Flower turbines

Generating energy on rooftops is usually done through solar panels, but wind turbines are also an option. A little less profitable, but sustainable nonetheless. These Flower Turbines are much quieter and more attractive than the models you may know. A wind turbine you would enjoy living or working next to. These are made on the RDM-wharf at Rotterdam Heijplaat. 

https://youtu.be/ERWh7A3Bg-o