Reducing CO2 Emissions from Shipping
|SkySails towing kite|
So now we are facing a big opportunity to explore renewable energy. Wind is the best solutions for shipping since it is sustainable, easily accessible, cost and emission-free.
|Figure 3 (a) Square rig|
|Figure 3 (b) Fore-and-aft rig|
Table 1. Performance comparison between square rig and fore-and-aft rig
Rigid SailFigure 4 shows two examples of rigid sails. They are all consisted of self-rotating aero foils standing on an end to meet wind direction. They are made of hard material, so structure reliability is higher. Flaps can be included to increase its efficiency. Also rigid sail can reduce ship motion and thus reduce ship resistance. 
|Figure 4 (a) rigid sail on deck|
|Figure 4 (b) rigid sail with flap|
|Figure 5 E-Ship 1 – first voyage with cargo in 2010|
|Fig 6 (a) Horizontal Axis wind turbine|
|Fig 6 (b) Vertical Axis wind turbine|
 Bøckmann, E., Wind Turbine Propulsion of Boats and Ships, master thesis, NTNU, 2010
C. T. Nance. Outlook for wind assistance. Journal of Wind Engineering and Industrial Aerodynamics, 19:1-17, 1985.
 Silvanius, M., Wind assisted propulsion for pure car and truck carriers, master thesis, KTH Center fro Naval Architecture, 2009
 Craft, T. J., H. Iacovides, and B. E. Launder. Dynamic performance of Flettner rotors with and without Thom discs. Proc. 7 th Symp. on Turbulence & Shear Flow Phenomena. 2011.
 Naaijen, Peter, and Vincent Koster. Performance of auxiliary wind propulsion for merchant ships using a kite. 2nd International Conference on Marine Research and Transportation. 2007.