What is propeller efficiency

Shipping: economical propellers, lightweight components and efficient diesel engines

"1000 LNG ships will be delivered by the end of the decade," says Jan Tellkamp from the Norwegian ship auditor Det Norske Veritas, who advises shipowners on LNG. That would be around 15 percent of the new buildings.

But gas is not a panacea. Seafaring not only needs to become cleaner, it also needs to become more efficient. Because rising fuel prices and trading in emission certificates will drive up their costs. For Martin Stopford, head of the British shipping market research company Clarkson Research, one thing is certain: "Fuel-saving technology will be as important on the water as it is on the road today."

The start-up DK Group from Amstelveen in the Netherlands is therefore testing a fascinating idea on the North Sea in autumn: The Dutch are equipping a transport ship belonging to the Danish shipping company Dannebrog with a system that creates air bubbles under the ground. The 13,000-tonne colossus should glide through the water with little friction on the air cushion - and swallow ten percent less fuel.

Engineers are also working on economical propellers, lightweight components and efficient diesel engines. Siemens is equipping 20 new container ships for the Danish shipping company Maersk Line with a generator that uses the heat of the exhaust gases to produce electricity for the on-board network. This should reduce energy costs by twelve percent.

Engineers can even find room for improvement in the hull, the foundation of shipbuilding, so to speak.

Dirty pleasure

Which cruise ships in Europe do particularly badly in terms of wastewater treatment and air pollution control

Ship namePeople on boardgrade
Adventure of the Seas5020F.
Crown Princess4963F.
Crystal Serenity1725F.
Emerald Princess4963F.
Navigator of the Seas5020F.
Ruby Princess4963F.
Splendor of the Seas2794F.
Vision of the Seas3177F.
Voyager of the Seas5014F.

* Grades A (very good) to F (unsatisfactory);

Source: Friends of the Earth environmental organization, 2010

In Duisburg, less than five minutes' walk from the main train station, Joachim Zöllner stands on a platform above what is probably the longest covered water basin in the Ruhr area. The pool measures 200 meters, a dream for endurance athletes. But swimming is forbidden.

Instead, technicians in blue overalls ride bicycles to the end of the giant pool to set up machines there. It is the large laboratory of the development center for ship technology and transport systems. Economical barges are built in the engineering office.

The platform on which the customs officer stands will later rush over the basin and pull a six-meter-long model boat through the water. Cameras, tachometers and lasers then sense every vortex and relentlessly reveal friction losses.

Zöllner is convinced that the devices will not find much to complain about. Because his economy boat should glide through the water almost as effortlessly as the conical body of a seal.

The secret can be seen at the stern: on many ships today, metal plates protect the propeller from air flowing in from the side, which would weaken its thrust. Although such shields are only needed now and then - depending on the load - they have so far been permanently installed and create gas-guzzling eddies.

Zöllner has built a shield that can be folded in: two six-meter-long steel flaps that are attached to the left and right of the screw. Zöllner hopes that this will enable inland vessels to advance more cheaply: "The technology saves 30 percent fuel."

It would be a huge gain in efficiency. British engineers, however, have an even more ambitious goal: They want to build a freighter that no longer emits any carbon dioxide - at least on a net basis.

Diane Gilpin has a precise idea of ​​what such a zero-emission vehicle would look like: like a sailing schooner of the past. Gilpin is developing a freighter for B9 Energy, the largest British wind farm operator, with three sailing masts rising 50 meters from the deck. The company wants to transfer its experience with wind and currents to ships.

The more than 100-meter-long three-master is supposed to move only with the wind - in European waters on around 60 percent of the routes. When there is calm, an engine kicks in, which Gilpin wants to run with biogas from plant waste: "The ship will sail entirely without fossil fuels."

An ambitious maneuver. It was not without reason that sailing ships disappeared from the world's oceans: hoisting the cloths was too labor-intensive compared to the new steamers. The freighter Prussia set sail with 46 sailors in 1902 - the container ship Emma Mærsk, which is 34 times larger, is now sailing with 13 men.

In order to compete with heavy fuel oil propulsion systems, Gilpin's freighter is to be fitted with automatic rigging. The captain presses a button, and sails, which are lashed to the masts, spread outwards like curtains.

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