The overall aim of the TOPKO project is to produce growing media for horticulture from mixtures of compost and coal.

Two types of coal are used in the project: Hydrochar from the hydrothermal carbonisation (HTC) process and biochar from the pyrolysis process. Both types of charcoal are mixed with compost individually or together in different ratios. These growing media are used in growth trials with different plant varieties to test their suitability as a substrate in tree nurseries and beyond. The focus of the products is on regionality and climate friendliness. Regionally produced green composts are used; the charcoal is made from agricultural residues or from growth from landscape conservation.

The project uses life cycle assessments to evaluate sustainability in relation to the carbon cycle. Socio-economic analyses are carried out with the aim of reflecting the reaction of potential customers to the alternatives developed and determining the market opportunities.

Image: Sedge-rich growth on a raised bog site near Oldenburg (Lower Saxony) for the production of hydrocarbons. Photo: M. Röhrdanz

Funding period: 06/2024 to 06/2027

Project organiser: Federal Office for Agriculture and Food