Materials Performance in Liquid CO2 for Maritime Transport MARCO2
Status: Project
Date Announced: March, 2026
Challenge
The deployment of liquid CO2 (LCO2) transport in the maritime sector is advancing rapidly in support of large-scale carbon capture and storage (CCS) developments; however, robust technical evidence required to ensure safe, reliable, and economically optimized shipboard storage and transport remains limited.
The requirements of the International Code for the Construction and Equipment of Ships Carrying Liquefied Gases in Bulk, IMO circulars and related standards have limited provisions for corrosion testing and materials qualification for carbon steels exposed to impurity-containing liquid CO2 under representative maritime service conditions. This JIP call presents a structured process to address the identified gap, by delivering a comprehensive framework that provides assurance in material selection and performance, safeguarding both asset integrity and environmental safety.
Uncertainty regarding the impact of impurities on LCO2 phase behaviour, corrosion kinetics, and materials compatibility has resulted in highly conservative design and operational constraints. Current industry guidance for LCO2 transport relies heavily on project-specific impurity specifications notably those developed for the Northern Lights project, including a 1.5 ppm-mol NOx limit widely regarded as excessively restrictive. These conservative limits increase system complexity and capital and operational costs. Simultaneously, elevated concentrations of SOx, NOx, O2, H2S, and H2O can accelerate localized corrosion, promote stress corrosion cracking and drive materials degradation, increasing inspection and maintenance demands and the risk of corrosion-induced failures.
Stakeholders in the CO2 ship transport sector lack validated corrosion and performance data for carbon steels exposed to impurity-containing liquid CO2. This gap has led to overly conservative impurity limits, raising costs and uncertainty in material supply, shipbuilding, and LCO₂ transport, while also limiting regulators’ ability to set proportionate, risk-based material assurance standards.
A previous study by TWI and Lloyd’s Register (herein referred to as LR) identified the need to validate predictive models using laboratory-generated experimental data for low pressure/ low temperature conditions. Currently, limited experimental data exists for the specified low temperature/ low pressure triple point conditions. This lack of validation data introduces uncertainty in model accuracy and reliability. Targeted laboratory testing is therefore required to generate benchmark data, reduce technical risk, and ensure confidence in model predictions.
Solution
The current JIP scope is limited to low-temperature/low-pressure conditions (approximately –55°C and 8 bar) in line with the indicative budget and programme.
Subject to sufficient participant interest, medium-pressure conditions (approximately –35°C and 15 bar) may be considered under a separate funding structure. While modelling of medium-pressure scenarios could be incorporated within the present JIP scope, any associated experimental testing would be undertaken as part of a separately funded project.
Find out more about this project by downloading the PDF presentation.