Wind and solar farms could turn the Sahara green for the first time in over 4,500 years

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What would happen if we covered the world’s largest desert with solar and wind farms?

A study in the journal Science shows that covering even part of the Sahara’s nine million square kilometers with solar panels and wind turbines could produce more than enough power for the entire world. Plus, it would bring rain to the Sahara and make parts of it green for the first time in over 4,500 years.

Previous studies have shown that large wind and solar farms can change local climate. That’s because wind turbine blades pull warm air from higher altitudes down to the earth’s surface. Dark solar panels, meanwhile, absorb solar energy so less of it is reflected back into space, also effectively increasing air temperature near the ground.

The new study is the first to show how vegetation can also change as a result of immense solar and wind farms. Researchers from the University of Maryland considered a scenario in which 20 percent of land in the Sahara and the neighboring semi-arid Sahel region is covered with solar panels and wind turbines that are over 300 feet high. The wind and solar farms would respectively generate about 3 and 79 terawatts of power, which is over four times the world’s energy use.

Using a computer program to model how these farms would change the local environment, the team found that the wind turbines would increase air temperatures near the ground and slow down wind speeds. This would bring more moisture to the area. Solar panels would also increase average air temperature and hence precipitation.

This would increase the average local temperature by about 5 degrees Fahrenheit. The warmer temperature would lead to more rainfall, particularly in the Sahel. This enhances plant growth, which further increases rain. The simulation showed that the wind and solar farms more than doubled the average rain across the entire Sahara from 0.24 mm per day to 0.59 mm per day.

Any hikes in temperature from solar and wind farms are limited in geographical area, the researchers point out. The impact on global temperature would be small compared to the carbon dioxide emissions from burning fossil fuels.

Massive wind and solar farms in the Sahara could not only provide clean energy to Europe, the middle East and sub-Saharan Africa, the researchers write, it could also “promote economic development in the Sahel, one of the poorest regions in the world, as well as provide clean energy for desalination and provision of water for cities and food production.”

Source: Yan Li et al. Climate model shows large-scale wind and solar farms in the Sahara increase rain and vegetation. Science, 2018.

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