Solar and wind farms could increase vegetation and rain in the Sahara

Large wind and solar farms built in the Sahara region could have an added benefit of increasing rainfall in the area and vegetation, according to a new study led by University of Maryland (UMD) scientists.

The team conducted climate and vegetation model experiments to show that wind and solar farms could lead to a more than doubling of the current rainfall levels in the Sahara and an increase of up to about 500mm/year in the Sahel, a semi-arid transition region that lies south of the Sahara.

The theory is that large solar panel farms would reduce the surface albedo (the amount of sun reflected into the atmosphere) of the areas they are installed in.

Similarly, wind farms would increase land surface friction and convergence of air, thus producing upward motion and precipitation. These feedback mechanisms suggest that both large wind and solar farms in the Sahara would significantly increase precipitation and vegetation.

Large-scale renewable energy projects could also provide enough energy to replace much of the fossil fuel energy currently used in the region.

The primary effect of such renewable energy farms would be a substantial reduction of human-generated greenhouse gas emissions and the resulting mitigation of climate change.

“Our model results show that large-scale solar and wind farms in the Sahara would more than double the precipitation in the Sahara, and the most substantial increase occurs in the Sahel, where the magnitude of rainfall increase is between ~200 and ~500 mm per year,” said Yan Li, a lead author of the paper. “As a result, vegetation cover fraction increases by about 20 per cent.”

“Precipitation increases predicted by our model would lead to substantial improvements of rainfed agriculture in the region, and vegetation increases would lead to the growth in production of livestock,” said Safa Motesharrei, UMD Systems Scientist and a lead author of the paper.

“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. Our study has major implications for addressing the intertwined sustainability challenges of the ‘Energy-Water-Food’ nexus in this region.”

“Moreover, the availability of vast quantities of clean energy would allow for desalination of seawater and transporting it to the regions that suffer most from severe freshwater scarcity, in turn, leading to improvement of public health, expansion of agriculture and food production and even restoration of biodiversity.”

Many solar and wind power projects in Africa and the Middle East are already underway in places such as Morocco, Dubai and Ethiopia. In total, over 200 GW of solar power is planned by 2030.

Power created by new projects in the Sahara area could also be transported to regions a few thousand kilometres away. Long-distance transmission lines have already been constructed in Africa and elsewhere.

“This study accomplishes something completely new: it looks at how human action can affect the land surface through construction of solar and wind farms, and shows that for land use change of this magnitude, it is fundamental to look at the impact on regional climate using global climate models that account for land-atmosphere feedbacks,” commented Paolo D’Odorico, Professor of Ecohydrology at the University of California, Berkeley (D’Odorico was not a co-author on the paper).

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