Building materials could store an impressive amount of CO2

New versions of widespread building materials such as concrete and bricks designed to store carbon dioxide could provide a powerful climate change solution, according to a new analysis.
The Intergovernmental Panel on Climate Change (IPCC) has estimated that in addition to broad-scale decarbonization of the global economy, between 2 and 15 billion metric tons, or gigatons, of carbon dioxide will need to be removed from the atmosphere each year to meet the goals of the Paris Agreement and limit global warming to 2 or preferably 1.5 °C.
This carbon will need to be stored more or less permanently, which people have proposed doing by injecting it underground or into the deep ocean, for example. Instead of these difficult, costly, and risky strategies, the researchers in the new study turned to an utterly commonplace solution: the built environment.
“Building materials can be a good option for carbon storage given the massive quantity of materials produced each year, and the long lifetime and durability of these materials,” says U.S. Department of Energy National Renewable Energy Laboratory researcher Elisabeth Van Roijen, who conducted the work as a graduate student at the University of California, Davis.
Van Roijen and her collaborators calculated how much carbon could potentially be stored in specialized carbon-sequestering forms of concrete, brick, asphalt, plastic, and wood building materials worldwide. This could include, for example, adding biochar, a material produced by heating waste biomass, to concrete; incorporating biomass fiber into bricks; or using artificially carbon-loaded rocks as aggregate in concrete and asphalt.
Replacing all conventional building materials with carbon-sequestering versions could store as much as 16.6 gigatons of carbon dioxide each year, the researchers report in the journal Science.
“The sheer magnitude of carbon storage potential is pretty impressive,” Van Roijen says: the total is equivalent to about half of all human-caused carbon emissions in 2021.
The heaviest hitters are concrete, asphalt, and bricks due to their huge volume of production, the researchers found. Even though these materials could store only a small amount of carbon by weight, all those little bits really add up. Just replacing conventional cement and concrete aggregates with carbon-storing versions could remove 13.1 gigatons of carbon dioxide from the atmosphere annually.
Some of the technologies investigated in the study are still being piloted, while others are ready for wide rollout. Using these technologies at scale would likely require rejiggering various industries. For example, there’s plenty of agricultural waste biomass to satisfy demand for bio-based oil, bio-plastics, and biochar for cement. Biochar production would have to be massively scaled up, though, from the 0.4 million metric tons (megatons) produced in 2021 to 600 megatons.
Sourcing minerals that react with atmospheric carbon dioxide to form carbonates for cement and asphalt aggregates could pose supply challenges. Industrial waste products such as blast furnace slag, steel slag, mine tailings, and coal ash could be used to produce carbonated concrete, but some of these materials may become less available as the industries they result from green up.
But the potential of even just the low-hanging fruit is substantial. “We found that if we make the transition to these low-carbon materials by 2045, even if we just use resources that are currently available today, we could stay below median targets for 1.5 °C warming,” Van Roijen says.
A key concern with carbon storage is making sure the carbon really stays out of the atmosphere for the long term. But building materials are likely up to the task, Van Roijen argues. “The main source of carbon storage examined in this study, carbonate-based aggregates, are an extremely stable form of carbon storage,” she says. “Therefore, even if they are only used in a building with a lifetime 70 years, they will likely continue to store carbon after being demolished and recycled or landfilled.” However, strict recycling or other end-of-life regulations will be necessary to make sure bio-based plastic and wood building materials store carbon durably, she adds.
Source: Van Roijen E. et al. “Building materials could store more than 16 billion tonnes of CO2 annually.” Science 2025.
Image: ©Anthropocene Magazine
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