After the record-breaking heat experienced in Tokyo this summer, the metropolitan government is pursuing a number of projects to cool the capital, one of which is making the metropolis greener with rooftop gardens, which have a cooling effect. To increase Tokyo’s green areas, it will be mandatory for buildings over a certain size built or remodeled after 2001 to have rooftop gardens.
To water the gardens, a watering system powered by natural energy sources has been developed.
As average wind speed and number of hours of sunlight per day in Tokyo are low, the Tokyo Metropolitan Industrial Technology Research Institute came up with a hybrid system that uses both wind and solar energy to power water sprinklers. They have already built a windmill and four solar panels atop their building (no further details unfortunately.)
Researchers are now trying to develop an accumulator system that will store the electricity generated by the two different energy sources.
They also want to recycle rainwater and use it to create lush greenery on the city’s buildings.
Another benefit to the method would be that the output of carbon dioxide would be zero.