ETH Zurich turns cheese and tofu waste into protein beads for low-energy direct air capture of CO2

Researchers at ETH Zurich have developed a new direct air capture method that uses protein waste from cheese and tofu production. The waste is processed into porous protein beads loaded with potassium hydroxide, which bind CO2 from ambient air. In lab tests, one gram of material captured 97 milligrams of CO2, a rate 10 to 50 percent higher than conventional DAC methods. Unlike traditional DAC systems that require high heat and negative pressure to release CO2, this process uses a mild acid and base spray at room temperature. The beads remain stable over 30 cycles in testing, and the acid, base, and beads can all be reused. The researchers expect the method to be cheaper and more sustainable than existing approaches because it uses a widely available waste product and requires less energy. The technology still needs to prove it can scale beyond the lab, where the team tested only a few grams of beads. If it does, the organic beads could eventually be used as fertilizer or converted into biofuel at end of life, creating a circular system for carbon removal.