Giant sail technology could make shipping greener

One of the first large cargo ships in 100 years to cross the Atlantic with the help of the wind will set off from European shores this month on a voyage which is due to make maritime history.

When the 10,000-tonne Beluga Skysail is well clear of the land, it will launch a giant kite, which wind tunnel tests and sea trials suggest will tug it along and save 10-15% of the heavy fuel oil it would normally burn. If the journey from Bremen in Germany to Venezuela and back proves successful, it could become common to see some of the largest ships in the world towed by kites the size of football fields.

"This is a serious attempt to reduce bunker [fuel] costs and polluting emissions. The kite will be used whenever it is possible on the voyage, and we are convinced it will revolutionise cargo shipping. We would consider fitting them to all our ships," said Christine Bornkessel, a spokeswoman for the Bremen-based Beluga shipping line, which has 52 merchant vessels.

The ship's maiden voyage will use a 160 sq metre kite which is expected to cut fuel consumption by 10-15%, but in time it will be fitted with much larger kites, possibly saving 30-35% on fuel, she said.

The largest kites could be as big as 5,000 sq metres and theoretically be capable of assisting giant container ships.

Shipping is now a booming global industry, with most manufacturing being concentrated thousands of miles from consumer centres in Europe and the US. Nearly 100,000 cargo ships transport 95% of world trade by sea, and the world shipping industry is expanding rapidly as countries such as India and China become major players in the global economy. But the cost of shipping or "bunker" fuel has nearly doubled in the past two years, forcing the industry to consider alternatives. At the same time, concerns have grown about climate change and air pollution from shipping.

It is estimated that commercial shipping, which traditionally uses the most polluting fuel, uses nearly 2bn barrels of oil a year and emits as much as 800m tonnes of CO2, or 4% of the world's man-made emissions. Shipping also pollutes the atmosphere with more sulphur dioxide than all the world's cars and lorries.

The notoriously conservative industry has so far failed to harness renewable energy, either because conventional fuel has been cheap, or because modern cargoes, mostly carried in containers, need to remain stable on deck or in holds. Sails or spinnakers have been proposed for merchant ships, but these can take up storage space and cause vessels to heel.

The kite system, which has been developed over 10 years with help from the German government, uses an automatic pilot, is controlled by computers and runs on a metal track around the ship. This allows the "sail" to move around to collect wind and also prevent tilting.

The kite is not designed to replace engines, however. There are still questions about how the system behaves in high winds and what would happen if the kite landed in the sea.

According to the company, orders have been placed with trawlers and a super-yacht. The system could be applied to nearly two out of three boats registered at Lloyd's register of shipping in London.

· This article was amended on Monday January 7 2008. In the article above we said that sails or spinnakers had been proposed for merchant ships but that these can cause vessels to keel. We meant heel (lean over). This has been corrected.

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