Large wind and solar farms in the Sahara would increase heat, rain and vegetation

Wind and solar farms are known to have local effects on heat, humidity and other factors that can be beneficial or even harmful to the regions where they are located. A new climate modeling study reveals that a massive wind and solar installation in the Sahara Desert and the neighboring Sahel would increase local temperature, rainfall, and vegetation. Overall, the researchers report that the effects would probably be beneficial for the region.

The study, reported in the review Science, is among the first to model the climatic effects of wind and solar installations while taking into account the response of vegetation to changes in heat and precipitation, said lead author Yan Li, a natural resources and postdoctoral researcher. Environmental Science at the University of Illinois.

"Previous modeling studies have shown that large-scale wind and solar farms can produce significant climate change on a continental scale," said Li. "But lack of feedback from vegetation could make impacts modeled climates very different from their actual behavior.

The new study, co-led with Eugenia Kalnay and Safa Motesharrei at the University of Maryland, focused on the Sahara for several reasons, said Li.

"We chose it because it is the largest desert in the world, it is sparsely populated, very sensitive to changes of terrain and is located in Africa and close to Europe and the Middle East. -Orient., "He said.

The wind and solar farms simulated in the study would cover more than 9 million square kilometers and would produce, on average, about 3 terawatts and 79 terawatts of electricity, respectively.

"In 2017, global energy demand was only 18 terawatts, which is obviously a lot more energy than is currently needed worldwide," Li said.

The model revealed that wind farms caused a regional warming of near-surface air temperature, with greater variations in minimum temperatures than the maximum temperatures.

"The nightly warming is all the more important as wind turbines can improve vertical mixing and lower global warming," the authors wrote. Precipitation has also increased by an average of 0.25 millimeters per day in areas with wind farms.

"It was a doubling of rainfall compared to control experiments," Li said. In the Sahel, average rainfall increased by 1.12 millimeters per day when wind farms were present.

"This increase in rainfall in turn leads to an increase in vegetation cover, creating a positive feedback loop," Li said.

Solar farms had a similar positive effect on temperature and rainfall, the team found. Unlike wind farms, solar panels have had very little effect on wind speed.

"We have found that large-scale installation of solar and wind farms can generate more precipitation and promote vegetation growth in these areas," Kalnay said. "The increase in precipitation is a consequence of the complex earth-atmosphere interactions that occur because solar panels and wind turbines create rougher and darker surfaces.

"The increase in rainfall and vegetation, combined with clean electricity through solar and wind energy, could help agriculture, economic development and social well-being in the Sahara, Sahel, the Middle East and other neighboring regions, "said Motesharrei.

Explore more:
The public health benefits of adding offshore wind to the network

More information:
Y. Li el al., "The climate model shows that large-scale wind and solar farms in the Sahara increase rainfall and vegetation" Science (2018). science.sciencemag.org/cgi/doi… 1126 / science.aar5629