Efficiency of the power-to-gas-to-liquid-to-power system based on green methanol

This article analyzes a system consisting of a renewable energy source, hydrogen generator, methanol generator, and Direct Methanol Fuel Cell. The overall system energy efficiency was derived based on the efficiencies of the hydrogen generator, methanol generator, and Direct Methanol Fuel Cell. Based on our research, the maximum efficiency of the hydrogen generator (Anion Exchange Membrane and Proton Exchange Membrane) was measured to be 83.7%, taking into account the own needs indicator. A methodology was developed to determine the efficiency of the methanol production installation depending on the thermodynamic parameters of the reactor. This method allows one to choose these parameters to ensure the maximum efficiency of the methanol generator ∼77% (7.2 MPa, 190 °C in reactor). Using the test stand presented in this work, the operating characteristics of the methanol-powered cell were evaluated to measure its maximum efficiency 23.4% (in relation to Higher Heating Value). By measuring these individual efficiencies, the efficiency range of the entire analyzed system was found to be less than 20%. This low efficiency was discussed, including a method for substantial improvement.