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Comment by reverendbedford | Hacker News Reader

Sodium reactor outlet temperatures are around 550 C. There are other reactor concepts that come close to 1000 C, but it's a huge technical challenge.

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Electric heating?

That works for some processes (making aluminum and more recently steel) but I'm not aware of any electrically heated processes for making concrete. Cheap, clean electricity could unlock a lot of things though.

I read an article about this recently and there's at least one company working on exactly such a process:

> Swedish green-tech firm SaltX Technology demonstrated that it can produce clinker with its Electric Arc Calciner: a proprietary system similar to the plasma torches widely used by automakers and other manufacturers for cutting metal. Plasma torches pass an electric current through a jet of inert gas, typically nitrogen or argon, which ionizes the gas and heats it to temperatures over 20,000 degrees Celsius. In June, SaltX announced a partnership with the Swedish limestone supplier SMA Mineral to accelerate commercialization of its technology.

Article: https://arstechnica.com/science/2022/11/the-road-to-low-carb...

Heating by electricity is not a problem. But both production and setting of concrete chemically produce CO2.

Hydraulic cement does not produce CO2 during setting. Non-hydraulic cement actually consumes CO2 while setting.

Doesn't it essentially just re-absorb the same co2 it emitted when it was made?

Yes. I was replying to parent's comment that concrete produces CO2 when setting, which is clearly not the case for hydraulic cement.

Probably, like for steel production, it would involve producing hydrogen then using that as a heat source.

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