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Environmental assessment: the greatest risk to offshore wind farm development

The UK has ambitious plans for offshore wind, but rigorous environmental assessments are proving to be the major stumbling blocks for project developers

Sensitive bird species provide major challenges for windfarm developers
Sensitive bird species provide major challenges for wind farm developers

When it comes to offshore wind, the planning issues – both in terms of deciding whether a project can be viable in the first place and whether it can get through the consent process – are vast. Being granted a site lease for development is just the beginning of the story.

In its recent state of the industry report, British trade association RenewableUK points out that while seven projects totalling 2.24GW are currently under construction in UK waters, just one offshore wind farm in the planning system was actually approved in the last year and this was the first approval in three years.

While the overall level of deployment is encouraging, Maria McCaffery, RenewableUK Chief Executive says it is being driven by a historic backlog of projects finally coming through the system. “The number of planning refusals of new projects by local authorities is alarming, with the lack of new offshore approval and the Dudgeon onshore substation refusal setting a worrying precedent.”

The industry still remains confident that 18GW can be built offshore by 2020, McCaffery says, but “only if the planning system is streamlined to promote growth and avoid putting further deployment at risk".

Obtaining consent for offshore wind projects is a complex task. This is highlighted in a report, Consenting Lessons Learned, published by RenewablesUK in October 2011. “Not only are there a wide variety of environmental factors to be taken into account, but there are technical and engineering challenges to be balanced with the predicted environmental impacts,” the report states.

“All this must be achieved within the constraints posed by the challenges of working offshore, and the overriding requirement to develop an economically viable project.”

Specific site selection criteria need to be considered, including wind resource and geology, which will determine the type of equipment and installation methods that can be adopted – and thus costs. Potential spatial constraints have to be factored in requiring geophysical, geotechnical and metocean surveys and management plans to be put in place.

And, critically, environmental impact assessments (EIAs) and assessments required by the Habitats Directive have to be conducted, covering marine mammals, metocean data, ornithological, marine ecological, fisheries, underwater noise, landscape/seascape assessment, cable routes and so on.

According to the UK Department of Energy and Climate Change (DECC), the formal planning process takes into account bird and fish populations, noise levels, electromagnetic radar interference, shipping and flight navigation. The impact of an offshore wind farm on the visual landscape is also taken into account.

Just as with onshore wind, arguably the biggest potential stumbling block for offshore project developers is the EIA. “Analysis of the consenting process for offshore wind farms to date indicates that the time taken for consent determination has been increasing, and that increasing difficulties in resolving environmental impacts have been encountered with nearly 2GW of projects stuck in the planning system,” says RenewableUK.

“As the industry moves into Round 3, with an increase in the size of projects and increased distances offshore, these challenges will arguably increase. This must also be balanced with the new requirements and additional uncertainty associated with a new consenting regime and new regulators.”

In fact, a recent survey by RenewableUK of developers highlighted consenting concerns as “the greatest risk to Round 3 development programmes”.

The core concerns

In its analysis of the consent process for offshore projects to date, some key causes for delays jump out. These relate to impacts on fish, marine mammals and birds in addition to potential impacts on industries that are dependent on transporting goods and services via the sea. Possible interference on air traffic control radar systems is also an issue.

The Centre for Environment, Fisheries and Aquaculture Science in the UK believes that wind farming will not affect fish stocks as a whole. However, individual developments may have an impact on fish and shellfish at particular locations.

The EIA is undertaken in consultation with the fishing industry and the Sea Fisheries Inspectorate. RenewableUK points out that “the potential impact of piling noise on the spawning success of several noise-sensitive fish species of commercial or ecological value has led to delays in the consenting process caused by the need to find agreement over seasonal piling restrictions”.

The industry has invested both time and money, it says, in collecting data to inform the extent of spawning seasons and argues that “a reduction in the restriction period by several months can save projects tens of millions”.

Similarly, there is debate about the effect of turbines on bird populations, bird habitats, breeding and feeding grounds, migration routes and other well-used flight paths. “However, many of the perceived adverse effects can be eliminated through good design and location,” says DECC.

