Wednesday, 17 January 2007
Understanding the local and regional impacts of large wind farms
Exhibit Hall C (Henry B. Gonzalez Convention Center)
Wind power is the fastest growing non-fossil source of primary energy. As concern over CO2 emissions pushes society towards cleaner energy sources, the demand for wind power will continue to increase. As the number and size of wind farms grows, their influence on the local and regional climate must be considered. Large wind farms directly influence the atmospheric boundary layer by (1.) reducing wind speeds, (2.) generating blade scale turbulence in the wake of the turbines, and (3.) generating shear driven turbulence due to the turbine wake. Consequentially, large wind turbines can also have indirect effects on the local climate by influencing surface fluxes, advection of heat and moisture, and turbulent transport in the boundary layer. Using a force based approach the Weather Research and Forecasting Model (WRF) has been modified to include a wind farm parameterization. The new parameterization exerts an elevated drag force on the wind, converts a fraction of the resolved flow into turbulent kinetic energy, and keeps track of the energy generated by the parameterized wind turbines. Keeping track of the energy generated by the turbines allows for examination of the intended climate benefit of wind energy (reduction of CO2 emissions) to the unintended climate impacts (changes in the atmospheric boundary layer). This paper will present results from simulations using the new wind farm parameterization and discuss the local and regional climate changes associated with large wind farms.