The implications for visual simulation and analysis of temporal variation in the visibility of wind turbines

Abstract

The visual impact of wind turbines is a central issue in their public acceptance. New wind farm proposals are commonly subject to visual simulation and visual impact assessment. Guidelines for both these processes are already used in a number of jurisdictions and there is widespread interest in making simulation and impact assessments as meaningful as possible. To a large degree the guidelines for both processes tend to be based on worst-case (full-frontal) conditions. There are two quite good reasons for this. Firstly, the worst-case sets a boundary for visual impact. Secondly, we seldom know enough about how visibility or visual impact changes over time and what ‘typical’ conditions are like – or how the range of conditions is distributed. This paper argues that if we can address this knowledge gap, then we may also be able to take a more nuanced approach to simulation and analysis. It should be possible, using widespread atmospheric visibility data, to determine the temporal distribution of visual impacts at a particular location rather computing a single estimate. It may also be valid to create simulations of both worst-case and more typical conditions. This paper explores the key variables affecting visual impacts – visual magnitude and color difference – and how they may be monitored and analyzed efficiently and effectively. A wind farm in southern Victoria, Australia is used as the case study. Recommendations are made on how the approaches could be used more widely.