Researchers from UC Davis propose altering conventional building materials, like concrete and bricks, to capture and store carbon dioxide (CO₂), potentially removing up to 16.6 gigatons of carbon annually, though challenges in supply chains and adoption remain significant.
Alterations to conventional building materials would allow construction projects to capture and store CO₂, aiding the fight against climate change. Just by existing, such buildings could push the world closer to the net-zero greenhouse gas goal necessary to avoid a worsening crisis.
“What if, instead, we can leverage materials that we already produce in large quantities to store carbon?” lead author Van Roijen said about pulling the 30 billion tons of building materials produced annually into the fight against climate change.
Building A Future Against Climate Change
University of California, Davis researcher and civil engineering PhD Elisabeth Van Roijen led the team conducting the research. According to the team’s analysis, simply updating construction materials to climate-friendly alternatives could remove 16.6 ± 2.8 gigatons of CO₂ from the atmosphere. That’s about half of the carbon dioxide humans released into the atmosphere in 2021. Materials ripe for such use include concrete, brick, asphalt, plastic, and wood. For example, producers could add carbon aggregates to concrete or use biological materials to manufacture bricks.
The civil engineering team conducted detailed estimates and analyses, combining 2016 figures for construction supply consumption and cross-referencing those with the properties of carbon-absorbing materials. Substances studied included olivines like forsterite (Mg₂SiO₄), from which carbonatable materials, including magnesium, iron, and calcium oxides, can be extracted. These oxides react with atmospheric CO₂ to form carbonates such as magnesium, iron, and calcium carbonates.
Due to their large-scale use, the most effective materials in the UC Davis calculations were asphalt aggregates, bricks, cement, and concrete aggregates. Concrete and cement alone could remove 13 gigatons of CO₂ annually if replaced with carbon aggregates.
Challenges In The Fight
The researchers acknowledge that each of these solutions offers limited help on its own. Per unit of mass, cement aggregates and other solutions store very little carbon. Their effectiveness lies in how ubiquitous these materials are in our world, and the team suggests that with the right financial incentives, their findings represent a workable bulwark against climate change.
However, implementing these solutions presents significant challenges. Contractors may fear liability if these new materials don’t prove as resilient and buildings fail. Even if producers and proponents of the new materials could convince builders of their safety, there isn’t yet an adequate supply chain.
Olivines can be difficult to procure in certain parts of the world. Not only does sourcing carbon-sequestering materials pose a challenge, but monitoring their effectiveness would require establishing a reputable independent agency. Additionally, separating carbonatables from olivines requires enormous heat sources, which could hinder greenhouse gas emission reduction goals.
Solving Climate Change
Fortunately, the team has proposed solutions to address these issues. Electric heating and acid leaching mitigate some of the energy consumption concerns. Additionally, common limestone acts as a viable alternative to olivines. Limestone is readily available and commonly used as a precursor to cement production.
While the limestone calcification process used to create cement does produce CO₂, the research team highlights the calcium looping process utilized in LEILAC to capture CO₂ from limestone cement production. The calcium carbonate produced in the process could be used in building materials instead of calcium oxide, though this would result in greater limestone consumption.
Current estimates indicate that between 2 and 15 billion tons of CO₂ will have to be removed from the atmosphere annually to achieve the 2015 Paris Agreement goals of limiting warming to 2 degrees above preindustrial levels.
The recent paper, “Built to Remove Carbon,” appeared in Science on January 9, 2025.
Ryan Whalen covers science and technology for The Debrief. He holds an MA in History and a Master of Library and Information Science with a certificate in Data Science. He can be contacted at ryan@thedebrief.org, and follow him on Twitter @mdntwvlf.