Certain schools of urban planning love to push the thinking that density equals sustainability. And while rampant pollution in several the world’s densest cities might question that assertion, certainly, the Japanese capitol city of Tokyo provides an excellent model for their cause. 

The city runs on one of the most extensive, efficient and clean running rail networks in the world, and, despite a definite lack of available real estate, was still an early adopter in clean energy technologies. The tight quarters have produced a number of clever and entertaining solutions for the downsides of urban life, and newer and wilder ideas are being cranked out and adapted to the city’s unique environment every day.

If a newly-proposed revision’s to Tokyo’s metropolitan laws goes through next month, Tokyo will make another important first: the first city to impose cap-and-trade limits on individual industrial firms. The soon-to-be proposed changes would cut greenhouse emissions from the metropolitan area 25% by 2021, well in excess of the 6% mandated country-wide by the Kyoto Protocol agreement.