The capture of moving air to do useful work — grinding grain, pumping water, and now generating electricity at enormous scale. Wind power is among the oldest energy technologies humans have used and, as of the early-to-mid 2020s, one of the fastest-growing sources of new electricity, whose giant spinning blades have become a signature image of the energy transition even as its variability makes it a persistently difficult fit for a grid built around steady, controllable plants.
A thousand years before the first power station was built, people were already harvesting the wind. Persian millwrights enclosed spinning reeds in stone towers to grind grain. Dutch engineers built four-bladed towers to drain water from low-lying land. American prairie farmers set small steel wheels on wooden towers so cattle could drink. These machines worked because moving air carries energy, and a blade turned sideways to the flow catches a push. In the twentieth century, engineers made that push turn a generator. The result is one of the cheapest and most rapidly expanding electricity sources on the planet — and one of the most inconvenient, because the wind blows when it wants to, not when the grid needs it.