Offshore wind power is viewed as an essential part of Japan's energy mix, even while the government aims to recommission mothballed nuclear energy plants. Announcing a basic energy policy on 11 April prime minister Shinzo Abe said he would position nuclear, coal and hydropower as "base-load" power sources, interpreted to mean sources capable of supplying power on a stable, 24-hour basis. At present all Japan's commercial nuclear reactors are offline.
At the same time, the prime minister commented that the expanded introduction of offshore wind power is essential for Japan over the medium to long term, as suitable locations for onshore wind power are limited, giving hope to the industry.
"Comments regarding the introduction of offshore wind power being essential over the medium to long term support our company's project," says Kozo Domori, a spokesman for Maeda Corporation, which is developing a 20-turbine fixed-foundation offshore wind project in waters off Shimonoseki in south-west Japan. "Our project is on target."
The most powerful winds in Japan blow off the northern island of Hokkaido and in the north-east of the country, but incomplete or insufficient grid infrastructure make it difficult to harness this power and transmit it to the more populous areas to the south-west.
Closer to the urbanised and industrial hubs, powerful offshore winds can also be found in the Pacific Ocean off the approximately 110-kilometre stretch of coastline from the city of Omaezaki in Shizuoka prefecture to Iragomisaki in Aichi prefecture, and around the Boso peninsula in Chiba prefecture. The island of Kyushu is another area noted for strong winds.
It is not surprising that existing wind-power facilities are located close to these areas, with four experimental projects now under way.
Two fixed-foundation turbines are generating electricity off the city of Choshi in Chiba and at Hibikinada, Kyushu island. Both are operated in cooperation with the New Energy and Industrial Technology Development Organisation, an independent administrative agency with ties to the Ministry of Economy, Trade and Industry (METI).
The Choshi project is powered by a 2.4MW turbine with a gravity foundation, produced by Mitsubishi Heavy Industries (MHI), while the Hibikinada project features a 2MW turbine with a jacket and gravity hybrid foundation, produced by Japan Steel Works.
Two floating structures are also under testing. A Ministry of the Environment-run project operates around one kilometre off the coast of Kabashima, Goto islands, powered by a 2MW Hitachi turbine, with a spar type floater made by Toda Corporation.
The much-publicised METI Fukushima project is located some 20 kilmetres off the coast of Fukushima prefecture, and is also powered by a Hitachi 2MW turbine. However, there are plans to introduce the 7MW MHI-developed SeaAngel, which is currently undergoing tests. The project includes a semi-sub type floater developed by Mitsui Engineering & Shipbuilding.
The viability of such projects depends on maintaining good relations with local fishing cooperatives. Japan has no central government agency to manage the country's seas, and the fishing cooperatives have legal rights over the waters where developers are looking to position wind-power facilities.
"It is important to develop and maintain good relations with the local fishermen," says Chuichi Arakawa, a professor in the engineering faculty at the University of Tokyo. "The fishermen need to see a success story from offshore wind power to allay their concerns."
Fishing rights do not extend to port facilities, which are controlled by local government agencies, and Arakawa expects to see near-term development concentrated relatively close to shore in such waters.
Arakawa has served as chairman of a committee investigating the possibility of locating offshore wind-power facilities close to Omaezaki in Shizuoka prefecture. The committee has given the go-ahead and is expected to canvass for a developer in the summer, he says.
Arakawa believes that Japan could generate approximately 20GW of offshore wind power by 2030, but expects only a quarter, or a third at most, of that capacity will be in place by 2020.
Most new projects are on hold due to an environmental assessment code introduced in October 2012. The severe assessment process can take up to four years and, despite talk of possibly shortening the process, industry observers say they do not expect to see wind-power development pick up until 2016 at the earliest.