Built through the 2000s just as China’s rise was at its most headlong, the world’s largest power station can generate 22.5 gigawatts, equivalent to 20 nuclear plants. Two more of the world’s six biggest generators are upstream of its reservoir on the Yangtze River. Together, they pump out enough electricity to light up Poland.

Daily hydro generation has fallen 51% amid the worst drought on the Yangtze since the early 1960s, part of a worldwide drying that’s also closed the Rhine to barge traffic. That’s led to factory shutdowns as soaring demand from air conditioners collides with the constraints of a provincial grid that depends on dams for four-fifths of its electricity.