Government promises to speed up planning inquiries to ensure that wind farms play a valuable role in providing clean energy are not being fulfilled, with many schemes waiting up to five years for the go-ahead. Ministers have pledged to remove or reduce barriers faced by companies that want to build sustainable power projects, but this is proving difficult.

The development of E.ON's Humber Gateway project is one of the schemes mired in difficulties and facing ever-increasing delays. "When built, this wind farm will be one of the biggest in the UK and will play a vital role in the fight against climate change," said E.ON's project manager, Chris Sherrington. But the planning authorities are stuck, debating the effects on shipping routes despite the site having being chosen specifically to avoid interference with shipping and having full support from ABP, which owns Humber ports.

The fragility of the wind power business was highlighted recently when Shell pulled out of the world's biggest offshore wind farm - the London Array, off Kent - because of spiralling costs associated with planning delays. Britain is already struggling to meet the EU target of producing 20% of the country's total energy from renewables by 2020. That target has been reduced to 15% but even that is a major leap given the current level of 2% - a figure that has not risen for several years.

The Clyde Wind Farm in Scotland, being developed by Airtricity, is also suffering at the hands of the planning authorities. The project is more than five years behind schedule, with the planning application made in February 2003 and the referral from local planning authorities to public inquiry not occurring until August 2006. Airtricity, now part of Scottish and Southern Energy, says it remains hopeful that "a decision is imminent".

Planning for Gwynt-y-Môr wind farm situated 16km off the coast of north Wales, was proposed by npower in November 2005. The project, capable of generating up to 750MW or enough to power almost half of the households in Wales, is still awaiting a decision from planning authorities despite the fact that it would prevent the release of approximately 2m tonnes of carbon dioxide into the atmosphere.

The average time for planners to reach a decision has increased to more than 24 months in the past four years and delays often depend on the part of the country in which the scheme is being developed. E.ON estimates that, on average, a project spends between two to three times longer in the Scottish planning system than in the English one.