History
For the shipping industry the potential to enhance the existing propulsions is almost exhausted. Therefore new technologies are needed, especially using renewable energies. Wind is an optimal resource because it is free of charge, available without limits and has especially strong power at seas.
The shipping industry has high requirements on propulsion technologies using wind: powerful and continuously available but without any restrictions on hull and safety as well as manageability. Various methods were developed to fulfil the requirements. Unfortunately until now no system was able to come up to the expectations on a global scale.
- Sail-propulsion using masts: Under the direction of Knut E. Hanson a "windship" was developed in Denmark. This fully automatic system used six masts with fixed sails. Energy savings of up to 27 % were calculated, but in practice the system was never tested. There were many disadvantages; reduction of loading space, restriction during loading and unloading, safety risk for the crew because of the inflexibility of the system with regard to changing wind conditions.
- "Flettner rotor": This rotor is a vertical pillar which uses aero dynamical effects similar to an aerofoil. It was first demonstrated in 1928. Since then it has been tested several times on different ships. Currently the Enercon company is planning to equip a ship newly built with four Flettner rotors for its transport of wind turbine equipment. By using flettner rotors there is a high risk of heeling. This heeling could result in a dangerous shift of cargo which is not acceptable in merchant shipping
- Single sail (kite, spinnakers): Test projects with kites and spinnakers have been undertaken in different ways. Such systems are used in sport sailing. But for commercial use these systems are not practicable. For example, no system exists which includes an automatic control system although this is essential for easy handling. Furthermore, by using spinnakers there is a high risk of heeling. This heeling could result in a dangerous shift of cargo which is not acceptable in merchant shipping.
None of them were accepted by the industry in practice.
The SkySails-System
The towing kite system is a completely new and highly innovative technology. SkySails has developed the kite system and is demonstrating the general feasibility and energy savings in the EU co-funded WINTECC project.
The developing process has been financially supported by local and national public funding programmes. International shipping companies as well as the advisory board of SkySails have supported the development process with suggestions, ideas and comments. Because of a lot of input from shipping companies (formless market study) the kite system of SkySails is the first technology fulfilling the requirements of shipping companies because
- it has lower investment costs than other systems but higher efficiency of energy savings
- no additional human resources are necessary (only instruction lessons for the crew)
- it has an automatic control system resulting in easy handling and a high reliability of the system
- the textile-based towing kite can be folded away easily and requires little space on board
- in comparison to other sailing propulsions, the SkySails-System has no disturbing superstructures, which could restrain load and discharge at the harbour or bridge crossings
- unlike conventional wind propulsions the SkySails-System causes minimal heel irrelevant to the ship’s safety and operation
- it does not expose the crew or the ship to any additional risks (winch compensates gusts, existing option to reduce power of kite, "emergency button" to detach the towing kite)
There is no competitive system known because no other system fulfils the requirements. Compared to other kite and spinnaker systems the towing kite technology of SkySails has more power and a fully automated control system.
