MAIN PUBLICATION :

• APPENDIX
• ABREVIATIONS
• GLOSSARY
• REFERENCES
• EVENTS

Environmental

In certain conditions, dirt can form on the blades, or over time the surface of the blade may degrade.  Also, ice can build up on a wind turbine.  These influences can affect the energy production of a wind farm in the ways described below.  Extremes of weather can also affect the energy production of a wind farm; there are also described below.  

Performance degradation – non-icing

The performance of wind turbines can be affected by blade degradation, which includes the accretion of dirt that may be washed off by rain from time to time, as well as physical degradation of the blade surface over prolonged operation.

Performance degradation - icing

Small amounts of icing on the turbine blades can change the aerodynamic performance of the machine, resulting in loss of energy.

Icing shutdown

As ice accretion becomes more severe, wind turbines will shutdown or will not start.  Icing can also affect the anemometer and wind vane on the turbine nacelle, which may also cause the turbine to shut down.

Temperature shutdown

Turbines are designed to operate over a specific temperature range.  For certain sites, this range may be exceeded, and for periods when the permissible temperature range is exceeded, the turbine will be shut down.  For such sites, an assessment is made to establish the frequency of temperatures outside the operational range, and the correlation of such conditions with wind speed.  From this, the impact on energy production is estimated.

Site access

Severe environmental conditions can influence access to more remote sites, which can affect availability.  An example of this might be an area prone to severe snow drifts in winter.  

Tree growth/ felling

For wind farm sites located within or close to forests or areas of trees, the impact of how the trees may change over time and the effect that this will have on the wind flow over the site, and consequently the energy production of the wind farm, must be considered.  The impact of the future felling of trees, if known, may also need to be assessed.