Underground methanation in aquifer storage (UMAS). Final report

The project UMAS investigates the use of aquifer storage systems as methanation reactors in the renewable energy system, especially at the Berlin site. Six subprojects deal with the question of feasibility from different perspectives (plant evaluation, reservoir engineering, microbiology, energy system modelling and socio-economics/life cycle analysis). All relevant underground and surface components were identified, analyzed, and evaluated with regard to their suitability for safe underground methanation and a cost calculation was made. The nature of the reservoir has a significant influence on the microbial process and the recoverability of the resulting synthetic gas. A high salinity of the reservoir brine inhibits the microbiological activity. Due to insufficient volumetric conditions, production is only possible to a very limited extent. The analysis of the role of microbiological methanation in Berlin in the energy system showed no beneficial contribution to the renewable energy supply with the given dimensioning of the storage. When assessing the profitability of the project, in addition to the different H${}_2$ production processes using PEM electrolysis and waste water plasmalysis in various scenarios for the economic parameters, logistical and macroeconomic implications of the production processes were also taken into account. Profitability could not be proven. However, an ecological assessment of the hydrogen and methane production processes makes it clear that waste water plasmalysis can make a major contribution to climate protection. In terms of legal approval, the project is generally eligible for approval provided that the proof of integrity worked out in the technical part of the feasibility study and compliance with the safety distances to objects in need of protection in the event of an accident.