At current prices, the average land-mounted wind turbine has a design life of 20-25 years (this is getting longer as designs improve) and will generate sufficient free electricity (over and above the cost of maintenance etc.) to pay for itself in 40-45 years (this figure is coming down due to economies of scale). This means that at the moment no turbine is generating sufficient electricity to pay for itself, however, their cost-efficiency is not bad compared with coal-fired power stations (nobody ever values their break-even costs - we need the power regardless).

The predicted environmental impact of manufacture of turbines is no greater than that involved in providing similar generation capacity from a NEW coal-fired station (obviously, with an existing station, the only impact is that due to ongoing operation). Pollution in operation is minimal, although there is ongoing research into the potential health impacts of vibrating equipment on cardiac arrhythmia which this will no doubt contribute to.

As a political issue, the environmental lobby are obviously pro-wind and will tend to marginalise the impacts to highlight the benefits, while the government will do the opposite, since they are "strongly influenced" by the fossil-fuel lobby.

It is apparent that this government is only interested in funding researhc which supports its own pre-conclusions and will actively manupulate research funding criteria to ensure that only positive outcomes reach publication. The environmental lobby appear to be retaliating, judging from the above links. What we can be sure of is that most research output will exhibit inherent bias in this emotionally-charged area.