Large-scale, renewable energy projects are promoted globally as tools to help countries reduce carbon emissions, especially on the African continent where the Sahara Desert, the largest in world, offers plenty of space and has no shortage of sunlight and wind.
Both the Sahara and the Sahel, a region between desert and wooded savanna, have few inhabitants and little competition for land use.
The study, led by Yan Li of the University of Illinois, found renewable energy installations in Africa can boost local economies, improve local climates and provide energy for neighboring regions.
Researchers said wind farms increased near-surface air temperatures, and rainfall by as much as 0.25 millimeters per day, creating more favorable conditions for vegetation.
“The greater nighttime warming takes place because wind turbines can enhance the vertical mixing and bring down warmer air from above,” the authors said in a statement. “This increase in precipitation, in turn, leads to an increase in vegetation cover, creating a positive feedback loop.”
The climate model study is one of the first to examine the effects of wind and solar installations on climate and subsequent impact on vegetation.
Previous studies have found that wind and solar farms can have either beneficial or detrimental effects on local heat, humidity and vegetation in the regions where they’re located.
“Previous modeling studies have shown that large-scale wind and solar farms can produce significant climate change at continental scales,” Li said in a statement, adding the response to vegetation analyzed in this study shows the impact would be beneficial.
Li, along with Eugenia Kalnay and Safa Motesharrei of the University of Maryland, co-leaders of the study, focused on the Sahara and Sahel because of the role they can play in Europe and Africa’s energy futures.
“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,” Li said.
But the hypothetical wind and solar energy projects from the study the potential to produce more energy than is needed worldwide. The nearly 3.5 million square mile project could generate about 3 terawatts in wind and 79 terawatts in solar power. In 2017, the entire planet’s energy demand was just 18 terawatts.
In the Sahel, one of the poorest regions in the world, the projects would provide clean energy for seawater desalination plants that can then supply cities and farms.
Solar farms had a similar positive effect on temperature and precipitation, researchers said. But unlike the wind farms, the solar farms had very little effect on wind speed.
“We found that the large-scale installation of solar and wind farms can bring more rainfall and promote vegetation growth in these regions,” Kalnay said. “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.”
The study’s authors said it was unclear whether smaller projects in other deserts would have similar impacts but noted that renewable energy installations are becoming more feasible as the cost of the technology goes down and political will increases.
Motesharrei said other countries should take note that the increase in rainfall and access to green energy as a result of the Sahara and Sahel projects is expected spur “agriculture, economic development and social well-being” on the African continent, the Near East and nearby regions.