Until recently, the notion of offshore turbines built on floating structures seemed far-fetched. But this perception is giving way under the weight of engineering developments and the realisation that gaining access to good winds in deep waters holds serious commercial prospects.
Design requirements for floating turbines are now well understood, and floating offshore wind is emerging as a third wind energy technology, distinct from onshore and fixed-structure offshore wind.
Cost is always a concern for new energy technologies. Added value arguments, however, are stacking up in the technology's favour. Floating turbines may be the only opportunity for harnessing good winds where accessible wind resources on land are out of economic reach. Even in regions where shallow water sites are available, locating arrays of floating turbines for the most efficient use of transmission capacity, irrespective of water depth, adds measurable value to the entire power system.
Floating structures can also offer direct economic benefits over fixed foundations, as they can be built in harbour — in any weather. As experience has grown in Europe of installing fixed jacket foundations in deep waters, the indications are that floating foundations can be competitive in shallower water than previously thought.
Developers have expressed interest in the deep waters and excellent winds off the north-east and Mid-Atlantic coasts of America and along large swathes of the Mediterranean and western seaboard of Europe. Full-scale floating turbine systems are already being tested off Norway and Portugal.
Big in Japan
It is perhaps in comparatively energy-resource starved Japan that floating wind meets the most promising combination of conditions. GL Garrad Hassan's analysis suggests that the vast bulk of Japan's 600GW of offshore wind resource is in waters more than 100 metres deep — out of the reach of conventional fixed structures.
The way ahead for grand-scale wind power in Japan is offshore has not gone unnoticed. Government energy policy initiatives in the wake of the 2011 tsunami and the nuclear disaster at the Fukushima Daiichi power station included the formation of a consortium of some of Japan's leading industrial and academic institutions to demonstrate floating turbines. The group says that turbines on floating structures will prove resilient to extreme shocks, such as from typhoons, and could withstand earthquakes and tsunami better than fixed structures. It plans to install floating turbines with rated capacities of up to 7MW off the coast of Fukushima by 2015, along with the world's first floating 66kV electrical substation.
The experimental project, with the first turbine to be installed this summer, will make Japan a world leader in floating offshore wind. If the group's ultimate objective of a 1GW floating wind power station is met, Japan will have gone some way towards capturing the employment and industrial benefits that accompany any new industry.
On the cusp of a new industry, Japan's industrial giants may have an opportunity to put their competitive advantage in heavy and difficult engineering to good use.
Converting this opportunity into clean, reliable offshore power and a source of future jobs will require strong government commitment. Public support has to be secured and fishing industry concerns allayed. Safety must be assured, particularly given the uncertainty over possible radioactive contamination, however slight, and leaks into the sea. Provision of a sound investment structure is also a must if capital-intensive floating wind is to find its sea legs. Mixed signals from the recently elected and nuclear-friendly Liberal Democratic Party government on Japan's green energy aspirations are not especially promising.
Japan has the demand to unilaterally stimulate a new industry. Its need for clean, secure sources of energy and new industrial growth sectors is real and urgent. It has the wind resource and the engineering capacity to make a serious impact with floating wind turbines. By demonstrating the viability of floating wind, both technically and economically, it can maximise the return on its investment over the long term by exporting equipment and know-how. Reconciling these factors will require visionary leadership by government and unflagging determination to succeed. It may also require a little luck.