They are the polarising structures at the heart of the Scottish Government’s plans for a cleaner, greener energy supply.
Wind turbines have long attracted controversy in Scotland, with some arguing they are a blight on scenery and tourism as others hail them as a symbol of the country’s progressive outlook on renewables.
That argument is now set to intensify as moves are being made to almost double the size of turbines nearing the end of their lifespans, according to a new report.
The plans have also prompted environmental concerns as it would cause further disruption to Scotland’s peatland – which most turbines are built on – damaging the soil’s vital carbon cutting resource.
Mountaineering Scotland said the move would “increase the visual impact”on Scotland’s mountains and landscapes, and called for the “environmental and aesthetic impact on the landscape” to be made a “key consideration”.
Environment Protection Scotland also said that the report, by researchers at the Universities of Glasgow and Aberdeen, raises questions over the development of windfarm policy in Scotland.
Charity spokesman John Bynorth said: “Scotland’s peatlands have a powerful natural role to play in slowing climate change through carbon capture and everything must be done to prevent damage to this vital part of our eco-system.
“Research by scientists has also found that even the ‘wake’ from wind turbines can have an impact on air temperatures and humidity, impacting on the temperature of soil and on the surface of soil – so it’s clear that digging deeper or wider foundations in which to place bigger and more powerful windfarms will also potentially have a damaging impact on Scotland’s environment.”
The report reveals that Scotland is home to more than 3,200 operational wind turbines, with a further 2,300 either under construction or awaiting planning permission.
The majority of these (74 per cent) are on peatland.
Renewable energy accounted for around 60% of the country’s gross annual consumption in 2015, up from just 12% in 2000, with much of that increase attributed to onshore wind farms.
The report revealed that as the turbines come to the end of their lifespan, usually after around 25 years, they need to be upgraded or replaced via a process known as repowering.
This means either disturbing the peat by regenerating existing turbine foundations or creating completely new foundations elsewhere on the site.
The existing turbines would then be increased from 100 metres to roughly 170 metres to harness “better wind”.
Professor Susan Waldron, of the University of Glasgow’s School of Geographical and Earth Sciences, said that while the damage to peatland is serious, the “payback time”, i.e. the time it takes before the turbines become beneficial to the environment, is relatively short.
Research suggests this is usually between two to three years, compared to the 25-year lifespan of the turbine.
Ms Waldron said the report was”of significance internationally”, and showed that Scotland is keen to lead the way in repowering, which has only been done on a small scale so far.
“We’ve completed the most comprehensive and collaborative report on repowering to date,” she said, adding that it considers “the ecological, hydrological, biogeochemical and carbon security impacts of the repowering process”.
“This shows that foundations could be re-engineered to take bigger turbines (for another 30 years), but reusing the foundation generally requires more construction materials and disturbs the soil as much as a new foundation.”
She added that of the two repowering options,creating new foundations would be the most environmentally friendly as regeneration involved more materials and more disruption to the peat.
Friends of the Earth Scotland said the report was a “helpful contribution” to the developing debate on repowering existing wind farms.
Charity director Dr Richard Dixon said: “Scotland needs to develop our renewable energy capacity if we want to progress towards a zero carbon economy.
“Increasing onshore wind production, whilst minimising disruption to communities and the environment, is absolutely key to achieving that aim.
“Through a process of engagement with stakeholders and expert analysis of the benefits arising, repowered sites can play a significant role in the decades ahead.
“With careful development on shallower peatland, the net emissions savings over the lifespan of a turbine project can make a very large contribution to our collective climate action.”
Scottish Renewables said wind was the cheapest form of green energy and the Scottish government’s “robust” planning system already factored in the impact of on carbon emissions.
The Scottish Government said it supported upgrading “in principle” while protecting the country’s natural heritage, which included assessing and minimising the “carbon impact” of wind farms on peatland.