Integrated decarbonization system for ethane cracking: Carbon capture, CO2 hydrogenation, solar-powered water electrolysis and methanol to olefins

Abstract

Achieving Net Zero emissions is a crucial goal for mitigating climate change, with chemical production processes being major contributors to greenhouse gas emissions. Conventional ethylene production plants, primarily fueled by cracked hydrogen and methane, are significant sources of carbon emissions from chemical plants. These emissions present not only environmental challenges but also economic risks due to impending carbon taxes and stricter regulations. Introducing carbon capture in ethylene production is therefore essential for reducing the carbon footprint, aligning with global sustainability targets, and ensuring economic resilience in a future where carbon emissions are increasingly penalized. This work aims to decarbonize and expand the existing ethylene plant by incorporating solar power, carbon capture process and methanol to olefin (MTO) technology. The raw materials of the MTO process include CO₂ captured from flue gas, cracked hydrogen from the ethylene cracker and green hydrogen from proton exchange membrane (PEM) electrolyzer driven by solar power. Hybrid modelling is utilized to develop a mathematical model of the solar-driven PEM water electrolyzer in MATLAB, and simulate the rate-based carbon capture process, methanol production process and MTO process in Aspen Plus. The results indicate that 85 % of CO₂ is converted using cracked hydrogen and green hydrogen, leading to 5.4 % increase in ethylene production and 53.6 % increase in propylene production, respectively. The levelized revenues for ethylene in the original plant, the 70 % carbon mitigation scenario, and the 85 % carbon mitigation scenario are 813 USD/tC₂H₄, 525 USD/tC₂H₄, and 258 USD/tC₂H₄, respectively. Sensitivity analysis reveals that mitigating 85 % of CO₂ becomes economically unviable if solar power exceeds 100 USD/MWh.