“CO₂ Safe & Sour”; How pure must CO₂ be for CCS?

The project has received funding of over NOK 4.8 million from CLIMIT. DNV is collaborating with Equinor, Shell, TotalEnergies, and Gassco, with the work expected to conclude by summer 2025.

Background

Klas Solberg, DNV’s project manager, explains the origins of the project.

«Safe & Sour»

In the context of carbon capture and storage (CCS), “safe” refers to ensuring CO₂ is handled securely, reducing risks of leaks or harm to the environment and humans. This includes proper design and operation of storage sites. “Sour” is a term from the oil and gas industry related to the presence of H₂S, a substance with a foul smell reminiscent of rotten eggs.

Strict purity requirements for CO₂ can drive up costs since removing H₂S and other impurities is both complex and expensive. The DNV project is exploring whether the limits for H₂S can be safely increased, and what material choices are necessary to accommodate H₂S presence.

This could make CCS more economically feasible for more stakeholders. The topic is particularly relevant for projects like Longship, where pipelines are a critical part of the infrastructure. By understanding how H₂S affects materials, this research project aims to contribute to updated and more cost-effective design and operational standards.

Objectives

The project’s recommendations will be used to update DNV’s Recommended Practice – DNV-RP-F104: Design and Operation of Carbon Dioxide Pipelines. – This guidance is used by the industry for the design and operation of CO₂ pipelines. We aim to provide the industry with tools to balance safety and cost effectively, Klas Solberg says.

Joint Industry Project

– The project operates as a ‘Joint Industry Project,’ where we collaborate with stakeholders across the CCS value chain. Partners like IFE, Wood, and DNV USA contribute their expertise in material testing and analysis, Klas explains. The primary focus is testing what concentrations of H₂S can be tolerated without damaging pipelines.

The project also leverages experience from the oil and gas industry, applying established methods and knowledge to address CCS challenges. – By combining knowledge and experience across sectors, we can contribute to a safe and cost-effective framework for CCS. Norway, as an energy nation, has many significant advantages, which this DNV project capitalizes on. In turn, it makes CCS more accessible to global stakeholders, enabling knowledge sharing beyond borders, says Ernst Petter Axelsen. He is Gassnova’s advisor in the DNV project, which is part of CLIMIT’s contribution.

CLIMIT provides legitimacy

– Broad and trusted collaboration is critical for a project like this, says Klas Solberg. DNV plays a key role as a facilitator and independent party, helping industry partners reach a common understanding, and develop standards and practices acceptable to the entire industry. CLIMIT’s support enhances the project’s legitimacy, particularly internationally.

Results so far

– To date, we have developed test procedures that identify mechanisms causing pipeline damage from high H₂S concentrations. This has provided valuable insights into how materials are affected under different conditions. Although the experimental work is ongoing, the project has already established an important foundation for further research and development.
The recommendations so far offer the industry new perspectives on managing H₂S in CO₂ streams, Klas Solberg concludes.

Gassnova has covered related topics in articles such as Low-Pressure CO₂; Greater Transport Volumes and Increased Capacity and CO₂ Transport; Norwegian Expertise Sets Impurity Limits.