Windmills have become the symbol for an eco-friendly future of energy power. However, new research shows that they become a hazard to the environment when no longer in service.
The results from a Danish study published in the International Journal of Technology, Policy and Management show that by 2040, wind power dominated countries will be left with millions of tonnes of scrap metal, much of which cannot be recycled.
Windmills have a typical lifespan of 20 to 30 years before they need to be replaced, and almost a quarter of a million windmills worldwide will need upgrading by 2030.
'The rubbish problem exists and it's mainly the blades that cause the problem. They are made from composite materials, which are difficult to separate into clean sections for recycling,' said the head of the study, Per Dannemand Andersen from the Technical University of Denmark.
Andersen recommended that manufacturers start thinking about the potential scrap material, when designing new windmills.
Jakob Larsen, of Danish windmill manufacturer Vestas, confirmed that the blades typically end up on the scrap heap.
'We took part in a project that set out to break down and crush the blades so they could be burned and create another source of energy. But it's a commercially expensive solution,' said Larsen.
Enron Wind, a former manufacturer of wind turbines, had previously estimated that it would cost 30 million kroner to remove a 30-turbine wind farm, located seven kilometres out to sea, reports Berlingske Tidende newspaper.