Tuesday, May 14, 2013

Why are Wind Turbines White?

By Ralph,
Do you know why wind turbines are invariably white in colour? Henry Ford, the father of mass production famously said of his Model T-Ford, you can have any colour as long as it’s black. It seem the same is true of wind turbines. Except that the colour is white. Given that some people claim that they are an eye-sore, why paint them white so that they stand out more against the surrounding greenery, desert, sky and clouds?
It seems that most technicians say that whereas colours absorb the sun (and heat), white, an absence of colour, reflects sunlight and therefore reflect heat. Heat causes expansion, drying up of lubrication, and blistering. Consequently any colour would either shorten the life of a wind turbine by introducing increased wear and tear, or be more expensive in terms of maintenance. This seems to be the primary reason, although others have said that while sometimes the skies are blue, they are more often overcast (at least in the UK!) and therefore white is a neutral colour that can best blend in with all types of skies. Hmmm. Not sure about that one!
There was even a call a few years ago for wind turbines to be painted purple! A study in 2010 has revealed that a wind turbine’s colour affects how many insects it attracts, shedding more light on why the turbines occasionally kill bats and birds who are seeking insect prey. Support for the idea came from another study showing that bats are most often killed by turbines at night and in summer, when insects are most abundant.
It had been speculated that insects may be attracted to turbine structures for some reason and this then could attract insectivorous species, such as birds and bats, to forage in the vicinity,” said PhD student Chloe Long of Loughborough University, UK.
However, she added, “no other study has looked in detail at what specific insect species might be attracted to turbine installations or why”.
The researchers measured how many insects were attracted to a range of paint colours, including pure white, light and dark grey, sky blue, red and purple.They did so by laying out coloured cards in a random sequence next to a 13m-high three-blade wind turbine situated in a meadow near Leicestershire, UK. Squares painted pure white and light grey drew the most insects. Apart from one other colour- yellow- the colour of the majority of plants trying to attract insects for pollination.
The least attractive paint colour to insects was purple. Hmm… can you imagine the furore from anti-wind farm protesters if turbines were painted a lurid purple? Also the researchers admitted that there could be other factors attracting insects to wind turbines colour aside? This could be the sounds, the air-current movements, or the heat generated by the blades warming up the air. It could also be that insects are just curious to investigate these large, sighing, three-petal metal flowers that are helping them by reducing carbon in their air!