Congratulations to Nora Rilke on defending her diploma

On October 20, 2025, Ms. Nora Rilke submitted her diploma thesis with the title
"Influence of essential operating parameters on the hydrogen yield of a fixed-bed gasifier operated with steam and oxygen for the utilization of digestate pellets from the anaerobic treatment of organic residues and waste materials in the Cométha project (Paris)" successfully defended.

As part of the Cométha project, a Franco-German innovation partnership, Ms. Rilke investigated the operation of a fixed-bed gasifier for the energy recovery of digestate pellets from the dry fermentation of organic residues and waste materials. The aim was to optimize the operating conditions in such a way that a maximum hydrogen yield is achieved with high carbon conversion at the same time.

In an extensive test campaign, the input ratios of oxygen (O/C) and steam (H₂O/C) were varied in order to analyze their influence on the temperature curve, fuel throughput, gas composition and gasification efficiency. At a ratio of around 1.1-1.14 H₂O/C and 0.24-0.25 O/C, a maximum hydrogen yield of 40 g H₂ per kg of fuel and a carbon conversion of 72-78 % were achieved.

To evaluate the test data, Ms. Rilke developed an Excel-based balancing tool that enables mass, material and energy balances to be checked and estimates components that are not directly measured, such as tars or sulphur compounds. In addition, a multi-stage equilibrium model was created using the open source software Cantera in order to theoretically validate the experimental results and identify potential for process optimization.

The work provides valuable insights for the efficient use of biogenic residues and the hydrogen-oriented further development of thermochemical gasification processes.

We would like to congratulate Ms. Rilke on her successful defense and thank her supervisors Michael Tietze (GICON - Großmann Ingenieur Consult GmbH) and Antonia Nikoletta Sikotakopoulou, M.Sc. (TU Dresden) for their dedicated technical support.