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I am doubting that the metal hydride storage vessels will be cheaper than equivalent-capacity batteries, but I could be mistaken. Usually they are described as

by ncmncm 4y ago

I am doubting that the metal hydride storage vessels will be cheaper than equivalent-capacity batteries, but I could be mistaken. Usually they are described as offering better mass-energy density than batteries. Ammonia can be synthesized electrically from water and air by a cheaper and lower-volume process than is used today to make it from air and NG. Methane has the unfortunate quality that, for practical transport in liquid form, it needs to be at cryogenic temperature. Ammonia stores and transports in liquid form at room temperature and not too high pressure. But ammonia is not suitable for home use because of its toxicity. Methane is not, either, because it needs reliable cryogenic refrigeration, or extreme pressure. Likewise, probably, hydrogen. You probably need synthetic propane for domestic storage, a more expensive proposition than others.

pfdietz 4y ago
Methanol, or perhaps dimethyl ether (which is a liquid at room temperature when compressed, similarly to propane.)
- Schroedingersat 4y ago
  Neither are much better than ammonia toxicity wise, and with methanol vs ammonia, at least ammonia makes you really really want to leave the area before it sends you blind or kills you.
  - pfdietz 4y ago
    Ammonia exposure limits are about an order of magnitude smaller than methanol. Methanol is also much less volatile.
Schroedingersat 4y ago
> Ammonia can be synthesized electrically from water and air by a cheaper and lower-volume process than is used today to make it from air and NG. This is news to me. Can it be done with a catalyst as abundant as nickel, or is it only platinum group or similar? Does it happen in conditions as easy to make as a sabatier reactor (or even better, one of the nickel catalysed methane reactions)? Edit: Just found the magic words Barium Zirconate proton conductor. I think it works out to $130/MWh (including hydrogen?) https://www.energy.gov/sites/default/files/2021-08/12-proton-ceramics-using-ammonia.pdf https://www.energy.gov/sites/default/files/2021-08/12-proton... and seems to apply to fuel cells as well. This basically obviates nuclear, and is only a factor of four (three with unwanted solar power?) off of replacing many fossil fuels if true. Why isn't it getting more attention? This is far more important than fusion. > But ammonia is not suitable for home use because of its toxicity. Methane is not, either, because it needs reliable cryogenic refrigeration, or extreme pressure. Likewise, probably, hydrogen. Methane stores okay in stationary pressurized metal vessels at densities on the order of 1MWh/m^3 or about 5x as much as lpg albeit with a more expensive high pressure tank. This is bulky, but viable to store behind the garage or underground or similar. It's harder to make into electricity though without 70% losses. Hydrogen doesn't really pass this test as it's about 5x again (there's probably enough room for many uses even if people need 50m^3, but a 300bar tank that won't embrittle is far too expensive). Small (<1kg) retail metal hydride containers are currently about the price of retail batteries by the one shop I found ($8-9k for 3000L). Given it's an extremely niche industry without the benefits of mass production, I see this as very weak evidence for rather than against the hypothesis that a 20 price reduction in 10 years if you want 20x the storage is as plausible as the other things we're talking about.

by ncmncm 4y ago

pfdietz 4y ago

Methanol, or perhaps dimethyl ether (which is a liquid at room temperature when compressed, similarly to propane.)

Schroedingersat 4y ago
Neither are much better than ammonia toxicity wise, and with methanol vs ammonia, at least ammonia makes you really really want to leave the area before it sends you blind or kills you.
- pfdietz 4y ago
  Ammonia exposure limits are about an order of magnitude smaller than methanol. Methanol is also much less volatile.

Schroedingersat 4y ago

> Ammonia can be synthesized electrically from water and air by a cheaper and lower-volume process than is used today to make it from air and NG. This is news to me. Can it be done with a catalyst as abundant as nickel, or is it only platinum group or similar? Does it happen in conditions as easy to make as a sabatier reactor (or even better, one of the nickel catalysed methane reactions)? Edit: Just found the magic words Barium Zirconate proton conductor. I think it works out to $130/MWh (including hydrogen?) https://www.energy.gov/sites/default/files/2021-08/12-proton-ceramics-using-ammonia.pdf https://www.energy.gov/sites/default/files/2021-08/12-proton... and seems to apply to fuel cells as well. This basically obviates nuclear, and is only a factor of four (three with unwanted solar power?) off of replacing many fossil fuels if true. Why isn't it getting more attention? This is far more important than fusion. > But ammonia is not suitable for home use because of its toxicity. Methane is not, either, because it needs reliable cryogenic refrigeration, or extreme pressure. Likewise, probably, hydrogen. Methane stores okay in stationary pressurized metal vessels at densities on the order of 1MWh/m^3 or about 5x as much as lpg albeit with a more expensive high pressure tank. This is bulky, but viable to store behind the garage or underground or similar. It's harder to make into electricity though without 70% losses. Hydrogen doesn't really pass this test as it's about 5x again (there's probably enough room for many uses even if people need 50m^3, but a 300bar tank that won't embrittle is far too expensive). Small (<1kg) retail metal hydride containers are currently about the price of retail batteries by the one shop I found ($8-9k for 3000L). Given it's an extremely niche industry without the benefits of mass production, I see this as very weak evidence for rather than against the hypothesis that a 20 price reduction in 10 years if you want 20x the storage is as plausible as the other things we're talking about.