work.

How is that going to work? Cryogenic liquid hydrogen? High pressure tanks? Those don't seem practical for an airplane.

What does work for airplanes is to use carbon atoms that hydrogen atoms can attach to. Then, it becomes a liquid that can easily be stored at room temperature in lightweight tanks. Very high energy density, and energy per weight!

(I think it's called kerosene.)

[TheSpiceIsLife]

Diesel, kerosene, rocket propelled RP1, and fuel oil / bunker fuel in the case of cargo ships.

It’s not a coincidence that where easy of handling, storage safety, and high energy density are needed everything seems to converge on compression ignition medium to long chain liquid hydrocarbons.

[saalweachter]

What if you just, like, put the hydrogen in a big balloon?

[nandomrumber]

Has the hydrogen storage problem been solved yet?

Last time I checked it needs to be stored in cryo / pressure vessel and it also leaks through steel and ruins its structural properties in the process.

[dogma1138]

There are some innovation like hydrogen paste but it’s not going to be useful for a combustion engine cycle.

[idiotsecant]

We store hydrogen all the time for industrial processes. It's not some super science, it's just expensive.

[cheema33]

> Has the hydrogen storage problem been solved yet?

No. Not for using Hydrogen for transportation. People have been trying to use Hydrogen for transportation for more than 50 years. These people are trying to bend the laws of physics. And there are a lot of con artists in the mix who prey on the gullible. See the convicted fraudster Trevor Milton of Nikola fame.

[hogehoge51]

WTF , you are commenting about FCEV - these things dont have engines!

The strategy clearly stated by Akio Toyoda is multiple power train technology. You can listen to his interviews on the subject, some are in Japanese, but as you have stated a clear and unambiguous interpretation of Toyota's policy I will assume you have that fluency.

(Automotive OEMs are assemblers, the parts come from the supply chain starting with Tier 1 suppliers. In that sense TMC does not do "making engines", but possibly the nuance and consequences here of whether not it "wraps it's head" to "makes things", vs if it has the capability to specify, manufacture distribute something at scale with a globally localized supply chain AND adjust to consumer demand/resource availability changes 5 years after the design start - in this context i ask you, can you "wrap your head" around the latest models that are coming out in every power train technology fcev, (p)hev to bev)

[WarmWash]

Toyota has had this hydrogen bug since the early 90's.

What's that old meme?

Stop trying to make ____ happen, it's not going to happen.

[api]

Biofuel makes more sense for airplanes. No conversion even necessary. You could fuel up a 737 with properly formulated biofuel and fly it now, though a lot of validation would be needed to be generally allowed especially for passenger flights.

If we want easier to produce biofuels then LNG aviation makes sense. We are flying LNG rockets already. You could go ahead and design LNG planes now and they’d emit less carbon even on fossil natural gas. Existing turbofan jet engines could be retrofitted to burn methane.

Biogas is incredibly easy to make to the point that there are pretty easy designs online for off grid biogas digesters you can use to run a generator. You can literally just turn a barrel upside down in a slightly larger barrel full of water, shit, and food waste, attach a hose to it, and as the inner barrel floats up it fills with biogas under mild pressure that you can plug right into things. May need to dry it for some applications since it might contain some water vapor but that’s not hard.

Industrial scale biogas is basically the same principle. Just large scale, usually using sewage and farm waste.

LNG rockets also mean “green” space launch is entirely possible.

[lstodd]

LNG aviation does not make any more sense than H2 aviation. Even LPG does not make any sense since you neither can haul 16 bar fuel tanks, nor can you realistically maintain temperature for 1-2atm pressure. And any leak is not 'oh. look, a kerosene stain on tarmac', it's ready-made fuel-air explosion.

On the plus side we would be able to retire airport fire engines because they would never be able to get to a crash before it completely burns out.

[breve]

> It's coming from Toyota because Toyota can't wrap its head around not making engines.

Of course they can. Toyota sells BEVs. As time goes on BEVs will become a greater percentage of their sales.

[dehrmann]

The bZ4X? 10+ years after the Nissan Leaf?

