Popular Science has an article about the 50 Greenest cities in the USA. It was interesting what they highlighted as green efforts by different cities.

CASE STUDY: Grass Power
Boston has preliminary plans for a plant that would turn 50,000 tons of fall color into power and fertilizer. The facility would first separate yard clippings into grass and leaves. Anaerobic bacteria feeding on the grass would make enough methane to power at least 1.5 megawatts’ worth of generators, while heat and agitation would hasten the breakdown of leaves and twigs into compost.
CATEGORY LEADER: Electricity
Much of the wet Pacific Northwest draws its energy from hydroelectric dams. But Eugene draws an additional 9 percent of its municipal electricity from wind farms. It also buys back excess power from residents who install solar panel
See how Chicago's power plants produce twice the energy with a third the carbon, here.
CASE STUDY: Green Concrete
Fly ash, a by-product of coal-burning power plants, usually ends up in landfills. Researchers at the University of Colorado Denver found a way to reuse this industrial by-product. They add it at concentrations of about 20 percent to a new green concrete mix. The addition of fly ash also reduces the amount of sulfur- and carbon-spewing concrete production needed to finish a job. The mayor has signed an executive order requiring the use of green concrete in new city projects, and a $550-million infrastructure bond makes demand for the mix likely to grow.
CATEGORY LEADER: Recycling and green perspective
Lexingtonians recycle everything from surplus electronics to scrap metal, and they listed the environment as their third most important concern (behind only employment and public safety)—the highest ranking in our survey.