The Ministry of Defence (MoD) and the British Wind Energy Association (BWEA) will tomorrow call an end to hostilities over new wind farms with both parties agreeing to co-operate to better address concerns over the disruption new wind farms can cause to radar coverage.

The two parties are expected to join the department for Business, Enterprise and Regulatory Reform (BERR) and the Civil Aviation Authority in signing a new Memorandum of Understanding at the BWEA's offshore wind energy conference in London tomorrow. The agreement will see all signatories commit to work together to address the contributory factors that have seen a large number of planned onshore and offshore wind farms blocked due to concerns over their impact on radar systems.

Speaking earlier today, BWEA chief executive Maria McCaffery MBE said the memorandum was essential if the sector was to improve the rate at which projects are approved and restore investor confidence after a period that has seen a number of projects blocked because of MoD opposition.

She said the BWEA had identified 11 schemes from nine separate developers where the MoD had originally said it would not obstruct the projects only for the department to subsequently raise concerns about their impact on radar systems. She added that these projects alone had cost developers £7m in planning, only for final approval to be denied. "More money was wasted in planning than it would have cost the MoD to upgrade the radar system so that there would not have been a problem," she observed.

BWEA chairman Adam Bruce said the MoD's opposition to a number of proposed projects was likely to have been a contributory factor in the recent drop-off in the rate of new projects entering the planning system. He said that while the industry has consistently proposed about two gigawatts per year of new projects, the past 18 months had seen a drop-off in activity with last year seeing only about 1,500MW of new projects entering the planning system.

"The slowdown may in part be down to the fact that some of the best sites have already gone, but our members are also wary of putting new projects into planning without more clarity from the MoD and civil aviation [on which projects are likely to be opposed]," he said, adding that the BWEA would be conducting further investigations into the cause of the recent slowdown over the summer.

McCaffery warned that the projects opposed by the MoD, combined with several other bottlenecks in the planning system, had left some wind turbine manufacturers "demoralised". She added that of the 19GW of wind capacity currently in the UK system, 9.6GW is stuck in the planning phase with projects taking an average of two years to receive a decision from planning authorities, "and some projects taking much longer than that".

The BWEA is lobbying for a number of changes in planning policy to speed up the process, including calling on central government to exercise its powers to force through more projects and advocating a more streamlined approach to environmental assessments.

"Currently, a project has to take two years to assess the impact it has on birdlife," she said. "We see no reason why that cannot be reduced to one year, without any harm being done to local wildlife… the burden of environmental assessments has to be reduced."

However, despite continuing obstacles to expansion both McCaffery and Bruce remained upbeat about the long-term prospects for the UK wind industry, observing that much of the capacity required to meet the UK's renewable energy targets were already in the planning system and reporting that wind projects were having little difficulty in attracting investor support.

"By 2013 we will have more installed wind capacity than nuclear capacity," predicted Bruce. "The renewables sector will become a manstream energy generator within the next four to five years."