Boulder's B-cycle program is a nonprofit organization, with funds provided through donations, government grants, and user fees. The relatively small program, with 110 bikes and 15 stations, saw 18,500 trips since it launched last year.

By Anne VanderMey, reporter @FortuneMagazine - Last updated July 19 2012: 8:49 AM ET
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Google's zero-carbon quest

The search giant has an ambitious plan to achieve its goal: becoming the world's most energy-efficient company.