A team of chemists at Stanford University has developed an innovative, low-cost method to capture carbon dioxide (CO₂) using common minerals and standard industrial kilns. The approach, inspired by traditional cement-making techniques, offers a potentially scalable and energy-efficient alternative to conventional direct air capture (DAC) methods.
A Simpler, More Scalable Solution
Conventional CO₂ removal technologies, such as large-scale DAC systems, require significant energy input and rely on expensive infrastructure. In contrast, the new method leverages silicate minerals—abundant in the Earth’s crust—to naturally absorb CO₂ from the atmosphere. Under normal conditions, this process, known as weathering, takes thousands of years. However, the Stanford researchers have successfully accelerated the reaction by chemically activating the minerals through ion exchange.
By heating magnesium silicate and calcium oxide in a kiln, the process creates highly reactive minerals that absorb CO₂ from the air much faster than in nature. Initial laboratory tests demonstrated that when exposed to water and concentrated CO₂, the transformed materials captured and stored carbon within hours. When tested in open air, where CO₂ concentrations are much lower, the reaction still occurred within weeks to months—thousands of times faster than in nature.
Applications and Potential Benefits
The technique could be deployed in multiple ways to maximize its impact. One proposed application involves spreading the reactive minerals over large land areas to passively capture CO₂. Another promising use is in agriculture, where the minerals could be added to soil. This approach could replace traditional liming, a process used to adjust soil pH, while simultaneously storing CO₂ in the ground. Additionally, as the minerals weather, they release silicon, a nutrient that can enhance crop yields and soil health.
If widely adopted, the technique could become a sustainable, cost-effective tool for reducing atmospheric CO₂ levels while benefiting farmers and landowners. Unlike other capture methods that require complex infrastructure, this approach uses materials that are already being mined and processed in large quantities.
Challenges and Path to Scale-Up
While the method has shown great promise in the lab, significant challenges remain in scaling it to a globally impactful level. Currently, the research team is producing only 15 kilograms of the material per week. To make a meaningful dent in CO₂ emissions, production would need to be increased to millions of tons annually.
One advantage is that existing cement kilns could be repurposed to process the silicate minerals, using waste materials from mining operations as feedstock. Each year, over 400 million tons of suitable silicate waste are generated, offering a vast potential resource for carbon capture. In addition, the Earth’s reserves of reactive minerals are estimated to be far greater than the total amount of CO₂ ever emitted by human activities.
Further advancements are needed to refine the process and develop kilns that operate without fossil fuels. If successful, this cement-inspired carbon capture method could become a major breakthrough in the fight against climate change, offering a practical and scalable solution for long-term CO₂ removal.