The researchers explored two solutions for permanent storage of CO2: 1. Mineralisation in recycled demolition concrete manufactured in Switzerland and 2. Mineralisation in a geological reservoir in Iceland. When storing in recycled demolition concrete, the efficiency and thus the ratio between stored emissions and resulting new emissions is 90%; when transporting Swiss CO2 and then storing it in a geological reservoir in Iceland, it’s around 80%. One aspect that did surprise researchers, on the other hand, was the regulatory difficulties encountered when trying to transport CO2 through several countries to Iceland. Another question ETH researchers are addressing is whether CO2 can also be stored underground closer to home, in Switzerland. A possible injection test in a borehole in Trüllikon no longer required by the National Cooperative for the Disposal of Radioactive Waste (NAGRA) could provide some initial answers.