Dr. Mark Žagar: A wind turbine and the variable atmosphere

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Povzetek:

       A wind turbine and the variable atmosphere

        Dr. Mark Žagar,  Vestas Technology R&D, Aarhus, Danska

As the attractiveness of wind energy grows, the locations available for development become increasingly more complex. Among the factors that affect local conditions, the state of the atmosphere. i.e. the local micro climate conditions, has the strongest impact on efficiency, longevity, and profitability of a wind farm. As a consequence, knowledge of local not-only-wind climate conditions largely reduces uncertainties in energy yield estimates, life time, and maintenance costs and thus directly increases the value of an investment and optimizes required resources. Depending on the vertical structure of the boundary layer a few meters increase in turbine hub height can cause a difference of several GWh in yearly electricity production for a single wind turbine generator. 

In the seminar I will present and discuss various modes of spatial and temporal variability and their impact on a wind farm: horizontal differences in wind speed on mesoscale and microscale, low-level jet and in general vertical wind shear which is in turn tightly linked with atmospheric stability and turbulence, and wind gustiness versus turbulence as a particular problem. Many efforts are focused at connecting these variability modes to wind turbines' performance using measurements from the sites and numerical models.