BioRestFuel

Motivation

In order to generate maximum added value as part of the energy transition and to avoid other competing uses, land use and land use changes in the sense of an advancing bio-based economy, smaller material flows of biogenic residual and waste materials are increasingly coming into focus alongside the main components of solid fuels such as forest residues or landscape conservation wood. With material recycling taking priority, 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 by making appropriate use of them. 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 expand the range of fuels used in biomass heating (power) plants (BMHKWs) in the output range from 1 MW to 50 MW by developing processing strategies for two specific material flows of biogenic residues and waste materials and investigating them with regard to efficient, trouble-free co-combustion in the plants. The two selected material streams are screenings from biowaste treatment and specific residual material streams from grassland management. GNR is involved in the practical further development of forward-looking and competitive concepts for the sustainable and efficient energetic use of specific residual material flows from grassland management, such as green cuttings from watercourses or roadside verges.

Innovations and prospects

Fuel technology adaptations are important in order to improve the combustion conditions when using alternative biogenic fuels so that no increased emissions and plant malfunctions occur during thermal utilization and efficient energy conversion can be guaranteed. The overall objective of the project is therefore to improve the fuel properties from the above-mentioned residual material streams by adapting the respective treatment processes and blending with a commercially available wood fuel in different mixing ratios in such a way that no increased plant damage occurs.

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. However, an adaptation and further development to the residual material flows from grassland management is necessary in order to optimize the energy yield of the further energetic utilization of the two resulting material flows (pressed juice and pressed cake). The GNR sub-project is investigating 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 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 in the press juice?
• Do the starting materials differ in their pressing behavior with regard to the previous questions?