[formerly_proven]

Toyota sells bad EVs and was the last OEM to offer one. It’s the most anti-EV OEM by far and engages/engaged in the most EV FUD.

[Plasmoid]

We're actually not that far off.

Right now, liquid fuels have about 10x the energy density of batteries. Which absolutely kills it for anything outside of extreme short hop flights. But electric engines are about 3x more efficient than liquid fuel engines. So now we're only 3x-4x of a direct replacement.

That means we are not hugely far off. Boeing's next major plane won't run on batteries, but the one afterwards definitely will.

[WalterBright]

> So now we're only 3x-4x of a direct replacement.

The math leads out an important factor. As the liquid fuel burns, the airplane gets lighter. A lot lighter. Less weight => more range. More like 6x-8x.

Batteries don't get lighter when they discharge.

[breve]

> Boeing's next major plane won't run on batteries, but the one afterwards definitely will.

Jet engines work better. Boeing's next major plane will have jet engines, just like their previous major planes.

Synthetic, carbon neutral jet fuel will be the future for commercial jets.

[capitainenemo]

Well, there's also burning regular fuel in a fuel cell, a FCEV. That doubles the efficiencies over ICE, so I guess that bumps it back up to 8x away?

Given the great energy densities and stability in transport of hydrocarbons, there's already some plants out there synthesising them directly from green sources, so that could be a solution if we don't manage to increase battery densities by another order of magnitude.

[rgmerk]

Hmmm. If we do simple extrapolation based on a battery density improvement rate of 5% a year, it takes about 30 years to get there. So it's not as crazy as it sounds - and it's also worth noting that there are incremental improvements in aerodynamics and materials so that gets you there faster...

However, as others have pointed out, the battery-powered plane doesn't get lighter as it burns fuel.

[TheSpiceIsLife]

More accurately, the calculation needs to factor in the fact that battery weight doesn’t decrease as charge is used.

Commercial aviation’s profitability hinges on being able to carry only as much fuel as strictly[1] required.

How can batteries compete with that constraint?

Also, commercial aviation aircraft aren’t time-restricted by refuelling requirements. How are batteries going to compete with that? Realistically, a busy airport would need something like a closely located gigawatt scale power plant with multi-gigawatt peaking capacity to recharge multiple 737 / A320 type aircraft simultaneously.

I don’t believe energy density parity with jet fuel is sufficient. My back of the neocortex estimate is that battery energy density would need to 10x jet fuel to be of much practical use in the case of narrow-body-and-up airliner usefulness.

[vkou]

> It's coming from Toyota because Toyota can't wrap its head around not making engines.

Which is also the reason why its plug-in hybrids are so reliable, despite being dramatically more complex than either an EV or an ICE.

Toyota is very good at making engines, and it would be insane to throw away all that expertise to deliver a half-assed new product.

[qingcharles]

The energy density doesn't work for now. Everybody hoping for that breakthrough, and battery aircraft are moving into certain sectors (drone delivery, air taxis etc).

[aunty_helen]

One of the trade offs is that engines are actually ridiculously heavy. Compact, extreme high power electric motors are starting to be commercialised. But also, fuel burns so you lose weight as you’re flying whereas batteries stay the same.

Electric aviation is interesting but as someone who knows a bit about the industry, biofuels make more sense here.

[Lerc]

Structural batteries were supposed to be the solution where the density wasn't so important. I don't really have a good understanding of the ration of fuel weight to structural weight in existing aircraft though.

[WalterBright]

Jet engine and wing efficiency have increased enormously over the last 50 years.

[Braxton1980]

It might also be because the Japanese government works very hard to have full employment and EVs require less labor.

[satvikpendem]

What does this mean? They have electric vehicles too.

[dev1ycan]

They are just too much in bed with big oil to want to switch, instead they spend rnd on hydrogen in order to mess up with renewables on purpose.

[Braxton1980]

Hydrogen only makes electric vehicles look good and the only alternative. In fact, if this purposeful which I doubt, it probably helped stopped other companies from making hydrogen

[beAbU]

The Mirai is a fuel cell EV. There is no engine. Not sure what your point is regarding engines?