elephants and sweet potatoes

Osaka will be using elephant dung and sweet potatoes to mitigate the urban heat island effect in summer. Actually, they will be planting sweet potatoes on the rooftop of City Hall and using the plant vines and leaves that are usually disposed of after harvesting them, to feed the elephants in Tennoji zoo. Elephant dung is then used as fertilizer to grow sweet potatoes. Ingenious! It's literally a closed-loop system.

Osaka also has plans to green other govt. offices as welll as schools with"green curtains" of goya (bitter gourd).