Power-to-Liquid (PtL) plants can viably implement carbon capture and utilization technologies in Europe. In addition, local CO₂ sources can be valorized to substitute oil and gas imports. This work’s aim was to determine the PtL efficiency obtained by combining a solid oxide electrolyzer (SOEC) and Fischer–Tropsch synthesis. In addition, a recommended plant configuration to produce synthetic fuel and wax at pilot scale is established. The presented process configurations with and without a tail gas reformer were modeled and analyzed using IPSEpro as simulation software. A maximum mass flow rate of naphtha, middle distillate and wax of 57.8 kg/h can be realized by using a SOEC unit operated in co-electrolysis mode, with a rated power of 1 MW_el.. A maximum PtL efficiency of 50.8% was found for the process configuration without a tail gas reformer. Implementing a tail gas reformer resulted in a maximum PtL efficiency of 62.7%. Hence, the reforming of tail gas is highly beneficial for the PtL plant’s productivity and efficiency. Nevertheless, a process configuration based on the recirculation of tail gas without a reformer is recommended as a feasible solution to manage the transition from laboratory scale to industrial applications.

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.

The production of sustainable, biomass-based synthetic natural gas (SNG) and Fischer–Tropsch (FT) diesel can contribute significantly to climate neutrality. This work aims to determine the commercial-scale production costs and CO₂ footprint of biomass-based SNG and FT diesel to find suitable integration scenarios for both products in the Austrian energy system. Based on the simulation results, either 65 MW SNG and 14.2 MW district heat, or 36.6 MW FT diesel, 17.6 MW FT naphtha, and 22.8 MW district heat can be produced from 100 MW biomass. The production costs with taxes for wood-based SNG are 70–91 EUR /MWh and for FT diesel they are 1.31–1.89 EUR /L, depending on whether pre-crisis or crisis times are considered, which are in the range of fossil market prices. The CO₂ footprint of both products is 90% lower than that of their fossil counterparts. Finally, suitable integration scenarios for SNG and FT diesel in the Austrian energy system were determined. For SNG, use within the energy sector for covering electricity peak loads or use in the industry sector for providing high-temperature heat were identified as the most promising scenarios. In the case of FT diesel, its use in the heavy-duty traffic sector seems most suitable.