2 ms·

Why? Hydrogen is dangerous and difficult to store, dangerous and difficult to transport, and has egregious specific energy density--all of them are deal-killer

Why? Hydrogen is dangerous and difficult to store, dangerous and difficult to transport, and has egregious specific energy density--all of them are deal-killers for any widespread fuel. The only two benefits of hydrogen over other fuels are: 1. The cleanest and most efficient combustion 2. Ease of synthesis on a distributed scale Ammonia beats hydrogen on every front aside from: 1. Less efficient/clean combustion (which we can handle with extant NoX scrubbing technologies) 2. Currently, it's only efficient to manufacture it in large-scale non-distributed industrial plants. The great thing about ammonia is we've been manufacturing and storing it at-scale for about a century so we're really good at it. Ammonia is the best current candidate for replacing bunker oil and diesel in shipping.

rich_sasha 2y ago
Ammonia is also incredibly toxic. Hydrogen is explosive, but not toxic. In fact, fun fact, it makes for an incredibly good dilutant for extremely deep scuba diving (you can't breathe pure oxygen underwater and most gases, including oxygen, become toxic under pressure). For some reason though, people are queasy about the idea of mixing pure hydrogen and oxygen hundreds of meters underwater.
- calmbonsai 2y ago
  Ammonia in a form suitable for combustion is extremely toxic and even produces chemical burns on direct skin contact. There's been quite a few deaths from industrial ammonia tank (plant, truck, railcar), leaks but unlike hydrogen there's zero chance for a combustion explosion or incidental damage from fire. Ammonia also almost immediately diffuses and dissipates in air at atmospheric conditions, so while it's VERY toxic it's only VERY toxic for a VERY brief period of time (a few minutes). One of the odd "safety" benefits with ammonia is that it takes a rather special set of circumstances for it to combust in the first place. That makes it a sub-optimal fuel in many applications--notably aviation. Thanks for that neat fact about using hydrogen in diving. I'm only familiar with trimixes or bimixes of oxygen, nitrogen, and helium.
  - rich_sasha 2y ago
    Interesting re ammonia. But is it the same when there would be a huge spill? E.g. imagine a leak at a large storage facility, of comparable size to how we store hydrocarbons today. Wouldn't that turn into a massive toxic cloud? Interesting read re breathing hydrogen: https://en.m.wikipedia.org/wiki/Hydreliox https://en.m.wikipedia.org/wiki/Hydreliox
    - calmbonsai 2y ago
      It does leak and it has turned into a massive toxic clouds, but ammonia is much, much lighter than air and a (comparatively) unreactive gas so any large release dissipates extremely quickly and rises straight up out of buildings and infrastructure. It doesn't linger and there's no danger of invisible structural embrittlement or fires. It's also extremely noxious at even very low (safe) concentrations so, unlike odorless methane, hydrogen, or carbon monoxide, people know immediately to stay away from the area. The natural gas (mostly methane) that's piped into housing for heating or cooking is deliberately ordorized with hydrogen sulfide to make it noxious so gas leaks can be smelled.

rich_sasha 2y ago

Ammonia is also incredibly toxic. Hydrogen is explosive, but not toxic. In fact, fun fact, it makes for an incredibly good dilutant for extremely deep scuba diving (you can't breathe pure oxygen underwater and most gases, including oxygen, become toxic under pressure). For some reason though, people are queasy about the idea of mixing pure hydrogen and oxygen hundreds of meters underwater.

calmbonsai 2y ago
Ammonia in a form suitable for combustion is extremely toxic and even produces chemical burns on direct skin contact. There's been quite a few deaths from industrial ammonia tank (plant, truck, railcar), leaks but unlike hydrogen there's zero chance for a combustion explosion or incidental damage from fire. Ammonia also almost immediately diffuses and dissipates in air at atmospheric conditions, so while it's VERY toxic it's only VERY toxic for a VERY brief period of time (a few minutes). One of the odd "safety" benefits with ammonia is that it takes a rather special set of circumstances for it to combust in the first place. That makes it a sub-optimal fuel in many applications--notably aviation. Thanks for that neat fact about using hydrogen in diving. I'm only familiar with trimixes or bimixes of oxygen, nitrogen, and helium.
- rich_sasha 2y ago
  Interesting re ammonia. But is it the same when there would be a huge spill? E.g. imagine a leak at a large storage facility, of comparable size to how we store hydrocarbons today. Wouldn't that turn into a massive toxic cloud? Interesting read re breathing hydrogen: https://en.m.wikipedia.org/wiki/Hydreliox https://en.m.wikipedia.org/wiki/Hydreliox
  - calmbonsai 2y ago
    It does leak and it has turned into a massive toxic clouds, but ammonia is much, much lighter than air and a (comparatively) unreactive gas so any large release dissipates extremely quickly and rises straight up out of buildings and infrastructure. It doesn't linger and there's no danger of invisible structural embrittlement or fires. It's also extremely noxious at even very low (safe) concentrations so, unlike odorless methane, hydrogen, or carbon monoxide, people know immediately to stay away from the area. The natural gas (mostly methane) that's piped into housing for heating or cooking is deliberately ordorized with hydrogen sulfide to make it noxious so gas leaks can be smelled.