Concrete as CO₂ storage
The "Mining the Atmosphere" research initiative shows that excess CO₂ from the atmosphere can be permanently stored in building materials such as concrete. With a storage capacity of up to ten billion tonnes of carbon per year, this approach could help to reduce CO₂ levels to a climate-friendly level.
Reducing greenhouse gas emissions alone is not enough to slow down climate change. It is just as important to actively remove CO₂ that has already been emitted from the atmosphere. Empa researchers have calculated that up to ten billion tonnes of carbon could be sequestered annually through targeted CO₂ storage in concrete. In the long term, this process could help to reduce the CO₂ level in the atmosphere to the target value of 350 ppm.
The concept is based on the conversion of CO₂ into solid carbon compounds that are used as concrete aggregates. In addition to concrete, other building materials such as asphalt or plastics could also contribute to storage. The challenge lies in incorporating large quantities of carbon efficiently and quickly into these materials without impairing their properties.
Silicon carbide as a key technology
One promising approach is the production of silicon carbide as a concrete aggregate. This compound can bind carbon almost permanently and at the same time improves the mechanical properties of the concrete. However, the production of silicon carbide is very energy-intensive, which is why the full utilisation of this technology is only realistic after the energy transition.
Without the use of silicon carbide, it would take more than 200 years to remove the excess CO₂ from the atmosphere. However, a combination of porous carbon and silicon carbide could significantly accelerate this process.
New paths for a CO₂-binding economy
The “Mining the Atmosphere” research initiative aims not only to reduce CO₂, but also to utilise it as a valuable raw material. In addition to storage in building materials, carbon can also be used for the production of polymers, carbon fibres or graphene.
However, technological advances as well as economic and regulatory incentives are required for successful implementation. The researchers emphasise that a combination of CO₂ reduction and active removal is necessary to mitigate climate change in the long term.
Using concrete as a carbon sink could make a decisive contribution to stabilising the climate. A sustainable solution for the future of the construction industry.