The streetcars (not trolleys) are operated electrically and are connected to an overhead electrical cable. Unlike the red cars on the Canal Street line, this St. Charles Avenue line is not air-conditioned and passengers experience the Mississippi River breezes and the sounds of the streetcar tracks through the open windows.
I would LOVE to ride one of these some day. And it's a bonus (sort of) to have no air conditioning and to experience the actual breeze coming off the river.