[Thorrez]

>thermodynamic minimum energy required to extract CO2 from ambient air is about 250 kWh/ton CO2

How is Heirloom doing it? Are they spending 250 kWh/ton for the extraction? They're reacting it with limestone, and it doesn't sound like that's taking a lot of energy.

[jgilias]

They need to initially (and then repeatedly) heat the limestone in order to release and capture the CO2 in it. This way they get some really CO2 hungry sand that binds it from the air.

I’d expect it’s the rock baking part that takes the most energy.