Hydrothermal carbonization (HTC) was first described by Bergius in 1913, and later refined by Berl and Shmidt in 1932.
Hydrothermal carbonisation (HTC) of biomass is a thermo-chemical process for the conversion of solid biomass matter at elevated temperature and pressure in the presence of water. The resulting product is a coal-water-slurry. The coal fraction can easily be separated and differs significantly in its chemical and physical properties from the starting material.
During the HTC reaction, water, carbon dioxide and other compounds are cleaved from the biomass. Thereby the energy density is raised significantly and the heating value is approximate to that of dry, high quality brown coal. At the same time, the macromolecular structure of the original biomass will be largely to completely destroyed. This provides a porous, brittle and in part dust-like product that is considerably easier to dry and to convert to electricity, heat or fuel than the origin biomass.