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The first large scale prototype of a floating wind turbine was due to be installed last month ten miles off the coast of southern Italy. Dutch firm Blue H Technologies BV says the water depth at the site for its tension-legged wind energy converter is 108 metres. The lightweight tower and 2 MW two-blade turbine, made in Italy, are designed specifically for deep sea use and will be mounted on a submerged deepwater platform. The buoyant hollow steel body of the platform is held semi-submerged underwater by chains which tether it to anchor blocks on the seabed. Blue H says it has adapted the concept from the offshore oil industry.

The company's strategy is to develop lightweight deepwater turbines with an output of 3 MW or more. It says that compared with conventional offshore turbines using monopile or tripod foundations in shallow waters, the cost of floating technology rises only marginally with increases in water depths. Martin Jakubowski, the technology designer, points out that the Repower 5 MW turbines installed in deep water off Scotland each weigh some 2100 tonnes, while Blue H units of similar size are to weigh less than 800 tonnes.

The first commercially operating unit -- also rated at 2 MW -- will be installed off the coast of Puglia, Italy, in autumn 2008. Blue H has also applied for permits to build a 90 MW wind station in the same area in water depths of 100-120 metres. The company, while registered in the Netherlands, is incorporated in Britain and has Italian involvement. It is owned by a group of private investors, which in the middle of last year numbered 19.