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1. A.C. Tupper (actupper@scicomm.xyz)'s status on Wednesday, 15-Feb-2023 04:34:56 JST A.C. Tupper

   Because I'm incorrigible, I just spent the last hour doing the specific energy and energy density math for Magnesium combustion in a Carbon Dioxide atmosphere, comparing it to the same metrics for Lithium Ion batteries.

   Assuming you can get a conversion efficiency of 40% (optimistic, to be sure), Mg/CO2 is, per kWh:

   - A quarter the weight of Lithium Batteries
   - Half the volume of Lithium Batteries

   Pretty compelling reasons to peck away at the idea, IMO.

   #renewableenergy #climatechange

   • A.C. Tupper (actupper@scicomm.xyz)'s status on Wednesday, 15-Feb-2023 04:34:53 JST A.C. Tupper

     in reply to

     If you were filling your CO2 tank with CO2 captured from say, atmospheric or emission sources, you could even say with a straight face that the system is carbon negative.

     Even if you couldn't guarantee the CO2 was truly being taken out of circulation, the system would still be carbon neutral.

     And magnesium has none of the big scarcity/toxic metal mining problems nickel-manganese-cobalt batteries do.

   • A.C. Tupper (actupper@scicomm.xyz)'s status on Wednesday, 15-Feb-2023 04:34:54 JST A.C. Tupper

     in reply to

     I've talked about this Magnesium / Carbon Dioxide reaction before as part of my various rambles on utilizing Magnesium as a circular, renewable fuel.

     CO2 is ideal as an oxidizer for Magnesium combustion, as it's easily compressible, relatively safe, (too) widely available, and will reduce down to a solid once burned with Magnesium. This allows for a completely closed combustion system, no air in, no exhaust out.

     It can even be used as a working fluid for supercritical power cycles.

     Adrian Cochrane repeated this.