CO2 removed from the atmosphere by Direct Air Capture is stored in concrete for the first time

Yesterday we posted about a group of about 20 companies from the carbon removal industry that launched the coalition Carbon Removal Alliance to lobby US Government policies.

Today we are posting about a statement from last February 3rd from one of them, Heirloom, that in partnership with CarbonCure Technologies and Central Concrete annouced that for the first time it managed to permanently store in concrete, CO2 removed from the atmosphere by Direct Air Capture (DAC).

Heirloom indicates to run North America’s only operational DAC facility. And adds about its process "It uses limestone, an abundant, easy-to-source and inexpensive material, to pull CO2 from the air. Harnessing a cyclic process, the limestone is broken down into calcium oxide rock and CO2 gas using heat from a renewable-energy powered, electric kiln. The calcium oxide is spread onto vertically stacked trays where it acts like a sponge – pulling CO2 from the air before it is returned to the kiln and the process begins again." The cycle goes on and the captured CO2 gas is then permanently stored safely underground – or as was the case with this milestone – embedded in concrete.

If you want to see technical and chemical details, click at the image below to download the company's white paper "An scalable direct air capture process based on accelerated weathering of calcium hydroxide".

Obviously, there are at least four perspectives that need to be answered and are relevant to be taken into account:

• masses and volumes balances e.g. 1 ton input required to produce 1 kg output

• energy, such as any process step requiring cooling or heating

• quality, like variation of concrete durability with more or less CO2

• economic e.g. cost of grinding and mass losses after several cycles

A process worth monitoring. Click here for the press release from Heirloom.

And here other concrete and cement related posts:

• "Carbon negative concrete. And without cement"

• "Heidelberg Cement produces cement using hydrogen technology"