Microsoft-backed start-up Heirloom uses limestone to capture CO2

California-based startup Heirloom has a different approach: using limestone to capture CO2 from the atmosphere. CO2 naturally occurs in limestone. Heirloom removes that CO2 by heating the limestone into a powder and stores the extracted CO2 underground. The remaining powder is then thirsty for more CO2. Heirloom spread that powder out on trays, with a robot determining location for maximum CO2 absorption. A process that naturally takes years is reduced to just three days. Once the powder is full, the process starts again.

For more details - https://www.cnbc.com/2022/12/05/microsoft-backed-start-up-heirloom-uses-limestone-to-capture-co2.html