Wind turbines, flicker, and photosensitive epilepsy: Characterizing the flashing that may precipitate seizures and optimizing guidelines to prevent them

Authors: Harding, Graham¹; Harding, Pamela¹; Wilkins, Arnold²

Source: Epilepsia, Volume 49, Number 6, June 2008 , pp. 1095-1098(4)

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Abstract:

Summary

Wind turbines are known to produce shadow flicker by interruption of sunlight by the turbine blades. Known parameters of the seizure provoking effect of flicker, i.e., contrast, frequency, mark-space ratio, retinal area stimulated and percentage of visual cortex involved were applied to wind turbine features. The proportion of patients affected by viewing wind turbines expressed as distance in multiples of the hub height of the turbine showed that seizure risk does not decrease significantly until the distance exceeds 100 times the hub height.

Since risk does not diminish with viewing distance, flash frequency is therefore the critical factor and should be kept to a maximum of three per second, i.e., sixty revolutions per minute for a three-bladed turbine. On wind farms the shadows cast by one turbine on another should not be viewable by the public if the cumulative flash rate exceeds three per second. Turbine blades should not be reflective.

Keywords: Photosensitive epilepsy; Flicker; Rotors; Visual discomfort; Wind farms; Wind turbines; Green power

Document Type: Research article

DOI: http://dx.doi.org/10.1111/j.1528-1167.2008.01563.x

Affiliations: 1: Neurosciences Institute Aston University, Birmingham, United Kingdom 2: Department of Psychology, University of Essex, Colchester, United Kingdom

Publication date: 2008-06-01