Supply chain optimization for Ocean Alkalinity Enhancement: A Norwegian case study

Negative Emissions Technologies (NETs) can contribute to capture atmospheric CO 2 and mitigate climate change. One promising NET is Ocean Alkalinity Enhancement (OAE), which is the dispersal of slaked lime into ocean water to induce chemical processes that enhance the oceans’ CO 2 uptake capability. As OAE implementations are just evolving, there are various open questions. In this study, we focus on the design of OAE supply chain networks and propose a first optimization model for the Ocean Alkalinity Enhancement Supply Chain Optimization Problem (OAE-SCOP). The model aims at achieving a specified net CO 2 uptake at minimum cost by deciding on the establishment of extraction sites, processing plants, and ports, as well as investments in processing capacities and carbon capture and storage (CCS) technologies in the plants, the transport modes to use, the ship fleets involved for ocean distribution and the material flows within the entire network. It accounts for emissions generated by the supply chain processes, and balances these against the induced CO 2 uptake in the ocean. We apply the model to artificial test instances and a realistic case study in Norway. The results indicate that economies of scale could significantly reduce costs in large-scale implementations. Compared to land-based NETs, OAE seems more costly when considering purely financial metrics, but it may show the advantage of leveraging existing logistics networks for limestone processing and comes at less additional land use. • Ocean Alkalinity Enhancement (OAE) is a promising technology for uptaking CO 2 from the atmosphere. • We provide a Mixed Integer Programming (MIP) model for the design of an OAE supply chain. • A case study is presented for a possible Norwegian OAE supply chain. • Economies of scale could reduce costs in large-scale implementations. • OAE abatement cost per ton CO 2 seems higher compared to land-based NETs.