It's called flickering. This is what the Ministry of Health of the Government of the Canary Islands has warned about and that the residents of San Bartolomé de Tirajana, neighbors of wind farms, would suffer.
What they don't know in those areas is that in addition to the earth that is seeping into their houses due to the effect of soil foundations, a visual effect that no one dares to investigate will be added for at least the next 25 years. The authorities are silent about the employment generated by the maintenance of mills and the money from licenses. In some areas of Germany, wind power is only allowed at night.
The theory of the Ministry of Health of the Government of the Canary Islands is that this effect can be harmful in the south of Gran Canaria and this has been made known to the central Government to oppose the installation of turbines eight kilometers from the coast. The question that no one wants to answer is: if flickering is harmful at sea eight kilometers away, how negative will it be on land for neighbors who live less than eight kilometers from turbines? Since 2019, the Government of the Canary Islands has promoted the largest floating wind farm in the world, a park of 200 megawatts for generation and another 100 reserved for testing new technologies that could enter service in 2025.
The Galician renewable energy company Ecoener develops wind farms with a total power of 22,4 megawatts in the municipality of San Bartolomé and in which it plans to invest 37 million euros. These new five parks are added to the two that were already in operation in that same municipality and make up the largest wind complex in the Canary Islands. The CEO of Ecoener, Luis de Valdivia, highlights that the new parks "will be located next to one of the existing thermal power plants on the island, so their visual and environmental impact is zero, thus becoming a symbol of the change of fossil energies with renewable energies". The new wind facilities, called "La Caleta", "Arcos del Coronadero", "Lomo del Moral", "Las Casillas 1" and "El Rodeo", will use Enercon E-48 wind turbines.
And the shadow cast by the wind turbines, like the rest of the tall structures, cast a shadow on neighboring areas when the sun is visible, which is the south of Gran Canaria practically all year round. That is, if you live near a wind turbine you may be disturbed if the rotor blades cut off sunlight, causing a flickering effect when the rotor is in motion. Shadow casting is generally not explicitly regulated by planning authorities. However, in Germany there has been a court case in which the judge allowed 30 hours of actual flickering per year on a particular neighbors property. It appears that the 30 hours only include the flickering that occurs when the property is actually being used by people (who are awake).
Shadow Flicker Prediction
Fortunately, we appear to be able to predict fairly accurately the probability of when and for how long there may be a flicker effect. We cannot know in advance if there will be wind or what its direction will be, although using astronomy and trigonometry we can calculate either a probable scenario or a "worst case", that is, a situation where there is always sunshine when the wind is all the time. time blowing and the turbine rotor follows the sun exactly, orienting the turbine exactly as the sun moves. Getting the exact shape, location and time of a wind turbine shadow requires a lot of calculations, but at least a professional wind computer program can do it very precisely, even in rugged terrain, and with house windows of any size, shape, location and inclination orienting in any direction.
