Analysis and modelling of the biological methanation process for Power to Gas applications

In response to global warming and the increasing necessity for energy independence, there is a pressing need for nations to augment their utilization of renewable energy sources. Nonetheless, the intermittent nature of renewable energy production often results in mismatch between supply and demand. In this context, biological methanation, particularly when integrated with ex-situ anaerobic digestion, emerges as a promising solution for the efficient utilization of excess energy. This is achieved by converting hydrogen, produced through water electrolysis, and carbon dioxide, derived from biogas, into biomethane. This study focuses on the analysis and modeling of the ex-situ biological methanation stage, as a key element of Power-to-Gas applications. This study provides a thorough examination of the biological methanation process, emphasizing reaction kinetics, operational parameters, and modelling within the Aspen Plus simulation environment. It offers an in-depth analysis of the biological methanation process, specifically highlighting the role of methanogenic archaea in the conversion of carbon dioxide and hydrogen into methane. Unlike conventional catalytic methanation, which relies on catalysts that are sensitive to contaminants, biological methanation can be performed ex-situ in a dedicated reactor. The research identifies and evaluates representative kinetic models applicable to industrial settings and simulations. It includes sensitivity analyses of critical operating parameters such as temperature, pressure, retention time, and flowrate of reactants. Economic aspects are evaluated to assess the feasibility of the process through an increase of the biomethane production, taking into account the scalability for industrial-scale implementation.