Time to up your game, Burlington, Boulder, and Portland! Last August, the Austin, Texas, city council approved a plan to make solar energy its default power source and to reduce city-controlled greenhouse gas emissions to zero by 2030. The council has the clout to turn its proclamations into action: Austin Energy, which is the nation's eighth-largest public utility and serves a population of almost 1 million, is a city department.

A city task force recently found that solar energy is cost-competitive. In fact, in early 2014 Austin Energy signed a purchase agreement for 150 megawatts of utility-scale solar that will cost less than power from its own natural gas plants. 

About 85 volunteers from the Sierra Club's Lone Star Chapter rallied at Austin City Hall two days before the council met, and council members were flooded with upwards of 1,000 phone calls and emails in the week leading up to the vote, according to Jeff Crunk, a volunteer with the Club's Austin Beyond Coal campaign. "It's a struggle, but Austin is continuing to make the clean energy future a reality," Crunk says.