Comment by ForHackernews
12 hours ago
Why is it such a terrible idea? In theory you can generate it via electrolysis in places with plentiful renewable energy, and then you've got a very high-density, lightweight fuel. On the surface, it seems ideal for things like cars or planes where vehicle weight matters. Batteries are huge and heavy and nowhere near as energy dense as gasoline.
It’s horrible to work with - dangerous, embrittlement issues etc., and very energy intensive to compress into very heavy cryogenic storage containers…
> dangerous
It is actually less dangerous than other fuels, for the simple reason that it is extremely light and buoyant. A gasoline fire is bad, because the gasoline stays where it is until it fully burns. A hydrogen fire is less bad, because it will tend to move upwards.
That's assuming the hydrogen is just loose in the area, like it'd been released from a balloon in a chemistry classroom. That amount of hydrogen is extremely small, from an energy standpoint. Equivalent to a teaspoon of gasoline or so.
If you assume a realistic fuel capacity for a hydrogen vehicle, the hydrogen tank will be both much larger than a gas tank and the hydrogen will be under extreme pressure. A tank like that in your car would be extremely dangerous even if it were filled only with inert gas.
Hydrogen mixed with air has a very wide range of concentrations where it is explosive. It accumulates inside containers or just the roof of the car… where the passengers are. It takes just one lit cigarette for it to go boom.
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Ignoring some of the other issues:
Imagine we have this electrolysis plant, splitting up water to produce the hydrogen we need for an area. That's fine.
But it needs fed electricity to keep the process going. Lots of it. It needs more electrical power to split the water than combining it again produces.
So it starts off being energy-negative, and it takes serious electricity to make it happen. Our grid isn't necessarily ready for that.
And then we need to transport the hydrogen. Probably with things like trucks and trains at first (but maybe pipelines eventually). This makes it even more energy-negative, and adds having great volumes of this potentially-explosive gas in our immediate vicinity some of the time whether we're using it individually or not.
Or: We can just plug in our battery-cars at home, and skip all that fuel transportation business altogether.
It's still energy-negative, and the grid might not be ready for everyone to do that either.
But at least we don't need to to implement an entirely new kind of scale for hydrogen production and distribution before it can be used.
So that's kind of the way we've been going: We plug out cars into the existing grid and charge them using the same electricity that could instead have been used to produce hydrogen.
(It'd be nice if battery recycling were more common, but it turns out that they have far longer useful lives than anyone reasonably anticipated and it just isn't a huge problem...yet. And that's not a huge concern, really: We already have a profitable and profoundly vast automotive recycling industry. We'll be sourcing lithium from automotive salvage yards as soon as it is profitable to do so.)
It’s not even the grid, by the time you’ve done the electrolysis you’d be better off just charging a battery.
Also, compressing and cooling a gas takes another huge hit at the efficiency. Electrolysis comes out at atmospheric pressures.
Oh and the platinum electrodes you need…
I’m also just now visualising a hydrogen pipeline fire… terrible terrible idea.
It's the everything, yeah. There's a lot working against using hydrogen as the local energy source for automotive propulsion in the world that we presently have.
Some advantages are that a fuel cell that accepts hydrogen and air at one end and emits electricity and water at the other can be lighter-weight than a big battery, and it can [potentially] be refueled quickly for long trips.
Some disadvantages: We need a compressed hydrogen tank -- which isn't as scary to me as it may be for some people, but that's still a new kind of risk we need to carry with us wherever we drive. And we still need a big(ish) battery and the controls for it in order for regen braking to do its thing (which hybrids have shown to be very useful).
And, again, the grid: If it were cheaper/better/efficient to move energy from electrical generating stations to the point of use using buckets [or trucks or trains] of hydrogen, we'd already be doing that. But it isn't. So we just plug stuff in, instead, and use the grid we already have.
A quick Google suggests that a regular 120v US outlet might charge EVs at a rate somewhere in the range of 3 to 5 miles per hour. So a dozen or so hours sitting, plugged in at home every day, is enough to cover most folks' every-day driving. There's far faster methods, but that's something that lots of regular people with a normal commute and normal working hours can already accomplish very easily if they have private parking with an outlet nearby.
For most folks, with most driving, that's all they ever have to do. It shifts concerns about refueling speed from "Yeah, but hydrogen is fast! I waste hardly any time at all while it refills!" to "What refueling stops? I just unplug my car in the morning and go. I haven't needed to stop at gas station in years."
The main advantages of hydrogen are real, but they just aren't very useful compared to other things that we also have.
Zubrin's "Hydrogen Hoax" from 2007[1] is basically an ironclad critique. The physics are inescapably poor, and always will be. (Zubrin makes other points in that article which should probably be taken with more salt, but his critique of hydrogen stands).
1: https://www.thenewatlantis.com/publications/the-hydrogen-hoa...
It's hell to store. The energy density is terrible and as a tiny molecule it escapes most seals. When it transitions from a liquid to a gas, it expands manyfold (i.e., explodes).
Check out the "Clean Hydrogen Ladder" document.
Hydrogen wastes a large amount of energy.
Unless you produce it using the Sulfur-Iodine cycle in a high-temperature nuclear reactor.
See: https://en.wikipedia.org/wiki/Sulfur%E2%80%93iodine_cycle
and: https://www.jaea.go.jp/04/o-arai/nhc/en/research/hydrogen_he...
The cheapest way to make hydrogen is to use fossil fuels.
Besides being expensive to generate unless you already happen to have an electrolysis plant handy, hydrogen is awkward and hazardous to store. Once generated, it costs yet more energy to liquefy, and then it seeps right through many common metals, weakening them in the process. It's just not a good consumer-level energy source, and nobody could figure out why Toyota couldn't see that.
Interestingly, liquid hydrogen is nowhere near the most energy-dense way to store and transport it. I don't recall the exact numbers but absorption in a rare-earth metal matrix is said to be much better on a volumetric basis. [1] Still not exactly cheap or convenient, but it mitigates at least some of the drawbacks with liquid H2.
1: https://www.fuelcellstore.com/blog-section/what-hydrogen-sto...
Remember that China briefly embargoed Japan for rare earth metals in 2010, and Toyota launched the Mirai in 2014. My theory was that it was developed as a national fallback for Japan in case that embargo continued or got worse. Think 1930s Volkswagen. Anyone can comment on that?
Japan went heavy into hydrogen for a couple of decades ago. The only reason we are even talking about hydrogen passenger vehicles now is because Japan thought it was the future, they made a mistake.
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Hydrogen is the minimum viable atom: one proton, one electron. H2 is a tiny molecule. "hydrogen embrittlement" is when it's small enough to diffuse into solid metal, because it's that much smaller than iron atoms.
It's hard to work with because of this, and what's the point? For most uses, electricity supply is already everywhere.
>Hydrogen is the minimum viable atom: one proton, one electron.
Wait until you hear about H+