Ordos, a city in China's Inner Mongolia, is transforming the Kubuqi Desert with a "Solar Great Wall," a 400-kilometer belt of photovoltaic panels that generates clean electricity while holding back the sand. 

The Ten Kongdui tributaries, seasonal flood gullies that once poured sediment into the Yellow River, have also been systematically restored. 

The desert is retreating, the rivers are clearing, and Ordos has become a model for what happens when renewable energy meets restoration.