Prospective techno-economic and environmental assessment of carbon capture at a refinery and CO₂ utilisation in polyol synthesis

CO₂ utilisation is gaining interest as a potential element towards a sustainable economy. CO₂ can be used as feedstock in the synthesis of fuels, chemicals and polymers. This study presents a prospective assessment of carbon capture from a hydrogen unit at a refinery, where the CO₂ is either stored, or partly stored and partly utilised for polyols production. A methodology integrating technical, economic and environmental models with uncertainty analysis is used to assess the performance of carbon capture and storage or utilisation at the refinery. Results show that only 10% of the CO₂ captured from an industrial hydrogen unit can be utilised in a commercial-scale polyol plant. This option has limited potential for large scale CO₂ mitigation from industrial sources. However, CO₂ capture from a hydrogen unit and its utilisation for the synthesis of polyols provides an interesting alternative from an economic perspective. The costs of CO₂-based polyol are estimated at 1200 €/t polyol, 16% lower than those of conventional polyol. Furthermore, the costs of storing the remaining CO₂ are offset by the benefits of cheaper polyol production. Therefore, the combination of CO₂ capture and partial utilisation provides an improved business case over capture and storage alone. The environmental assessment shows that the climate change potential of this CO₂ utilisation system is 23% lower compared to a reference case in which no CO₂ is captured at the refinery. Five other environmental impact categories included in this study present slightly better performance for the utilisation case than for the reference case.