| Summary: | A revolution of the global energy industry is without an alternative to solving the climate crisis. However, renewable energy sources typically show significant seasonal and daily fluctuations. This paper provides a system concept model of a decentralized power-to-green methanol plant consisting of a biomass heating plant with a thermal input of 20 MW<sub>th.</sub> (oxyfuel or air mode), a CO<sub>2</sub> processing unit (DeOxo reactor or MEA absorption), an alkaline electrolyzer, a methanol synthesis unit, an air separation unit and a wind park. Applying oxyfuel combustion has the potential to directly utilize O<sub>2</sub> generated by the electrolyzer, which was analyzed by varying critical model parameters. A major objective was to determine whether applying oxyfuel combustion has a positive impact on the plant’s power-to-liquid (PtL) efficiency rate. For cases utilizing more than 70% of CO<sub>2</sub> generated by the combustion, the oxyfuel’s O<sub>2</sub> demand is fully covered by the electrolyzer, making oxyfuel a viable option for large scale applications. Conventional air combustion is recommended for small wind parks and scenarios using surplus electricity. Maximum PtL efficiencies of <i>η<sub>PtL,Oxy</sub></i> = 51.91% and <i>η<sub>PtL,Air</sub></i> = 54.21% can be realized. Additionally, a case study for one year of operation has been conducted yielding an annual output of about 17,000 t/a methanol and 100 GWh<sub>th.</sub>/a thermal energy for an input of 50,500 t/a woodchips and a wind park size of 36 MWp.
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