Multi-period, multi-objective optimisation of the Northern Lights and Stella Maris carbon capture and storage chains

A multi-objective optimisation model for CCS chains, aiming to minimise costs and greenhouse gas emissions, considering various transport options is presented. The model builds upon previous work and covers the CCS chain elements after CO₂ is captured, including conditioning, pipeline and batch-wise transportation, intermediate hub storage and injection at CO₂ storage fields. A prospective Life Cycle Inventory is integrated to evaluate emissions from batch-wise transportation. The model is parameterised for accurate estimations based on site-specific characteristics and is implemented in two standalone CCS chains, that are analogues to the Northern Lights project with dominant ship transport and the Stella Maris concept with direct injection ship transport, also incorporating distinct emission profiles, intermediate storage hubs and injection sites. A third implementation combining both chain concepts is implemented. By increasing in a step-wise manner the weight of the emissions in the objective function, the model evaluates cost and emission trade-offs. The optimisation selects costlier wells to minimise emissions and shifts from batch-wise ships to cross-continent pipelines. Chain emissions decrease over time with CO₂ supply increase. Shipping operation dominates emissions, followed by well construction and infrastructure construction. Across all the implementations, the GHG emission intensity of the chain, after CO₂ is captured, ranged from 3.3 to 14.2 %, depending on the concept and transport option adopted and accounting for regional characteristics (i.e., the electricity supply mix per country).