Decommissioning offshore wind farms: where innovation makes the difference now
The first Dutch offshore wind farms are approaching the end of their operational life, yet there is hardly any experience of dismantling them at scale. A new TNO study for RVO and TKI Offshore Energy shows where the bottlenecks lie and which innovations can make decommissioning cleaner, ecologically responsible, cheaper and more circular.
Turbines have been operating off the Dutch coast since 2007. What began as a demonstration project has grown into an offshore energy system that more and more households and businesses rely on. But every wind farm has an end point, and for that end point there is yet no proven playbook. Worldwide, only a few commercial offshore wind turbines have been fully decommissioned. For the full removal of today’s large monopiles, there is virtually no practical experience.
From building to dismantling: a task without a playbook
The first Dutch offshore wind farm, at Egmond aan Zee, will remain in operation until the end of 2031 following a technical and ecological evaluation. More farms will follow, while the construction of new ones continues. Ports, vessels and processors will therefore have to handle two flows at once: material going out to sea and material coming back.
It is also not yet settled what ‘cleaning up properly’ actually means. International frameworks such as UNCLOS, the IMO guidelines and the OSPAR Convention take complete removal as their starting point, but were largely written for oil and gas platforms.
The Dutch Offshore Wind Energy Act requires complete removal, with scope for a permit for partial removal. There is still uncertainty about the scour protection around foundations (the rock layer that stops the seabed from washing away). OSPAR is working on rules that better fit offshore wind.
‘For the first farms, full removal is sometimes expected, while the technology to do it reliably has not yet been proven at scale. We need to be honest about that gap, because only then can we work on closing it.’
Combining literature and practical knowledge
Commissioned by RVO and Energy Innovation NL | Offshore Energy, TNO investigated which knowledge and innovations contribute most to ecologically responsible decommissioning. The researchers combined a review of the literature and the market with a workshop held in Amsterdam on 7 April 2026. There, 32 experts from industry, research, government and civil society organisations shared their views on logistics, legislation, ecology and recycling.
The team then assessed nearly fifty innovation areas against six criteria: cost reduction potential, ecological footprint, circularity, technical readiness, regulatory readiness and opportunities for Dutch industry. The prioritisation is explicitly indicative. It helps to structure choices about solutions and innovation pathways.
Uncertainty is the costliest factor
A common thread in the study is that many decisions are being made with little evidence specific to decommissioning. Does a monopile have to be removed entirely, or may the part below the seabed stay in place? Does scour protection remain as a reef, or does it go ashore for recycling or reuse? As long as these questions have to be answered afresh for every project, risks and costs will keep rising.
This also affects the financial side. Since 2016, the Netherlands has applied a decommissioning bank guarantee of €120,000 per megawatt. It was intended to cover full removal, but according to the researchers it is barely enough to remove the 3 to 5 MW turbines alone.
‘Decommissioning isn’t finished when the last component is on shore. Without port space and processing chains for blades, polymers and magnets, circularity remains an ambition on paper.’
For foundations, full removal of monopiles scores highest. Techniques that reduce friction with the seabed through vibration, sometimes combined with water jetting, or that push the pile upwards from the inside using water pressure, show potential. But after twenty years or more in the seabed, it is hard to predict how much force is needed to free a pile. Sand and clay also behave very differently.
Cutting below the seabed is the common approach and, for now, the more feasible route. However, it disturbs the ecosystem more and recovers less steel. And because monopiles keep getting bigger, the gap between installation and removal technology is widening. The biggest brake on progress is the lack of full-scale testing opportunities in soil that has had years to settle.
Around every monopile lies a layer of rock that protects the seabed from erosion. It is removed using grabs, which is slow, costly and disturbs the seabed. According to the study, this complexity is often underestimated, while relatively little research is under way into efficient removal.
At the same time, a rich community of seabed life develops on these rocks over the years. Complete removal destroys that habitat. Scour protection solutions that enhance nature and can be left in place therefore score highly in the prioritisation, as does the reuse of rock in other offshore projects. Whether leaving it in place is ecologically the best choice does vary from site to site. And who remains responsible for what is left behind has not yet been settled.
Cables are currently pulled out of the seabed and cut into sections on deck. This is relatively cheap, but it damages the cable and rules out reuse or high-value recycling. Cable crossings, deeply buried sections and older cables with bitumen in the sheath make the work labour-intensive. Recycling focuses mainly on copper, aluminium and steel, while polymer insulation such as XLPE still receives little attention.
For turbines, offshore lifting is the biggest cost item. Just as challenging is what happens next. Quay space in ports is scarce, especially when decommissioning coincides with the construction of new farms. For composite blades, polymers and permanent magnets, processing at scale is not yet in place. Investment lags as long as volumes and planning remain uncertain.
What is ecologically better depends on the chosen end state. Complete removal brings the seabed closer to the original sandy bottom but also allows bottom trawling to return. Partial removal retains some of the hard substrate, but sometimes conflicts with regulations and can act as a stepping stone for non-native species.
The disturbance during the work itself is also still poorly understood. Underwater noise, turbidity and vessel traffic are often estimated on the basis of construction and operation, not on measurements taken during decommissioning. If several farms are dismantled in the same period, effects can accumulate. In the Dutch Framework for Assessing Ecological and Cumulative Effects (KEC), decommissioning is not yet a separate lifecycle phase. Targeted monitoring before, during and after decommissioning should fill these knowledge gaps.
The first farms as a demonstration ground
The key recommendation: use the first Dutch decommissioning projects to demonstrate technology at full scale. This means removing, transporting and processing selected piles, cables and scour protection, coordinated by an independent party together with industry associations such as GROW.
The condition is that owners, contractors, technology providers and government share costs and risks. Only then can data and lessons learned be shared widely. The researchers advise separating the innovation scope from the commercial removal contract, because innovation has a different risk profile. A comparable initiative is under way in Germany around the Alpha Ventus wind farm, which the Netherlands can build on.
They also call for subsidies across the full range of technology readiness levels, including early-stage research. In addition, they ask for investment in port and processing infrastructure in coordination with other North Sea countries, and for better European alignment of end-of-life research.
‘If we set up the first projects smartly, it won’t be one party that learns, but the whole sector. That is the fastest route to decommissioning that is both affordable and nature friendly.’
What TNO contributes
TNO has been working on the end-of-life of offshore wind for some time. Previously, we calculated decommissioning costs for the Ministry of Climate and Green Growth. In projects such as CIRCLE4WIN and EoLO-HUBs, we work with partners on high-value recycling of composite blades.
In this study, we brought together technical, ecological, legal and economic knowledge and translated it into concrete innovation priorities. As an independent party, we can help set up, assess and monitor demonstration projects, and make the results available to the whole sector.
Download the report and join the conversation
The full report, with the prioritisation per component and all workshop outcomes, is now available to download.
Are you a wind farm owner, contractor, technology developer, port operator or policymaker, and would you like to contribute to a demonstration programme? Please get in touch with Harald van der Mijle Meijer. Together, we will explore how the first decommissioning projects can move the whole sector forward.
Contact us
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Harald van der Mijle Meijer
Functie:R&D portfolio managerIr Harald van der Mijle Meijer is a materials engineer and has been working in offshore wind research since 2007. Harald has a passion for wind, sea and sustainability and applies this for the strategy and implementation of the development of innovations in wind energy together with the industry. At TNO he has carried out several national and international projects on a wide range of topics. In addition to being a consultant, he is R&D portfolio manager on the research line 'Offshore Wind Farms'.
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Standplaats:Petten - Westerduinweg
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Email:Email Harald
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