A WRF simulation of the effect of a large wind farm on 40 years of precipitation in the eastern United States

The world currently consumes about 17 TW of energy, created mostly from fossil fuel combustion. About 2 TW of fossil fuel is combusted in the United States to produce 0.5 TW of electrical power. The US Department of Energy (DOE) plans to satisfy 20% of US electricity demand through wind power generation by 2030, or approximately 0.132 TW of wind power. Assuming an average efficiency of 0.3, a wind farm capable of meeting a demand of 0.132 TW must have a total generating capacity of at least 0.44 TW. This requires deploying wind turbines over a vast area, with potential consequences for weather systems. Using the Weather Research and Forecasting Model (WRF) with the Adams and Keith wind farm parameterization and a 30 km grid, we model 40 years of weather in a domain that includes the eastern 2/3 of the United States. Boundary conditions to WRF are supplied by the NNRP. The Adams and Keith parameterization includes elevated wind drag, generation of turbulent kinetic energy, and electricity production. The parameterized wind farm ranges from the Texas panhandle to northern Nebraska, covering 182,700 square kilometers with 1.25 turbines per square kilometer, for a total of 228,375 wind turbines. The wind turbines parameterized are based on a Bonus 2.0MW turbine with a 60 m hub height and a 76 m rotor diameter resulting in an installed capacity of 0.457 TW. Simulations are performed for only the warm season, from 1 May to 31 August, which supplies the majority of the annual rainfall in the Great Plains and the Southeastern United States. It also represents the growing season, when changes to precipitation patterns have the largest potential to impact agriculture. Initial results show that the presence of a wind farm causes the 40-year precipitation to vary by as much as 6%, both within the wind farm and downstream. The processes involved in the precipitation changes will be explored, and the implications of the results will be discussed.