Impact Of Wind Farms On Air Quality In China

The total installed capacity and new installed capacity of wind power in China have increased in the past twenty years.As clean energy,wind power has reduced the burning of fossil fuels.It also has some impacts on climate and environment.In order to study the impacts of wind farms on air quality in China,we use the Weather Research and Forecasting?WRF?model and Community Multi-scale Air Quality?CMAQ?model to simulate pollutants'concentration with and without wind farms from 2009 to 2018.We use observed data to verify WRF/CMAQ.The consistency?IA?of meteorological parameters?wind speed,wind direction,temperature,and relative humidity?is greater than 0.7,and the root mean square error?RMSE?and mean deviation?MBE?are small.The correlation coefficient?R?of pollutants(NO₂?PM_2.5?SO₂)is 0.69,the mean fractional bias?MFB?is 10%and the mean fractional error is50%,which are both meet the requirements of“devidiation standard”.The diffences of NO_x?PM_2.5 and SO₂ concentrations between cases with and without wind farms are analyzed.The results show that under the influence of wind farms in winter,concentrations of pollutants have increased in Beijing-Tianjin-Hebei and central Inner Mongolia.The concentrations in the southeast coast and central region of China have decreased.80%of monthly average concentration differences in winter are between-2?g/m³ and 2?g/m³.The differences of pollutants'concentrations in summer are larager than those in winter.The concentrations in the northeast region of China,Biejing-Tianjin-Hebei and Shanxi province have increased,and the concentrations in the Pear River Delta,Yangtze l River Delta,and Sichuan-Chongqing regions have decreased,87%of which are between-10?g/m³ and 10?g/m³.We use the integrated process rate analysis?IPR?technology to evaluate the PM_2.5generation rates of 8 physical and chemical processes.In winter,the main source processes of PM_2.5 are all anthropogenic emissions and aerosol processes,with average contribution rates of 39%and 58%.The main sink processes are dry deposition processes and contribution rates is 52%.In summer,vertical diffusion and anthropogenic emissions are the main source processes of PM_2.5 in the four regions,with mean contribution rates of 55%and 31%.With the impacts of wind farms,PM_2.5generation rate of each physical and chemical process is basically unchanged in winter,and it varies greatly in summer.The effect of vertical diffusion process is weakened,which decreases the PM_2.5 concentration.The dry sedimentation and aerosol processes are weakened,and the elimination effect on PM_2.5 is weakened,which leads to an increase of PM_2.5 concentration.Based on the random forest algorithm,we evaluate the impacts of meteorological parameters on PM_2.5 concentration.The importance of the characteristics indicates that wind speed,relative humidity,and temperature are of great importance to PM_2.5.The properties are 0.031,0.025,and 0.023,respectively.