Spatiotemporal variation of power law exponent on the use of wind energy

The power law, a common method in wind energy assessments, often assumes a global power law exponent (α) of 1/7, potentially leading to inaccuracies in estimating wind conditions and energy potential. This study uses high-frequency measurements from eight wind towers to assess the power law's reliability and demonstrates its general applicability, except in complex topography. The α value is found to differ significantly from 1/7 in validation sites, yet it can be reliably used in ERA5 data based on regional verification. To evaluate the global spatiotemporal variation of α, we analyze the hourly α from 1980 to 2022 using ERA5 wind speed data at 10 m and 100 m. Our findings reveal varying α value with time and geography, with particular disparities between land and ocean. Additionally, we observe changes related to diurnal cycles, seasons, and latitudes. This analysis of α value carries significant implications for a global-scale wind energy resource assessment, site selection, and turbine design.