Startups Capture CO2 and Store It In Concrete

A California startup using rocks to soak up carbon dioxide from the air has teamed up with a Canadian company to mineralize the gas in concrete, a technological tie-up that is a first and they say could provide a model for fighting climate change globally. Reuters reports: Heirloom Carbon Technologies delivered about 30 kg (66 lb) of CO2 collected from the air around its San Francisco Bay Area headquarters to neighboring Central Concrete, a Vulcan Materials' (VMC.N) subsidiary that on Wednesday incorporated the gas into new concrete. That's equivalent to tailpipe emissions of driving about 75 miles (120 km) in a car. The joint effort was the first time that carbon dioxide absorbed from the atmosphere using such Direct Air Capture (DAC) technology had been secured in concrete, where the CO2 will stay put for centuries, several scientists said.

Heirloom heats crushed limestone to release naturally absorbed CO2, then puts the CO2-starved rock on columns of huge trays, where they act like sponges, soaking up close to half their weight in the gas over three days. The rock is then heated to release the collected ambient carbon dioxide, and the cycle repeats. Canada's CarbonCure, the concrete technology company, mixes CO2 with concrete ingredients, turning it into a mineral that strengthens the concrete, cutting the need for cement -- the part of concrete with the biggest carbon footprint.

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