A central shaft is oriented in a position that is normal to the surface of the ground and normal to a direction of fluid flow. The central shaft has a plurality of blades emanating from the central shaft, wherein each one of the plurality of blades has an outside edge and an inside edge, the inside edge being attached directly to an outside surface of the central shaft. The outside edge of the blade extends upward curving around the central shaft and the inside edge of the blade extends upward curving around the central shaft. The turn rate of the inside edge of the blades about the central shaft is less than the turn rate of the outside edge of the blades about the central shaft.