DNV GL has helped more clients to evaluate the economic viability of a project than any other company.
The steps involved in a wind and energy assessment are as follows:
- Site visit to review site characteristics, e.g. terrain, and wind monitoring equipment
- Wind data filtering and quality control to detect any erroneous or suspect observations
- Wind data analysis and processing to define best possible prediction of long-term wind speed and direction frequency; where appropriate, including on-site data reconstruction, long-term adjustment and vertical extrapolation
- Wind flow modelling, typically undertaken with a linear model such as WAsP and in certain cases augmented with the results from a computational fluid dynamics model or even a conceptual model if site terrain leads to an unusual wind flow regime
- Energy calculation, including prediction of wake losses
- Calculation of likely wind farm loss factors, e.g. wake loss, non-availability, electrical efficiency, turbine performance, environmental losses or curtailments
- Uncertainty analysis to enable financial decision makers to take well informed decisions, e.g. by presenting the probability of exceeding energy levels at P75 or P90, i.e. a 75% or 90% chance of exceeding the predicted energy production figure
- Detailed reporting
Outcomes from the wind and energy assessment deliver information on the wind regime at a site. This is crucial for the optimal design of the wind farm and in assessing the suitability of different turbine models for use at the site. The accuracy of the analysis is dependent on the extent, quality and duration of the wind data recorded at the site. Here, DNV GL can give clear guidance to developers on the requirements a site’s wind monitoring programme has to fulfil. Such guidance is described in detail in the Wind measurement service description.