Heirloom- A startup is assisting minerals in absorbing CO2 in days rather than years

• ByStartupStory     |    October 26, 2022

Heirloom is a startup that uses limestone to capture carbon dioxide and then permanently and safely stores it. Heirloom intends to open its first location in 2023 and hopes to remove one billion tonnes of CO2 by 2035. According to estimates, billions of tonnes of CO2 would need to be removed each year to meet global net zero goals by mid-century. According to Alexa Dennett, the company’s head of marketing and communications, Heirloom wants to be a part of the solution. Dennett claims that even if we drastically reduce emissions in line with best-case projections, the world will be much hotter, with more severe consequences, by 2050.

“Limestone is made up of calcium oxide (CaO) and CO2,” Dennett says. “When CO2 is removed from the limestone, the calcium oxide wants to return to its natural limestone state and is ‘thirsty’ for CO2, acting like a sponge by pulling CO2 from the atmosphere. Heirloom’s technology accelerates this natural property of limestone, reducing the time it takes to absorb CO2 from years to just three days.”

To remove CO2, they heat limestone mineral powder in a kiln powered by renewable energy. The powder is applied to vertically stacked trays, where algorithms are used to optimise the limestone’s ability to absorb CO2 under various environmental conditions. Heirloom continuously sponges CO2 from the atmosphere by looping limestone mineral powder through its facilities—a cyclic process that the company claims lowers operating costs while reducing the amount of mineral that must be mined. The primary input, limestone, costs between $10 and $50 per tonne.

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