Around the world, thousands of offshore oil and gas platforms are reaching the end of their operational life. The International Energy Agency estimates that more than 12,000 exist globally – with more than 1,500 ageing structures in the North Sea, another 1,500 in the Gulf of Mexico and over 2,500 in the Asia-Pacific region scheduled for decommissioning within the next decade.
Yet the decommissioning process can be lengthy and expensive, and innovators are finding creative ways to give old infrastructure a second life. Here are some of the ways nations are repurposing these heavy industry sites.
1. Carbon capture and storage (CCS)
One of the most promising pathways for repurposing offshore fields is carbon capture and storage (CCS).
These sites often already have the infrastructure to store CO₂ safely underground, with the pipes typically used to move oil and gas from seabed to shore repurposed to move carbon from onshore operations to the ocean floor.
The UK’s HyNet North West project, led by Eni, is among the first to put this concept into action. Approved in April, the initiative will use 149km of repurposed pipelines to transport CO₂ from industrial sites to depleted gas reservoirs beneath Liverpool Bay, providing a real-world test case for large-scale CCS integration.
Alastair Bisset, the North Sea Transition Authority’s (NSTA) Head of Decommissioning, tells Offshore Technology that the opportunity for CCS (and hydrogen storage) in the UK is particularly good.
“NSTA analysis identified more than 100 pipelines which could be suitable for CCS or hydrogen projects. This could save hundreds of millions of pounds by negating the need for the design, fabrication and installation of new pipelines,” he explains.
Jon Gluyas, Orsted/Ikon chair in CCS at Durham University, says the gas fields offshore of East Anglia and in Liverpool Bay provide a particular development opportunity due to their proximity to shore, favourable sea conditions and known geology.
While some technical considerations remain, such as adapting topside facilities and ensuring CO₂ is dry to prevent corrosion, Gluyas emphasises that much of the expertise from the oil and gas industry is directly transferable to CCS operations.
However, to make this a reality, he stresses that “Ultimately, the government needs to lead the way, just as it did to develop the oil and gas industry in the first place in the 1960s.
“Once the major infrastructure is in place [to repurpose offshore fields for CCS] it can start to earn revenue, and subsequent projects will be charged so as to recoup initial investments.”
2. Hydrogen hubs
As Bisset mentions, repurposing offshore pipelines and platforms to produce, store and transport hydrogen has also been tipped as a potential development opportunity, particularly as nations look to green hydrogen as part of the transition to a clean energy system.
“If you look at the platform infrastructure, most of it could be used for producing hydrogen,” Julio Garcia Navarro, programme manager of offshore hydrogen at research institution TNO, tells Offshore Technology. “This can be achieved by installing electrolyser topsides on top of existing sites, connecting them to the same gas connection substructure and transporting the hydrogen to land using the pipelines already there.”
Such projects are also particularly feasible when coupled with offshore wind, enabling the production of green hydrogen and helping meet nations’ renewable targets.
Projects such as the PosHYdon pilot in the Dutch North Sea demonstrate the viability of the concept, and Navarro says the only challenge lies in streamlining planning and policy around this repurposing.
“Replacing topsides or adapting substructures is feasible, but there is currently no unified strategy to coordinate between stakeholders. It is nothing to do with tech – it is a lot to do with politics,” he says.
3. Offshore wind
While no large-scale wind farms have yet been built directly on former oil platforms, a number of pilot projects and feasibility studies suggest the idea is technically and economically viable.
In the Netherlands and UK, joint initiatives by Nexstep and TNO have explored converting redundant jacket foundations into substructures for wind turbines or offshore substations. The studies found that repurposing infrastructure enables cost and environmental savings by avoiding a full infrastructure overhaul.
As mentioned, building offshore wind farms on repurposed infrastructure is being considered as a companion to green hydrogen.
“Integrating green hydrogen production into offshore energy infrastructure offers a powerful way to both decarbonise and accelerate offshore wind, helping governmental wind ambitions in the process,” says Navarro. “In addition to this, there is now the chance of using [oil and gas] infrastructure set to be decommissioned in the next 10–15 years.”
