Objections to proposed wind farms on the grounds of such interference are one of the biggest obstacles to project development in Britain - nearly 12 GW of potential wind capacity, either in the permitting system or at an earlier stage of development, is currently affected by some form of objection from the aviation industry.
Over 5 GW of this - 3 GW of which is in the permitting system - is affected by objections from NATS (formerly National Air Traffic Services) because of aviation radar interference. Objectors for the same reason include the Ministry of Defence (MoD) and local airport operators.
But while these organisations have objected to planned wind projects, they are also involved in researching solutions to turbine interference on radar. The Aviation Memorandum of Understanding is an R&D agreement signed by the British Wind Energy Association (BWEA), NATS, civil aviation regulator CAA, the MoD, and the UK's Department of Energy and Climate Change (Decc) and Department for Transport. NATS is managing the first project under the agreement. Working with Raytheon Canada, supplier of all of NATS' fleet of primary radar, and using a fix for hardware and software, it hopes to eliminate the "sparkle" effect that wind turbines can have on primary radar screens, where turbines look similar to approaching aircraft on screen.
The £5.15 million funding for the Raytheon project, as it is known, comprises £2 million from seabed landlord the Crown Estate, £1.55 million from Decc and £1.2 million from the wind industry's Aviation Investment Fund Company (AIFC), which is funded by 18 BWEA member companies. NATS is not contributing to funding.
"This is one of the most exciting developments for the potential removal of aviation objections," says Simon Christian of Scottish Power, who also chairs AIFC. David Hawken, head of infrastructure asset engineering for NATS, hopes to see a solution in place within three to five years. "Raytheon are reasonably confident they have got a solution that appears viable and we are certainly keen to be a partner to cooperate with them to help the industry," he says.
NATS's new fleet of 19 Raytheon radar systems is currently in the process of being installed, but the Raytheon solution will have to be retrofitted. Hawken defends the choice of Raytheon, explaining that the systems have been on order over a ten-year programme. There are no alternative radar suppliers that have a product that can filter out the effect of wind turbines, he says. "The question for us is who pays for the roll-out?" he adds. "We are not sure how much that will cost."
NATS maintains that any wind farm mitigation must be implemented at all 19 of its radar sites. BWEA, however, says that only seven or so radar sites are affected by planned wind farms. "Who pays is a very good question," adds BWEA's head of aviation, Nicola Vaughan. "There is currently no vehicle in place for the wind industry to pay for this." This needs to be addressed before the Raytheon solution is developed, she adds.
While the Raytheon project is looking at a fix for the civil air traffic control radar problem, the AIFC is also funding a study into reducing the effect of wind turbines on air defence radar. The MoD operates two types of radar: its UK Command and Control System (UCCS) for air defence and its own fleet of Watchman air traffic control radar. The four-month feasibility study, a joint project between the MoD and computer technology giant IBM, will look at expanding the UCCS system to accept feeds from its air traffic control radar to mitigate the effect of wind turbines. At the end of the study, the industry should know the cost of a solution, how long it will take to implement and possibly have a model for addressing other MoD concerns, says Vaughan. "The potential is huge."