Not sure why you're being downvoted; this seems like a totally legitimate concern. Depending on the efficiency, you might end up just moving the pollution to a different location.
... which was manufactured using energy from a coal-burning electrical plant :-)
All of the green energy types (wind, electric cars) should be examined in the context of their manufacturing costs in addition to their cost to operate. (For example, smelting aluminum requires a great deal of energy.)