this post was submitted on 26 Nov 2023
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But why hydrogen? I'm asking from ignorance here, but hydrogen is volatile, corrosive, and notoriously hard to store. What is the advantage over gravity/hydrological batteries, molten salt, compressed air etc?
Because it is not as difficult as you think it is. A lot of gas infrastructure can be converted to use hydrogen and we have the technology to handle hydrogen. That basicly means new seals and pumps for pipelines and some storage sites can be converted as well. With that you get a massive storage site. Even more importantly a lot of chemical processes use hydrogen and some steel production processes as well.
The problem is that hydrogen is going to be more expensive then electricity and electrolysis units are very expensive today. So if you can electrify something it propably is smarter to do that then to use hydrogen.
I thought the issue with hydrogen is that it is literally small enough in gas form to just pass through materials used in existing infra.
And storing it in liquid form is very difficult (ie, have to keep it cold, as the high pressure will just force the gaseous hydrogen through the tank/pipe walls).
I wouldn't be comfortable with the thought of wall/roof cavities filling up with hydrogen.
Did a gig a while ago that ran on hydrogen generators as a publicity stunt.
There was a 10m exclusion zone around the fuel tanks.
I presume that was just "new tech? hyper health&safety".
A lot of the gas infrastructure was originally built for coal gas and that has a high hydrogen content. Standards have often been kept and so a lot of infrastructure is able to handle it.
https://en.wikipedia.org/wiki/Coal_gas
Did it have high hydrogen? Or was it hydrocarbons rich in hydrogen?
Hydrogen gas. The basic reaction is something like:
3C (i.e., coal) + O2 + H2O → H2 + 3CO
It depends on the process thou and it is usually not super clean.
Since 95% of current hydrogen production is from fossil fuels with no foreseeable scalable replacement, the benefit is profits for fossil fuel companies who wouldn't make money off those of those proven methods.
This is largely FUD. Previous industrial H2 use made H2 as a Natural Gas or Methane derivative.
Hydrogen production from electrolysis is being expanded. Hydrogen is favored over other fuels because while it can cause enbrittlement, that can be accounted for by using materials resistant to that. It's how we've handled hydrogen for decades till now, just not in the retail sector, but also why it would not be pipelines around the country like Natural Gas is with the same pipes. This is a solved problem.
Hydrogen when used in a fuel cell or in a hydrogen combustion engine produces 0 or near 0 emissions. That is one of the biggest appeals here. The emissions of a hydrogen fuel cell is water, H2O. You can drink from the tail pipe (don't). In HICE engines, the emissions are a microscopic amount of NOx fumes, in a different world from existing gas or diesel engines.
This positions hydrogen as a much more scalable and less polluting fuel than even batteries long term. And much, MUCH lighter than batteries of similar power density. These are the appeals.
Also, while volatile as a molecule, it's also quick burning and the smallest molecule on the periodic table. Meaning a 700psi tank that has a 2in tear in it, would entirely vent /burn in around 30seconds to 1 minute. Because the molecule can literally leave faster. Unlike the never ending fires that EVs have when they light up, a H2 fire is over rapidly. There are also safety measures like quick disconnects involved. Finally, the tanks are carbon fiber wrapped and reinforced, and the tank of the Toyota Mirai can resist fire from a AR-15 directly. Puncturing these is hard.
Much less NOx, and we already have technology to reduce NOx for gasoline or diesel engines. Even better, because what usually hurts the systems used to reduce NOx is soot from the exhaust. There will be almost none of that on a hydrogen engine.