Fraunhofer develops bio-concrete using cyanobacteria

Fraunhofer research institutes have developed a new, climate-friendly method for producing construction materials. Their "BioCarboBeton" project utilizes cyanobacteria, also known as blue-green algae, which can bind carbon dioxide through photosynthesis. This process offers an environmentally advantageous alternative to traditional concrete production, a major source of CO2 emissions.

The core of the new technology involves cyanobacteria cultivated in a nutrient solution. By adding aggregates and fillers such as sand, solid, rock-like structures are formed. This biological process mimics the formation of stromatolites, rock formations created by cyanobacteria in nature for billions of years. Instead of releasing CO2, as in cement production, the harmful gas is sequestered within the material.

Fraunhofer researchers, including project initiator Matthias Ahlhelm and a team led by Ulla König at FEP, have successfully reconstructed and technologized this natural process. Through the development of photobioreactors, the cultivation of cyanobacteria and the production of biomass can be scaled up.

In the initial steps, light-sensitive cyanobacteria are cultured in a controlled environment where light intensity and temperature are adjusted to optimize photosynthesis. The addition of calcium sources enables the bacterial colony to undergo a mineralization process and form stromatolite-like structures. Subsequently, a hydrogel is mixed with various types of sand, and additional carbon dioxide is introduced to support the process.

The new biogenic construction material holds the potential to significantly reduce the construction industry's carbon footprint by offering a sustainable alternative to conventional materials and actively sequestering atmospheric carbon dioxide within the building material itself.