The report presents the results of experimental tests aimed at studying and optimizing processes of electromethanogenesis. This innovative biotechnology uses microbial electrochemical systems to produce methane from CO₂, following a power-to-gas (BEP2G) approach. In the experiments conducted, hydrogenotrophic microorganisms from the Methanobacteriaceae family (domain Archaea) were selected from a biogas digestate, and tested in dual-chamber bioelectrochemical systems. The methane produced, ranging from 0.3 to 0.8 mol/m²g (normalized to the cathode area), is slightly lower than the yields reported in the literature. Additionally, materials for high-surface electrodes (porous terracotta and biochar composites) and nitrogen-doped carbons with Cu and hydroxyapatite (HAP) were studied as innovative chemical catalysts for CO₂ reduction (CO₂RR). The new Cu/HAP-doped materials exhibited CO₂RR efficiencies greater than 80%, promoting the generation of formate, a precursor of methane that is easily biodegradable by hydrogenotrophic methanogenic archaea. Experiments at 80°C with hyperthermophilic hydrogen-producing bacteria in dual-chamber systems confirmed a strong affinity of Thermotoga neapolitana for electrodes polarized in the range of 0–1.2 V vs SHE. The use of these bacteria, along with the tested chemical catalysts, could represent an innovative, more efficient, and cost-effective approach to electromethanogenesis.

Based on the results obtained, an experimental design was developed to define key parameters for optimizing methane yields in the electromethanogenesis process. An experimental setup was developed for the parallel execution of an optimized number of tests using enriched inoculum of Methanobacteriaceae. The identified experiments (24) are expected to provide statistically significant feedback both in relation to literature data and to the innovative approaches explored. The parameters considered in the experimental design include: i) type of material, ii) surface area of electrodes, iii) temperature, and iv) pH. Further electromethanogenesis tests will be conducted at 80°C, using pure strains of microorganisms and single- and dual-chamber cells, to determine which of the tested processes (mesophilic or hyperthermophilic) provides higher methane yields.