Canadian technology helps achieve green concrete milestone

The team mix CO2 taken from the atmosphere into concrete bound for California construction projects.

A CarbonCure truck transports concrete that sequesters CO2. – CarbonCure

Key Takeaways:

  • The CO2 was collected using direct air capture technology. 
  • The carbon won’t return to the atmosphere, even if the concrete is demolished. 
  • The team believes that CO2 storage in concrete could be a major asset to achieve climate goals.

The Whole Story:

Carbon dioxide (CO2) captured via direct air capture (DAC) has been permanently stored in concrete for the first time in a demonstration project led by CarbonCure Technologies and Heirloom.

The team announced that Heirloom captured CO2 from the atmosphere using their DAC technology at their headquarters in Brisbane, California. Technology developed by Nova Scotia-based CarbonCure was used to to inject the captured CO2 into the process wastewater at a Central Concrete batch plant in San Jose, California. Central Concrete used the CO2-treated wastewater to make fresh concrete, which was produced for a range of construction projects across the Bay Area. 

Stored forever 

The team explained that the CO2 is sequestered in the concrete as calcium carbonate, and will not be returned to the atmosphere, even if the concrete is demolished. 

Heirloom runs America’s only operational DAC facility. It uses limestone, an abundant, easy-to-source and inexpensive material, to pull CO2 from the air. 

The team explained that this is done by 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 captured CO2 gas is then permanently stored safely underground or embedded in concrete.

Using Canadian technology 

CarbonCure Technologies licenses a suite of carbon mineralization solutions for hundreds of concrete plants globally. CarbonCure’s reclaimed water technology was used to store Heirloom’s CO2 at Central Concrete. The technology injects CO2 into reclaimed water (recycled water collected from washing out concrete trucks) at concrete plants. When injected, the CO2 immediately reacts with cement in the water and mineralizes, permanently storing the CO2 and stabilizing the cement for reuse. The CO2-treated slurry is then used in new concrete mixes.

Central Concrete was the first concrete supplier in the Bay Area to adopt CarbonCure’s technologies for ready-mixed concrete. 

“This demonstration project is a global milestone for carbon removal technology that confirms concrete’s enormous potential as a climate solution that can permanently store carbon in our most essential infrastructure – from roads and runways to hospitals and housing,” said Robert Niven, chair and CEO of CarbonCure Technologies. “We’re thrilled to be collaborating with Heirloom and Central Concrete on this groundbreaking world first.”

“The science is clear: In order to reach climate goals we must remove billions of tons of already emitted CO2 from the atmosphere each year,” said Shashank Samala, CEO of Heirloom. “This is an important step toward that future and shows the promise of DAC technologies combined with smart, permanent methods of sequestration.”

Looking to a zero-carbon future

The team stated that the application of a DAC-to-concrete solution is a significant step forward in permanent atmospheric CO2 removal. 

“As the world moves toward zero-carbon energy generation, DAC technologies will play a key role in remediating past emissions, and helping to decarbonize industries as they develop and scale carbon-cutting solutions,” they said. 

They noted that even the most aggressive emissions reduction projections from the UN Intergovernmental Panel on Climate Change will require the removal of 6-10 billion tons of CO2 per year by 2050 to stick to a 1.5 C warming pathway. 

“DAC technologies are some of the most promising methods of carbon dioxide removal, and have recently received large investments from the U.S. government through the Department of Energy’s $3.5 billion DAC hub program and the Inflation Reduction Act,” they said. 

The added that the world’s most-utilized building material, concrete provides an important repository for permanent CO2 storage. With the global building stock expected to double by 2060 – the equivalent of building another New York City every month – concrete presents a key opportunity to store immense quantities of carbon dioxide in our built environment.


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