One of the challenges confronting efforts to expand green energy in major cities is that it is often not appropriate to site typical wind turbines on downtown high rise buildings, especially in the northern climes. Propeller-type turbines often cannot handle the swirling winds that occur in cities, and they frequently shed ice that builds up during periods of relative calm. Fortunately, there are a number of different parties working on the design of new types of wind turbines that don't have these problems. One of my favorites is the work of Aerotecture in Chicago, which has two designs -- a vertical shaft version and a horizontal shaft version -- that seem to be very effective where propeller turbines are not. Although these turbines are only now being field tested, they have installed one of their larger horizontal turbines on the roof of the Mercy Lakefront project.
