5 ms·

Using more ... aggressive metals might help energy density here, though it would require more energy losses during rebuilding the oxides. Now before one points

by zaarn 6y ago

Using more ... aggressive metals might help energy density here, though it would require more energy losses during rebuilding the oxides. Now before one points out that burning lithium just makes this a battery; kinda but also no. If you burn lithium to turn a generator, I'd argue it's not much more a battery than burning oil to turn a generator. If you wanted a battery, you'd need a non-generator variant. That is where I'd differentiate. Could also use Flourine and burn CO2, might be a viable carbon sink. Flouroalkanes from burning CO2 would be organically inert, don't deplete ozone if released and don't bioaccumulate. Only downside is they're very good greenhouse gases if you don't burn them down to the alkanes that are solid or liquid are normal temperatures. Those you could easily bury deep below the earth. The only issue is obtaining a shitton of flourine to burn your carbon with and then not blowing yourself up in the process. (Also yes, Flourine will burn CO2 and act as the oxidizer)

La1n 6y ago
>Using more ... aggressive metals might help energy density here I think breweries are one of the types of business that could more easily use low density fuels. Right now a lot of the beer is moved by road, and the trucks that transport beer are often empty on their way to a brewery.
- adwn 6y ago
  > the trucks that transport beer are often empty on their way to a brewery. You have to transport the iron oxide back to where it can be recycled. That's the "advantage" of burning fossil fuels: most of the combustion products are volatile, so you can release them into the atmosphere.
  - jacobush 6y ago
    It could be recycled on site.
    - adwn 6y ago
      Yes, but then there's also no use for the empty trucks en route the brewery.
      - jacobush 6y ago
        How much beer do they really need at the iron electrolysis plant? :)
        adwn 6y ago
        Not that much, but I imagine a lot of bars would spring up in the vicinity of iron electrolysis plants, on account of the steady supply of cheaply transported beer.
        mlatu 6y ago
        so you want the lorry that brings the iron powder to be empty on the return trip to the electrolysis plant instead? drink less beer perhaps.
  - socialdemocrat 6y ago
    That is also the problem with fossil fuel. No simple way of capturing and reusing waste. Anyway transport is a small part of cost. For fossil fuel drilling and refining adds much more cost.
KMag 6y ago
A lithium-air battery running an inductive heater strikes me as likely more efficient, but Lithium is much more expensive than Iron. I can't remember if it was Fluorine or Chlorine Trifluoride referenced in the book "Ignition" as being capable of burning as fuels water, sand, and rocket test engineers.
- KSteffensen 6y ago
  It's chlorine triflouride. Things that can light asbestos on fire doesn't mess around. Another bit of discussion on the stuff here[0], including the John Clarke "Ignition" quote you refer to. [0]: https://blogs.sciencemag.org/pipeline/archives/2008/02/26/sand_wont_save_you_this_time https://blogs.sciencemag.org/pipeline/archives/2008/02/26/sa...
- zaarn 6y ago
  Flourine is electronegative enough to be able to burn with asbestos, but not willingly, it needs a lot of encouragement to do so. It'll happily burn spent coal or other oxygen burn byproducts. For asbestos you'll need some chlorine to make that flourine very excited about the idea of tearing apart some strong molecular bonds. Chlorinetriflouride is the candidate here, though Dioxygendiflouride also likes doing it, if in a more explosive fashion (it'll probably detonate in a hypergolic fashion with asbestos or sand).
japanuspus 6y ago
There is a scatter plot on exactly this in the background story linked in TFA [0]. B and Be come out on top, both with around 10 times the mass density and 3 times the volume density of Fe. [0]: https://doi.org/10.1016/j.pecs.2018.05.001 https://doi.org/10.1016/j.pecs.2018.05.001
marcosdumay 6y ago
Using more aggressive metals will also make this more expensive.
pjc50 6y ago
The trouble with more exciting metals is they want to self-oxidise, whereas iron powder in dry air isn't particularly enthusiastic about oxidising. Aluminium produces its surface oxide and then stays relatively inert, although aluminium powder is prone to powder explosions (as is coal dust and even grain/flour). Everything on the left side of the table gets lively with air and especially water; everything from sodium downwards explodes in water. (I wonder if anyone is doing the 21st century version of Ignition!'s approach of setting random things on fire to see if they're good rocket fuels with potential electrolysis-cycle storable fuels?)

