Wind and solar assisted ship propulsion optimisation and its application to a bulk carrier

The renewable energy capture for a ship's propulsion system was optimised for a combination of wind sail and solar power using two models. The first model optimised the rigid wind sail angle under varying wind conditions, while the second model optimised the available deck area of the ship assigned to wind and solar systems to maximise total power production. The optimum power obtained from the results was used in the Energy Efficiency Design Index calculation to evaluate the carbon dioxide emission reduction per unit transport work. In a case study using a bulk carrier vessel, the results showed that sailing at optimal sail angle and optimising the available deck area with combined installation of solar and wind system allowed maximising the renewable power to contribute 36% reduction of carbon dioxide emissions compared to the same ship without innovative technologies. It was concluded that if the ship speed was reduced to 56% of its original speed, the ship could sail on renewable energy captured on-board only. The developed methodology can be employed during both ship design and operation stages as an assessment tool, not only for bulk carriers but also other types of vessels with an appropriate tailoring.