Technical carbon: STRABAG expands its portfolio for sustainable building materials
9 June 2026
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- STRABAG acquires a 50.65 % stake in Ökologische Klärschlammtrocknung Offenhausen GmbH
- Expansion of activities in the field of technical carbon (biochar)
By acquiring a majority stake in Ökologische Klärschlammtrocknung Offenhausen GmbH (ÖKT), STRABAG is strengthening its activities in the field of technical carbon and further expanding its commitment to sustainable building materials. A separate unit has already been working on the development and scaling of renewable and mineral raw materials, technical carbon and CO₂-reduced concrete for two years.
ÖKT operates an integrated plant for pyrolysis and sewage sludge drying in Offenhausen, Bavaria. Here, biomass and biogenic residues from forestry and agriculture (e.g. wood chips and maize cobs) are utilised and converted into certified EBC biochar (European Biochar Certificate), i.e. technical carbon, in accordance with the highest quality standards. This innovative technology enables active net CO₂ removal from the carbon cycle with additional energy generation.
The waste heat generated in the pyrolysis process is used to dry the material used. It also dries sewage sludge, which can then be used as a low-emission fuel.
The aim is the long-term binding of CO₂ in building materials such as concrete and asphalt. Biochar serves as a permanentCO2 storage medium, as set out in EU Regulation 2026/285 on carbon removals and carbon farming, and also has the potential to improve the material properties of concrete, for example.
Biochar is also used in agriculture and in substrates, such as for urban trees for climate-resilient urban greening ("sponge city"). Due to its pronounced water and nutrient storage capacity, it helps to improve the growing conditions of plants.
ÖKT operates an integrated plant for pyrolysis and sewage sludge drying in Offenhausen, Bavaria. Here, biomass and biogenic residues from forestry and agriculture (e.g. wood chips and maize cobs) are utilised and converted into certified EBC biochar (European Biochar Certificate), i.e. technical carbon, in accordance with the highest quality standards. This innovative technology enables active net CO₂ removal from the carbon cycle with additional energy generation.
The waste heat generated in the pyrolysis process is used to dry the material used. It also dries sewage sludge, which can then be used as a low-emission fuel.
The aim is the long-term binding of CO₂ in building materials such as concrete and asphalt. Biochar serves as a permanentCO2 storage medium, as set out in EU Regulation 2026/285 on carbon removals and carbon farming, and also has the potential to improve the material properties of concrete, for example.
Biochar is also used in agriculture and in substrates, such as for urban trees for climate-resilient urban greening ("sponge city"). Due to its pronounced water and nutrient storage capacity, it helps to improve the growing conditions of plants.
ÖKT was founded in 2019 from an agricultural business in Bavaria and has strong regional roots. By joining the company, STRABAG is strengthening its regional commitment to sustainable materials and driving forward decarbonisation in the construction industry.
The STRABAG Group's stake in ÖKT GmbH is 50.65%. The parties have agreed not to disclose the purchase price.