by zaarn 6y ago

La1n 6y ago

>Using more ... aggressive metals might help energy density here I think breweries are one of the types of business that could more easily use low density fuels. Right now a lot of the beer is moved by road, and the trucks that transport beer are often empty on their way to a brewery.

adwn 6y ago
> the trucks that transport beer are often empty on their way to a brewery. You have to transport the iron oxide back to where it can be recycled. That's the "advantage" of burning fossil fuels: most of the combustion products are volatile, so you can release them into the atmosphere.
- jacobush 6y ago
  It could be recycled on site.
  - adwn 6y ago
    Yes, but then there's also no use for the empty trucks en route the brewery.
    - jacobush 6y ago
      How much beer do they really need at the iron electrolysis plant? :)
      - adwn 6y ago
        Not that much, but I imagine a lot of bars would spring up in the vicinity of iron electrolysis plants, on account of the steady supply of cheaply transported beer.
        mlatu 6y ago
        so you want the lorry that brings the iron powder to be empty on the return trip to the electrolysis plant instead? drink less beer perhaps.
- socialdemocrat 6y ago
  That is also the problem with fossil fuel. No simple way of capturing and reusing waste. Anyway transport is a small part of cost. For fossil fuel drilling and refining adds much more cost.

KMag 6y ago

A lithium-air battery running an inductive heater strikes me as likely more efficient, but Lithium is much more expensive than Iron. I can't remember if it was Fluorine or Chlorine Trifluoride referenced in the book "Ignition" as being capable of burning as fuels water, sand, and rocket test engineers.

KSteffensen 6y ago
It's chlorine triflouride. Things that can light asbestos on fire doesn't mess around. Another bit of discussion on the stuff here[0], including the John Clarke "Ignition" quote you refer to. [0]: https://blogs.sciencemag.org/pipeline/archives/2008/02/26/sand_wont_save_you_this_time https://blogs.sciencemag.org/pipeline/archives/2008/02/26/sa...
zaarn 6y ago
Flourine is electronegative enough to be able to burn with asbestos, but not willingly, it needs a lot of encouragement to do so. It'll happily burn spent coal or other oxygen burn byproducts. For asbestos you'll need some chlorine to make that flourine very excited about the idea of tearing apart some strong molecular bonds. Chlorinetriflouride is the candidate here, though Dioxygendiflouride also likes doing it, if in a more explosive fashion (it'll probably detonate in a hypergolic fashion with asbestos or sand).

japanuspus 6y ago

There is a scatter plot on exactly this in the background story linked in TFA [0]. B and Be come out on top, both with around 10 times the mass density and 3 times the volume density of Fe. [0]: https://doi.org/10.1016/j.pecs.2018.05.001 https://doi.org/10.1016/j.pecs.2018.05.001

marcosdumay 6y ago

Using more aggressive metals will also make this more expensive.

pjc50 6y ago

The trouble with more exciting metals is they want to self-oxidise, whereas iron powder in dry air isn't particularly enthusiastic about oxidising. Aluminium produces its surface oxide and then stays relatively inert, although aluminium powder is prone to powder explosions (as is coal dust and even grain/flour). Everything on the left side of the table gets lively with air and especially water; everything from sodium downwards explodes in water. (I wonder if anyone is doing the 21st century version of Ignition!'s approach of setting random things on fire to see if they're good rocket fuels with potential electrolysis-cycle storable fuels?)