Sequestering Carbon in Building Materials, with Dr. Sabbie Miller

Introduction to the SolutionUC Davis researchers are examining a novel approach to combating climate change: turning our buildings into carbon sinks. The solution is based on incorporating biochar, a carbon-rich material obtained from plant material, into common construction materials like concrete, brick, and asphalt. By embedding carbon directly into long-lasting infrastructure, this approach reduces atmospheric CO₂ and also transforms one of the most carbon-intensive industries in the world into a tool for climate mitigation.Background: How Carbon Storage in Building Materials WorksBiochar is created through pyrolysis, a process involving heating organic material, such as crop residues or wood waste, in a low-oxygen environment. This process locks in carbon that plants absorb during photosynthesis and prevents it from being re-released into the atmosphere through decay or burning.The research team at UC Davis, headed by Professor Sabbie Miller and Dr. Elisabeth Van Roijen, proposes the use of biochar as a partial replacement for the materials in concrete and other construction compounds. Since more than 20 billion tons of concrete are produced every year by the construction sector, substituting 10% of that with biochar-based mixtures could store up to 1 gigaton of CO₂ annually, or the equivalent yearly emissions from Japan.Unlike temporary carbon storage methods, like soil burial, embedding biochar in durable infrastructure ensures long-term sequestration, potentially spanning decades or even centuries. It also leverages the global scale of construction as a medium for climate action.Advantages of This SolutionApart from net carbon emissions reduction, the introduction of biochar-enriched building materials has tangible engineering benefits. It has been found that the addition of biochar can enhance thermal insulation, fire resistance, and durability in some uses. The process also fits well within the circular economy principles because of the organic waste used and reduced need for virgin materials.Because construction is already a high-volume, resource-intensive industry, integrating biochar into existing supply chains could make climate-positive practices scalable and economically viable without requiring dramatic infrastructure overhauls. Equally important, this solution provides dual benefits: supporting both carbon sequestration and the development of sustainable materials.Drawbacks and CritiquesThe approach faces several scientific and logistical obstacles despite such a promising premise. Producing biochar requires energy in quite significant quantities, with sourcing biomass at large scales risking unforeseen ecological impacts such as nutrient depletion or habitat disruption. Some critics even ask whether its broad adoption might inadvertently encourage the removal of older buildings in favor of the construction of newer, carbon-storing ones, offsetting any climate gains.Another factor is the life cycle of the biochar-infused materials themselves. While they can store carbon for decades, it remains undetermined how these materials at the end of a building's life are to be managed to avoid re-release of CO₂. Future policy frameworks and recycling technologies will be required to address these challenges if there is to be long-term effectiveness.About the GuestDr. Sabbie Miller is an Associate Professor of Civil and Environmental Engineering at UC Davis. Her research focuses on sustainable infrastructure materials, life-cycle assessment, and reducing the environmental footprint of the construction industry.Further ReadingUC Davis News: Storing Carbon in Buildings Could Help Address Climate ChangeNature Geoscience: Carbon Sequestration Using BiocharScience Magazine: Building Materials as Carbon SinksScienceDirect: Alternative Sequestration Options in Construction MaterialsFor a transcript, please visit https://climatebreak.org/sequestering-carbon-in-building-materials-with-dr-sabbie-miller/

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