hulled vessel would slip by unnoticed on most seas if not for the white kite, high above her prow, towing her to what its creators hope will be a bright, wind-efficient future. The enormous kite, which looks like a paraglider, works in tandem with the ship's engines, cutting back on fuel consumption, costs, and carbon footprint. “Using kites you can harness more energy than with any other type of wind-powered equipment,” said German inventor Stephan Wrage, whose company SkySails is looking for lift-off on the back of worldwide efforts to boost renewable energy. The 160-square-meter (524-square-foot) kite, tethered to a yellow rope, can sail 500 meters into the skies where winds are both stronger and more stable, according to the 38-year-old Wrage. The secret to the kite's efficiency lies in its speed and computer-controlled flight pattern. The idea is for the kite to describe figures of eight, which increases airspeed, said Wrage, who has been working on the new technology for 10 years and who still enjoys flying kites on the beach for fun. “If you double the airspeed you multiply the energy by four. That's the secret of the system,” he added. A new 320-square-meter kite, recently produced, “has a towing force of 32 tonnes which is more than what two engines on an A320 Airbus (aircraft) can produce. So we're not talking toys,” he said. The kite towing the 87-meter-long ship Theseus would produce a maximum of 16 tons of thrust in perfect wind conditions. Retailing at half a million and one million euros (715,000 to $1.3 million), the kites allow fuel savings of 15 to 25 percent depending on wind and shipping routes, said Wrage. The strongly-built kites are best suited for slow moving ships, such as bulk carriers and tankers, which do not exceed 15 to 16 knots and which ply windy trans-Atlantic or trans-Pacific routes, according to SkySail engineers. Customers could recoup their money within two to six years, depending on bunker fuel prices, shipping routes, and types of carrier, they added. But the company, with funding of 47 million euros mostly from venture capital investors, has struggled to stay afloat. To date, only five kites are in commercial use around the world. But the economic recovery – along with rising oil prices – is fuelling new interest in this new “green” technology, not only from ship-owners, but from large trading companies eager to advertise efforts to reduce carbon footprints. But not everyone in the shipping industry is convinced. The system “isn't suitable for most fast-going container ships,” said Max Johns, a spokesman for the Association of German Ship-owners. “The system works but has proved difficult to use, with expensive kites being torn, and all this at a time when the industry is suffering a severe downturn,” added Johns. Uwe Hollenbuch, an expert on resistance and propulsion at the Hamburg center for ship research agreed, saying wind propulsion “won't play much of a role for now.” “I don't think we'll be going back to wind power,” said Uwe Bruemmer, a sea captain now in charge of inspection at the German heavy lifting shipping company SAL, which operates a 16-strong fleet. “We've looked at the kite, but it wouldn't be worth it,” he added. “To use this sail you need at least six to seven knots of tail wind and you only find this rarely, and only on certain routes,” the captain said. For now, “we are concentrating on reducing fuel consumption by reducing engine power to 90 or 80 percent”, says Bruemmer, who is pinning his hopes on the development of gas-powered turbines. – Agence France-Presse FACTBOX n The SkySails system consists of a towing kite with rope; a launch and recovery system; and a control system for automatic operation. n SkySails uses large towing kites for the propulsion of the ship. Their shape is comparable to that of a paraglider. n By means of dynamic flight maneuvers , e.g. the figure of “8”, SkySails easily generate five to 25 times more power per square meter sail area than conventional sails. n The ship's crew can operate the SkySails-System from the bridge. n The SkySails-System is designed for operation in predominantly prevailing wind forces of 3 to 8 Beaufort at sea. __
