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Aerial shot looking down at white offshore wind turbines, waves breaking on surface of blue sea
New metrics could help policymakers assess the benefits and environmental effects of offshore wind more effectively. dragancfm/Shutterstock

Offshore wind farms: policymakers are more influenced by reports that accentuate negative impacts – new study

Towering up to 260m above the ocean’s surface, modern wind turbines are impressive feats of engineering, producing much-needed renewable energy. But what happens beneath the waves?

Government policymakers need reliable evidence to make planning decisions about new offshore wind developments and ensure positive outcomes. Currently, this evidence comes from a huge variety of sources, resulting in a lack of consistency and conflicting conclusions.

“Primary literature” refers to studies published in scientific journals, following a structured peer review process. “Grey literature” includes all other types of reports and evidence sources.

For offshore wind farms, decision-makers more frequently rely on grey literature such as environmental statements, impact or habitat risk assessments, survey reports, social studies, and pre- and post-construction reports. But new research by myself and colleagues into these different forms of evidence reveals some unexpected findings.

Shades of grey

Our team of marine researchers compiled evidence from grey and primary literature for environmental and social impacts of UK offshore wind farms published between 2002 and 2022. We discovered that primary and grey literature do not always present the same information.

Policymakers tend to favour grey literature even though it gives a less balanced outlook, perhaps due to access issues. Primary literature often sits behind paywalls, the process of review can lead to lengthy delays in publication, and these studies may just investigate one species or process in detail. Grey literature is easier to access, available much sooner, and can provide a useful overview or synthesis of available knowledge, which is exactly what regulators need.

Overall, 71% of outcomes reported in grey literature for the impacts of offshore wind farms are negative, compared with 36% in primary literature. This disparity could in part be due to the fact that environmental impact assessments address potential rather than specific impacts, and reflect a high proportion of the grey literature.

In addition, some positive outcomes related to offshore wind farms that are reported in primary literature are not found in grey literature. These can include positive impacts on food provision – for example, certain fish, such as cod and pouting, seem to aggregate around these structures. Other aspects not evidenced in grey literature are improved water quality through filtration by shellfish, and carbon export, whereby deposits of faecal pellets by shellfish living on the wind turbines bring carbon down to the seabed for longer-term storage.

Lobster fishermen report better catches inside turbine arrays, but boats with mobile fishing gear such as trawlers and dredgers are often excluded from turbine arrays or cable routes due to practical and safety issues. This could provide a refuge for certain fish species, but is slowly eroding the right to commercial fishing where wind farms and cables are sited over important fishing grounds.

Negative impacts include underwater noise, increased boat traffic, and risk of collision and disturbance to marine mammals, particularly during construction. Also, preferred feeding sites or migration routes can be disrupted by the physical barriers caused by turbines and cables on the seabed that emit electro-magnetic fields.

There is also a fundamental lack of evidence for decommissioning, as well as disagreement on strategy – for example, whether to completely remove, partially remove, or repurpose old turbines. Decommissioning turbines could result in pollution from chemicals and changes in nutrient cycling in the sea, depending on the strategy. This evidence gap urgently needs to be filled so that decommissioning strategies meet environmental targets.

Big red and white boat, next to offshore wind turbines, flat blue sea
Service vessels are an essential part of ongoing maintenance for offshore wind farms, but can contribute to boat traffic and acoustic pollution. David_Maddock/Shutterstock

Future frontiers

Low-carbon, renewable energy sources are essential for a sustainable future. The offshore wind industry is growing rapidly, and the Dogger Bank wind farm in the North Sea will be the world’s largest on completion.

But any marine urbanisation has implications for the environment. For offshore wind, we need to identify the positives and negatives of such large-scale development on our seabed.

The UK government’s proposed marine net gain policy specifies that new developments should result in more or better quality natural habitat than there was beforehand. But, given that we found just 2% of outcomes reported in UK grey literature are positive, compared with 28% of outcomes in primary literature, opportunities to assess and achieve these targets may be missed.

The next frontier for offshore wind is floating turbines, in which seabed anchoring systems replace the fixed base. These turbines can be sited in much deeper water, further from shore. That introduces a host of novel, and as yet poorly understood, environmental outcomes. We need to rapidly increase our understanding of the cumulative effects on ocean inhabitants and vital physical processes. Only then can we ramp up our renewable energy capacity while avoiding a myriad of unknown ecological and socio-economic consequences.

In the race to speed up the consenting process for offshore wind and increase the evidence base for decision-making, the industry needs standardised methods of data collection in grey literature, clear policy frameworks, and better communication between scientists and industry so evidence from primary literature can be used in evaluations. Environmental impacts need to be consistently and fairly assessed, as do the risks associated with each wind farm development.

Definitive metrics for assessing and measuring improvements to the environment need to be decided to achieve marine net gain. And we need diverse voices from the energy industry, wildlife conservation, fishing and recreational sectors to ensure that this marine urbanisation favours positive gains across the board.

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