Study calls for action to explore potential impacts of decommissioned offshore structures

The research comes at a time when oil and gas platforms are being phased out, but renewable energy structures are being installed in their place
offshore gas platform - INSITE
Making uniform decisions to justify the decommissioning of offshore artificial structures at the end of their lives could pose significant environmental challenges, a new study has said.
In line with the global decarbonisation agenda, governments and industries worldwide are exploring how best to expand the use of renewable energy technologies to replace fossil fuels. 
This means that worldwide, an increasing number of structures such as wind turbines are being sited on land and in the sea, while oil and gas infrastructure is reaching its end-of-life and requiring decommissioning. 
Writing in Trends in Ecology and Evolution, researchers say evidence is limited as to how best to manage such structures when they reach the end of their lives, with some arguments that any artificial structure should be removed in entirety and others proposing structures be repurposed. 
To counter that, scientists have called for urgent global action so that the construction of future artificial structures – or the decommissioning of existing ones – doesn’t create an additional ecological burden on areas of the planet already being severely impacted by the effects of climate change.
The study was carried out by researchers at the University of Plymouth, Plymouth Marine Laboratory and the UK Government’s Centre for Environment, Fisheries and Aquaculture Science (Cefas).
It formed part of the Decommissioning – Relative Effects of Alternative Management Strategies (DREAMS) project, a three-year initiative funded by UKRI’s INSITE programme.
Dr Anaëlle Lemasson
Dr Anaelle Lemasson
Dr Anaelle Lemasson , Post-Doctoral Research Fellow at the University and the study’s lead author, said:
“Through our research, we only found around 50 studies worldwide that have provided direct evidence of how the decommissioning of offshore structures is impacting the marine environment. Most of these were off the coast of the USA or in the North Sea, which primarily focus on what happens to fish or invertebrates when structures are removed, but ignore consequences for other features. Clearly, this leaves a lot of gaps from both a geographical and environmental perspective.”
Given an estimated 1,800 offshore wind turbines likely to require decommissioning by 2030, the need for consensus on future approaches has never been more pressing.
This is the latest study involving the University of Plymouth to examine the potential ecological impacts of both the construction and adaptation of coastal and ocean structures.
Dr Antony Knights , Associate Professor in Marine Ecology and Co-Principal Investigator on the DREAMS project, added:
“Despite the current evidence being minimal, the last few years have seen a surge in the number of studies looking at this issue. It highlights the global recognition, within the scientific community at least, that efforts are critically required to prevent this from becoming a major environmental concern. We know that industry, national and international governments are keen to ensure that structures are decommissioned most effectively and efficiently. However, the evidence required to underpin best-practice decision-making and develop environmental policy that benefits both nature and society remains disparate with our knowledge of how best to tackle the issue falling short of what is required.”
Dr Antony Knights
Dr Antony Knights
  • The full study – Lemasson et al: Challenges of evidence-informed offshore decommissioning: an environmental perspective – is published in Trends in Ecology and Evolution, DOI: https://doi.org/10.1016/j.tree.2023.04.003.
 

DREAMS: Decommissioning – Relative Effects of Alternative Management Strategies (2020-2023)

Dr Antony Knights is Co-PI of two NERC INSITE (Influence of Man-made Structures in the Ecosystem) funded grants (DREAMS and INSITE Synthesis). He works closely with Dr Anaëlle Lemasson, who is a Post-doctoral Fellow on both the DREAMS and INSITE Synthesis projects, and Dr Louise Firth (INSITE Synthesis).
DREAMS is a collaborative project with Plymouth Marine Laboratory (PML) and Centre for Environment, Fisheries & Aquaculture Science (Cefas), and partnership with Texas A & M University at Corpus Christi, Harte Research Institute, USA.  DREAMS is a highly integrated project designed to develop new understanding of how man-made structures, and different decommissioning strategies for them, influence the structure, functioning and dynamics of marine ecosystems and affect delivery of ecosystem services from a whole ecosystem perspective. 
Our approach – to use novel integration and analyses of existing data from a wide range of sources, using structured, systematic and meta-analytic approaches, to quantify the effects of man-made structures on ecosystems and services.
Oil platform on sea. Oil platform on sea is offshore structure with facilities to drill wells, extract and process oil and natural gas and temporarily store produced goods until it can be brought to the shore for refining. In most cases the platform contains facilities to house the workforce.
Outcomes are being fed into state-of-the-art ecosystem models to forecast ecosystem states and estimates of goods and services, with associated trade-offs across spatial and temporal scales, based on a range of different decommissioning strategies. Working closely with academic, governance and environmental management stakeholders, we aim to inform decision-makers and stakeholders about the relative benefits and detriments of different strategies for decommissioning structures in the North Sea for the environment and people (Lemasson et al. 2021).