Development at sea

How we use our seas

Development at sea

Dave Dunlop

Part of nature's recovery

We believe that development at sea should be environmentally sustainable. It should do as as little harm to the environment as possible regardless of what the development is. Development should take place using the right technology in the right place and make a positive contribution to nature’s recovery at sea.

Why is it important?

Our seas need to be managed to recover from past damage, disturbance and neglect. With the demands on our seas for resources and energy, the scale of future development is increasing. Offshore renewables, particularly offshore wind, is a fast-growing industry. Although producing green energy, the construction of offshore wind farms has environmental impacts including loss and disturbance to habitats and species.

What The Wildlife Trusts are doing

Due to the scale of offshore marine renewable developments, we are engaging closely with this sector. We engage on individual developments and work with government, regulators and statutory nature conservation bodies to influence policy at a national level. Our work also focuses on the impacts of underwater noise from the construction of offshore wind farms. This has the potential to cause injury and disturbance to marine mammals. We believe noise reduction plans should be implemented at a whole seas level.

Harbour Porpoise

Harbour Porpoise ©Niki Clear

The scale of offshore wind development

Offshore wind farms are not simply ‘onshore wind farms at sea’; they are on a much larger scale. A single onshore wind turbine has a capacity of around 2.5 MW and the average size of an onshore wind farm is only 7 turbines. The offshore wind farm projects applying for planning permission are looking to use wind turbines with a capacity of up to 20 MW each and each project could have an average of 300 turbines. The largest of these projects will cover an area nearly five times the size of Hull. 

Currently there is around 10GW of offshore wind installed in the UK. Fast forward to 2030 when the ambition is for 40GW to be installed.  Finally, to meet net zero by 2050, the ambition is to have 75GW of offshore wind installed.  This means that in the next 30 years, 65GW of offshore wind farm infrastructure will be installed in our seas.  The cumulative impact on the marine environment from this amount of building offshore could be catastrophic if not managed correctly.  It is essential that this scale of offshore wind farm development planned using the right technology in the right location.

Marine planning

Humans use the sea in a variety of ways. From fishing, to aggregates, to recreational use we make huge demands on the marine environment. Marine plans aim to set out the sustainable use of our seas. We believe more could be achieved through marine planning. We want to see a regional seas marine spatial planning programme. This would create wildlife areas, resource areas and sustainable fishing areas. Read The Way Back to Living Seas to find out more.

Impact of noise

Marine mammals are particularly sensitive to underwater noise during the construction phase of offshore wind farms. We believe noise should be consistently managed for whole seas e.g. the North Sea. Offshore wind farms are constructed using piling; this is essentially a large hammer which drives the foundations of the turbines into the ground. The noise can injure harbour porpoise near to the turbines. Disturbance noise can also travel up to 26 km from the point of construction. 

Harbour porpoise use echolocation to detect their prey, predators and mates. Very loud noises can interfere with their ability to echolocate. This is a particular issue as harbour porpoise which feed constantly and need to consume up to 10% of their body weight per day. If noise stops a harbour porpoise’s ability to find food or stops them from accessing good feeding areas, they can only survive a few days. This will not only have an effect on an individual animal but on a population.

Impacts on the seabed 

Offshore wind farm infrastructure, if located in the wrong place, can cause the loss of seabed habitat.  For example, cables to bring the energy produced from offshore wind farms onshore are normally buried below the seabed.  However, sometimes this is not possible and consequently cables are covered with rock armour, causing a loss of habitat.  As a result, this could cause a loss of important nursery grounds for fish and feeding areas for marine mammals and birds. 

Unfortunately we are already seeing negative impacts on seabed habitats from the combined effects of offshore wind farm infrastructure alongside fishing activity, resulting in the decline in the condition of Marine Protected Areas.  This is without taking into account the cumulative impacts of the ambitious target of 75GW of offshore wind farm development to meet the zero by 2050 target.  Tools such as marine spatial planning must be used to plan where future activities can take place without damaging the marine environment.

Examples of our work

The Wildlife Trusts secure better management of Dogger Bank SAC

In 2015, we began judicial review proceedings regarding the approval of Dogger Bank Teesside offshore wind farms. This was due to fisheries being left out of the wind impact assessment. 

Dogger Bank is a large glacial sandbank situated 62 miles from the English coastline. Formed during the last ice age, it was part of ‘Doggerland’ which connected Britain to mainland Europe. The sandbanks are home to an interesting range of species living both on and in the sand. Although well offshore, this sandbank is home to the fish that feed us and the harbour porpoises, dolphins, whales and seabirds that we enjoy seeing along the east coast.

Unfortunately, Dogger’s sandbanks are currently considered to be at unfavourable condition. The biggest driver of this declining ecological health is fishing. Add to this the impacts of aggregate dredging, oil and gas extraction and now the construction of over 800 wind turbines – and you can understand our concerns.

Following our action, the government gave assurances that management of fisheries would be taken forward for Dogger Bank SAC and that fishing would be included in future offshore wind impact assessments. We were delighted with this outcome. However, we are still seeing the exclusion of fisheries in cumulative impact assessments and we continue to work with government resolve this issue.