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Re:A CO2 capture solvent with exceptionally low total costs ... by HPsquared on Sunday April 04, 2021 @07:26AM (#26688577)
Remember those facilities would have very high running costs (energy usage), it's not just a case of building them.
Re:A CO2 capture solvent with exceptionally low total costs ... by DennisP on Sunday April 04, 2021 @09:38AM (#26689286)
The paper says 2.0 GJ per tonne CO2. One GJ is 278kWh, and annual emissions about 36 gigatonnes, so that comes to 2.4 terawatts to absorb all our emissions.

Global energy consumption is about 18 TW[1], so 2.4 TW is a lot but not outlandishly so. It makes sense to look at global energy rather than just global electricity, because the input to this process is heat. We'd need clean energy sources, but we have those. Since we need heat and can use a fixed amount of energy constantly, high-temperature nuclear reactors would probably be ideal.

It would be silly to do this instead of decarbonizing electricity production and converting to electric cars, but we also have to deal with steel and concrete production, agricultural emissions, long-haul jets, etc. Let's say we need one TW to cover emissions we can't easily decarbonize.

Nuclear power produced 2657 TWh of electricity in 2019.[2] Divide by hours in a year, that's 0.3 TW. Assuming 50% thermal efficiency, it's 0.6 TW of heat energy. So basically, triple the number of nuclear plants in the world and we can absorb 40% of our emissions.

Some of the high-temperature designs are fast reactors or thorium breeders. If we use either of those, we won't remotely strain our nuclear fuel supply.

There are other methods of absorbing CO2, like reforestation, topsoil restoration, and olivine beaches. But most methods have scaling limits. Direct air capture with basalt sequestration[3] and/or carbon-neutral fuel production could easily play a large role.

[1] https://www.theworldcounts.com/stories/current_world_energy_...

[2] https://www.world-nuclear.org/information-library/current-an...

[3] https://www.carbfix.com/