Techno-economic evaluation of anaerobic digestion and biological methanation in Power-to-Methane-Systems

Power-to-Methane is a key element for achieving the European climate goals (Paris Agreement) and replacing natural gas. Biological methanation offers the possibility to produce methane from CO 2 and hydrogen by methanogenic archaea. As a green carbon source, the CO 2 from biogas can be used. Green hydrogen can be produced via electrolysis with electricity from renewable sources or balancing energy, making this technology a valuable storage and balance solution for the energy grid. However, questions relating to the economic operation of methanation are increasingly coming into focus. As part of this study, a simulation model is set up through which various operating modes of biological methanation are investigated and evaluated in terms of their economic efficiency. The decisive factors are the marketing opportunities for the biomethane itself on the one hand, and the mode of operation and the associated costs/revenues on the other. The results show that currently the most viable marketing method for biomethane is to market it as a fuel in the mobility sector (51 % more revenue compared to the conventional feeding into the gas grid for electricity and heat generation). When analyzing the provision of electricity, the provision of balancing energy appears particularly promising, as high full load hours can be achieved in combination with revenues for the provision of capacity (mixed biomethane production cost of 11.93 ct/kWh). Although economically viable operation can already be reached in most of the scenarios analyzed, the investment risk still remains high. At present, the ecological benefits of methanation are not sufficiently rewarded to offset those risks. Profits from the avoided release of CO 2 can currently increase the overall revenue by around 4 % in the case of balancing energy if a participation on the European trading system would be possible. Beside a remuneration of the ecological advantages, the costs for hydrogen production must be significantly reduced for good market integration.