The development of offshore renewable energy (ORE) – wind farms in the sea – is expected to see the greatest leap in energy independence in Ireland since the construction of the Ardnacrusha dam on the river Shannon exactly 100 years ago.
The Government has set out its stall, aiming to be a “world leader” in the field and setting targets of five gigawatts (GW) of generation by 2030, 20GW by 2040 and 37GW by 2050 (for context, the proposed Sceirde Rocks wind farm off the coast of Connemara, which is due to be decided upon by An Bord Pleanála later this year, will use 30 turbines to generate nearly half a GW).
The rollout of this infrastructure is essential for meeting legally binding climate targets. It is, nevertheless, big infrastructure which, like all such developments, has the potential to result in serious negative impacts to biodiversity.
The fact that this is taking place in the marine environment, where relatively little is known about biodiversity, surveying and monitoring are difficult, and where legal protections are few, raises alarm bells.
The impacts to biodiversity from these developments are set against a background of hundreds of years of habitat destruction and overexploitation from fishing activities. Many commercial fisheries (herring, cod, etc) have collapsed while whaling ceased only in the 1980s, with many populations still in recovery.
Additional pressures from shipping, seismic blasting for oil and gas exploration, military exercises using sonar and pollution are also well documented so that assessing the impacts on biodiversity from ORE can be challenging. Indeed, such is the degradation that many in the ORE industry are claiming that the turbines will benefit biodiversity by acting as refuges from fishing activity.
It also presents an opportunity for misinformation, most notably the suggestion that wind turbines are killing whales. Dead whales have indeed been washing up in unusual numbers off the east coast of the United States but there are “no links whatsoever between the offshore wind development activity and especially the humpback whale mortalities. None. Zero” according to marine scientist Douglas Nowacek of Duke University in North Carolina, speaking to Scientific American in 2024. The real impacts are from a combination of ship strikes and entanglement with fishing gear.
In the first instance, construction of turbines, including their foundations and the laying of cables for grid connection will remove habitats on the seafloor. Most of the seafloor around Ireland has been swept clean by repeated bottom trawling so that what’s left is mostly relatively low biodiversity mud and stones.
Higher-value habitats, such as sand banks, reefs with shellfish or maerl (a hard seaweed) can be avoided if the data has identified their presence. It is however, the less obvious impacts that are so far known to cause the biggest effects.
The potential impacts to the vast majority of marine life, particularly fish and invertebrates, are simply not known. Sharks, for instance, navigate and find prey using sensitive organs which detect electromagnetic fields. How will they be affected by networks of high-voltage cables?
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One available study (and there are not many), led by Annemiek Hermans of Wageningen University in the Netherlands, did not find negative impacts to the few shark species they looked at, while stressing that further studies in this field are needed. It is, as usual, the more conspicuous species of birds and mammals that have attracted most of the research to date.
Ariel Brunner is regional director of BirdLife Europe and Central Asia, a Brussels-based NGO. “It’s clear that wind farms do have impacts on sea birds” he says.
“One is collision, birds crash into wind farms occasionally and for some species, in some areas, the mortality can be significant enough to have a population impact,” he adds, mentioning black-backed gulls and endangered kittiwakes specifically. “The second problem is displacement. Most birds are able to see the wind farms and there is a lot of tracking data that shows the birds actively avoid the wind farm ... which means they lose feeding grounds, they become a no-go area for the birds.”
He points out that the effects will vary from species to species. Shags, for instance, typically fly low and close to the water surface and so are unlikely to be impacted. He also highlights the potential benefits of wind farms where bottom trawling has been excluded. “There is increasing evidence of an explosion of marine life because of artificial reef effects and the curtailment of damaging fishing activities. So, it’s not a one-way-street.”
All the same, he cautions, those species and habitats which suffer may not be the same ones that benefit. In addition, there is the creeping effect of multiple developments, what is referred to as “cumulative impacts” in the jargon. Brunner says BirdLife has long campaigned for good planning to avoid cumulative impacts and to ensure turbines are placed in areas where fewer impacts are likely to arise.
This point would surely be echoed by NGOs in Ireland, and indeed by many in the industry here, who wanted to see a plan-led approach whereby areas suitable for ORE would be identified.
To their dismay, however, this did not happen and, despite a subsequent attempt to move away from a developer-led approach, the last government failed to even pass legislation for the creation of marine protected areas (MPAs); never mind identify where the MPAs should be. “If we don’t have the MPAs and we don’t know where the next wind farm will be, then an individual development may become a problem,” Brunner says – something he describes as a “systemic failure in planning”.
Laura Palmer is the offshore industries co-ordinator for Whale and Dolphin Conservation, an NGO with global reach. She notes there are risks to all whales, dolphins and porpoises (collectively referred to as cetaceans) and since much of the ORE development has occurred in northern Europe, and the North Sea especially, the available research concerns small cetaceans, such as harbour porpoise, that inhabit these waters.
All cetaceans communicate and navigate using sound, so that “they are especially vulnerable to noise disturbance” says Palmer, adding that “our primary concern over ORE stems from noise emissions”. These effects normally arise during the surveying phase when powerful sound waves are used to map the seafloor, and during construction, when hammers are used to drive supports into the bedrock, a process known as pile driving.
During operation there are also noise emissions but these are “a lot less of a concern”. Surveying and construction noise “can cause hearing damage, on a temporary or permanent basis”, she says, while “studies have shown that there are cardiovascular reactions when animals are exposed to the noise of seismic surveying, essentially stress and panic”.
There is also suspected to be a link with mass strandings, although Palmer stresses this is very difficult to demonstrate conclusively. All this noise presents “extreme impacts on their health and survival” while, like with birds, the turbine installations themselves can result in displacement of animals so that they cannot, or do not, access areas which are needed for feeding or resting.
Since cetaceans rely on sound for communication, if they cannot hear themselves above the background noise, this can disrupt their social interactions, including their ability to mate. And although floating turbines are proposed by some as a solution to many issues, Palmer notes that these still require pile driving and introduce other issues, such as the potential for entanglement with tethering ropes and chains.
Like Brunner, Palmer worries about the cumulative effect of multiple ORE projects across the ranges of important species, but the good news is that they both agree that there is a lot that can be done to reduce the impacts.
Temporary shutdowns to allow for bird migration and curtains of bubbles that substantially dissipate the noise from pile driving, for example, but these measures need to be enforced and monitored for effectiveness. Indeed, they are keen for ORE to proceed as climate change itself is such a threat to biodiversity.
Both are also united in the need to not just limit negative impacts but for active measures to restore biodiversity which, Brunner says, has been “completely hammered, essentially by destructive fishing”.
This points to the need for effective MPAs and reducing the footprint of the most damaging activities, particularly fishing, to allow for more harmonised climate and biodiversity action.
