Construction materials resembling concrete and plastic have the potential to lock away billions of tons of carbon dioxide, in line with a brand new study by civil engineers and earth systems scientists on the University of California, Davis and Stanford University. The study, published Jan. 10 in Science, shows that combined with steps to decarbonize the economy, storing CO2 in buildings could help the world achieve goals for reducing greenhouse gas emissions.
“The potential is pretty large,” said Elisabeth Van Roijen, who led the study as a graduate student at UC Davis.
The goal of carbon sequestration is to take carbon dioxide, either from where it’s being produced or from the atmosphere, convert it right into a stable form and store it away from the atmosphere where it cannot contribute to climate change. Proposed schemes have involved, for instance, injecting carbon underground or storing it within the deep ocean. These approaches pose each practical challenges and environmental risks.
“What if, as an alternative, we are able to leverage materials that we already produce in large quantities to store carbon?” Van Roijen said.
Working with Sabbie Miller, associate professor of civil and environmental engineering at UC Davis, and Steve Davis at Stanford University, Van Roijen calculated the potential to store carbon in a wide selection of common constructing materials including concrete (cement and aggregates), asphalt, plastics, wood and brick.
Greater than 30 billion tons of conventional versions of those materials are produced worldwide yearly.
Concrete potential
The carbon-storing approaches studied included adding biochar (made by heating waste biomass) into concrete; using artificial rocks that will be loaded with carbon as concrete and asphalt pavement aggregate; plastics and asphalt binders based on biomass reasonably than fossil petroleum sources; and including biomass fiber into bricks. These technologies are at different stages of readiness, with some still being investigated at a lab or pilot scale and others already available for adoption.
Researchers found that while bio-based plastics could take up the most important amount of carbon by weight, by far the most important potential for carbon storage is in using carbonated aggregates to make concrete. That is because concrete is by far the world’s hottest constructing material: Over 20 billion tons are produced yearly.
“If feasible, just a little little bit of storage in concrete could go a great distance,” Miller said. The team calculated that if 10% of the world’s concrete aggregate production were carbonateable, it could absorb a gigaton of CO2.
The feedstocks for these latest processes for making constructing materials are mostly low-value waste materials resembling biomass, Van Roijen said. Implementing these latest processes would enhance their value, creating economic development and promoting a circular economy, she said.
Some technology development is required, particularly in cases where material performance and net-storage potential of individual manufacturing methods should be validated. Nonetheless, lots of these technologies are only waiting to be adopted, Miller said.
Van Roijen is now a researcher on the U.S. Department of Energy National Renewable Energy Laboratory. The work was supported by Miller’s CAREER grant from the National Science Foundation.
