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How it Works

We know modeling and simulation. Our risk analysis tools are driven by high-fidelity simulation code. Our four physics-based simulation modules, covering blade and ice throw, shadow flicker, turbine visibility (viewshed), and noise analysis, are grounded in accepted scientific methods and corroborated by experimental data where possible. We leverage online terrain height databases to compute accurate results for your specific wind installation site.

Blade and Ice Throw. Persimia’s blade and ice throw simulation program models the trajectories of blade or ice fragments that may potentially be thrown from wind turbines. Once a user specifies the location of wind turbines and surrounding structures of interest (such as buildings, roads, pastures, schools, etc.), thousands of blade or ice throw simulations are rapidly performed in our cloud computing environment, in which the initial release conditions are automatically randomized. High-fidelity rigid-body and aerodynamic modeling techniques are used to ensure rapid runtimes, while maintaining accuracy in trajectory predictions. The ground impact locations for these simulations are recorded and used to quantify impact risk to the surrounding structures. Results are commonly available in hours or even minutes. Detailed information on our simulation model can be found here and here.

Environmental Noise. Persimia’s environmental noise prediction tool uses the ISO-9613-2 standard for sound propagation outdoors. Using the specific turbine placement provided by the user, the local terrain at the wind installation, and the octave-band sound power levels for the specific make and model of installed turbines, our noise prediction software computes the predicted A-weighted sound power level at each geographic location in the surrounding area. Results can be used in the creation of environmental noise assessments or to predict sound power levels at specific points of interest.

Shadow Flicker. Persimia’s shadow flicker prediction tool uses a geometric model for sun position in terms of the solar azimuth and elevation angles. The sun position is calculated at the wind farm location for all days of the year, and the turbine shadow is predicted using a ray tracing algorithm. The shadow position and extent is calculated based on the underlying local terrain, gathered from a web-based terrain database. This algorithm computes the predicted number of shadow flicker hours per year at each geographic location in the surrounding area. These results can be used in environmental impact assessments, or to predict shadow flicker hours at specific points of interest near the turbine locations.

Turbine Visibility. Persimia’s turbine visibility prediction tool determines whether turbines are visible from each geographic location in the surrounding area. The code uses a ray tracing algorithm to determine whether local terrain features block a turbine from view. Partial turbine visibility is also considered, in cases where only part of the turbine disk or tower is within view from a certain location. Results are provided in the form of a turbine visibility map, showing the number of turbines visible over the surrounding area, and a table showing the number of turbines visible at specific points of interest.


Quantifying Environmental Impact

You need actionable results. We are here to help. All of our simulation tools leverage the latest online mapping and terrain height databases. This means that all you need to provide is the layout of the wind installation and the locations of nearby features of interest. Our simulations generate actionable data in the form of map overlays that provide the results (sound power, flicker hours per year, etc.) at each geographic location near the wind farm. These maps are easy to visualize and can be used directly in environmental impact assessments. Our simulation codes also provide tabular outputs at specific features of interest defined by the user, such as homes, schools, or parks in the surrounding area.

Our results are designed to be used directly for wind turbine siting studies, environmental impact assessments, determination of setback standards, or evaluating community risk near current turbine installations. For Premium members, our expert staff is available to help with additional customized interpretation of the results.


How to Use Your Results

Use us for Siting. Are you designing a new wind farm installation? Our analysis tools can help you locate the best turbine locations that minimize impact and risk to surrounding structures. We designed our interface to easily support iterative siting studies so that you can try out new locations quickly.

Use us for Permitting. Are you involved in the permitting process for a potential new wind installation? Environmental impacts such as noise, shadow flicker, and blade and ice throw risk to nearby structures is important to quantify. Our easy-to-understand results, provided in the form of overlay maps and tabular outputs, can be easily incorporated into environmental impact studies and can be used directly to derive setback standards.

Use us for Evaluating Community Risk. Is there a wind installation near your community? If you are worried about the potential affects of noise, shadow flicker, turbine visibility, or blade or ice fragments, Persimia offers an easy way to calculate these effects and risks in your specific area.