A new study published in Science suggests that the installing large-scale clean energies in the Sahara Desert could greatly change the region.
Wind turbines could go so far as to influence the amount of rainfall in the region – up to double – and solar panels would also impact rainfall, vegetation, and temperatures on the Sahara. "Our model results show that large-scale solar and wind farms in the Sahara would more than double the precipitation, especially in the Sahel, where the magnitude of rainfall increase is between 20mm and 500mm per year," said Dr. Yan Li, the lead author of the paper from the University of Illinois, US. "As a result, vegetation cover fraction increases by about 20%."
This rise in vegetation cover could mean a lot for local farmers. As co-author Dr. Safa Motesharrei explains, "Precipitation increases predicted by our model would lead to substantial improvements of rain-fed agriculture in the region, and vegetation increases would lead to the growth in production of livestock. The Sahara, the Sahel, and the Middle East include some of the driest regions in the world while experiencing high growth of population and poverty, and our study has major implications for addressing the intertwined sustainability challenges of the energy-water-food nexus in this region."
But we should back up a minute. How does this even work? Is it just the presence of these renewable energies changing rainfall? Not quite. Wind turbines’ rotating blades act to mix higher, warmer air with lower air, thus creating evaporation. "Wind farms increase surface roughness and therefore increase wind converging into low-pressure areas," explained Dr. Li. "The converging air has to rise, making it cool off and moisture condense, which will lead to increased rainfall."
It’s different with solar panels. Solar panels reflect sunlight and produce a positive albedo-precipitation-vegetation feedback loop. "The panels directly reduce the surface albedo which leads to more solar energy absorption and surface warming, which in turn strengthens the Saharan heat low, leading to more rising air and precipitation," elaborated Dr. Li.
Now, to be clear, the study’s model is talking about renewable energies on a huge scale – i.e. covering 9 million square kilometers with wind and solar farms. Due to the region’s conditions, the Sahara has no lack of sun and wind, and the model predicts that such an installation could generate over four times the annual amount of energy we consume globally. It is also conveniently located to large energy markets in Europe and the Middle East where energy could be exported. The researchers say that only such a large-scale system would have as significant an impact on the climate in the region like that they described in the study.