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_th. (oxyfuel or air mode), a CO₂ 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 O₂ 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 CO₂ generated by the combustion, the oxyfuel’s O₂ 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 η_PtL,Oxy = 51.91% and η_PtL,Air = 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_th./a thermal energy for an input of 50,500 t/a woodchips and a wind park size of 36 MWp.

This paper discusses certain specific problems of small-scale biomass combustion control and their investigation. It describes development of an experimental stand based on market available boiler for wooden pellets that has been equipped with special control unit based on a PAC. In the paper is shown elimination of CO peaks appearing after periodical grate sweeping and main effort is focused on replacement of mostly used on/off heat output control by a PI controller. Application of the PI controller has lowered CO emissions during transition states and improved stability of the combustion process.

This paper deals with characterization of the oxyfuel combustion in a bubbling fluidized bed. The paper proposes a calculation procedure to evaluate gas flow streams, adiabatic flame temperature and concentrations of species in the flue gas. The second part describes a laboratory scale 30kW oxyfuel BFB and presents results of experiments with various semi-oxyfuel and full oxyfuel modes. The results are compared with experimental results, the agreement is satisfactory with less than 10% relative difference. Sustaining of similar fluidization regime along all different cases resulted in decrease of the adiabatic flame temperature that had to be compensated by thermal volumetric load increase from 3.3 to 4.1 MW/m3