Mining the atmosphere: A concrete solution to global warming

Abstract

To neutralize anthropogenic climate impacts, excess carbon dioxide (CO₂) – about 400 Gt of carbon – needs to be removed from the atmosphere. After the energy transition is accomplished, we propose that excess renewable energy can be used to extract CO₂ from the atmosphere and convert it into methane or methanol, which are further processed into polymers, hydrogen, and solid carbon. End-of-life polymers are pyrolysed and part of the carbon is used to produce silicon carbide. Solid carbon and silicon carbide become then aggregates and fillers for concrete and asphalt. At the end of their lifecycle, landfilled construction materials become the final carbon sink. Up to 12 Gt of carbon could be stored per year, mostly as concrete aggregates. The synthesis of carbon-based materials in cycles of increased chemical reduction has multiple advantages, including long-term stability, high storage density of the carbon, decentralized implementation, and replacement of current CO₂-emitting materials.