Spatial optimisation of carbon dioxide transport costs in Europe: from large industrial sources to offshore storage.

Greenhouse gas (GHG) emissions, particularly carbon dioxide (CO2), are a major driver of climate change. Carbon Capture and Storage (CCS) is considered a key option to achieve the decarbonisation of the industrial sector, particularly of the hard-to-decarbonise industry. CCS involves a series of technologies designed to capture, transport and ultimately store CO2 in secure geological formations. In this context, this Thesis investigated how large stationary industrial CO2 sources in Europe could be spatially aggregated and connected to offshore storage through a cost-efficient transport network based on pipelines and ships. A database of 147 large stationary emitters was compiled, including 50 refineries, 19 steel plants, and 78 cement plants, together with 15 ports and selected CCS projects already operational or under construction. Quantum Geographic Information System (QGIS) software was used to map the sources, test clustering configurations, and calculate onshore and maritime distance matrices. The transport chain was optimised through a Mixed Integer Linear Programming (MILP) framework implemented in the General Algebraic Modelling System (GAMS). Different scenarios were considered to identify the optimal configurations in terms of infrastructure created and costs. The optimisation results showed that Scenario B, based on Density-Based Spatial Clustering of Applications with Noise (DBSCAN), with six sequestration gateway ports, provided the most favourable transport-economic outcome, with a total annual transport cost of 860.54 M€/y and a unit cost of 5.48 €/t CO2. Scenario A, based on DBSCAN with a single gateway port, yielded 942.29 M€/y and 5.99 €/t CO2, while Scenario C, based on K-means with six gateway ports, reached 1099.29 M€/y and 5.92 €/t CO2. In all cases, pipelines represented the dominant cost component, accounting for 83.4–91.4% of annual transport expenditure, while shipping played a complementary but necessary role for selected maritime connections. Overall, this Thesis demonstrates that European CO2 transport should be planned as a coordinated multimodal system rather than as a single-mode problem. Its main contribution was to show that transport performance depends not only on cost parameters, but also on how industrial sources are spatially aggregated and how access to offshore storage is organised. These findings support the use of spatial optimisation as a credible tool for the early-stage design of shared CCS infrastructure in Europe.