Power Tower

FIG. 1 is a front elevation view of a power tower, showing my new design; FIG. 2 is a rear view thereof; FIG. 3 is a left side elevation view thereof; FIG. 4 is a right side elevation view thereof; FIG. 5 is a top plan view thereof; FIG. 6 is a bottom plan view thereof; FIG. 7 is a front and top perspective view thereof; and, FIG. 8 is a rear and bottom perspective view thereof. The broken lines depict portions of the power tower in which the design is embodied that form no part of the claimed design.