The green alternative?

New Scientist: The hidden cost of wind turbines [subscribers only]

… [Richard] Lindsay [, University of East London] is an advocate for renewable energy but has become concerned by the scale and number of wind-farm developments on peat bogs in Europe. "This is the Cinderella ecosystem," he says. "Peatland is busy performing a series of important functions for us and we just don't see it." Bogs often play a critical role in providing clean drinking water. More significantly in the context of renewable energy, they store three times as much carbon as is held in tropical rainforests. "We build wind farms in order to reduce carbon emissions," Lindsay says. "Yet peatlands represent the one land-based habitat in the world that is a major long-term carbon store. By building on peat, we release this carbon store as carbon emissions into the atmosphere."…

To calculate carbon savings, [Mike] Hall [,Cumbria Wildlife Trust] uses the [wind powerstation] developers' own predictions, which generally give figures for overall electricity generation of about 30 per cent of the maximum rated capacity of a turbine. The average achieved output for existing wind farms is actually lower than this—25.6 per cent according to industry figures. Using the conservative "minimal scenario", Hall calculates that a 2-megawatt turbine built on peat moorland 1 metre deep will take 8.2 years to pay back its CO₂ cost. The figure for the "high scenario" is a whopping 16 years. Even the minimal figure is a substantial portion of a turbine's normal lifespan of 25 years, and considerably higher than the industry's own figures, which range between three and 18 months…

Research into the ecological impact of offshore renewable energy developments is even sparser than for onshore projects. Writing in the Journal of Applied Ecology last year (vol 42, p 605), Andrew Gill from the Institute of Water and Environment at Cranfield University in Silsoe, Bedfordshire, UK, noted that only 1 per cent of all papers on renewable energy published in the past 15 years considers environmental impacts onshore, and none offshore.