Wind turbines are learning to swim: The latest development in the offshore sector is revolutionising energy generation from wind power. Floating power plants, water-borne wind turbines tap the immense wind power on the high seas to generate environmentally-friendly electricity. A global industry consortium headed up by DNV GL is launching a new project to establish harmonised standards for floating power plants. This will drive the new technology forward significantly.
Even when there is only a gentle breeze blowing inland, there is generally a stiff breeze at sea. To utilise this natural energy source, more and more offshore wind farms are being built on the coasts of the North and Baltic Seas, to produce environmentally-friendly electricity at sea. “The energy yield of an offshore turbine is higher the further out to sea it is, as the wind there is even stronger than in coastal waters,” says Jan Rispens, Managing Director of the Renewable Energy Hamburg Cluster. “For technical reasons, we cannot build foundations to anchor offshore wind turbines permanently in the seabed in waters deeper than about 50 metres.” As a result, experts worldwide are developing technologies for floating designs. There are currently various technical approaches to teach wind turbines how to swim. A consortium of 13 international companies from the wind, oil and gas industry and the maritime sector has formed a first joint industry project to harmonise the floating technology and drive it forward together. The project is headed up by DNV GL, the world’s largest consulting and certification service provider in the energy sector. The goal is to develop a new technical standard for floating wind turbines, to establish universal requirements for production and technical monitoring and analysis.
Floating power plants: advantages, development status and pilot projects
Floating power plants have a high energy yield thanks to the wind at sea. Also, no costly installation ships are needed to build the turbines. The wind turbines can be assembled on land and towed out to sea by simple tugboats. “Development of floating wind turbines is still at an early stage," says Rispens. “Most of the floating power plants built to date are prototypes and are generally used for test purposes.” Norwegian oil corporation StatoilHydro is the industry pioneer. The Norwegians have been operating a floating wind turbine in the Åmøy Fjord near Stavanger since 2009. By 2017, the corporation aims to build a floating wind farm for 215 million euros off the coast of Scotland, comprising six wind turbines. In Portugal, a consortium led by EDPR is building the floating testing ground “WindFloat Atlantic Project” with four turbines, scheduled for completion in 2018. Further test systems of various sizes are located off the coasts of Japan. The floating models built to date differ in three key areas. Firstly, whether the floating structure carries one or more wind turbines on the water, second in the buoyancy technology – e.g. floating buoys – and in how the floating power plant is anchored and secured in place.
Floating power plants are complex technical structures whose construction and operation involves many different technical disciplines. “To further advance the floating technology, experts from a wide range of areas must put their heads together and share their expertise,” says Rispens. They are currently highly cost-intensive – much of the structure is made of expensive steel. “Concrete solutions would be ideal, as it is a less cost-intensive material. That would make floating power plants more economical without affecting the efficiency,” explains the managing director, who is certain that the recently founded joint industry project by DNV GL can drive the technology forward significantly.