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Energy-efficient use of secondary biogenic residues and waste materials in biomass furnaces through stepwise processing and fuel fabrication


In order to generate maximum added value in the context of the energy transition and to avoid other competing uses, land use and land use changes in the sense of a progressive biobased economy, in addition to the supporting components among the solid fuels such as forest residues or landscape conservation wood, smaller material flows of biogenic residues and waste materials are increasingly coming into focus. Under the priority of material recycling, it is therefore important to identify the material flows at the end of the utilization cascade and to utilize them in a resource-efficient manner through appropriate utilization. High-quality energy recovery of these materials in biomass furnaces offers an alternative recovery route, contributes to resource efficiency and contributes to the input flexibility of the plants.

Goals and approach

The general objective is to extend the fuel input spectrum of biomass cogeneration plants in the power range from 1 MW to 50 MW by developing treatment strategies for two specific material streams of biogenic residual and waste materials and investigating them with regard to efficient, trouble-free co-combustion in the plants. The two selected material streams are screen residues from biowaste treatment and specific residue streams from grassland management. GNR is involved in a practical further development of future-oriented and competitive concepts for the sustainable and efficient energetic use of specific residual material streams from grassland management such as grass cuttings from water bodies or roadside strips.

Innovations and perspectives

Fuel technology adaptations are important in order to improve combustion conditions when using alternative biogenic fuels in such a way that no increased emissions and plant malfunctions occur during thermal utilization and that efficient energy conversion can be ensured. The overall work objective of the project is therefore to improve the fuel properties from the aforementioned residue streams by adapting the respective treatment processes as well as the admixture with a commercially available wood fuel in different mixing ratios in such a way that no increased plant damages occur.

Therefore, one of the project tasks is the technological optimization of the Integrated Solid Fuel and Biogas Production from Biomass (IFBB) process. The IFBB process was developed at the University of Kassel and tested on a laboratory and pilot plant scale. But an adaptation and further development to the residue streams from grassland management is necessary to optimize the energy yield of the further energetic utilization of the two resulting material streams (press juice and press cake). The GNR subproject investigates the following research questions:

  • With which setting variant (screw pitch, screen perforation, speed) are the highest dry matter contents in the press cake achieved?
  • Which setting variant achieves the lowest raw ash contents and the most favorable ash compositions in the press cake?
  • To what extent do the different press settings influence the mass flows of dry matter and raw ash into the press juice?
  • Do the starting materials differ in their pressing behavior with respect to the preceding questions?

Project information