A power generation assembly for use in generating electrical power from air or water currents includes a tiered rail system forming elongated loops, a vane assembly having a frame and at least one vain, and car assemblies sidably mounted to each rail, including linkage portions coupled to the frame of the vane assembly and a power-take-off arrangement includes an element that is operatively coupled to the car assembly and a drive wheel coupled to a generator and configured to take power off the moving car assembly by the drive wheels being rotated by the passing power-take-off element or a power-take-off system using a cable and clamps.