Yan Li from University of Illinois and his colleagues have learned how wind and solar installations could increase humidity and temperature in North Africa. Li hypothesizes that this would allow for vegetation to expand from the Sudanese savanna in to a substantial portion of the Sahara Desert.
Lis team were the first to incorporate vegetation feedback in to their model. Transpiration is a word used to describe the evaporation of hydration from a plant back in to the atmosphere. The concept would be an important factor to simulate in any environment where plants play a key role.
“Previous modelling studies have shown that large-scale wind and solar farms can produce significant climate change at continental scales,” says Yan Li of the University of Illinois at Urbana-Champaign, US. “But the lack of vegetation feedbacks could make the modeled climate impacts very different from their actual behaviour.”
If renewable energy covered over 9 million square km solar panels could generate around 79 terrawats whereas windmills would generate an average of 3 terrawats
“In 2017, the global energy demand was only 18 terawatts, so this is obviously much more energy than is currently needed worldwide,” says Li.
Wind farms changed nighttime minmum temperatures more then maximum temperatures by sucking down warmer air from above in what is called “vertical mixing”
In the Sahara precipitation increased by as much as 0.25 mm per day whereas in the Sahel it rose to a max of 1.12 mm per day
This was a doubling of precipitation over that seen in the control experiments,” says Li. “This increase in precipitation, in turn, leads to an increase in vegetation cover, creating a positive feedback loop.”
Solar panels with an efficiency rating of 15% can reduce ground reflectivity caused by the lighter color of sand which increases perspiration by about 50%. However, futuristic highly efficient solar panels wouldn’t have much more of effect, as the upper threshold kicks in at around 30% according to Li.
“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,” says Safa Motesharrei of the University of Maryland, US.
The team focused on the Sahara and Sahel because it “is in Africa and close to Europe and the Middle East, all of which have large and growing energy demands”.