Wind energy has become one of the most promising solutions to mitigate climate change. Offshore wind farms, in particular, have gained momentum as a clean and efficient way to generate power. These large structures stand tall in the open ocean, harnessing wind to produce renewable energy. However, new research from the University of Portsmouth suggests that offshore wind farms may have an unintended consequence: the release of metals into surrounding waters. These metals could impact marine life, seafood safety and, ultimately, human health.
Our research highlights the importance of keeping a close eye on the chemicals released by OWFs. We are definitely not saying stop building them, we just need to monitor them appropriately – especially as they expand
Gordon Watson
A hidden environmental cost
The Paris Agreement set ambitious goals to reduce greenhouse gas emissions and limit global warming. Offshore wind energy plays a key role in achieving these targets. But while the focus has been on its benefits, there has been little attention on the environmental side effects of systems such as those used to protect against corrosion.
Large offshore wind turbines are made primarily of steel. When exposed to salt water, steel corrodes over time, leading to structural damage. To prevent this, offshore wind farm developers use corrosion protection systems. One of the most common methods involves attaching sacrificial anodes to the turbines. These metal blocks, mainly composed of aluminium, zinc and indium, dissolve into the seawater to protect the steel structure.
The research team at the University of Portsmouth set out to quantify how much metal is being released from corrosion protection systems used in European offshore wind farms. Their findings suggest that the accumulation of these metals in the ocean could have long-term consequences for marine ecosystems, with particular concern over the potential to enter food chains.
Aquaculture and offshore wind: A risky combination?
The idea of combining offshore wind farms with aquaculture is gaining popularity. This concept involves growing seafood, such as mussels, oysters and seaweed, around wind turbines (Figure 1). The benefits are clear: these species help absorb carbon, improve water quality and provide a sustainable food source. In 2024, the world’s first co-located commercial seaweed farm and offshore wind farm was launched in the North Sea.
Credit. AI image created using Canva Magic Studio by G. Banfield.
However, there is a potential downside. Shellfish and seaweed are efficient at absorbing elements from their surroundings, including contaminants. If metals released from wind farms accumulate in these organisms, they could enter the human food chain. This raises concerns about the safety of seafood harvested from these areas. Researchers fear that without adequate regulations, future large-scale aquaculture projects near wind farms could lead to increased exposure to toxic metals.
Credits. University of Portsmouth
How much metal is being released?
The study found that offshore wind farms currently produce around 3,000 tonnes of aluminium, 1,000 tonnes of zinc and nearly 2 tonnes of indium for a current output of 30 gigawatts of energy across Europe (2024). These metals dissolve into seawater and settle in sediments near the wind farms. As offshore wind capacity grows, metal emissions are expected to increase significantly.
Credit. G. Banfield
By 2050, offshore wind energy production in Europe is projected to increase by nine to twelve times. This could lead to an estimated annual release of 30,000 to 38,000 tonnes of aluminium, 11,000 to 14,000 tonnes of zinc and 11 to 14 tonnes of indium. These figures highlight the need for further investigation into the long-term effects on marine ecosystems and human health.
What does this mean for seafood safety?
To assess potential risks, researchers compared metal concentrations in shellfish to safety limits set by the European Food Safety Authority (EFSA). They calculated the tolerable weekly intake (TWI) of these metals, defined by the EFSA as “the maximum intake of substances in food, such as nutrients or contaminants, that can be consumed weekly over a lifetime without risking adverse health effects”. As no data currently exists for tissue concentrations of organisms in close proximity to OWFs, authors had to rely on global data.
The results were concerning. Six oysters from an area with low/ typical levels of environmental zinc contamination could provide between 63%-189% of a 68-kilogram adult’s weekly zinc intake limit. This value would further increase to 252-589% if the tissue concentration was exposed to a site of high or very high Zn levels, which is representative of OWF sites. Mussels from similarly contaminated sites could contribute up to 7-14 percent of the weekly limit.
If metal accumulation continues to rise, it could impact the commercial viability of aquaculture projects near wind farms. Farmers may face restrictions on harvesting and selling their products, which could affect the economic benefits of co-locating seafood production with wind energy generation. This highlights the need for regular monitoring at offshore wind farm sites to ensure risks are adequately assessed.
Why is this issue being overlooked?
Research by the team at the University of Portsmouth revealed that environmental impact assessments for offshore wind farms rarely address the potential effects of metal pollution with marine corrosion and the impacts of sacrificial anodes often overlooked in environmental reports. In many cases, there is no post-construction monitoring of metal concentrations in surrounding waters.
Furthermore, when researchers attempted to compare offshore wind farm emissions with other human activities, they found a lack of data. While some information exists on zinc emissions from industrial sources, there is little to no data for aluminium and indium. This knowledge gap makes it difficult for decision makers to assess the full impact of offshore wind farms on marine ecosystems now and under future offshore wind farm expansion targets.
Finding solutions
The expansion of offshore wind energy is essential for a sustainable future, but it must be done responsibly. Researchers recommend several measures to minimise risks. One solution is to replace sacrificial anodes with alternative corrosion protection systems, such as impressed current cathodic protection or protective coatings. These methods could significantly reduce metal emissions.
Regular monitoring of water, sediment and seafood quality is also essential. By tracking metal concentrations over time, policymakers can make informed decisions about offshore wind farm expansion and aquaculture safety. Governments should introduce stricter regulations requiring wind farm operators to monitor and report metal emissions. Increased transparency would allow scientists and policymakers to develop better strategies to mitigate potential risks.
Governments and industry leaders must take proactive steps to ensure offshore wind energy remains a truly sustainable solution. The challenge is not just about producing clean energy, but also about protecting marine ecosystems and human health in the process.
A call for action
Offshore wind farms are a crucial part of the world’s transition to renewable energy. However, this research highlights an issue that cannot be ignored. The potential risks of metal pollution must be addressed before they escalate.
Should governments enforce stricter environmental regulations for offshore wind farms? What steps should be taken to ensure seafood remains safe for consumers? As the industry continues to grow, these are questions that demand urgent attention. Without timely action, the environmental benefits of offshore wind energy could be overshadowed by unforeseen consequences.
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Journal reference
Watson, G. J., Banfield, G., Watson, S. C. L., Beaumont, N. J., & Hodkin, A. (2025). Offshore wind energy: assessing trace element inputs and the risks for co-location of aquaculture. npj Ocean Sustainability, 4(1), 1. https://doi.org/10.1038/s44183-024-00101-6
