Climate change, driven by increased greenhouse gas emissions from fossil fuels, is a critical global challenge. The Netherlands aims for a 55% CO2 reduction by 2030, with the Port of Rotterdam as a significant emitter. Renewable methanol production from biomass offers a promising solution to reduce these emissions significantly. This thesis aims to study the techno-economic trade-offs and synergies of CO2 compared to H2 syngas conditioning for a biomass-based methanol plant. Syngas produced through biomass gasification typically lacks the adequate stoichiometric ratio for methanol production, requiring a conditioning step. The conventional WGS approach, while increasing hydrogen content, also increases CO2 production, leading to higher costs and reduced efficiency. Carbon removal further limits efficiency and methanol production. While H2 syngas conditioning routes and synthesis have been extensively investigated, other approaches like RWGS and CO2 -co-electrolysis require further study. The configurations are assessed employing process simulations from Aspen Plus, which were developed using data from the literature. The gasifier was modelled and validated using the IGT experimental data. OLGA and Rectisol were employed for syngas cleaning. Similarly, four syngas conditioning configurations were modelled: water electrolysis, WGS, RWGS and CO2 co-electrolysis. The conditioned syngas compositions for each configuration were used in a separate isothermal methanol reactor model, including purification. CO2 co-electrolysis and RWGS configurations showed the highest biomass utilisation efficiency, but required significant energy input. Water electrolysis had moderate efficiency and the best environmental performance with nearly zero direct CO2 emissions. WGS was the least efficient and had the highest CO2 emissions. This was primarily due to the separation of CO2. Economically, all options were less competitive than market methanol prices. CO2 coelectrolysis had the lowest levelized methanol (LCOM) cost at €2.39/kg, followed by water electrolysis at €2.42/kg and RWGS at €2.63/kg. WGS performed worst at €3.55/kg. The study reveals that RWGS and water electrolysis configurations demonstrate the lowest CO2 emissions, making them ideal for scenarios where reducing the carbon footprint is a priority, primarily when electricity is sourced from low-cost, renewable energy. CO2 co-electrolysis, while achieving high biomass utilisation efficiency and the lowest LCOM does not have the lowest CO2 emissions due to its reliance on natural gas for heating. Conversely, the WGS configuration, although minimising electricity consumption at 0.60 kWh/kg MeOH, is the least efficient overall, with high CO2 emissions and the highest LCOM. CO2 co-electrolysis and RWGS are more suitable in scenarios where high biomass utilisation and competitive costs are prioritised and where electricity prices are stable or low. The WGS process may be more suitable for high electricity costs, and minimising capital expenditure is crucial. In conclusion, this study presents valuable insights into the techno-economic synergies and trade-offs of syngas upgrading through CO2 conditioning compared to hydrogen conditioning for methanol production from biomass gasification. Addressing the identified challenges and leveraging the synergies can advance towards a more sustainable and economically viable methanol production industry. Future optimisation and validation efforts will be essential for translating these findings into practical, scalable solutions.

Climate change, driven by increased greenhouse gas emissions from fossil fuels, is a critical global challenge. The Netherlands aims for a 55% CO2 reduction by 2030, with the Port of Rotterdam as a significant emitter. Renewable methanol production from biomass offers a promising solution to reduce these emissions significantly. This thesis aims to study the techno-economic trade-offs and synergies of CO2 compared to H2 syngas conditioning for a biomass-based methanol plant. Syngas produced through biomass gasification typically lacks the adequate stoichiometric ratio for methanol production, requiring a conditioning step. The conventional WGS approach, while increasing hydrogen content, also increases CO2 production, leading to higher costs and reduced efficiency. Carbon removal further limits efficiency and methanol production. While H2 syngas conditioning routes and synthesis have been extensively investigated, other approaches like RWGS and CO2 -co-electrolysis require further study. The configurations are assessed employing process simulations from Aspen Plus, which were developed using data from the literature. The gasifier was modelled and validated using the IGT experimental data. OLGA and Rectisol were employed for syngas cleaning. Similarly, four syngas conditioning configurations were modelled: water electrolysis, WGS, RWGS and CO2 co-electrolysis. The conditioned syngas compositions for each configuration were used in a separate isothermal methanol reactor model, including purification. CO2 co-electrolysis and RWGS configurations showed the highest biomass utilisation efficiency, but required significant energy input. Water electrolysis had moderate efficiency and the best environmental performance with nearly zero direct CO2 emissions. WGS was the least efficient and had the highest CO2 emissions. This was primarily due to the separation of CO2. Economically, all options were less competitive than market methanol prices. CO2 coelectrolysis had the lowest levelized methanol (LCOM) cost at €2.39/kg, followed by water electrolysis at €2.42/kg and RWGS at €2.63/kg. WGS performed worst at €3.55/kg. The study reveals that RWGS and water electrolysis configurations demonstrate the lowest CO2 emissions, making them ideal for scenarios where reducing the carbon footprint is a priority, primarily when electricity is sourced from low-cost, renewable energy. CO2 co-electrolysis, while achieving high biomass utilisation efficiency and the lowest LCOM does not have the lowest CO2 emissions due to its reliance on natural gas for heating. Conversely, the WGS configuration, although minimising electricity consumption at 0.60 kWh/kg MeOH, is the least efficient overall, with high CO2 emissions and the highest LCOM. CO2 co-electrolysis and RWGS are more suitable in scenarios where high biomass utilisation and competitive costs are prioritised and where electricity prices are stable or low. The WGS process may be more suitable for high electricity costs, and minimising capital expenditure is crucial. In conclusion, this study presents valuable insights into the techno-economic synergies and trade-offs of syngas upgrading through CO2 conditioning compared to hydrogen conditioning for methanol production from biomass gasification. Addressing the identified challenges and leveraging the synergies can advance towards a more sustainable and economically viable methanol production industry. Future optimisation and validation efforts will be essential for translating these findings into practical, scalable solutions.