Major Orsted offshore wind project in military radar row

Mooir Vannin project would place 1.4GW of capacity in the territorial waters of the Isle of Man and connect to the UK grid.

Britain’s Ministry of Defence (MOD) has opposed a 1.4GW offshore wind farm that Danish developer Orsted is planning to build in the Irish Sea on the grounds that the proposed 87-turbine array would interfere with aviation radar systems.

The MOD objections were raised during the planning process for the Mooir Vannin array that Orsted aims to build between six and 12 nautical miles east of the Isle of Man.

In a public consultation process, the MOD stated that the project would have a "significant and detrimental impact on the effective operation and capability of the air traffic control radar" at the British Aerospace Warton base in Lancashire, on the west coast of the UK.

"Wind turbines have been shown to have detrimental effects on the performance of Primary Surveillance Radars. These effects include the desensitisation of radar in the vicinity of the turbines, shadowing and the creation of “unwanted” aircraft returns which air traffic controllers must treat as aircraft returns," the MOD stated.

The MOD's submission also mentioned impact on operational activities conducted at the Eskmeals Firing Range and the potential to create a physical obstruction to air traffic movements.

"Based on the information provided, and until a suitable mitigation scheme has been submitted, assessed, and accepted, the MOD must object to the proposed development," it continued.

Orsted’s project documents said the company had submitted its application for Marine Infrastructure Consent to the Island’s authorities after “two years of extensive environmental and technical studies, as well as in-depth consultation with statutory stakeholders and the public”.

The application was accepted for examination by the Council of Ministers in August.

The MOD submission referred to a maximum blade tip height of up to 350 metres above Lowest Astronomical Tide, and up to three offshore substation platforms.

Orsted is also carrying out scoping work on how to connect the Mooir Vannin Offshore Wind Farm to the UK National Grid at Penwortham in Lancashire and the Douglas area in the Isle of Man.

Orsted states that the project is expected to reach commercial operations in 2032 or 2033.

A spokesperson for the company said: “A Ministry of Defence representation at this stage is a normal, technical part of the process. Potential radar impacts are routinely identified so that mitigation can be properly assessed, and the offshore wind sector has a range of proven solutions that protect both defence capability and renewable energy delivery.

"Many offshore projects have resolved similar issues, including our own in the Irish Sea, and we’re confident that the right technical solutions can be agreed for Mooir Vannin.”

The Isle of Man government’s Council of Ministers has referred the application to an independent examining body, which will review responses, assess issues and advise on whether Marine Infrastructure Consent should be granted, subject to an initial statutory time frame of 130 working days.

The name Mooir Vannin comes from the Manx language term for the Irish Sea.

Growing concerns

Concerns about possible interference with radar systems pose an increasingly delicate problem for the offshore wind industry, amid growing geopolitical tensions.

Sweden, in particular, withdrew massive areas of prime seabed from its plans for offshore wind, due to military concerns.

The UK's MOD has been engaged in a major procurement process with defence contractors to increase the resilience of its radar systems, but offshore wind industry leaders worry about how long this will take.