Building materials like concrete and plastic have the potential to store billions of tons of carbon dioxide, according to a new study by civil engineers and Earth system scientists at the University of California, Davis and Stanford University. The study was published on January 10th Scienceshows that, combined with steps to decarbonize the economy, storing CO2 in buildings could help the world meet greenhouse gas emissions reduction goals.
“The potential is pretty big,” 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 where it is created or from the atmosphere, convert it into a stable form and store it outside the atmosphere where it cannot contribute to climate change. The proposed systems include, for example, injecting carbon into the subsurface or storing it in the deep sea. These approaches pose both practical challenges and environmental risks.
“What if we could instead use materials that we already produce in large quantities to store carbon?” said Van Roijen.
Working with Sabbie Miller, associate professor of civil and environmental engineering at UC Davis, and Steve Davis at Stanford University, Van Roijen calculated the carbon storage potential in a variety of common building materials, including concrete (cement and aggregates), asphalt, and Plastics, wood and bricks.
More than 30 billion tons of conventional versions of these materials are produced worldwide every year.
Concrete potential
Carbon storage approaches studied included adding biochar (produced by heating waste biomass) to concrete; Using artificial stones that can be loaded with carbon as aggregate for concrete and asphalt; Plastics and asphalt binders based on biomass instead of fossil petroleum sources; and incorporating biomass fibers into bricks. These technologies are in different stages of development, with some still being studied at laboratory or pilot scale and others already available for deployment.
Researchers found that while bio-based plastics could absorb the largest amount of carbon by weight, by far the greatest potential for carbon storage lies in the use of carbonized aggregates to make concrete. Because concrete is by far the most popular building material in the world: over 20 billion tons are produced every year.
“If possible, a little storage in concrete could go a long way,” Miller said. The team calculated that if 10% of the world's concrete aggregate production was carbonateable, one gigaton of CO could be absorbed2.
The raw materials for these new processes for producing building materials are predominantly low-quality waste materials such as biomass, said Van Roijen. Implementing these new processes would increase their value, create economic development and promote a circular economy, she said.
Some technology development is required, particularly in cases where the material performance and net storage potential of individual manufacturing processes need to be validated. However, many of these technologies are just waiting to be adopted, Miller said.
Van Roijen is now a researcher at the U.S. Department of Energy's National Renewable Energy Laboratory. The work was supported by Miller's CAREER grant from the National Science Foundation.