Every proposed site in UK waters must be assessed for the presence of birds, whether they use it for roosting, breeding or feeding, or even flying nearby. Again, this is required as part of the EIA and forms a key part of the planning application. “Whilst a number of concerns regarding the potential impacts on birds are recognised, the key issues leading to consenting delays has largely been restricted to a small number of species associated with Special Protection Areas,” says Renewable UK.

“These species are sensitive to wind farm development and the issues surrounding cumulative impacts on these species have been particularly challenging. For example, in the Wash, three projects have yet to receive consent due (in part) to changing stakeholder requirements and a lack of decision making ability in the ongoing cumulative assessments for Sandwich terns.”

Ecological significance

In addition to national and international ecological designations, the UK’s local authorities also identify sites for their local ecological value using a variety of designations. The identification of such special areas has extended the consenting period for several projects, says Renewable UK.

“The ‘higher bar’ and evidence-base necessary to meet the requirements of Appropriate Assessment has had a negative impact on the consenting time scales for wind farm projects close to, or within cable routes passing through designated areas,” it says.

“In addition to this, in some cases, lack of clarity on conservation objectives and management measures hampered the assessment of the significance of impacts. Designated sites may also lead to more onerous requirements on pre-construction or operation and maintenance activities.”

Good planning can help reduce any adverse effects, insists DECC. “Examples include a habitat management plan before work starts, and the presence of an ecological officer during construction and decommissioning. It is also important to time work carefully, taking into account migration habits.”

Meantime, the effects on the landscape and other visual implications of wind farm developments “are among the most far-reaching”, says DECC. “They are generally of greatest concern to the public, and often the reason why people oppose wind farm proposals.”

A number of UK offshore projects have all suffered delays due to local opposition on the grounds of visual impact. “At Gwynt y Mor, issues related to the cumulative impacts of multiple wind farm developments on the North Wales coast, resulting in a requirement for reconsideration of turbine layout and project extent,” says RenewableUK.

So, when preparing planning applications, this all has to be factored in. “Any potential developer of an offshore wind farm must undertake a seascape and visual impact assessment as part of the environmental impact assessment process,” stresses DECC.


Depending on their location, large offshore wind farms could also conflict with the rights of navigation enjoyed by marine users. In public international law, foreign ships have the right of innocent passage through the UK’s territorial waters, as they do in other countries. Beyond the 12-nautical-mile limit of UK territorial seas, shipping has the freedom of navigation.

At the same time, under international law, the UK is able to construct wind farms and other installations or structures to produce energy from tidal and wave power in a 200-mile Renewable Energy Zone. Owners or operators of ships and ports, their associated service businesses and navigation agencies could potentially suffer economic losses as a result of the diversion of navigation around wind farms.

“The consenting process should take into account, on a case-by-case basis, the extent to which businesses might suffer economic losses”, the UK government emphasises.

The Energy Act 2004 included provisions for safety zones to be placed around renewable energy installations or structures, to protect them and passing shipping from collision and damage.

Meantime, wind turbines also impact aviation, particularly on radar systems or low-flying aircraft. “Wind turbines can cause false returns on radar as the rotating blades can trigger the Doppler threshold of the Radar Data Processor and therefore may be interpreted as aircraft movements. This impact can affect all aviation radars, both civil and military,” explains RenewableUK.

“The issue is particularly sensitive offshore as degradation of Air Defence radars is considered as a national security concern. Mitigation is possible but expensive.”

Indeed, cumulative Ministry of Defence (MoD) radar issues in the Wash took 17 months of to resolve and resulted in developers co-funding a new multi-million pound MoD radar.

There are, of course, a host of other planning issues confronting offshore wind and some of these relate to the onshore connection side. Ensuring the timely consent of an onshore substation has “proven problematic” for a number of projects including London Array and Dudgeon. “This has led to project-wide delays.” notes RenewableUK. “There have been issues in obtaining minor consents when existing consents could have been amended”.