Experts fear offshore wind farms being built around Britain’s coast could jeopardise UK air defences.
Turning turbine blades may interfere with radar designed to pick up foreign fighter jets or long-range bombers approaching UK air space or the area of national interest.
Studies suggest offshore wind farms could interfere with vital military communications.
The Government is so concerned that it has launched a £3.6million competition for companies to suggest ways to mitigate the impact – and prevent giant wind farms accidentally obscuring airborne threats.
Phase two of the Wind Farm Mitigation for UK Air Defence competition, run by the Defence and Security Accelerator and the Department for Business, Energy and Industrial Strategy, will launch on April 21 and run for two months.
Five or six projects are expected to receive backing.
Advertising the contest, the Government said: “The continued development of wind turbine sites can have an adverse impact on civil and military air traffic control, and air defence surveillance.
“If you think you have an idea that can be developed to support the coexistence of offshore wind farms and UK air defence systems, DASA would like to see your technology in Phase 2 of the competition.
“The Windfarm Mitigation for UK Air Defence competition seeks proposals that can develop technologies to permit the coexistence of future offshore wind farms alongside UK air defence surveillance systems.”
A 2008 study for the US Department for Homeland Security found that “wind farms interfere with the radar tracking of airplanes”.
It warned that America’s “ageing long range radar infrastructure significantly increases the challenge of distinguishing wind farm signatures from airplanes or weather”.
The report said “mitigation measures may include modifications to wind farms (such as methods to reduce radar cross section; and telemetry from wind farms to radar), as well as modifications to radar (such as improvements in processing; radar design modifications; radar replacement; and the use of gap fillers in radar coverage)”.
The world’s largest offshore wind farm is being built on Dogger Bank in the North Sea.
It is being constructed in three stages between 80 and 120 miles off the North East coast, and will be able to power six million homes using the world’s most powerful turbines – General Electric’s Haliade-X.
They stand 853ft (260 metres) tall, have a rotor diameter of 722ft (220m) and the blades are each 351ft (107m) long.
Russian planes testing British air defences regularly approach over the North Sea.