The remote Nini oil field in the Danish sector of the North Sea, once a site for fossil fuel extraction, is being transformed into a cornerstone of Europe’s emerging offshore CO2 storage industry. Operated by chemical giant INEOS through its Greensand Future project, the depleted oil reservoir is being repurposed to permanently trap carbon dioxide deep beneath the seabed. In a process that effectively reverses oil production, liquefied CO₂ will be injected 1,800 meters underground into sandstone formations that once held hydrocarbons. When commercial operations begin next year, Greensand is expected to become the European Union’s first fully operational offshore CO2 storage facility.
INEOS plans to start by storing 400,000 tons of CO₂ annually, with the goal of scaling up to as much as 8 million tons per year by 2030. According to INEOS Energy Europe CEO Mads Gade, Denmark alone may have the capacity to store several hundred years’ worth of its own emissions, positioning the country as a major carbon storage hub for Europe. The project has already secured agreements with Danish biogas facilities, whose captured emissions will be transported and injected into the Nini field’s depleted reservoirs. Supporting infrastructure is also being constructed, including a CO₂ terminal at Denmark’s Port of Esbjerg and a custom-built transport ship, the “Carbon Destroyer 1,” currently under construction in the Netherlands.
Proponents argue that carbon capture and storage offers a critical tool for climate mitigation by removing the primary greenhouse gas driving global warming and isolating it deep underground. The Intergovernmental Panel on Climate Change has recognized carbon capture as part of the solution set needed to meet climate targets. At the policy level, the European Union aims to develop at least 250 million tons of CO₂ storage capacity annually by 2040 as part of its strategy to reach net-zero emissions by 2050. Gade emphasizes that offshore CO2 storage allows Europe to cut emissions without dismantling its industrial base, offering a “decarbonization without deindustrialization” pathway.
Geological studies further underpin the project’s feasibility. Researchers from the Geological Survey of Denmark and Greenland report that the Greensand sandstone formations are particularly well suited for CO₂ storage. Nearly one-third of the rock volume consists of pore space capable of absorbing liquefied CO₂, while the overlying seal rock has sufficient strength to contain the increased pressure. Importantly, tests show no harmful reactions between the injected CO₂ and the surrounding reservoir rock, reinforcing long-term storage stability.
Despite its promise, the project faces significant criticism. While the planned annual storage of 8 million tons by 2030 is substantial, it remains tiny compared with the nearly 38 billion tons of CO₂ emitted globally each year. Environmental groups warn that carbon capture is often used to justify continued fossil fuel use rather than aggressive emissions reductions. Greenpeace Denmark argues that offshore CO2 storage should be reserved only for sectors where emissions are genuinely unavoidable, not as a substitute for broader systemic change.
Controversy is further intensified by INEOS’s parallel plans to develop another North Sea oil field even as it expands carbon storage. The company counters that producing domestic energy has a smaller carbon footprint than imports and can serve as a transitional measure. As Europe accelerates its climate transition, Greensand stands as both a technological milestone and a lightning rod in the broader debate over the true role of offshore CO2 storage in achieving net zero.