Energetische Bewertung der Prozessketten zur hydrothermalen Karbonisierung von häuslichem Bioabfall

The thesis presented here was produced as part of a research project metabolon IIb (EFRE-0500033). In terms of the circular economy, the focus was on closing energy cycles and material circulations. The goal was either to generate regenerative energy or to return valuable materials back to the anthropogenic material cycle, with the focus on biogenic or waste residues as input material. The thesis arose while dealing with the question of the importance of hydrothermal carbonization (HTC) regarding future regenerative energy supply. The overall goal of the thesis was then to integrate the HTC process into holistic process chains and to evaluate its energetic
use considering the global warming potential (GWP). Due to the lack of HTC plants on an industrial scale and standardized model implementations, a feasible reactor model based on an empirical kinetic approach for HTC was developed. The model was used to calculate the mass and energy distribution in the three production phases (solid, liquid, and gaseous) and evaluated with experimental analyses. The HTC offers a potential application from the organic fraction of municipal solid waste (OFMSW) and its digestate, which were used as feedstock. In addition, the process chains were assessed based on their efficiencies and compared with conventional process chains. The representative conventional process chains in this case were the incineration of OFMSW in a waste incineration plant (“I“) and the treatment in an anaerobe digestion plant followed by composting (“AD+comp“). Here, the exergetic net efficiency was 13,7 % for “I“ and 12,1 % for “AD+comp“. The implementation of an HTC-process increased the exergetic efficiencies by 70 % compared with “I“ and by 93 % compared with “AD+comp“. The GWP was ∼500 g CO2,Eq kW−1 h−1 in the reference cases. The integration of an HTC unit reduced the GWP by 30 % compared to the conventional pathway.