Greensburg, Kansas, was hit by a tornado in 2007. A scant six years later, the town of 785 became the first city 100 percent powered by renewable energy, Business Insider reports.
Two other towns, Burlington, Vt., and Aspen, Colo., also completely forgo power from natural gas, nuclear, or any carbon-based energy source. Seven other cities, from Georgetown, Texas, to San Diego, aim to join them within the next 20 years.
San Francisco will harness solar power, while others, such as East Hampton, N.Y., will capitalize on wind energy.