7 questions about CO₂ transport and storage

In April the moment had finally arrived and ground was broken for Porthos. Thanks to this ambitious CO₂ transport and storage project there will soon be fewer carbon emissions at the Port of Rotterdam. And that’s good news for the energy transition. But how exactly does carbon transport and storage work? And what else is happening in the field of CCS in the Netherlands? We provide the answers to seven questions.

With carbon capture and storage, or CCS, CO₂ can be ‘captured’ at its source and transported to where it can be stored below ground, such as in empty gas fields deep underneath the North Sea. The climate targets are clear. The energy transition has us working towards an energy mix without CO₂ emissions. Carbon capture and storage is a solution that will have a positive impact very quickly, with a significant reduction in emissions within ten years. It’s also a badly needed solution: this way greenhouse gas emissions can be cut immediately in industries where it’s difficult to lower their emissions, like refineries and chemical companies.

What’s more, it’s one of the most affordable ways to lower carbon emissions, giving our industries a healthy foundation for the long term. This way we stimulate employment and the economy. 

There are already several places around the world where CO₂ is being captured and stored safely. Norway is one of these. There CCS is used in two locations to permanently store CO₂ in empty natural gas fields, which is also what the Netherlands is planning to do. Similar CCS projects are underway in Canada and the US, too.

Yes. Although no CO₂ has been stored as of yet, preparations are in full swing. The first concrete step was taken last April when construction on the Porthos carbon transport and storage project got underway. And it was spectacular right from the start, with drilling under the seawall at the Maasvlakte industrial park. CO₂ captured in the port area will soon be arriving at the compressor station at Maasvlakte from where it will be transported by pipeline to the offshore platform, approximately 20km off the coast.

Work on the CO₂ pipeline will also be carried out at other locations in the port of Rotterdam in the near future. Crossing several waterways, railway lines and roads in the port area, this system of underground pipelines will bring the CO₂ captured at the companies to the compressor station. Porthos is a joint venture between EBN, Gasunie and the Port of Rotterdam Authority and is expected to be operational by 2026.

The aim is for Porthos to store around 2.5 Mt (million tonnes) of CO₂ per year over a period of 15 years, for a total of approximately 37 Mt. This will soon cut industrial emissions at the Port of Rotterdam by around 10%. And given that the new onshore compressor station and transport system will also provide capacity for future CO₂ storage projects, even more emissions can be mitigated later.

Aside from Porthos, another major CCS project, Aramis, is in development. Possible initiatives in the delta region of the south of the Netherlands and north of Belgium are also being explored. Gasunie and Vopak are also looking into the feasibility of building an independent reception and supply terminal for liquid CO₂ at the Maasvlakte industrial park (the CO2next project), which would ultimately be connected to Aramis and possibly other suppliers.

Gasunie is also one of the partners in the Delta Rhine Corridor project, which aims to lay multiple pipelines between Rotterdam and Germany to transport not only CO₂ but also hydrogen and other streams. To gather more information from potential customers and shippers about their interest in the CO₂ part of the Dutch section of the Delta Rhine Corridor, in April 2024 Gasunie launched a call for Expressions of Interest (EoI). A connection between Rotterdam, the Dutch province Zeeland and Antwerp in Belgium is also part of this call for EoI, though this project is being developed separately under the name Delta Schelde CO₂nnection.

The first step in CCS is capturing CO₂ at the source at industrial companies so that it is not emitted into the atmosphere. The company with the emissions is also responsible for capturing the CO₂, which they can do in several ways: through pre-combustion, post-combustion or oxy-fuel combustion. With pre-combustion carbon capture, CO₂ is captured during the production process before combustion is completed. This option is used, for example, in the production of hydrogen using natural gas. CO₂ is then separated by using activated carbon to absorb it. With post-combustion carbon capture, CO₂ is captured from the flue gases produced when burning natural gas (or coal or waste). Oxyfuel combustion involves burning flue gas using pure oxygen. Following this process, the gas is filtered, leaving CO₂.

The captured CO₂ is then transported to a compressor either directly through a pipeline or by ship. The latter option is used when the distance is too great to lay pipelines or when the volume is limited. The compressor compresses the CO₂ under high pressure to create a mixture of liquid and gaseous CO₂, making it easier to transport by pipeline to the permanent storage sites.

The captured CO₂ will then be stored in rock layers located 3 to 4km below the seabed in the Dutch part of the North Sea. These rock layers previously contained natural gas, which was trapped inside for millions of years. That natural gas has been extracted and now these depleted fields are available to store CO₂. After the CO₂ has been transported below the seabed via pipeline, the fields will be sealed to keep the CO₂ from escaping. A storage permit is required to store CO₂ under the North Sea’s seabed. These permits are granted by the Dutch Ministry of Economic Affairs and Climate Policy and checked and enforced by the independent Dutch regulatory authority the State Supervision of Mines.

Our animation on CO2 storage shows how it all works.

In addition to focusing on clean energy with hydrogen, heat and green gas, Gasunie is helping industry decarbonise through its participation in CO₂ storage initiatives. We are ready and willing to apply the knowledge and expertise we have amassed in the field of gas infrastructure to the transport of CO₂. So, together with our partners we will be working on the transport of CO₂ and its storage in depleted gas fields under the North Sea’s seabed and on the infrastructure required for this. We offer our clients reliable, safe, affordable infrastructure.