Research to make sure that future offshore wind farms do not interfere with crucial military communications is underway following a £2 million grant from the UK Government.
Contracts have been awarded to Thales, QinetiQ, Saab, TWI and Plextek DTS to fast-track their ideas for technologies that could mitigate the impact of wind farms on the UK’s air defense radar system.
According to the Ministry of Defence:
“By guaranteeing essential defense communications are not affected, more wind farms can be built, creating a greener and more technologically sustainable Britain.”
The MoD’s Defence and Security Accelerator (DASA) is spearheading the innovation competition on behalf of the Department for Business, Energy, and Industrial Strategy (BEIS), the Royal Air Force, and the Defence Science and Technology Laboratory (Dstl).
Defence Minister Jeremy Quin, said:
“We want more offshore wind farms to help deliver our ambitious environmental agenda while retaining the protection that radar provides. This is a great step forward in achieving this goal and shows Defence’s determination to support sustainability and deliver our green goals for Britain.”
Minister for Energy and Clean Growth, Kwasi Kwarteng, said:
“The continued growth of offshore wind is a national success story and this funding will ensure we continue to build bigger and more advanced projects vital to tackling climate change. The UK’s innovative spirit is second to none, which is why we are drawing from all areas of the country’s expertise to drive forward our incredible renewable energy fleet.”
DASA say they launched the Windfarm Mitigation for UK Air Defence competition in March, to find innovative solutions that lessen the impact off-shore wind turbines could have on military and civilian radar systems.
Wing Commander Helena Ramsden, Air Capability Strategy, Air Command, said:
“This is a positive first step in getting cutting-edge innovation off the ground to harness the best technology from the brightest minds in the country. We are committed to keeping the skies above the UK safe from aerial threats whilst accelerating crucial work to allow the nation to do more to combat climate change.”
The following proposals have also been mentioned:
- Thales, in collaboration with the University of Birmingham and SMEs, will develop surveillance to mitigate wind farm ‘clutter’, whereas Saab is developing a radar mitigation system using Artificial Intelligence and Doppler filtering.
- QinetiQ is developing two proposals — the first approach uses new materials to stop the radar from being distorted. Their second proposal will develop radar-absorbing materials that can be put on off-shore wind turbines to limit interference.
- TWI will develop novel methods for creating conductive coating for turbine blades that adsorb radar in partnership with the University of Exeter’s Centre for Metamaterial Research and Innovation. Finally, Plextek DTS is developing techniques to remove the effects wind farms have on radar data.
Robert Hammond-Smith, DASA delivery manager, said:
“This competition will not only help us meet our green energy needs but it will also help boost UK prosperity, entrepreneurs and innovators by investing in their potentially game-changing technology. DASA is proud to be working closely with BEIS, the RAF and Dstl to lead this important work which could transform the UK’s approach to offshore wind power generation.”
Why not as an interim step simply position remotely monitored radar station beyond the wind farm – using Aesa radar (ie flat plate) couldn’t we just mount it on a turbine stand ?
Technical and feasibility issues.
Well the radar station on remote Scotland is entirely remote so connectivity must be achievable. Height I get the point but not all our coastal radars were up a mountain. Power might be an issue but then it’s sitting next to a wind farm 🙂 slightly tongue in cheek reply
Typically it’s the curve of the earth that limits radar range which is why height matters and the bigger the radar – range terms more power required but unless it’s an over horizon radar I bet the distance one based on a pole in North Sea vs land wouldn’t be hugely different
Most wind farms already run high bandwidth data connections back to shore, it wouldn’t be out of the question to run another one at the same time.
The newer 5+ MW turbines are really very big, with very heavy nacelles on top of a 100 m tower. I think they’d likely be able to take a pretty sizeable AESA array. Even if not, many wind farms include a jacket leg structure used to take the transformers for distribution back to shore, there’s no reason why they couldn’t put another one on the far edge of the field.
Wind farms do draw a “base load” of power which is used to monitor and control the field, even when they’re not producing themselves due to lack of wind. This could be tapped into for radar, as long as all the cabling was suitably sized etc.
Maintenance is a good point, it may be financially more sensible to have the system mounted on a vessel. It could then come into port for maintenance and even upgrade in a much more cost effective manner. Sure, it would be off station sometimes, but there’d be downtime for maintenance regardless. It takes ~12 hours for a Service vessel to sail out from Great Yarmouth to the current windfarms in the southern North Sea, not too much of an increase in the down time compared to the difficulty and cost in bringing the upgrade to the platform rather than the other way around.
One thing may be security though, many of our windfarms are actually run by Equinor and other state energy companies from rest of Europe. Centrica divested themselves of theirs a while back. We are of course allies, but do we really want advanced and sensitive radar equipment on assets operated by foreign states’ nationalised companies?
It has been thought of before, but using disused oil/gas platforms. The advantage of the platform is the size. You can mount a much larger antenna (more power + greater receiver sensitivity) on the “rig”.
This was plan a devised in the 80’s towards the end of the Cold War. It was binned after the ending of the cold war, but the concept would still be valid today, except the signal processing could be done remotely. Today, you would use two different frequency band radars. If you use the lower end of the L band or the UHF band. The radar can be used for large area volume searching. It will also have a significant range advantage, depending on the frequency used, use the ground effect, where the radar beam can bend over the horizon. The issue with using these frequencies is target resolution is not very accurate. This is where the radar would be backed up with a higher frequency one for better target resolution. However, its view would be limited from the horizon up.
Towing a decommissioned but still structurally sound oil rig there and mounting it may be the best approach though you likely would want a token garrison of a dozen or so to negate the risk of foreign special forces raiding it for intel.
I think the cheaper and less risky approach might be the idea of a reference signal being broadcast from the edge of the field so that the shore based radar can calculate a noise filter.
The main issue with wind turbines is that they generate a doppler return when illuminated by a radar. Not only that, they also move in azimuth to always be pointing into the wind. So not only does the signal looks like it is moving, but it also varies in amplitude. This means for pulse doppler radars in particular, the signal becomes quite confusing. For radars using frequency modulated interrupted carrier wave (FMICW) it is a problem, but can be overcome by processing. The processing problem is that moving target algorithms use doppler shift comparison to indicate a moving target amongst background clutter. This is especially a big problem for traditional non-active array radars, as their beam width is generally a lot broader. Therefore a sweep will include a load of wind turbines all generating a doppler signal. With an active electronically scanned array (AESA). The beam width can be much narrower. Therefore the sweep, although including spinning turbines, can have a fewer number, making it easier to process.
The other issue with wind turbines are the materials used to construct the blades. Some are made from aluminium, whilst others are composite with a metal leading edge erosion strip. Not all fields will use turbines with the same type of blade. This further complicates matters, as the composite blades create a doppler return, but not as strong as an all aluminium one.
The best method of mitigating a threat hiding amongst a wind turbine field. Is to use a narrow beam with either a FMICW waveform or a Doppler-invariant waveform. These two types of waveform are more tolerant to doppler vagaries caused by a spinning wind turbine. However, they don’t rid of the issue completely, but through significant processing can mitigate the problem to allow a radar to see within and beyond a wind turbine field.