Superstructure optimisation in various carbon capture and utilisation supply chains

Carbon capture and utilisation (CCU) appeared as an attractive complementary scenario to carbon capture and storage for CO₂ sequestration and climate change mitigation. CCU covers various routes that use CO₂ as a feedstock for the generation of value-added commodities, which are classified under four main categories: chemical conversion, mineral carbonation, enhanced oil recovery and biological conversion. CCU networks encompass a variety of material, process, and technology options at every node of the supply chain. This forms a superstructure network of multiple CO₂ sources, carbon capture and separation methods, transportation links, and CO₂ utilisation routes (sinks). The purpose of this work is to investigate the economic performance of different CCU pathways and to determine the most optimal CCU integrative configuration. A mixed linear integer programing (MILP) model is developed that aims at optimising the CCU supply chain. A case study for the State of Qatar is presented in this work to illustrate the application of this optimisation framework, with the use of real data for existing CO₂ sources and sinks, and transportation networks along with potential CO₂ sinks. Findings indicate that for high CO₂ concentration and gas flowrates such as the ones studied in the case study, adsorption provides the most economical option for carbon capture. Moreover, the chemical conversion to GTL route presented the best economic performance amongst the other CO₂ utilisation pathways despite the low readiness level. However, biological conversion in agricultural greenhouses could be a more environmentally viable utilisation route with the potential of a carbon-neutral network.