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> The problem with sequestering CO2 as hydrocarbons is that you need to put a whole load of energy (embodied in the hydrogen you're combining it with) into the
by gnode 8y ago
> The problem with sequestering CO2 as hydrocarbons is that you need to put a whole load of energy (embodied in the hydrogen you're combining it with) into the ground and leave it there.
If sequestering CO2, combining it with CaO to make CaCO3 (calcium carbonate) makes more sense, and is even exothermic. It's also biologically harmless and can be safely dumped, used in building materials, etc.
- khuey 8y agoIsn't CaO largely produced from naturally occuring CaCO3 though? Where do you get a large supply of CaO to react with your sequestered CO2 from?
- gnode 8y agoApparently when CO2 is injected into hot underground basalt deposits, it is absorbed. https://en.wikipedia.org/wiki/Carbon_sequestration#Mineral_carbonation https://en.wikipedia.org/wiki/Carbon_sequestration#Mineral_c... (last paragraph of section) So I would guess the reason for producing synthetic CaO from CaCO3 is that extracting natural CaO is uneconomical.
- technicalbard 8y agoCaO generally does not exist in natural stone deposits (no alkaline or alkali earths exist as oxides because they are very reactive). You produce CaO from CaCO3 by calcining and driving off the CO2 (which is emitted to the atmosphere).
- gnode 8y agoMy understanding (someone correct me if I'm wrong) is that virgin CaO is released from volcanic activity, and the aforementioned underground basalt is an igneous rock that has not been exposed to surface atmospheric conditions, and thus contains some amount of unreacted CaO.