Carpeting Sahara with wind and solar farms could make it rain

Enlarge / "Whaaaaaaaat?" (credit: Lisa de Vreede)

If you’ve spent any time thinking about the world’s dirty energy problem, you’ve probably pondered some impractical “What if?” scenarios. Solar panels in space beaming energy down, or covering Nevada in solar panels—that kind of thing. Well, a new study led by Yan Li, Eugenia Kalnay, and Safa Motesharrei at the University of Maryland actually asks something similarly out there. What would happen to the Sahara if it contained enough wind and solar farms to supply the entire world’s energy needs several times over?

Why the Sahara, you ask? Apart from the obvious things—lots of open land and a pretty potent solar resource—the area’s climate has shown to be pretty sensitive to nudges. The Sahel region between the Sahara Desert and the wetter lands to the south, in particular, can easily become wetter or drier with small atmospheric changes. And since studies elsewhere have shown that wind and solar farms can have an influence on local weather, it’s interesting to consider what effect they’d have in northern Africa.

Supersize me

With no constraints on their scenario, the researchers opted for the “supersized” version. In a climate model, they simulated the effect of adding three terawatts of wind power—a little more than the world’s current total electricity use. Next, they added 79 terawatts of solar farms. Global energy use of all types (including fuels) is about 18 terawatts today, so this is a scenario where all the fuel a growing world could want are made in the Sahara, and Africa's drinking water is probably desalinated, to boot. In all, this is something like nine million square kilometers covered by wind and solar farms—nearly the area of the United States.