You already know that using solar and wind power can influence the climate by reducing our dependence on heat-trapping fossil fuels. Now scientists say these renewable forms of energy can change the climate more directly — and do it in ways that might surprise you.
If wind turbines and solar panels were deployed across the Sahara, more rain would fall and more plants would grow in the massive African desert, according to research published in the journal Science.
“Renewable energy can have multiple benefits for climate and sustainable development,” wrote a team led by researchers from the University of Maryland’s Department of Atmospheric and Oceanic Science.
To figure this out, the researchers imagined three scenarios for the Sahara and the Sahel, a semi-arid region immediately to the south.
In one, the area is studded with wind turbines that stand more than 300 feet high. In another, solar panels cover 20 percent of the land. The third case combines wind and solar farms — a setup that would produce about 82 terawatts of electricity per year. (For the sake of comparison, the entire world used roughly 18 terawatts of electrical power in 2017, said study co-leader Yan Li.)
Once their hypothetical energy farms were built, the researchers fed the details into a computer program that simulates Earth’s dynamic climate. Then the program made predictions.
In the case of wind farms, the giant turbines would cause warmer air from above to mix with cooler air below, bringing more heat close to the surface. Air temperatures near the ground would increase by nearly 4 degrees Fahrenheit.
In addition, the turbines would interrupt the smoothness of the desert surface. Winds blowing through the area would move more slowly.
That, combined with the added heat, would change the atmospheric conditions over the Sahara and bring more moisture to the area. Average rainfall would increase by up to 0.25 of a millimeter per day — about double what it would have been otherwise, the study said.
The additional water would fuel plant growth, and those extra plants would reduce the amount of sunlight that’s reflected off the desert surface.
From there, it’s a positive feedback loop, the researchers said: The reduced reflectivity (or surface albedo) enhances precipitation, which fuels plant growth, which reduces albedo, and so on.
The story is a little different for solar farms. Instead of slowing the wind or causing hot and cool air to mix, the main effect of solar panels is to reduce albedo. That would increase average daily precipitation by about 0.13 of a millimeter in the Sahara and 0.59 of a millimeter in the Sahel. The additional water would induce more plant growth, reducing albedo and allowing the cycle to continue.
These changes were predicted to increase the maximum temperature by more than 2 degrees Fahrenheit, the researchers reported.
If wind and solar farms were combined, these effects would be “enhanced,” they said.
But the rain wouldn’t be spread evenly everywhere. The simulations predicted that parts of the Sahel could get as much as nearly 20 inches of additional precipitation per year. All that extra water could have “major ecological, environmental, and societal impacts,” Li and his colleagues wrote.