I learn something every day.
I’ve always assumed that wind is about the same, on average. Obviously, winds change from minute to minute and place to place, but, for a given place, the overall “average” wind over a year is about the same every year, no? And therefore, wind power is wind power, on into the future. Right?
Well, no. Apparently, around 1980 there was a measurable slowing of average winds around the globe.
This may be important for many reasons, but is certainly is a major problem for wind power systems. Diminishing winds mean less power from wind turbines.
This winter, and international team report that this trend reversed, and wind speed (over land) has increased since 2010 . This is based on analysis of data from many ground stations. This is a large and noisy dataset, so the study used statistical sampling to establish that the evidence for the global trend is robust.
These results suggest that there is a multi decade cycle of average wind speeds. In fact, the data show that the increase is three times as fast as the decrease before it.
This reversal seems to rule some hypotheses about the earlier decline. In particular, urbanization and changing land cover cannot be responsible for the changes.
The researchers show that over this period the wind speeds are correlated with ocean-atmosphere oscillations, i.e., cycles of warming. They note that many global models underestimate this relationship, probably due to limitations of the models. It should also be noted that this study covers winds over mid-latitude lands (where there are lots of weather stations and wind turbines).
As Matt McGrath (no relation) puts it, this “rise” in global wind speed is a boost green power, at least for the short run . In fact, the observed changes over the past few years amount to an increase of about 17%, which the study calculates amounts to an increase of about 2.5% in the US wind power. Of course, this will go back down if and when the trend reverses.
If this finding holds up, it means that development of wind power will need to plan for these periodic changes. The performance of systems should not be based on the trends from recent years, it should project the estimated cyclical behavior, which are predicted to follow the ocean-atmosphere oscillations.
And, of course, human activities may well be perturbing the ocean-atmosphere oscillations, so future rising temperatures could impact winds and wind power. So we’ll need to see what happens.
- Matt McGrath, Renewable energy: Rise in global wind speed to boost green power, in BBC News – Science & Environment. 2019. https://www.bbc.com/news/science-environment-50464551
- Zhenzhong Zeng, Alan D. Ziegler, Timothy Searchinger, Long Yang, Anping Chen, Kunlu Ju, Shilong Piao, Laurent Z. X. Li, Philippe Ciais, Deliang Chen, Junguo Liu, Cesar Azorin-Molina, Adrian Chappell, David Medvigy, and Eric F. Wood, A reversal in global terrestrial stilling and its implications for wind energy production. Nature Climate Change:1-7, 2019. https://doi.org/10.1038/s41558-019-0622-6