The Challenge

Radars and wind turbines: in short, primary radars think wind turbines are aircraft. Primary radars are designed to detect moving targets – turbine blades move at equivalent speeds to aircraft, having similar / greater radar cross sections as aircraft. Current military and civil air traffic control (ATC) primary radars are 2-D so cannot distinguish the elevation of the target and therefore differentiate tracks.

Military air defence (AD) PSR are 3D so are less impacted – but concerns remain particularly at low altitudes. This has led to national security concerns over wind farm deployment.

Applies to All Rotating Radar

Rotating Radar have limited time on target, resulting in insufficient target data to characterise targets (and so distinguish between wind turbines & aircraft)

MOD objects to wind turbines in radar line of sight

On grounds that wind turbine radar interference degrades MoD Air Defence and Air Traffic Control capability and that wind turbines continue to be “new” features in the built environment

This is the MOD radar challenge for UK offshore wind – what this maps says is that MOD is more likely than not to object to any wind turbine in the red zones – this is where most of the UK’s offshore wind capacity resides

The story so far in respect of MoD Air Defence Radar concerns

August 2002

Wind Energy and Aviation Interests Interim Guidelines published – this collaboration between DTI, MOD, CAA and BWEA (now RenewableUK) outlined the key technical issues posed by wind turbines for aviation stakeholders – it remains current – link to publication at https://www.gov.uk/government/publications/wind-farms-aviation-interests-and-guidance-for-stakeholders (document reference: ETSU W/14/00626/REP)

January & May 2005

RAF published two unclassified reports on the observed impacts on wind turbines on the RAF’s T101 Air Defence Radar (document reference: AWC/WAD/72/652/TRIALS) and Watchman ATC Radar (document reference: AWC/WAD/72/665/Trials)

August 2006

Derek Twigg MP, Parliamentary Under-Secretary for Defence wrote to Lord Peter Truscott, Parliamentary Under-Secretary for Energy, DTI as follows: “This Department is aware of the significance of the Air Defence radar replacement program·to the deployment of Offshore Round 2 wind farms and in the recent procurement process for replacement radar, wind turbine mitigation was included as a desirable requirement. Unfortunately the process has reached a far too advanced stage to now make the requirement for wind farm mitigation mandatory. [T102 procurement announced Jan 2007]… You will be pleased to hear, however, that wind turbine mitigation will be included as a mandatory requirement in future radar replacement programs but much will depend on the success and lessons learned from the radar the MOD is currently buying.”

November 2007

Prime Minister Gordon Brown MP in a speech on climate change hosted by the WWF at the Foreign Press Association stated: “To remove the barriers here [to the deployment of offshore wind] I have asked the Secretaries of State for Defence, Business and Transport to step up their efforts, in cooperation with industry and the regulators, to identify and test technical solutions to the potential difficulties windfarms pose to air traffic and defence radar.”

August 2008

Sheringham Shoal (a Round 2 offshore windfarm) consented with MOD agreed “Aviation Specification” – condition 3(e) – 0% Probability of Detection required in Volume extending to 2500ft amsl the agglomeration of 2km radius circles around each turbine in the Development

September 2008

TPS-77 “Draconian Gates” trials in Denmark which established the NAIZ (non-auto initiation zone) functionality of this Lockheed Martin AD radar, facilitating the Aviation Specification

April 2010

MOD announced procurement of TPS-77 for Trimingham – to replace newly installed T102

September 2011 – July 2012

Sheringham Shoal turbines erected

November 2013

Announcement of upgrade of Buchan to TPS-77

Trimingham, Brizlee, Staxton and Buchan – all funded by wind developers

September 2015

FOC (full operational capability) of Trimingham AD mitigation for Sheringham Shoal

July 2016

MOD informed SPR that NAIZ only available for 3 of 120

East Anglia THREE turbines on operational grounds – SERCO confirmed all turbines could be technically NAIZ’ed Operational sensitivity seems to arise from “edge of cover” concerns and inherent limitations in the NAIZ solution

September 2017

SPR submitted alternative AD mitigation proposal to MOD for consideration based on Aveillant Theia Holographic Radar™ East Anglia THREE first in line of offshore windfarms which are likely to be unable to benefit from TPS-77 NAIZ mitigation on operational grounds

August 2018

MOD issued the following statement with regards to TPS-77 performance in the presences of wind turbines: “The MOD has recently conducted a trial looking at the real life impact of 2 offshore wind farms in the vicinity of the Humber Estuary on the TPS 77 radar that was situated at Remote Radar Head Staxton Wold. The trial determined that the wind farms had a detrimental effect on radar operations, specifically probability of detection and the aviation specification performance. The detrimental effect was not expected and the MOD needs to consider the findings of the trial further. As a result, the MOD must pause the receipt and assessment of any technical mitigation reports/submissions e.g. SERCO reports, relating to the TPS 77 radars and multi-turbine wind farms with immediate effect … An informed position to review this situation will likely be established within a 6 month time frame.

Now is the time for action – both MOD and the wind industry need a solution – to enable MOD AD radar and wind turbines to co-exist