Catalytic and microbial methanation as basis for sustainable energy storage

01.01.2019 - 31.12.2022

Prof. Dr. Leonhard Ganzer

As major part of the energy turn around, the European Union and other countries are supporting the development of renewable energies in order to decrease the fraction of the nuclear and fossil energy producers. Thereby efficient use of renewable energy resources is one major challenge, as it is influenced by environmental conditions and hence, the intensity of resources such as wind or solar power fluctuate. To secure a constant energy supply in Germany, a suitable energy storage is required. Catalytic and microbial methanation are promising solutions to transform hydrogen, as a product from electrolysis, and carbon dioxide, captured from power plants, to methane. The produced methane can be stored directly in the underground bioreactor or can be injected after the catalytic methanation in existing storage facilities. Both processes are investigated in this project, giving way for performance comparisons. To investigate the feasibility of both transformation processes, experimental studies are coupled with numerical modelling and simulations in a multi-scale approach reaching from micro to macro scale. The experimental studies are separated into surface catalytic methanation on the one hand, where the methanation process occur in nickel catalysts under different wall temperatures, geometries and particles sizes, and the underground microbial methanation on the other hand, where microorganisms present in the reservoir water phase transform injected hydrogen with carbon dioxide to methane. To improve interpretation and quantification of the experimental results for use with numerical modelling and simulation the development of in-situ sensors is planned for both types of experiments. Detailed modelling and numerical simulations are performed for both approaches starting from micro-scale (pore-scale) with a non-continuum model, and up to a continuum model for the microbial methanation process.

Methanogenic bacteria in underground porous gas storages, initially present or artificially introduced, initiate in-situ methanation, where a mixture of H2 and CO2 is converted into CH4. The methanation process has been observed in hydrogen/town porous gas storages, but the respective microbiological activity in porous media is not entirely understood. This subproject intends to study experimentally how methanogenic bacteria behave in a porous medium saturated by two-fluid phases. The visual observation of the effects within the pore structure of the glass-silicon-glass micromodels will help to develop the pore scale simulation model and the derivation of an upscaled model on continuum scale. The focus is to investigate the bacterial activity in terms of their local position. Where do the bacteria prefer to live? Do they e.g prefer to live in the vicinity of the pore walls or in the vicinity of the gaswater phase boundary? Further, population dynamic and reaction kinetic parameters under static and under dynamic conditions will be estimated for the multiscale mathematical and numerical model.