Offshore wind end‑of‑life: must everything be removed, even when nature is thriving?

At present, most international frameworks require full removal of offshore wind installations at the end of their operational life. Only limited case‑by‑case exceptions are permitted. These typically apply where there is compelling evidence that removal would be unsafe, technically infeasible, disproportionately harmful to the environment, or economically prohibitive. 

Current European directives, regulations and guidance for wind farms’ end-of-life stage are largely inherited from the regulatory context developed for O&G and reflect the prevailing principle that the seabed should be restored to its pre‑project condition, leaving no physical trace of the installation. 

Although offshore wind farm sites are typically selected in areas of relatively low biodiversity, to minimize impacts on marine and coastal life, no offshore environment is “lifeless.” Even an apparently barren muddy and sandy seabed hosts important communities of marine life. Moreover, during the installation and operational phases, wind farm development areas limit or exclude many fishing activities for safety reasons, indirectly offering a potential refuge for marine organisms.

The deployment of Nature‑Inclusive Design (NID) elements, such as textured foundation surfaces, reef-like blocks for scour and cable protection and others, have shown that these solutions can create artificial habitats that support development of marine organisms throughout the projects’ 20–30‑year operational lifetime. As a result, seabed areas that were previously barren or degraded could develop more diverse and complex ecological communities over time, driven by the introduction of hard substrates and the reduction of seabed disturbance from fishing activities.

Consequently, under strict “full removal” decommissioning policies, even these ecologically beneficial features would be removed, potentially reversing decades of habitat development.  So, a fundamental question needs to be raised: is it valuable to remove everything, even when nature is thriving?

The UKRI-funded project VALMAS under the INSITE programme, is assessing the value of marine artificial structures and their potential ecological and social impacts and trade-offs under different development and decommissioning scenarios [4]. This research aims to inform debates among scientists, regulators, and NGOs about introducing greater flexibility in decommissioning requirements, particularly where partial decommissioning can be justified based on ecological value [5][6].

Alternatives to full removal are increasingly being explored. One of the most widely considered options is partial removal, which involves cutting monopile foundations at or below seabed level while leaving scour protection and buried cables in situ, or a combination thereof. In some cases, this approach has been considered as more beneficial for local biodiversity than the complete removal of all infrastructure, as it preserves habitats that have developed around the structures during the operational life of the wind farm, and any negative impacts from leaving elements in-situ, can be tolerated. Limited applications also include the use of biodegradable or natural materials for Nature-Inclusive Design (NID) features, which can remain in place and degrade naturally over time once the foundations have been removed.

Another alternative is repowering or lifetime extension, whereby the operational life of a wind farm is extended through refurbishment or replacement of turbines while reusing existing foundations, where feasible. Although this can significantly delay decommissioning and maximise the value of installed infrastructure, it ultimately postpones rather than eliminates the need to address end-of-life management.

The vision paper “Decommissioning Offshore Windparks in the Belgian Part of the North Sea” [7] presents a further alternative for sites where repowering is not planned, and no new offshore infrastructure installation is anticipated. Under this approach, a limited number of foundations could be retained after removal of the turbines, transition pieces and any structures above seabed level. The remaining foundations could then be repurposed for alternative uses, such as supporting aquaculture or passive fishing activities (e.g. longlines and baskets), providing platforms for marine and climate monitoring equipment, serving as test sites for emerging offshore technologies, or creating unique attractions for marine tourism and recreational activities. This approach seeks to extend the useful life of existing infrastructure while avoiding some of the environmental impacts associated with complete removal. Further examples and case studies can be found in [1] and [2].

Decommissioning of offshore windfarms is currently being reviewed by OSPAR as part of a wider review of environmental guidance for the sector.  We should consider several questions at this point:

1. Do partial in-situ decommissioning approaches deliver benefits that outweigh the negative impacts of marine environment disturbance and greenhouse gas emissions associated with full removal of all infrastructure?
2. Should partial decommissioning become an option available to offshore wind and who will retain liability for structures or material left in-situ? And what, if any, monitoring of these will be required?
3. Does current uncertainty on decommissioning requirements hinder the development and application of NID?

Decommissioning is clearly a complex and multi-dimensional issue, not only limited to the ecological aspect, but also involving technical, economic, policy, and legal considerations.