The Dutch Government, for instance, has a target of 70GW of offshore wind by 2050 (although the rollback of its 2040 target in July has now cast doubt on this). “Even if all this power is brought to shore and exported, the scale of the output would still exceed current demand. Hydrogen provides a pathway to balance this supply with viable, scalable offtake options,” Navarro adds.
4. Aquaculture
As offshore oil and gas platforms reach the end of their productive lives, some are finding a new purpose below the surface, with one being developing topside structures for commercial fish farms.
“When you are farming fish, you obviously need infrastructure in the water,” says Tyler Sclodnick, principal scientist at aquaculture company Innovasea. “An oil and gas rig could serve as a platform for operations – you can house staff there, store feed and even install your feed distribution systems like the pumps that deliver feed to the pens.”
Repurposed platforms often offer superior communications, power reliability and living conditions compared to bespoke aquaculture setups. However, decommissioning work is still required and facilities must be modified to operate within the tighter margins of commercial aquaculture.
Sclodnick cautions that repurposing oil platforms for aquaculture is not always the most cost-effective option, particularly when platforms are located far from shore. Yet, as the aquaculture industry pushes further into remote and exposed ocean environments, the model could become increasingly feasible.
“It looks like that will happen on a large scale over the next ten years or so. As that happens, the cost of pens, technologies, expertise and support services will decrease, making it more viable,” he says.
5. Marine research stations and artificial reefs
Decommissioned infrastructure naturally acts as a ‘fish aggregator’ – a habitat that supports biodiversity – and offers a strong basis for artificial reef systems.
In the US, ‘Rigs-to-Reefs’ programmes encourage oil companies to “reef” their retired oil rigs – removing their upper structures to make them safe for boats and divers – while in the Gulf of Mexico, hundreds of retired oil rigs now serve as artificial reefs.
The biodiversity these structures attract also makes them ideal locations for marine observatories, and the retired platforms offer built-in power, stability and offshore access to researchers.
As well as observing the marine life itself, these platforms could be used to monitor environmental conditions such as ocean acidification and temperatures, or to house a network of ocean sensors, enabling long-term data collection with minimal need for new construction.
While still in its design stage, one proposed example is the Acoustic Neutrino Detection In a Multidisciplinary Observatory concept in the Adriatic Sea, where offshore oil rigs would be repurposed to house sensors tracking acoustic ocean signals.
6. Dive sites
With decommissioned rigs often acting as a hub for marine life, the option to turn these underwater giants into dive spots is also being explored, and ensuring safety is critical.
“Rigs make excellent dive sites once they have been decommissioned,” Sclodnick says. “Divers are typically limited to about 30m depth, so infrastructure needs to be shallow enough for access and for sunlight to reach. In those cases, the top parts of the rig would be removed to prevent hazards to ships, but any submerged infrastructure within 30m can remain.”
In Malaysia, the world’s first oil rig-turned-dive resort, Seaventures, has operated off Mabul Island since 1997, with the site now also housing a floating hotel for guests.
Other examples include Platform HI-A-376 in the Gulf of Mexico and the Eureka, Ellen and Elly rigs in California.
7. Rocket launch pads
Another surprising concept is to turn offshore rigs into rocket launch platforms. With these sites already designed to bear immense loads, they offer a means of de-congesting the increasingly competitive orbital launch space.
Various nations have already thrown their hats in the ring. Last year, Italy’s space programme announced it will reopen its ocean launch pad off the coast of Kenya, while German start-up Offshore Spaceport Alliance has proposed an offshore space port in the North Sea.
Perhaps most famously, in 2021, Elon Musk’s SpaceX announced it had purchased two oil rigs in the Gulf of Mexico to be converted into rocket launch pads.
However, the company later sold the rigs, saying greater understanding and development of Starship was needed, although it said offshore launch pads remained a key sector for development.
While a real-world repurposing example is yet to be seen, interest in the sector is heating up. As satellite demand grows and companies pursue high cadence launch strategies, offshore platforms could evolve from being novel experiments to core infrastructure in the space economy.
