Building materials show huge carbon storage potential

Published in Science, the new study was carried out by civil engineers and Earth systems scientists at the University of California, Davis (UC Davis) and Stanford University. It found that building materials had the potential to store more than 16 billion tonnes of CO2 annually, roughly half of the 35 billion tonnes emitted globally each year.

“The potential is pretty large,” said Elisabeth Van Roijen, a researcher at the US Department of Energy who led the study while a graduate student at UC Davis.

The researchers calculated the potential to store carbon in a wide range of common building materials including concrete, asphalt, plastics, wood and brick. Carbon-storing methods included adding biochar into concrete; using artificial rocks loaded with carbon as concrete and asphalt pavement aggregate; plastics and asphalt binders based on biomass rather than fossil petroleum sources; and including biomass fibre into bricks.

While bio-based plastics were found to take up the largest amount of carbon by weight, by far the largest potential for carbon storage is in using carbonated aggregates to make concrete. This is because concrete is the world’s most popular building material by a distance, with more than 20 billion tons produced every year. The researchers calculated that if 10 per cent of the world’s concrete aggregate production were carbonateable, it could absorb a gigaton of CO2.

“If feasible, a little bit of storage in concrete could go a long way,” explained Sabbie Miller, associate professor of civil and environmental engineering at UC Davis.

While some technology development is required, many of the carbon-storing approaches are just waiting to be adopted, said Miller. What’s more, the feedstocks for enhancing the building materials are mostly low-value waste materials such as biomass. According to the researchers, implementing these new processes would increase their value, creating economic development and promoting a circular economy.