What happens to the nature that has developed on offshore platforms and wind turbines when these structures are removed at the end of their operational life? Two interactive infographics explore the ecological considerations involved in offshore decommissioning and what different scenarios could mean for biodiversity in the North Sea.
Over the past decades, hundreds of offshore oil and gas installations and, more recently, large numbers of offshore wind farms, have been built in the North Sea. Although these structures can negatively affect marine ecosystems during construction and operation, research shows that they can also develop ecological value over time as new habitats.
Developed as part of the Nature-friendly Decommissioning project, the infographics focus on offshore wind and grid infrastructure, and on offshore platforms such as oil and gas installations and electrical substations. Explore them to discover what we know so far and how nature may change after decommissioning.
Offshore wind and grid infrastructure Infographic
Click to open the infographic (PDF) We recommend downloading and viewing in your computer’s PDF reader application (i.e. Adobe) on “Single Page View”.
The infographics provide a general overview. In practice, ecological effects vary by location; decommissioning decisions should always be made on a case-by-case, site-specific basis.
Offshore platforms Infographic
Click to open the infographic (PDF) We recommend downloading and viewing in your computer’s PDF reader application (i.e. Adobe) on “Single Page View”.
Illustration & graphic design: Kate Snow Design
The infographics provide a general overview. In practice, ecological effects vary by location; decommissioning decisions should always be made on a case-by-case, site-specific basis.
Watch the introduction
Project Lead Nature-Friendly Offshore Energy Pim Somers explains how to use the infographics.
Project partners
These infographics were developed as part of the Nature-Friendly Decommissioning Project — a collaboration between environmental NGOs (the North Sea Foundation, Natuur & Milieu), EBN (the Dutch state participant in subsurface activities), NedZero (Dutch wind association), TenneT (TSO) and ElementNL (Dutch oil & gas association).
The aim of the project is to explore how to create policy-space to permanently leave nature-enhancing man-made structures (artificial reefs and components of offshore wind farms and oil & gas platforms) in place in the Dutch part of the North Sea for the benefit of underwater biodiversity. Based on clear ecological standards and requirements and without creating a precedent that would undermine the general principle of full removal of disused offshore installations.
Want to know more? Read the background document
Want to read the science behind the infographics? The background document takes a closer look at what we know about the nature that has developed on and around offshore structures — and what each decommissioning scenario means for those ecosystems.
End-of-life state and removal scenarios
We distinguish between the following theoretical states:
- The pre-decommissioning end-of-life state. In this state, the platform or wind farm is no longer producing energy, but the infrastructure remains fully intact. It is not considered a potential end state, but rather a baseline: ecological communities that developed during operation are still present, while operational disturbances such as noise, electric fields, and chemical pollution have ceased.
- Partial removal scenario. This is a theoretical example of a decommissioning scenario, in which only parts of the infrastructure have been removed. This scenario assumes that only components of infrastructure that leave a free draught of minimum 25 m are left in place. Cutting depth (below, at, or above seabed) affects habitat disturbance levels and environmental outcomes.
- Full removal scenario. This is the scenario that is currently the base case in the Dutch removal obligation and in OSPAR Decision 98/3. This implies full removal to shore of all infrastructure, with some exceptions for pipelines and rock dump connected to oil and gas platforms. After removal, the location may be reopened to other forms of use that are allowed for in the surrounding area.
The management aspects in the infographic focus on selected aspects that either differ before and after decommissioning or that are, in our view, essential in creating the basis for decommissioning decisions that seek to minimise damage to important ecological values/habitats/services without wasting valuable materials or jeopardizing the safety of other users.
The information provided in the infographic offers a general overview and is not intended to be exhaustive. The concepts and environmental drivers described will vary depending on local conditions. Therefore, decommissioning decisions should always be made on a case-by-case, site-specific basis supported by thorough in-situ assessments. Furthermore, the decommissioning scenarios discussed are theoretical options that may currently lack regulatory approval or proven technical feasibility.