Objectives  This paper develops a design method for a new concept energy conservation device.

  Methods  An energy recovery turbine is arranged in the slipstream of a marine propeller with the generator driven by the slipstream of the propeller, in such a way that the turbine converts the kinetic energy into electricity so as to reduce the energy consumption of the ship. In this paper, the propeller and aft turbine are holistically designed. The Vortex Lattice Method is applied in the propeller design while an in-house Matlab code based on the Modified Blade Element Momentum Theory (M-BEMT) is used for turbine performance evaluation. The turbine blade is design and optimized by a Genetic Algorithm (GA). An application case study is completed and a combined thruster solution put forward. The efficiency in open water is simulated on the basis of CFD.

  Results  At the same advance coefficient, the efficiency of the combined thruster is about 4% higher than that of the original propeller, with a slight increase in absorbed power. By adjusting the rotational speed, the combined thruster has lower power consumption of around 3.43%.

  Conclusions  The feasibility of this new concept device is validated by comparison with that of the original propeller.