Estimation of the influences of air density on wind energy assessment: A case study from China

Abstract

The distribution characteristics of air density in China were modelled on a high-spatial-resolution scale (4000 m × 4000 m) and the absolute error was calculated by comparing with constant air density. Daily mean air pressure and air temperature time series from 2403 meteorological stations for the period 1998–2018 were used to compute air density at the hub height of a typical wind turbine. The statistical air density distributions were applied in the study area and the influence of elevation on changes in air density was quantified. Mean annual energy production in the study area was estimated using extrapolated parameters of the Weibull distribution and adjusted power curves. Compared with energy production under the assumption of constant air density, the results demonstrate that over 33% of the study area had a mean air density less than 1.000 kg/m3 due to the effect of elevation. Values as low as 0.347 kg/m3 were observed in the Tibetan Plateau. Energy production was underestimated (0.04–1.76%) in the north-east and north when the variability of air density was considered, and wind resources were overestimated by more than 20% in approximately 13.1% of the study area. The results of this study will contribute to identifying suitable locations for developing the wind energy industry. The influence of air density on wind energy production at different elevations can now be quantified, allowing more efficient utilization of wind resources.