Offshore Wind: Navigation
Impact on navigation
Depending on their location, large wind farms in the sea could potentially conflict with the rights of navigation enjoyed by marine users. Rights of navigation derive from both national and international law.
There is a common law right of navigation over all navigable tidal waters. In public international law, foreign ships have the right of innocent passage through the UK’s territorial waters. 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. However, consent cannot be granted where installations would be likely to interfere with "recognised sea lanes essential to international navigation". BERR and DFT have produced a joint paper on how this term is to be defined.
The first, smaller wind farms will be located in shallow waters and are therefore unlikely to have an impact on larger commercial vessels, although some fishing boats and recreational craft may be affected. Future wind farms may have an impact on all vessels as technological expertise develops, making construction in deeper water possible.
The process
The safety of navigation is a key issue that should be addressed carefully during the consents process. The scale of the potential impact on navigation is also assessed as part of the Environmental Impact Assessment (EIA), which the developer submits as part of their application for development consents. This assessment involves:
- a survey of vessels in the vicinity of the proposed wind farm
- a full navigation risk assessment of the likely impact of the wind farm on navigation in the immediate area of the wind farm
- a cumulative impact assessment in relation to other wind farms and any other planned developments.
The consents process is structured in such a way that any individual or organisation has an opportunity to give their views on each application, before a decision is taken on whether or not to grant consent for the development.
Economic losses resulting from the diversion of navigation around wind farms may arise. Those adversely affected would be the owners or operators of ships and ports, their associated service businesses, and navigation agencies. The consenting process should take into account the extent to which such economic losses will be incurred on a case-by-case basis. The Energy Act 2004 includes provisions for safety zones to be placed around renewable energy installations or structures to protect them and passing shipping from collision and damage.
The Department for Business, Enterprise & Regulatory Reform (BERR) and the Department for Transport (DFT) have established the Nautical and Offshore Renewables Energy Liaison (NOREL) Group to provide a forum for government and industry to discuss matters of mutual interest related to navigation safety. You can find out more information on NOREL here.
How can adverse effects be mitigated?
If consent is granted, the relevant general lighthouse authority will stipulate how the installation should be lit and marked as a general navigation safety measure. They will include any requirement for foghorns and marker buoys. The installation will also be marked on Admiralty Charts.
The Maritime and Coastguard Agency may also require individual turbines to be numbered and for the installation to be able to be shut down automatically to assist the search and rescue services in the event of an emergency. Where appropriate, the Maritime and Coastguard Agency may also consider the need for special routeing measures to safeguard shipping in the vicinity of the installation.
While the installation is under construction, and during periods of maintenance, the developer is required to issue notices to mariners in the normal way.
As a result of concerns about the potential impact of installations on communication systems and on ships’ radar, the Department for Transport and the wind industry carried out sea trials involving ships and the North Hoyle wind farm. The results of that study confirmed that there is minimal impact of offshore wind farms on communication systems (VHF radios and cellphones where there is coverage), Automatic Identification Systems of ships, reception of Global Positioning System data (the satellite navigation system) and magnetic compasses, but that there were some performance issues for ship-borne and shore-based radar. The results from the trial will help inform siting and configuration of future installations and possible mitigation measures.
Reports
Further research
To improve the Government’s understanding of the various navigation impacts, the Department of Trade and Industry has recently commissioned two projects. The first project concerns the collection of marine traffic data in the three Round 2 strategic areas (the Greater Wash, the Thames Estuary, and the North West). The second project aims to develop a risk methodology for the assessment of developers’ navigation risk assessments. The results of both projects will be made available in due course.
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