Decarbonization in Carbon-Intensive Industries - Frameworks for Enhanced Early-Stage Identification of Optimal Decarbonization Pathways

Carbon-intensive industries account for a quarter of global annual CO2 emissions. Achieving mandated climate targets requires rapid deployment of decarbonization technologies in these industries. Such deployment typically involves substantial upfront investments amidst technical, economic, and policy uncertainties. Consequently, careful selection of decarbonization technologies or a combination thereof, coupled with measures such as process electrification and energy efficiency, is crucial.This thesis presents limitations in existing methodological approaches for comparing decarbonization pathways, spanning systems-, plant-, and site-level considerations. A generalized assessment framework was developed that addresses these limitations, with individual methodological frameworks developed in the appended papers. At the system level, extended boundaries and exergy as a metric were used to compare two CO2 capture technologies with inherently different heat and electricity demands per unit of CO2 captured, considering the perspectives of both plant owners and end-users. At the plant level, an iterative exergy-pinch analysis, combined with techno-economic analysis, was developed to identify promising process modifications in unabated process plants that maximize overall exergy utilization and CO2 avoidance, leading to successive designs towards net-zero emissions. At the site level, a site-specific techno-economic analysis was developed by incorporating quantitative and qualitative site-specific factors expected to influence the choice of decarbonization technologies. Finally, to address deployment barriers for low-emissions hydrogen, an integrated system of complementary production technologies was evaluated using a generalized optimization framework, enabling cost-optimal supply strategies under site constraints and market uncertainties. The frameworks were demonstrated in case studies on bio-CHP in a district heating system, propane dehydrogenation, and a steam cracker plant.The case study results show that integrating amine-based CO₂ capture with industrial heat pumps in bio-CHP plants could enable greater district heat delivery and provide product flexibility across heat, power, and CO₂ emissions. The iterative exergy-pinch analysis applied to the propane dehydrogenation plant identified an unconventional process modification, resulting in a substantial reduction in CO2 avoidance cost (58–70%) compared to CO2 capture from its highly diluted flue gas stream from the unmodified process. The site-specific techno-economic analysis revealed that incorporating site-specific cost factors yields higher avoidance cost estimates than standardized assessments, underscoring the risk of suboptimal technology selection. Finally, the integrated hydrogen production system demonstrated how combining multiple distinct production technologies can reduce costs, improve operational flexibility, and system redundancy. In summary, the generalized assessment framework, combining these individual framework methodologies, provides a comprehensive early-stage indication of the optimal decarbonization pathway for specific industrial sites.