On 8 March 2023, Denmark launched a carbon dioxide storage project 1,800 metres below the North Sea, making it the first country in the world to store CO₂ imported from abroad.

The CO₂ graveyard, where carbon is injected to prevent further atmospheric warming, has been established at the site of an old oil field. It is expected that by 2030, the “Greensand” project, led by the British chemical giant Ineos and the German oil company Wintershall Dea, will store up to eight million tonnes of CO₂ per year.

Carbon capture and storage (CCS) projects aim to capture and then sequester CO₂ to mitigate global warming; however, they are still in their infancy and are costly. Currently, about 30 projects are either operating or under development in Europe.

Unlike other projects that store CO₂ emissions from nearby industrial facilities, Greensand is unique in that it imports carbon from afar. First, CO₂ is captured at its source, then liquefied and transported (currently by ship, though potentially via pipelines) and stored in reservoirs such as geological cavities or depleted oil and gas fields. Danish authorities, who have set a goal of achieving carbon neutrality by 2045, claim that it is a “much-needed instrument in our climate toolkit”.

“It will help us meet our climate targets, and since our subsoil has a much greater storage potential than our own emissions, we can also store carbon from other countries,” said Minister for Climate, Energy and Utilities Lars Aagaard.

The North Sea is particularly suitable for this type of project because the region already has pipelines and potential storage sites following decades of oil and gas extraction.

Although the stored quantity is measured in millions of tonnes, it is still a small fraction of total emissions. According to the European Environment Agency (EEA), EU member states emitted 3.7 billion tonnes of greenhouse gases in 2020 alone.

Long considered a complex solution with minimal application, carbon capture has been recognised as necessary by the UN’s Intergovernmental Panel on Climate Change (IPCC) and the International Energy Agency (IEA).

Unfortunately, it is by no means a miracle cure for preventing global warming. According to the Australian think tank IEEFA, the CO₂ capture and storage process itself, which is highly energy-intensive, generates emissions equivalent to 21% of the amount of gas captured. Furthermore, this technology is not without risk, according to the think tank, which points out that a potential leak could have serious consequences. In addition, the project costs have not been disclosed.

“The costs of CO₂ storage must continue to be reduced so that, as the industry matures, it becomes a sustainable solution for climate change mitigation,” said Morten Jeppesen, Director of the Danish Offshore Technology Centre at the Technical University of Denmark (DTU).

The technology also faces opposition from environmentalists.

“It does not solve the problem and prolongs the life of harmful structures,” said Helene Hage, Head of Climate and Environmental Policy at Greenpeace Denmark.

“This method does not change our deadly habits. If Denmark really wants to cut emissions, it should focus on sectors that generate high emissions,” Hage noted, also highlighting sectors such as agriculture and transport.