The StreamCube® is a patent-pending, box-shaped energy production module with vertical rotor axes designed for current speeds between 1.0 m/s and 2.5 m/s. Powered by the impinging current, the rotors are set into rotation. The StreamCube® blades automatically adjust to their angular position with respect to the rotor. The folding and unfolding of the blades is driven and supported by the flowing fluid and the optimized current-guide-geometries. Depending on the use case and the respective circumstances, several StreamCubes® operate next to — and on top of — each other. The connection between the single modules is realized through standarized interfaces at the housing and the rotorshaft. Due to mechanical coupling of the rotors of multiple StreamCubes®, the pro rata cost of gears and generators are reduced. Further, the fluid dynamic properties of the whole system — especially caused by the growing ram pressure upstream of the system — improve significantly.