Wind in deep water

Floating platforms promise economic wind farms far out at sea

Can offshore turbines be freed from the limitations – and high costs – of fixed installation on the seabed? Yes, say the developers of floating platforms, designed to support wind farms much further out to sea than is currently viable.

The Blue H Group has just put its first floating wind turbine into commercial production. Instead of solid legs like the existing oil-rig-style constructions, it features a platform that is chained to foundations on the sea floor via six so-called ‘tension legs’. Consequently it is much lighter, and can be fully assembled in-harbour before being towed out to sea. It can go much further out, too, to positions with stronger and more regular wind.

The company’s successful prototype is currently anchored in 111 metres of water 20km off the coast of Italy – whereas the maximum depth generally considered viable for fixed installation is 45 metres. “[We don’t] need to prepare the seabed or use expensive crane ships, and it has lower decommissioning costs,” says Neal Bastick, CEO of the Blue H Group. “We are confident we can close the gap between the costs of onshore and offshore wind turbines.”

That gap is a big one, with typical shallow water offshore turbines costing over twice as much per MW for land-based wind farms. Duncan Ayling, head of offshore at the British Wind Energy Association, believes the new technology is “groundbreaking and exciting”. Floating wind turbines, he says, “open new possibilities and create a new future market”, even if the UK, with its abundance of shallow coastal waters, remains likely to favour fixed foundations for the near future. – Julia Sussams

1 October 2008

Julia Sussams