A positive trend in the stability of global offshore wind energy.

The recognition on the trend of wind energy stability is still extremely rare, although it is closely related to acquisition efficiency, grid connection, equipment lifetime, and costs of wind energy utilization. Using the 40-year (1979–2018) ERA-Interim data from the European Center for Medium-Range Weather Forecasts, this study presented the spatial-temporal distribution and climatic trend of the stability of global offshore wind energy as well as the abrupt phenomenon of wind energy stability in key regions over the past 40 years with the climatic analysis method and Mann-Kendall (M-K) test. The results show the following 5 points. (1) According to the coefficient of variation (C_v) of the wind power density, there are six permanent stable zones of global offshore wind energy: the southeast and northeast trade wind zones in the Indian, Pacific and Atlantic oceans, the Southern Hemisphere westerly, and a semi-permanent stable zone (North Indian Ocean). (2) There are six low-value zones for both seasonal variability index (S_v) and monthly variability index (M_v) globally, with a similar spatial distribution as that of the six permanent stable zones. M_v and S_v in the Arabian Sea are the highest in the world. (3) After C_v, M_v and S_v are comprehensively considered, the six permanent stable zones have an obvious advantage in the stability of wind energy over other sea areas, with C_v below 0.8, M_v within 1.0, and S_v within 0.7 all the year round. (4) The global stability of offshore wind energy shows a positive climatic trend for the past four decades. C_v, M_v and S_v have not changed significantly or decreased in most of the global ocean during 1979 to 2018. That is, wind energy is flat or more stable, while the monthly and seasonal variabilities tend to shrink/smooth, which is beneficial for wind energy utilization. (5) C_v in the low-latitude Pacific and M_v and S_v in both the North Indian Ocean and the low-latitude Pacific have an obvious abrupt phenomenon at the end of the 20th century. [ABSTRACT FROM AUTHOR]