Aviation constraints are currently restricting the expansion of wind energy in the UK – even offshore environments where radar of a different type plays an essential role in marine navigation. However new technology developments are progressing and offer potential future solutions.
Qinetiq, in partnership with Vestas have been in the R&D stage of a “stealth blade” for a number of years. The technology is being developed to solve issues of wind turbine blade returns appearing as “clutter” on radar screens, which some radar users find distracting.
Funding for the stealth blade has been assisted by the Technology Strategy Board, a non-departmental public body established in 2007 by the UK Government and supported by the Department for Innovation, Universities and Skills.
The test wind turbine blades are made of various radar absorbing materials (RAM) such as novel thin RAM, integral composite RAM and paints. Laboratory samples have been tested and QinetiQ say that a turbine with stealth blades is expected to be ready for demonstration by the middle of 2009.
Senior Media Relations Manager at QinetiQ, Christopher Mosley said “The stealth blade stabilises the image that the radar operates to see on the screen“. He said QuintiQ “was given very demanding specifications, which included making virtually no change to manufacturing processes, no mass increases, minimal cost increases and a solution which was fit-and forget for the lifetime of the wind turbine“.
Other technical mitigation measures in development include “Advanced Digital Tracker” a retrofitted box which digitally removes the clutter from the image on the radar screen and “Data Fusion” – a technology which – as the name suggests – fuses data from two different radars to give an unaffected image on the radar screen (due to one of the radars being positioned in a location which cannot see the wind farm).
Whilst wind turbine blade “clutter” appearing on radar screens can be difficult to automatically filter, it can often be straightforward for appropriately skilled radar users to identify and account for the effects of the clutter. Radar operators such as air traffic controllers already understand other sources of clutter such as lorries on high roads and make appropriate adjustments to their operations when such affects are suspected.
