Preliminary Study on Large-scale Installation of Renewable Energy and Its Impacts on Regional Climate WANG Shu (王 姝) China Electric Power Research Institute (CEPRI), State Grid Corporation of China (SGCC) 2019.05 On the 2nd place in world’s top 500 enterprises.

Overview Climate service need of power grid Present Renewable Energy (RE) in China Impacts of large-scale RE installation On atmospheric boundary layer On land surface processes On local (regional) Climate

Transmission & distribution Line icing Line dancing Power grid is Meteorology dependent Generation Wind, solar, hydro power Wind farm Solar park Hydropower Transmission & distribution Thunder, rime, typhoon, frost, heavy rain, etc. Line icing Line dancing Flood Landslide Mud avalanche In terms of Transmission: Physical structure and transmission capability are influenced Load Extreme temperature, drought, etc. Electricity Load vs temperature 3

1. Climate service need of power grid Electricity generation part Climate prediction in wind speed, solar radiance, precipitation, streamflow for RE installation plan, power prediction and dispatch & operation. Daily/weekly/monthly/annually pattern of wind/solar for generation schedule making. Prediction on Extreme climate events (eg. icing and sandstorms, typhoon) for risk assessment on RE installation and utilization.

1. Climate service need of power grid Electricity transmission and distribution part Climate signal detection and prediction on Extreme climate events (eg. storms, lightening, etc.) for securing electricity transmission and operation. Physical characteristics of meteorological disasters occur on power system, like pollution deposit on insulators, ice accretion on overhead lines, etc. Spatial and temporal distribution of hazardous weather/ climate and induced secondary disasters.

1. Climate service need of power grid Electricity load part Climate signal detection and prediction on Extreme climate events: Drought, increasing load by agricultural facilities. Extreme high/low temperature, increasing load by air-conditioner. Successive rain days, increasing load by dehumidification, etc. Other anthropogenic behavior alternation under climate change, etc.

PV installed capacity (MW) 2. Present RE in China Rapid growth of Wind and PV capacity: wind power 100 times/10yr, PV power 100 times/5yr. Till 2018, the bulk installation of wind power hit 1.84 ×108 kW, which has been top 1 in the world through recent 9 years. RE is essential for sustainable development of energy and dealing with climate change. The 8 power of ten Wind power installed capacity (MW) PV installed capacity (MW)

“turbine wake effect”：source of TKE and sink of KE 3. Impacts of large-scale RE installation Researches based on ground or satellite observation, and numerical models(WRF, CAM, LES, Fitch) demonstrate large-scale installation of wind power could lead to series impacts: On atmospheric boundary layer “turbine wake effect”：source of TKE and sink of KE Reduce near-surface wind speed (by 8-9% at 10 m, 0.5 m/s in 50 km or 3 m/s in several km at hub height…) Enhance turbulent kinetic energy (0.5 m2/s2 in 1.1 km vertically) Amplify vertical exchange of energy and substances… A onshore wind farm in Horns Rev, Denmark, Feb, 2008.

3. Impacts of large-scale RE installation On land surface processes Increase roughness and drag force Alter temperature (0.5K↑in stable while↓in unstable stratification…) Turbine motion alters the flux of energy and substances (15% ↓ in heat flux in stable stratification…) Alter albedo (especially for solar parks), radiation transfer… Alter vegetation fraction, evapotranspiration, soil hygroscopicity; Act as a heat source…

3. Impacts of large-scale RE installation On regional climate Complicated, varies for day/night and climate types： Alter temperature (0.72 K/10a; 0.18 K; ±0.5 K…) Increase near-surface humidity (0.03 g/m3…) Alter momentum and wind speed above near-surface Increase potential energy of convection triggering Alter cloud fraction, radiation forcing, precipitation (1%↑; tow-fold…) Alter regional vegetation fraction and runoff… Overall, conclusions on this issue vary, and depend on many atmospheric factors. It is necessary to establish systematic and continuous observation on typical RE bases and conduct in-situ effective models to figure it out.

Thanks! Part of References wangshu@epri.sgcc.com.cn CHANG R, ZHU R, GUO P 2016. A Case Study of Land-Surface-Temperature Impact from Large-Scale Deployment of Wind Farms in China from Guazhou. Remote Sensing [J], 8: 790. FIEDLER B H, BUKOVSKY M S 2011. The effect of a giant wind farm on precipitation in a regional climate model. Environmental Research Letters [J], 6: 045101. FITCH A C 2015. Climate Impacts of Large-scale Wind Farms as Parameterized in a Global Climate Model. Journal of Climate [J], preprint: 150508125018008. FITCH A C, OLSON J B, LUNDQUIST J K, DUDHIA J, GUPTA A K, MICHALAKES J, BARSTAD I 2012. Local and Mesoscale Impacts of Wind Farms as Parameterized in a Mesoscale NWP Model. Monthly Weather Review [J], 140: 3017-3038. KEITH D W, DECAROLIS J F, DENKENBERGER D C, LENSCHOW D H, MALYSHEV S L, STEPHEN P, RASCH P J 2004. The influence of large-scale wind power on global climate. Proc Natl Acad Sci U S A [J], 101: 16115-16120. MIROCHA J D, RAJEWSKI D A, MARJANOVIC N, LUNDQUIST J K, KOSOVIĆ B, DRAXL C, CHURCHFIELD M J 2015. Investigating wind turbine impacts on near-wake flow using profiling lidar data and large-eddy simulations with an actuator disk model. Journal of Renewable & Sustainable Energy [J], 7: 043143. PORT -AGEL F, LU H, WU Y-T 2014. Interaction between Large Wind Farms and the Atmospheric Boundary Layer. Procedia IUTAM [J], 10: 307-318. ROY S B 2011. Simulating impacts of wind farms on local hydrometeorology. Journal of Wind Engineering & Industrial Aerodynamics [J], 99: 491-498. ROY S B, PACALA S W, WALKO R L 2004. Can large wind farms affect local meteorology. Journal of Geophysical Research Atmospheres [J], 109: 4099-4107. ROY S B, TRAITEUR J J 2010. Impacts of wind farms on surface air temperatures. Proceedings of the National Academy of Sciences [J], 107: 17899-17904. SMITH C M, BARTHELMIE R J, PRYOR S C 2013. In situ observations of the influence of a large onshore wind farm on near-surface temperature, turbulence intensity and wind speed profiles. Environmental Research Letters [J], 8: 034006. SUN H, LUO Y, ZHAO Z, CHANG R 2018. The Impacts of Chinese Wind Farms on Climate. Journal of Geophysical Research: Atmospheres [J], 123: 5177-5187. Thanks! wangshu@epri.sgcc.com.cn