Development of An Integrated CO2 Capture, Transportation and Storage Infrastructure for the UK and North Sea Using An Optimisation Framework

Carbon Capture and Storage (CCS) is widely regarded as an effective medium-term CO₂ abatement technology. However, high cost of the capture technologies, at their current state of the art, and the huge upfront costs of the CO₂ transport pipelines and storage facilities are hindering the large-scale development and full-chain development at commercial scale. Thus, it is of utmost importance to minimize the associated costs, as much as possible, to facilitate optimal design of CCS networks – this emphasizes the need for rigorous optimization based approach such as the one we employed in this study.

Despite the aforementioned challenges, especially within the context of the UK, given the presence of large number of CO₂ emitters and the vicinity of large storage sites in the Southern North Sea, CCS potential for the UK is significant. Thus, it is worthwhile to investigate the economic feasibility of the development of an integrated CCS infrastructure (which may benefit from shared transport and storage components, and economies of scale) together with the possible physical layout and evolution of such a large-scale infrastructure.

In this study, we investigated the optimal deployment of such an infrastructure based on overall cost (including capital and operating costs) minimisation. This is formulated as a Mixed Integer Linear Programming (MILP) problem. The scope of this work includes 33 large UK CO₂ emitters and 6 Southern North Sea sinks. Relevant cost estimates and integrated infrastructure layouts are generated through ‘snapshot’ model for several scenarios with varying CO₂ reduction targets from 5 to 105 MtCO₂/year.

Our results show that, for all the scenarios, practical integrated infrastructures can be developed. An initial ‘seed’ infrastructure is required in the Southern Yorkshire and Humber region and captured CO₂ is routed towards Southern North Sea depleted gas fields via the Theddlethorpe terminal. With increasing reduction targets, the infrastructure evolves and incorporates Thames estuary area emitters whose CO₂ is separately routed offshore via the Bacton terminal. In the first stage, the CCS system is dominated by coal power stations, primarily Drax, while CCGTs’ contribution becomes significant above 75 MtCO₂/year reduction targets. An optimal overall cost of 81.5 $/tCO_2,Total is achieved at 30 MtCO₂/year after an initial decline primarily due to increasingly shared transport and storage infrastructures. As the reduction target increased beyond 30 Mt/year, more expensive CO₂ sources are included in the network – subsequently, the overall cost continually increases up to a maximum of 99.8 $/tCO_2,Total when the capture target increased to 105 MtCO₂/year.

Sensitivity analysis performed on key parameters – i.e., scaling factors and gas price – revealed that not only the overall costs and but also the timing of retrofit of gas-based power generation are affected. On the other hand, oil refineries, cement works and smaller capacity CCGTs are discarded as cost-optimal emitters to capture in all cases.

The MILP model is thus shown to be an effective framework for the optimal planning and, thereby facilitating, large-scale deployment of CCS infrastructure. (Disclaimer: This work is done while the 1^st and 2^nd authors were at Imperial College London and the content/opinions/results discussed do not necessarily represent those of the associated institutions).