1Off the coast of Denmark, enormous white turbines turn slowly above the grey waters of the North Sea.
2Each blade is now longer than the wings of the largest passenger planes ever built.
3On a windy day, a single modern turbine can produce enough clean electricity to power several thousand homes.
4Wind power has become one of the cheapest ways to make electricity in many countries.
5Yet the change has not been easy, and some coastal villages resisted the first projects.
6Fishermen worried about their nets and their routes, while bird watchers feared for the migrating seabirds passing overhead.
7In response, engineers moved the turbines further offshore and studied the flight paths of birds carefully.
8Today, many of those same villages take great pride in the clean energy they now export.
9The industry now offers skilled jobs to young people who might otherwise leave for the cities.
10Storing wind power for calm days remains the hardest problem that engineers still have to solve.
11Giant batteries and green hydrogen may finally hold the answer to that stubborn old question.