Editor’s note: Japan and Marubeni, a company based there, plan to make offshore wind power the country’s next-generation energy source. The company reports that several Japanese companies have form a consortium and tackle Fukushima Recovery and Floating Offshore Wind Farm Experimental Project sponsored by METI, a world-first technology project through which Japan intends to develop and commercialize large-scale floating, offshore–wind–power generation plants.
The Fukushima Recovery/Floating Offshore Wind Farm Experimental Project aims to carry out experimentation and verification for the
realization of a sufficient amount of offshore wind power generation plants to be commercialized, with floating wind turbines and substation installed about 23 km off the Fukushima coast.
The first phase of an experimental study, made in the summer of 2013, was to install two floaters on each of which stood a 2 MW wind turbine and substation. The floating platform, for power generation, supported a wind turbine named Fukushima MIRAI (Future). Platform and tower spanned 122-m with a turbine and 80-m diameter rotor. A downwind type of blade—located leeward—was adopted. The reason for this is that, on the ocean, wind blows mainly upward from the sea surface, a downwind type of blade will presumably increase power-generating efficiency by blowing wind upward. A 2 MW wind turbine is one of the largest wind turbines now in operation (in Japan), and no wind turbine of this size has yet been put into practical use on a floater. Annual energy production is a little greater than 6 million kW, which is equivalent to the power consumption of 1,700 households. In 2014, two 7 MW wind turbines were to be introduced as the second phase. Their blade diameter will be 160 m and total height will be about 200 m—among the world’s largest wind turbines.
The substation, which transforms power for more efficient transmission, is called “Fukushima KIZUNA.” It’s massive in size, 60 m above sea level with a draft of 50 m, totaling 110 m in height, nearly as large as “Fukushima MIRAI.” The turbine generator produces power at 22 kV and will be boosted to 66 kV at the substation to increase transmission efficiency. Power is then transmitted to an onshore substation 23 km away. In case of emergency, it shuts down all electrical current safely. Conducting these operations on a floating substation is the first time in the world that this challenge has been undertaken.
Transforming equipment, a series of precision apparatuses, and a huge wind turbine are all set on floating platforms or floaters. Power generation and transmission on the ocean is possible thanks mostly to Japan’s superior shipbuilding technology. The floater of “Fukushima MIRAI” is semi-submersible (half-submerged) and that of “Fukushima KIZUNA” is advanced spar (meaning advanced cylinder). Those floaters are loaded with the latest technologies to provide a no pitching or rolling floater. Equipment has been built on Japan’s strength in manufacturing technologies (monozukuri technologies), and these have been used in this national project, such as the development of a cable for the underwater transmission of electrical current with superior waterproof construction, which is unprecedented worldwide, and the manufacturing of an ultra-huge chain to moor “Fukushima MIRAI” and “Fukushima KIZUNA” offshore, of which the total length is more than 800 m. Each link weighs 200 kg.
Filed Under: News, Offshore wind