AMD features on the front page

Enemies could use wind farms for attack

The Ministry of Defence is considering measures to combat concerns that offshore wind turbines obscure military radar signals

Wind turbine blades made with stealth materials and masts considered to mitigate growing concern that offshore wind farms could hide enemy attacks from radar.

The Ministry of Defence (MoD) is also looking into the potential of using advanced machine learning to remove radar reflections from wind farms, as national security and energy security increasingly come into conflict.

The government has pledged to quadruple offshore wind power by 2030 as part of its goal to decarbonise the grid. European nations are increasingly finding though, that renewable energy projects are being opposed by their own defence ministries —with few areas suitable for wind energy generation that don’t also obscure military radar.

In November the Swedish government blocked 13 wind farm developments in the Baltic Sea, for fear they would provide cover for a Russian attack. In the UK too it has been a significant problem.

Philip Clark, an analyst at the Cowes radar research centre of BAE Systems, said: “The RAF stops wind farm developments in places like the North Sea, because they’ll say, ‘If somebody launches an attack against us that comes from behind the wind farm, we won’t be able to see it’.”

Radar works by pinging out radio waves, and waiting to see what returns. A raw radar feed is messy. Signals bounce back off hills, tall buildings and anything else within range. These can be removed afterwards by software. The problem with a wind farm, says Professor Marco Martorella from the University of Birmingham, is it is always moving, so the signal cannot be removed afterwards.

When radar signals come back from turbines they reflect off blades that are going hundreds of miles an hour at the tip, at walking pace at the base and that are always in different positions. Sometimes they bounce off one turbine then another before returning. “They create a lot of clutter … These wind farms make the job of the adversary much easier,” he said.

Clark said that for so many reasons this creates a serious problem. “Imagine a helicopter hovering in a wind farm.” Both have spinning blades, both are reflective. Would you, he asked, be able to spot the helicopter?

Much of their research is secret, but Clark said that BAE is investigating whether smarter software approaches could interpret spinning objects. When radar bounces off a moving object there is a Doppler effect, and its frequency changes. When an object spins, this frequency change can produce a recognisable signature. If there’s a signature it may be possible to delete it.

“We’re editing out the wind farm response so that you can see stuff behind it and stuff inside it,” said Clark. “That’s something that the RAF is very keen on.”

The RAF is not just relying on one approach though. The MoD and Department for Energy Security and Net Zero launched a competition to find other ways to enable early warning systems to see through and beyond wind farms.

Richard Lee, from UK company Advanced Material Development (AMD), is one of those with a project backed by the scheme. AMD’s approach involves stopping the reflections and it has developed a radar-absorbing paint that can coat the fibres used in construction, effectively giving the blades stealth technology.

“You add something to the blades that adds pretty much no weight and doesn’t have a huge amount of cost, and that reduces by 90 per cent or more the power coming back,” he said.

Livelink Aerospace takes a completely different approach. David Youngs, co-founder of the Chichester-based company, believes it could be possible to turn the problem into an opportunity. Livelink makes small, cheap, passive sensors. They would not see through a wind farm — but given there could be one on each turbine, they wouldn’t need to.

The plan is that the sensors would interpret incoming signals from across the electromagnetic spectrum making the turbines an extension of air defence, rather than an impediment.

“The utopia is rather than military and civil air traffic saying, ‘These wind turbines are in the way,’ they say, ‘Isn’t this convenient? Somebody’s gone and given us a lovely 300m antenna in a really difficult-to-reach bit of the sea,” said Youngs.

Nato sources are said to have already expressed fears that Britain is not spending enough on air and missile defence.

A draft of the Nato blueprint, called the Capability Target 2025, is said to raise the need for the UK to invest in air defence systems, known as surfaced-based air defence, to protect critical national infrastructure, such as nuclear power stations or military bases, The Sunday Times reported.

Listen to Chief Operations Officier, Richard Lee's interview by Times Radio>>> https://www.youtube.com/watch?v=Uqvmm240SbE

by Tom Whipple, Science Editor, The Times of London

6-January-2025

More News