Climate change shifts usable winds

Possible decrease in wind yields in the north, increase in the southern hemisphere

The changing temperatures also affect the wind currents. How this could affect the yields of future wind turbines, researchers have now determined. © Gary Kavanagh / thinkstock
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Windy climate effect: Climate change could affect future yields of wind turbines. According to forecasts by US researchers, wind yields in the northern hemisphere will decline until the year 2100, but will increase significantly in parts of the southern hemisphere. But just for Europe - the region with the largest share of wind power so far - the models did not provide a clear trend, as the researchers report in the journal "Nature Geoscience".

In addition to solar energy, wind energy is considered an important pillar of the global energy transition. According to some researchers, in the future it could even provide enough energy to meet the needs of all humanity. The expansion is already under way: "Worldwide, installed cumulative wind power has increased by an average of 22 percent a year since 2006, " report Kristopher Karnauskas and colleagues from the University of Colorado at Boulder.

How do wind yields develop until 2100?

But how will climate change affect the yields of wind turbines in the future? "The wind farms are usually designed and constructed under the assumption that the amount of energy that can be extracted from the wind will remain approximately constant in the future, " the researchers say. However, data suggest that the wind currents are beginning to change with the temperatures.

What this could mean for wind yields worldwide has now been determined by Karnauskas and his colleagues using ten climate models. They simulated the changes by the year 2100 with a warming of around 2.5 or by 4.8 degrees Celsius. From these data they calculated the possible wind power yields of the different regions.

Decrease in the north ...

The result shows a surprisingly opposite development: in the middle latitudes of the northern hemisphere, wind yields could decrease towards the end of the century, but increase in the tropics and in the southern hemisphere. The decline is particularly robust and pronounced in Central and North Asia and in the middle of the USA, among others. Depending on the scenario, wind yields could fall by 14 to 18 percent by 2100 here. display

The cause of this trend is primarily the warming of the Arctic, as the researchers explain. Because the polar regions heat up disproportionately, the temperature gradient weakens from the tropics to the Arctic. This also reduces the differences in air pressure and thus the driving forces for the winch. This process lowers the usable winds, especially in winter, according to the researchers.

more windfall in the south

In the southern hemisphere, on the other hand, some regions might even benefit from a strong increase in usable wind energy. For example, the scientists forecast a rise in wind yields of 41 and 42 percent for the northeast of Australia and the east of Brazil. Also in the Horn of Africa and parts of West Africa, the usable winds are increasing significantly in the second half of this century.

However, the underlying mechanism is different from the North: in the Southern Hemisphere, climate change is causing the country to heat up more than the ocean. As a result of this intensified gradient, the wind between land and sea also blows more and more strongly, as Karnauskas and his colleagues explain.

Europe without a clear trend

However, the trend is clearly unclear for Europe - the region with the largest share of wind energy today: "Europe is a big question mark, " adds Karnauskas. "We have no idea what we will see there because the trend in this region is simply too uncertain." Some of their climate models forecast a decline in wind yields, while others forecast an increase.

In fact, previous studies have already shown that the wind in Europe could fluctuate above all: phases with doldrums become more frequent and longer, at the same time more and more storms increase Windverhltnisse.

What are the consequences?

But what does this mean for the future of wind energy? As the researchers themselves state, their data are still too crude for concrete planning of future wind farms - especially in complex terrain. After all, how much wind a plant can actually "harvest" depends heavily on the location and its local conditions. The grid of 100 kilometers used for the study can not reproduce such small-scale structures.

In addition, according to some climate experts, such a long-term forecast of wind yields can hardly be reliable. "I very much doubt that with the climate models available today, the yield of wind turbines can be calculated in advance over more than 80 years", comments Bruno Burger from the Fraunhofer Institute for Solar Energy Systems in Freiburg.

These shortcomings also anger Karnauskas and his colleagues. In their opinion, however, their results provide at least indications of where more accurate, local analyzes of the coming wind conditions could be useful and necessary. (Nature Geoscience, 2017; doi: 10.1038 / s41561-017-0029-9)

(University of Colorado Boulder, 12.12.2017 - NPO)