Abstract: A system for generating energy from a streaming fluid having a mean streaming direction, comprising a generator and an assembly arranged to be entrained in the streaming fluid and which is moveably connected to a fixed point upstream of the assembly, wherein a generator is arranged to generate energy from movement of the assembly, parallel to and in the same direction as the mean streaming direction, against the fixed point, wherein the assembly comprises at least two interconnected blades, their surfaces extending substantially perpendicular across the mean streaming direction, wherein each of the blades has a conical cross section and a second blade extends at a distance downstream and staggered in a direction perpendicular to the mean streaming direction with respect to a first blade.