Techno-Economic and Life Cycle Assessment of Power-to-X Systems for the Defossilisation of the Chemical Industry

The chemical industry is a significant contributor to global greenhouse gas (GHG) emissions, making it a critical sector for decarbonization. This research investigates the potential of Power-to-X (PtX) systems as a pathway to produce essential chemicals with reduced environmental impact. PtX involves the conversion of renewable electricity into chemical products via integration with carbon capture and utilization (CCU) technologies. This thesis focuses on the development and assessment of three key PtX applications: olefins, ammonia, and formic acid. Each process is analysed through a combined techno-economic assessment (TEA) and life cycle assessment (LCA), providing a holistic evaluation of their feasibility and sustainability performance. The Power-to-Olefins (PtO) process integrates direct air capture (DAC) of CO₂, electrolytic hydrogen production, methanol synthesis, and methanol-to-olefins conversion, using offshore wind power. Despite its high energy intensity, the PtO system achieves a 49% reduction in global warming potential (GWP) compared to conventional fossil-based routes. The Power-to-Ammonia (PtA) process combines green hydrogen, cryogenic air separation for nitrogen, and the Haber-Bosch synthesis. A detailed model featuring kinetic reactor design and heat integration reveals a 94% reduction in GWP, though the levelized cost remains higher than traditional production. The results underscore the importance of low-cost renewable electricity in achieving economic viability. Finally, the Power-to-Formic Acid (PtFA) route, modelled via a thermocatalytic process, is the first of its kind to integrate TEA and LCA. The system demonstrates up to 90% reductions in CO₂ emissions, water consumption, and fossil resource use. Overall, this thesis provides a novel and comprehensive valuation of PtX systems for low-carbon chemical production. The findings contribute valuable insights for policymakers and industry stakeholders aiming to defossilising the chemical sector and align with global climate targets.