Rising temperatures threaten wind energy

Wind Energy Under Climate Change examines how greenhouse gases and polar amplification weaken temperature gradients, slowing prevailing winds and reducing renewable electricity output, requiring more wind turbines and early resource tapping in high northern latitudes.

As global temperatures rise, wind speeds drop, says a Texas researcher who has calculated by how much and points out it will mean less wind for powering turbines.

The conundrum is that while wind is promoted as a renewable source of wind energy across markets, greenhouse gases released by the burning of fossil fuels impede the ability to produce clean electricity from wind.

Wind is created when warm and cool air meet, said climate researcher Diandong Ren of the University of Texas at Austin. "The stronger the temperature contrast, the stronger the wind," he said in a release.

Ren's study, appearing in the current issue of the Journal of Renewable and Sustainable Energy, explains that prevailing winds in the "free" atmosphere about 1,000 metres up are maintained by the contrast in temperatures between the polar regions and lower latitudes, where global wind energy patterns may be shifting southward.

But with global warming, temperature contrasts drop because polar regions tend to heat up faster. As the temperature contrasts weaken, so too do winds.

Ren calculates that a 2 to 4 Celsius temperature increase at Earth's mid to high latitudes, even as a U.S. wind power surge continues, would result in a four to 12 per cent decrease in wind speeds in certain high northern latitudes.

Wind turbines are powered by wind at lower altitudes, where local topography such as mountains, valleys and even tall buildings influence its strength, even as high altitude wind machines are explored for stronger winds elsewhere.

"I assume that these effects are constant - like a constant filter - so wind speed changes in the free upper atmosphere are representative of that in the frictional lower layer."

The answer is not to give up on wind, Ren said, but the opposite. "We need to invest in more wind turbines to power the grid effectively, to gain the same amount of energy. Wind energy will still be plentiful and wind energy still profitable, but we need to tap the energy source earlier."

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