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2 October 2018

Solar power plants and wind turbines could bring rain to the Sahara

According to a climate modelling study published in the American scientific journal by a group of researchers (Yan Li, Eugenia Kalnay, Safa Motesharrei, Jorge Rivas, Fred Kucharski, Daniel Kirk-Davidoff and Eviatar Bach), covering 20% of the Sahara with wind turbines and solar panels would produce enough electricity to power the entire planet and double rainfall in the desert.


The work would require the construction of three million wind turbines and solar panels. Headed by Yan Li, postdoctoral researcher in natural resources and environmental sciences at the University of Illinois, the study estimates that covering nine million sq. m. with equipment would modify the flow of air by reducing wind speed and reduce the variations in temperature at ground level by raising the minimums. According to their calculations, daily precipitation would rise from 0.24 to 0.59mm, resulting in a 20% increase in vegetation cover, enabling the growing of new crops and farming… on the remaining 80%. The appearance of new vegetation would, in turn, promote precipitation, thus triggering a virtuous circle.


“We found that the large-scale installation of solar and wind farms can bring more rainfall and promote vegetation growth,” observes climatologist Eugenia Kalnay. “These changes stem from the complex land-atmosphere interactions that occur through the solar panels and wind turbines creating rougher, darker land areas.”


Yan Li chose the Sahara as the setting for his modelling “because it is the largest desert in the world; it is sparsely inhabited; it is highly sensitive to land changes; and it is in Africa and close to Europe and the Middle East, all of which have large and growing energy demands.”


“The impacts on regional climate would be beneficial rather than detrimental and the impacts on global mean temperature are still small compared with those induced by CO2 emission from fossil fuels,” the authors point out. “This highlights that, in addition to avoiding anthropogenic greenhouse gas emissions from fossil fuels and the resulting warming, wind and solar energy could have other unexpected beneficial climate impacts when deployed at a large scale in the Sahara, where conditions are especially favourable.”


Funding still needs to be found for such a gigantic project, not to mention answers to the technical challenges it would raise. The study’s authors recognize these drawbacks. “Efforts to build such large-scale wind and solar farms for electricity generation may still face many technological (e.g., transmission, efficiency), socioeconomic (e.g., cost, politics), and environmental challenges, but this goal has become increasingly achievable.”