Economic Assessment of Syngas Production by SOC Co-Electrolysis for Green Methanol

Abstract

Electric-methanol is a promising, sustainable alternative to fossil fuels for the shipping and chemical industry. One viable production route involves generating synthesis gas trough co-electrolysis of water steam and CO2 using renewable electricity, followed by methanol synthesis. However, solid oxide cell (SOC) co-electrolysis systems experience accelerated degradation compared to SOC steam electrolysis, leading to increased energy consumption and operational costs over time. To address this challenge, an economic optimization framework is developed that determines the optimal timing of replacement for SOC electrolyser stacks by balancing rising energy demand due to degradation and stack replacement costs. The model incorporates key operational parameters, including costs for electricity (50 €/MWh), heat (20 €/MWh), CO2 (50 €/ton), water (2 €/m3), waste water (2.5 €/m3), and a weighted average cost of capital (WACC) of 6.1%. Applying this framework to a case study, the achievable synthesis gas production costs are quantified and the most cost-effective replacement strategies identified across varying degradation rates and full load hours. The results show that in 2025, with an optimized stack replacement strategy, synthesis gas can be produced at costs as low as 0.10 €/kWh, corresponding to a methanol cost of 812 €/ton. These findings offer valuable insights that can be used to optimize the economics of renewable methanol production via SOC co-electrolysis.