No. 69: Prospect of natural energy in Japan – Offshore wind generation (June 24, 2011)

Offshore of Ibaraki Prefecture, Japan’s first full-scale offshore wind generation plant started operation in June 2010. It has a generation capacity of 14,000 kW. Managed by Window Power Ibaraki, it currently supplies electricity to 7,000 households. The company plans to build another 8 offshore windmills in 2012, and is having negotiations with the government to build about 100 offshore windmills in the sea between 500 m to 4 km offshore. The ambitious plan will realize a large-scale ocean wind generation plant with a generation capacity of 500,000-1,000,000 kW.

This plan attracts wind attention because the future of Japan’s wind generation depends on it. Onshore wind generation does not have a bright future as it did in the past because the discontinuance of subsidy system and the difficulty to find suitable locations. In contrast, offshore wind generation has a rather bright future. New Energy and Industrial Technology Development Organization (NEDO) estimates that the resource amount for offshore wind generation in the sea deeper than 200 m within 30 km from the revetment is about 1.2 billion kW. If a wind generation plant is running at 30% of the capacity and a nuclear power plant is running at 80% of the capacity, the 1,200 million kW is equivalent to the power generated by 450 nuclear power plants with a generation capacity of 1 million kW.

European countries like Great Britain and Denmark place importance on offshore wind generation, and about 10% of 9 million kW generated by wind generation comes from offshore wind generation. In Japan, various measures in designing are inevitable because Japan has severe natural conditions including earthquakes and tsunami. Japan Society of Civil Engineers set up an organization to study design guidelines for offshore wind generation and will publish the research report in two years.

The generation cost of onshore wind generation is about 10 yen per kW. It is higher than the generation cost of nuclear generation (5-7 yen), but it considerable lower than that of photovoltaic generation (40-50 yen). It costs more to build an offshore wind generation plant and onshore wind generation plant, but the former is far more stable and higher in performance than the latter because wind is strong and wind direction is stable. The big problems are with the acquisition of locations and indemnification for fishers. A Tokyo University professor suggests political leadership to spread offshore wind generation.