Size: 1.5 square miles
Annual carbon emissions per person: 22 tons
Annual amount to be offset: 19,800 tons
Equivalent to: 825,000 trees planted
Carbon-neutral by: 2017
On May 4, 2007, a tornado ripped through central Kansas. When it was over, nearly 95 percent of the small town of Greensburg was destroyed. Turning tragedy into opportunity, the community decided to rebuild itself as a model green town, powered by a mix of geothermal, solar and wind. A few of the city buildings even power themselves with their own wind and solar generators, and a 10-turbine wind farm outside of town went online in March.