Spatiotemporal distribution of nitrogen dioxide within and around a large-scale wind farm – a numerical case study

Jingyue Mo,Jianmin Ma,Xiaodong Zhang,Yuan Zhao,Tao Huang,Hong Gao,Jixiang Li,Xiao Liu

doi:10.5194/acp-17-14239-2017

Abstract

Abstract. As a renewable and clean energy source, wind power has become the most rapidly growing energy resource worldwide in the past decades. Wind power has been thought not to exert any negative impacts on the environment. However, since a wind farm can alter the local meteorological conditions and increase the surface roughness lengths, it may affect air pollutants passing through and over the wind farm after released from their sources and delivered to the wind farm. In the present study, we simulated the nitrogen dioxide (NO2) air concentration within and around the world's largest wind farm (Jiuquan wind farm in Gansu Province, China) using a coupled meteorology and atmospheric chemistry model WRF-Chem. The results revealed an edge effect, which featured higher NO2 levels at the immediate upwind and border region of the wind farm and lower NO2 concentration within the wind farm and the immediate downwind transition area of the wind farm. A surface roughness length scheme and a wind turbine drag force scheme were employed to parameterize the wind farm in this model investigation. Modeling results show that both parameterization schemes yield higher concentration in the immediate upstream of the wind farm and lower concentration within the wind farm compared to the case without the wind farm. We infer this edge effect and the spatial distribution of air pollutants to be the result of the internal boundary layer induced by the changes in wind speed and turbulence intensity driven by the rotation of the wind turbine rotor blades and the enhancement of surface roughness length over the wind farm. The step change in the roughness length from the smooth to rough surfaces (overshooting) in the upstream of the wind farm decelerates the atmospheric transport of air pollutants, leading to their accumulation. The rough to the smooth surface (undershooting) in the downstream of the wind farm accelerates the atmospheric transport of air pollutants, resulting in lower concentration level.

Highlights

Wind power has been the fastest-growing energy source and one of the most rapidly expanding industries around the globe
Yumen wind farm (YWF) started to build up, which delivered NO2 from JISCO region to YWF (Fig. 3b). This southeasterly wind regime became stronger at 20:00 UTC, enhancing the atmospheric transport of NO2 to the YWF, characterized by increasing NO2 levels in the northwest of the JISCO and the YWF (Fig. 3c)
Extensive model simulations in a case study were carried out to quantify the influence of the world largest wind farm on the spatial distribution of NO2 within and around this wind farm

Summary

Introduction

Wind power has been the fastest-growing energy source and one of the most rapidly expanding industries around the globe. China’s wind power has increased 100 % from 2006 to 2010. By 2015, the total installed capacity of wind power became the largest globally with the capacity of 140 GW (GWEC, 2016). It is projected that wind power capacity in the nation will reach 200 GW by 2020, 400 GW by 2030, and 1000 GW by 2050. In 2016, the wind power capacity accounted for 4 % of total national electricity consumption. It is expected that wind power will become one of five main power sources and meet 17 % of the total electricity demand in China in the mid-21st century (IEA, 2011)

Methods

Results

Conclusion