Dilemma over what to do with redundant North Sea man-made structures

UNITED KINGDOM / AGILITYPR.NEWS / July 13, 2020 / Essex marine biologists lead major research into impact of North Sea man-made structures

A team of University of Essex marine biologists is leading one of seven research projects sharing £5m of funding to assess the impact of North Sea man-made structures.

There are currently more than 1,300 energy-related structures in the North Sea – from oil rigs and gas platforms to wind turbines and underground cables. The issue is what to do with them when they are decommissioned.

Hundreds of oil drilling platforms in the North Sea are due to be decommissioned over the next three decades as they approach the end of their operational lifetime.

Current EU decommissioning regulations – which cover the North Sea – ban leaving installations in place once redundant, which means they must be completely removed when no longer in production. However, other parts of the world have adopted a “rigs to reef” programme where decommissioned rigs are converted into permanent underwater reefs.

The Essex project, led by marine biologist Dr Natalie Hicks from the School of Life Sciences, is one of seven INSITE projects to share £5m of funding over the next three years by the Natural Environmental Research Council (NERC), supported by Centre for Environment, Fisheries and Aquaculture (CEFAS).

This INSITE (Influence of Structures In The Ecosystem) programme aims to tackle the critical gaps in scientific understanding of the role that man-made structures play in marine ecosystems.

Working with colleagues at the University of St Andrews, CEFAS and the Scottish Association for Marine Science (SAMS), the Essex team will focus on the impact the man-made structures currently have on the seabed and the disturbance and wider impact if they are removed.

“The effect these structures have on marine ecosystems is largely unknown, and could be positive, negative, or a combination of both,” explained Dr Hicks. “As we start to consider how best to decommission these structures, it is important to understand the impact these structures have on the seabed.”

The North Sea is covered by sandy and muddy sediments, which store a significant proportion of carbon. These sediments also provide a habitat for many species, such as commercial fish. Despite being alien to the marine environments where they are based, the man-made structures actually provide unofficial 'Marine Protected Areas' (MPA) as they protect the seabed around them from other physical disturbances, such as trawling and dredging.

Dr Hicks added: “We know the impact of extracting oil and gas at many of these structures influences the local biodiversity. Whilst the stability of these sediments and their ability to store carbon is uncertain, the decommissioning and physical removal of these structures has the potential to disrupt these long-term carbon stores, releasing carbon into the seawater and affecting the seabed ecosystem.”

The £875k project includes fieldwork where samples will be taken around the man-made structures to measure the changes in carbon storage and biodiversity within the sediments. The research team will also be modelling environmental data, using new collected data alongside data from industry, to identify the role of these structures on key marine ecosystem processes.

Recent news reports on UK decommissioning decisions have drawn interest from other European oil nations, and the project’s findings are expected to have international interest and direct policy relevance for future decommissioning. The work will also inform decisions around the deployment of new wind energy structures and their long-term fate, as well as oil and gas infrastructure.

Commenting on the NERC awards, Professor David Paterson, Chair of Marine Alliance for Science and Technology for Scotland, said: “The question of what should be done with offshore structures at the end of their life is one that attracts interest and controversy from across industry, science, the public, NGOs and government communities.

“The decisions relating to decommissioning policy, planning and practice are often difficult and scientific evidence such as that coming from INSITE should be a core consideration in each individual case.”