Researchers at the Swiss Federal Laboratories for Materials Science and Technology(Empa) want to remove large quantities of excess carbon dioxide from the atmosphere with the Mining the Atmosphere working group. According to a press release, 5 to 10 billion tonnes of carbon could be used annually as concrete aggregate. This would be enough to permanently store the excess CO2 within 100 years after the energy transition and thus bring the atmosphere back to a climate-friendly level. This is estimated to be 400 billion tonnes of carbon or the equivalent of around 1500 billion tonnes of CO2.
However, surplus renewable energy is needed to realise this. This is the only way to convert the carbon dioxide into methane or methanol and then process it into polymers, hydrogen or solid carbon. “These calculations are based on the assumption that sufficient renewable energy will be available after 2050,” Pietro Lura, Head of Empa’s Concrete and Asphalt Department, is quoted as saying in the press release.
However, the amount of building materials required worldwide far exceeds the surplus carbon in the atmosphere. “Even if sufficient renewable energy is available, the key question remains as to how these huge amounts of carbon can be stored in the long term,” Lura continues. The researchers see one approach here in the production of silicon carbide, which can be used as a filler in building materials and the production of asphalt. This should bind the carbon in the long term and have excellent mechanical properties. However, Lura describes the production process as extremely energy-intensive. Production still requires considerable material and processing research in order to make it economically viable.
