4. Light Up Your City

Cities can save energy—and money—by illuminating public spaces with LEDs, or light-emitting diodes. Last December Raleigh, N.C., turned one floor of a municipal parking garage into a testing ground for LEDs (see the before-and-after photos at cree.com/LEDcity). The new white, brighter fixtures use 40% less electricity than the high-pressure sodium bulbs they replaced. Although they cost two to three times as much, they can go five or more years without upkeep. Traditional bulbs must be replaced every 18 months. Other types of LEDs are already at work in traffic lights, outdoor displays (like those in New York City's Times Square) and stadiums; airports even use LEDs on their taxiways. If your city is still burning tax money on old lights, ask the mayor why.