Sailing into the future

Innovation is not just about new gadgets, but also about using old technologies in new and improved ways. Sails are a case in point, as SkySails GmbH & Co. KG explains.

Consider this simple fact: wind is cheaper than oil and the most economic and environmentally sound source of energy on the high seas. So why don’t shipping companies take fuller advantage of this attractive natural resource? For centuries they did, of course, but today, when shipping companies look at sails, they tend to see high investment costs, space constraints on board and extra crew requirements, not to mention performance issues.

SkySails, a Hamburg-based company, is working to change this perception. We have developed an internationally patented wind propulsion system that meets all requirements of modern shipping: high performance, affordable and high practicality. The results speak for themselves. Depending on wind conditions, a ship’s average annual fuel costs and emissions can be reduced by 10 to 35% by using the system. This is good news for businesses and the environment.

How does it work? The SkySails-System consists of three main components: A towing kite with rope, a launch and recovery system, and an automatic control system. Instead of a traditional sail fitted to a mast, SkySails uses a large towing kite to propel the ship. Designed like paragliders to improve aerodynamics, these high-strength and weatherproof kites are connected to the ship by a tough synthetic towing rope, which transmits the tractive forces to the ship and which also houses a power cable linked to the control pod.

The kite’s launch and recovery system is installed on the ship’s forecastle. During launch the towing kite–which is folded like an accordion–is lifted into the sky from its storage compartment by a telescopic mast. When it is high enough, the kite unfurls to its full size and the towing rope is released until the kite reaches its operating position. To recover the kite, this process is simply reversed. An autopilot controls the towing kite during its flight, while the launch and recovery procedure is also carried out largely automatically.

The kites can operate at altitudes between 100 and 300 metres in stronger, more stable winds. And because of dynamic flight manoeuvers, the kite generates five to 25 times more power per square metre sail area than conventional sails, which means that comparatively small sails can generate high savings.

SkySails operates with development partners and suppliers from the shipping and airplane industry. Indeed, the technology consists of a combination of tried and tested components from both sectors, such as mooring winches from the offshore industry.

SkySails started developing its towing kite propulsion system for commercial shipping back in 2001. Basic research and engineering were completed by 2005, followed by two years of thorough testing on a former buoy tender, during which the technology was scaled to a towing kite of 160 m2 in size. Starting at the end of 2007 the system then underwent pilot-testing for two years on two cargo ships belonging to the Bremen-based Beluga Shipping and another of the Wessels Shipping Company during regular shipping operations. Both ships were outfitted with a towing kite of approximately 160 m2 in area. Overall, the test results exceeded expectations: the kites generated up to eight metric tonnes of tractive force–approximately the same thrust as an Airbus A318 jet engine. This makes the SkySails-System the most powerful and effective wind-propulsion system in the world.

SkySails is now equipping a series of three “Rhine” class ships belonging to Wessels. In March 2010, the SkySails-System was installed on Germany’s largest fishing vessel, the ROS- 171 “Maartje Theadora”, and will demonstrate how renewable energy sources can be used for deep-sea fishing. But development must go on, and our company is now testing a larger propulsion system, using a 300 m2 kite. The kite could generate as much as 16 tonnes of tractive force in good winds–and could save shippers twice as much fuel as the smaller towing kite. The prototype of this system was installed on a ship at the end of 2009 and pilot tests are still under way. By our estimation, if the 60,000 vessels suited for the SkySails- System used the technology, global CO2 emissions could be reduced by over 150 million tonnes a year, which is equivalent to about 15% of Germany’s annual CO2 emissions.

While SkySails is leading by example, policymakers could also do more to help. For a start, they could develop clear, meaningful and flag-neutral regulations to significantly improve energy efficiency and reduce CO2 emissions from international shipping. Only binding, international regulations and clear price signals will give the industry the assurance it needs for future investments. They should also include the IMO Energy Efficiency Design Index (EEDI) as an objective and mandatory measure of a ship’s inherent efficiency as part of the IMO climate regulations and make sure it is applied to both existing and new ships as soon as possible. Furthermore, legislation should be harmonised at an international level to ensure that the operation of innovative wind-propulsion systems is not restricted by national laws.

SkySails has work to do, with ambitious plans to equip some 3,000 ships with its towing kites by 2020. Thanks to the right policies, we will be able to further prove that working with nature, not against it, can be profitable for firms and their customers, as well as the planet.


©OECD Observer No 279 May 2010

Economic data

GDP growth: +0.6% Q3 2017 year-on-year
Consumer price inflation: 2.4% Nov 2017 annual
Trade: +4.3% exp, +4.3% imp, Q3 2017
Unemployment: 5.6% Nov 2017
Last update: 16 Jan 2018


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