Environmental benefits of leaving offshore infrastructure in the ocean

Abstract

The removal of thousands of structures associated with oil and gas development from the world's oceans is well underway, yet the environmental impacts of this decommissioning practice remain unknown. Similar impacts will be associated with the eventual removal of offshore wind turbines. We conducted a global survey of environmental experts to guide best decommissioning practices in the North Sea, a region with a substantial removal burden. In contrast to current regulations, 94.7% of experts (36 out of 38) agreed that a more flexible case‐by‐case approach to decommissioning could benefit the North Sea environment. Partial removal options were considered to deliver better environmental outcomes than complete removal for platforms, but both approaches were equally supported for wind turbines. Key considerations identified for decommissioning were biodiversity enhancement, provision of reef habitat, and protection from bottom trawling, all of which are negatively affected by complete removal. We provide recommendations to guide the revision of offshore decommissioning policy, including a temporary suspension of obligatory removal.

Ecological Role of an Offshore Industry Artificial Structure

“…The structures evaluated here are relatively small, but commonly used in the region. In addition, much larger oil industry structures, including platforms and pipelines are present in large numbers in the North Sea area (Fowler et al, 2018). The effect of the size and type of the structure in controlling colonisation dynamics is unknown.…”

“…Artificial structures in the marine environment alter ecological structure and functioning. They provide habitat for threatened species (Bell and Smith, 1999), contribute reef habitat (Fowler et al, 2018), enhance recruitment of overfished species (Love et al, 2006), increase connectivity (Henry et al, 2018), often produce considerable fish biomass (Claisse et al, 2014) and provide foraging areas for large predators (Todd et al, 2016). These factors may vary over time, relating to environmental conditions and stage of ecological succession (Fujii, 2015).…”

“…The imminent decommissioning of oil and gas infrastructure in all major basins has increased attention on their importance as hard substratum in the marine environment. This focus has led to an increase in observational studies on the role of oil and gas infrastructure in local ecosystems (Fowler et al, 2018) demonstrating that they support species of conservation importance (Rouse et al, 2019) including cold-water corals (Gass and Roberts, 2006). Oil and gas infrastructure likely increases, or at least focuses, fish production (Claisse et al, 2014), surrounding benthic biomass, diversity, and connectivity (Macreadie et al, 2011) so their removal may reduce secondary production (Pondella et al, 2015).…”

Enhancing the Scientific Value of Industry Remotely Operated Vehicles (ROVs) in Our Oceans

“…Offshore O&G structures used by industry have finite operational lives dictated by factors such as the size of underlying hydrocarbon reserves and mechanical lifetimes. Thousands of structures will require decommissioning globally over coming decades, with decommissioning activity already increasing rapidly in some regions (e.g., North Sea; Fowler et al, 2018). Data provided by ROVs will be essential for timely investigation of the ecological role of offshore infrastructure and to predict the environmental effects of their removal/abandonment.…”

Social network analysis as a tool for marine spatial planning: Impacts of decommissioning on connectivity in the North Sea

“…Decommissioning, which is stipulated in the licenses granted (e.g. OSPAR, ; UNICLOS, ; UK Energy Act, ; UK Petroleum Act, ), is seen as a particular concern owing to the artificial reef effect and connectivity occurring between structures being removed (Fowler et al, ). Over the next 30 years, it is expected that around 500 installations will be decommissioned (HM Government et al, ).…”