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deadplant_ca t1_iwsadsb wrote

Reply to comment by rossco311 in Overhyping hydrogen as a fuel risks endangering net-zero goals by filosoful

Ok, I was being a bit of a dick there. Sorry.

Hydrogen that is attached to all kinds of things is not usable in an engine or fuel cell.

Since there are no resources of free hydrogen on our planet. we have to produce it by splitting it out of molecules like water (h2o).

We do that using electricity

Now we can use it to turn our wheels, great.

We can do that with a fuel cell or by burning it. The fuel cell is most efficient. It combines the stored hydrogen with oxygen from the atmosphere producing clean water out the tailpipe!

At this stage you're probably seeing the problem. We start with water and end with water. The only energy entering the process is the electricity we used to split the hydrogen from the oxygen in the first step. Without a source of free hydrogen, the process is simply another type of battery to store that original electrical power.

That doesn't mean it's useless. It's a higher density battery than the solid state options or lithium ion batteries. But it's far less energy efficient so it's only likely to find a niche where very large capacity batteries are required.

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rossco311 t1_iwsii7o wrote

All good, I think we generally can agree that as a clean method to store energy, hydrogen is a good option. The efficiency of that production is perhaps the hurdle to overcome. I learned recently about chemical reactions that allow hydrogen to be released. These processes rely upon the reactivity of the elements rather than electrical energy. I think the more humanity can explore these options, the better off we all will be :)

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deadplant_ca t1_iwsj4fs wrote

Absolutely. I don't think it's an especially good option right now but it's not fundamentally bad. It definitely deserves a place in the mix. That niche could grow or shrink in the future depending on how tech develops.

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bremidon t1_iwu0z53 wrote

>The efficiency of that production is perhaps the hurdle to overcome.

No. It is *a* hurdle to overcome.

The next one is transport, and this is more difficult than is often appreciated. Sure, we *could* use our existing pipes, but anyone suggesting this tends to leave out a pretty big details: those pipes need to be refurbished to be able to transport hydrogen without losing most of it.

Closing out the big three is storage. This is a true pita. Either you need huge tanks (unviable), extremely thick, heavy tanks (expensive and heavy), or cold tanks (expensive and inefficient). If you want to speculate, there is the chance that we might be able to store it by injecting hydrogen into some solid material. This tech exists today, but it's unclear if it can be mass produced.

All three can be overcome. All three *must* be overcome for hydrogen to succeed. I personally think we are 20-30 years away from all three being ready for prime time, and by that time, I suspect that hydrogen will be mostly used as an industrial input.

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rossco311 t1_iwv3stj wrote

Production - I replied to your other post, there are methods that we aren't using that would be able to help us acquire hydrogen both inexpensively and without massive power use.

Transport - If we're simply talking about transporting hydrogen, I agree it's a bit tricky with our current infrastructure. I am working closely with some people that are developing lightweight tank systems using a combination of carbon fiber for strength and a hydrogen membrane to prevent leakage. There is also the option of transporting hydrogen compounds that don't need the special handling that pure hydrogen does.

Storage - There are a few interesting suggestions on how to store hydrogen that I've been made aware of. One such method is to sequester the gas inside existing underground salt cones. Another option is simply to store hydrogen containing compounds and then produce the hydrogen as required by combining them as needed. There is some very interesting work happening in Germany right now with Magnesium Hydride for example.

I agree that humanity has hurdles to overcome in putting hydrogen to work for us en masse. The sooner we start figuring out how to get over them, the better off we will all be.

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bremidon t1_iwvdg1b wrote

Production - You are going to have to be significantly more clear in what you are suggesting. Otherwise you are saying that the entire world is filled with idiots unable to see such a way forward and unwilling to become rich in the process. If such an inexpensive way forward exists, why did the hydrogen industry decide to give batteries such a head start before figuring it out? Quite sporting of them, really. But we were identifying hurdles, and this one was already accepted out of the gate.

Transport - Accepted as hurdle (and that is all I'm looking for here).

Storage - I'm underwhelmed that we are still at the suggestion stage here. I will take this to mean that it has been accepted as a hurdle.

I continue to maintain that we are 20-30 years away from a viable hydrogen system that can be rolled out across our economy. Because of this, I do not see hydrogen playing a part in most of the transport industry, as that will have been effectively solved by batteries; we will be in a near-closed system by then. But I do see a significant role in industry and heating.

Finally, I agree we should be on this as soon as possible. It may be disappointing for people who were still holding out hope that hydrogen would solve our transportation needs (I used to be one of them), but there is good news in that batteries have unexpectedly become an effective solution.

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rossco311 t1_iwvuyvd wrote

Indeed there is a lot of ground to cover on this and I think the more demand that can exist for hydrogen, the more emphasis will be placed on methods of acquiring it.

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