Carbon capture and utilisation (CCU) has the potential to provide business cases as CO₂ waste streams are turned into feedstock for the synthesis of marketable products. Although CCU could reduce fossil resource demand, its capability as a climate change mitigation option is under debate. In contrast to single-product CCU, this prospective study explores the techno-economic and environmental feasibility of novel systems that include more than one CO₂ utilisation product. The combination of multi-product CCU with CO₂ storage is also investigated. Two configurations have been designed, in which CO₂ is captured in a refinery and converted into dimethyl ether (DME) and polyols, simultaneously (parallel configuration) or in two consecutive cycles (cascade configuration). Compared to a reference system without capture, results show that the largest direct CO₂ emission reductions are achieved with CCS without utilisation (−70%) but at the expenses of higher total costs (+7%). Multi-product CCU systems show lower fossil depletion and costs than the reference without capture (−10% and −9%, respectively) because of feedstock replacement by the CO₂ utilised. Combination of multi-product CCU with storage turns to be the best alternative for reduced climate change potential (−18% relative to the reference) while still been economically feasible. In addition to lower upstream emissions due to fossil feedstock replacement by utilising CO₂, process direct emissions diminish owing to storage. No significant differences were found between the cascade and the parallel configurations. The extra effort to recycle CO₂ in the cascade configurations is neither penalised nor rewarded.

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.