By Prarthana Mitra
The world’s largest hot desert may not remain a dreary arid landscape for long.
A series of mammoth wind and solar installations intends to increase rainfall and abet vegetation in Africa’s Sahara Desert. According to the study published in the journal Science, this is among the first models to gauge the climatic effects of such installations that also assess the response in vegetation responds to changes in temperature and precipitation levels.
“Previous modeling studies have shown that large-scale wind and solar farms can produce significant climate change at continental scales,” said Yan Li, study author and postdoctoral researcher at the University of Illinois, US. But this is the first time vegetative feedback will be included to apply the hypothesis to ground reality.
Why Sahara?
Li cited several reasons for choosing Sahara as the location for the simulated study. “We chose it 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,” he said.
As per the study, the wind and solar farms cover more than nine million square kilometers and generate about three terawatts and 79 terawatts of electrical power on an average respectively. Once realised fully, this could meet the global energy demand of 18 terawatts, and then some.
A positive feedback loop for adjoining regions
The solar and wind farms were found to increase nocturnal temperature due to precipitation of warm air at night, but the solar models did not have a notable impact on wind speed. Rainfall increased by at least a 0.25 millimetres per day in regions with wind farm installations. “This was a doubling of precipitation over that seen in the control experiments,” Li said.
In the neighbouring Sahel, average rainfall increased 1.12 millimetres per day in areas with wind farms. “This increase in precipitation, in turn, leads to an increase in vegetation cover, creating a positive feedback loop,” he added.
According to fellow-researcher Eugenia Kalnay, from University of Maryland, large-scale installation of solar and wind farms could also bring more rainfall and promote vegetation growth in these regions. “The rainfall increase is a consequence of complex land-atmosphere interactions that occur because solar panels and wind turbines create rougher and darker land surfaces,” Kalnay told the Economic Times.
Safa Motesharrei from University of Maryland also said, “The increase in rainfall and vegetation, combined with clean electricity as a result of solar and wind energy, could help agriculture, economic development and social well-being in the Sahara, Sahel, Middle East and other nearby regions.”
Prarthana Mitra is a staff writer at Qrius