Visit the North Sea oil field where CO2 is pumped under the seabed

"Prepare for an offshore landing," the pilot announces, his voice cutting through the thrum of the helicopter’s rotors as the aircraft descends towards a remote platform shimmering on the choppy waters of the North Sea. The helicopter has just completed a circuit around Nini, a nearby rig that serves as a sentinel over an almost-depleted oilfield poised for a radical transformation. This forgotten reservoir is on the cusp of a second life, set to become the linchpin of a groundbreaking carbon storage project known as Greensand Future. The ambitious plan involves injecting thousands of tonnes of climate-warming carbon dioxide (CO2) directly into the ancient geological formations beneath the seabed.

The journey culminates on Siri, a larger "mother platform" that functions as the nerve center for operations, its control room staffed by seasoned offshore workers. Here, Mads Gade, CEO of Ineos Energy, gestures towards the formidable pipes of the wellhead – conduits that for decades have faithfully delivered oil and gas from the earth’s depths to the surface. "Instead of pulling the oil and gas up from the ground, we’re going to inject the CO2 into the ground instead," he explains, a subtle shift in purpose for infrastructure once synonymous with fossil fuel extraction.

This pioneering initiative harnesses the power of Carbon Capture and Storage (CCS) technology, a multifaceted approach aimed at capturing and permanently sequestering carbon dioxide. Greensand Future, a venture spearheaded by a consortium led by the British multinational chemicals company Ineos, is poised to become the European Union’s inaugural large-scale offshore CO2 storage facility once commercial operations commence in the coming months. The project’s immediate goal is to sequester approximately 400,000 tonnes of CO2 this year, with projections indicating a dramatic escalation to eight million tonnes annually by 2030, according to company claims. "That’s almost 40% of the Danish emission reduction target. So that’s quite impactful," Gade states, underscoring the potential significance of the project in the global fight against climate change.

However, the advent of CCS technology has not been without its detractors. Critics voice concerns that such solutions might inadvertently dilute efforts to reduce CO2 emissions at their source, potentially creating a false sense of security. The inherent expense of CCS is another significant hurdle, and some environmental advocacy groups argue that emission reductions could be achieved more cost-effectively by leveraging existing, proven technologies such as wind power, solar energy, and the burgeoning electric vehicle market.

Helene Hagel, head of climate and environmental policy at Greenpeace Denmark, articulates this perspective: "I don’t mind CCS on those sectors where emissions are truly hard-to-abate or impossible-to-abate. But there are also places where it makes no sense at all." She further cautions against the potential for creating intergenerational inequities, warning, "If our generation uses the seabed for storing carbon that we shouldn’t have emitted in the first place, then the generations coming after us won’t be able to use the seabed to store their emissions." This highlights a critical ethical consideration regarding the long-term implications of subterranean carbon storage.

Despite these reservations, the momentum behind CCS is undeniable. Globally, hundreds of CCS initiatives are either in progress or in various stages of development. The North Sea region, in particular, is emerging as a focal point for large-scale projects, with Norway, the Netherlands, Denmark, and the UK leading the charge. Norway’s Northern Lights project, heralded as the world’s first commercial carbon storage service, began injecting CO2 under the seabed off Bergen in August of the previous year. In the United Kingdom, several ambitious carbon capture clusters are under development, including Scotland’s Acorn Project and the Viking project off the coast of Lincolnshire.

A key factor driving the North Sea’s emergence as a CCS hub is its rich oil and gas legacy. Niels Schovsbo, a senior researcher at the Geological Survey of Greenland and Denmark (GEUS), explains that after decades of intensive production, the geological characteristics of potential storage sites have been extensively mapped and understood. This existing knowledge base significantly reduces the exploration risk and cost associated with identifying suitable geological formations. Furthermore, the presence of established offshore infrastructure and a highly skilled workforce provides a significant advantage. This synergy of existing assets and expertise is precisely why companies like Ineos are among the early adopters. "Nini’s coming to the end of its lifetime," Gade notes. "Instead of dismantling everything, we can actually reuse the facilities, the skills, the competencies we have."

The transition from oil and gas extraction to carbon storage offers a promising avenue for the continued employment and retraining of offshore workers, ensuring the preservation of valuable expertise. Inside a sprawling warehouse on the outskirts of Copenhagen, rows upon rows of rock samples, meticulously collected from the seafloor, stand testament to the scientific rigor underpinning these projects. Schovsbo carefully opens a box, revealing a grainy green slab, a tangible representation of the subterranean environment poised to play a crucial role in climate mitigation.

The geology in this particular region of the North Sea is exceptionally well-suited for CO2 storage. Schovsbo elaborates that the rock formations are characterized by a high porosity, meaning they contain a vast network of small cavities or pores capable of holding significant volumes of CO2. Crucially, a substantial layer of impermeable clay, or cap rock, approximately a kilometre thick, will act as a natural seal, effectively trapping the injected CO2. This sealing mechanism is identical to the one that has, for millions of years, held oil and gas captive beneath the earth’s surface. Schovsbo estimates that a comparable volume of CO2 can be stored to the amount of hydrocarbons that have been extracted, suggesting that CCS sites could have an operational lifespan ranging from 10 to 30 years.

For the region’s extensive offshore workforce, the burgeoning carbon storage industry represents a significant opportunity for adaptation and growth. Peter Bjerre, a maintenance manager, shares his optimism: "A lot of the work we’re doing today by maintaining turbines and gas compressors will be shifted to maintaining high-pressure pumps that inject the CO2." As an Esbjerg local, Bjerre reflects on the region’s economic evolution: "Fifty years back, it was fishing we made money off, then going into oil and gas. It is just amazing seeing a future building up here with the green transition here." This sentiment underscores the potential for a just transition, where established industries and their workforces can pivot towards sustainable solutions, securing a viable economic future while contributing to global climate goals. The reuse of existing infrastructure, coupled with the adaptation of existing skills, presents a compelling case for the strategic deployment of CCS technology in regions with a deep-rooted history in offshore energy production.