In 2018, a single power plant produced more energy than the world’s largest coal-powered and gas-powered plants combined. China’s Three Gorges Dam relies on running water, and is capable of producing more energy than any other power plant on Earth. So what allows Three Gorges to generate all this power? And how do hydroelectric plants work in the first place? Alex Gendler investigates. Lesson by Alex Gendler, directed by Franz Palomares.