March 4, 2014


Japan's First Floating Offshore Wind Power Project Making Progress, Addressing Challenges

Keywords: Newsletter Renewable Energy 

JFS Newsletter No.138 (February 2014)

Floating Offshore Wind Power
Copyright Fukushima Floating Offshore Wind Farm Consortium All Rights Reserved.

As reported in the November 2013 JFS Newsletter, the growth of the ratio of power generation from renewable energy out of total electricity generation in Japan has accelerated, partly because of the Excess Electricity Purchasing Scheme for Photovoltaic Electricity, introduced in 2009, and the Feed-In Tariff (FIT) introduced in summer 2012.

Renewable Energy in Japan -- Current Trends Show Promise and Opportunities

The trial operation of Japan's first floating offshore wind power facility off the coast of Fukushima Prefecture, which we also introduced in our November newsletter, is of significant importance for the expansion of renewable energy introduction. The project also stands as a symbol of the recovery and reconstruction of Fukushima, with the introduction of renewable energy being regarded as a pillar of regional recovery.

This newsletter introduces more details of the Fukushima floating offshore wind farm demonstration project, called Fukushima FORWARD, which is being promoted by the Fukushima Offshore Wind Consortium.

Wind Power Generation in Japan

One of the reasons why wind power generation is not increasing faster in Japan is that it is difficult to construct large-scale wind generation facilities on land, due to the limited availability of flat land. The limited amount of suitable land also limits the number of wind turbines that can be installed per wind farm, which leads to high costs compared to projects overseas.

Japan, however, has extensive sea areas. While it is 62nd in the world in terms of national land area, it has the world's sixth largest exclusive economic zone (EEZ), an area approximately 60 percent of that of the U.S.A., which has the largest EEZ. The potential offshore wind energy resources there are estimated to be 1,600 gigawatts, about 6.5 times Japan's total current power generation capacity .

If just 1.5 percent of its wind energy resources can be utilized, Japan's total power generation capacity would increase by 10 percent. It is expected that offshore wind power generation will be further developed to become one of the pillars of renewable energy resources in Japan.

Offshore Wind Power Generation

In offshore wind power generation, large-scale facilities can be established, since wind turbines can be installed on the flat sea surface and there is nothing to block the wind. Furthermore, since offshore facilities are away from residential areas, there are no problems of affecting residents with impacts such as noise, low-frequency waves, and shadow flickering (the phenomenon where the shadows of wind turbines' rotating blades cause the ambient light to flicker). It is also considered that offshore wind power generation has less impact on living creatures other than humans than wind power generation on land because low-frequency waves do not reach beneath the sea, and there are fewer birds on the ocean than on land in the first place.

Floating Offshore Wind Power
Copyright Fukushima Floating Offshore Wind Farm Consortium
All Rights Reserved.

Offshore wind power generation designs are broadly classified into (1) bottom-mounted and (2) floating types. Bottom-mounted offshore wind power generation is a tried and true technology throughout the world, and its operation cost can be reportedly lower than that of floating offshore wind power generation on the sea at depths of 25 meters or less. Furthermore, electric power substations installed offshore are fixed on the ground, and thus the same substations as those used on land can be used.

In Japan, however, since there is no track record of installing large bottom-mounted wind turbines with a capacity of 5 megawatts (MW) or more, little expertise has been accumulated and there is no dedicated installation ship. Renting an installation ship costs at least 600 million yen (about U.S.$5.8 million) per month.

In addition, since bottom-mounted wind turbines are fixed directly to the seabed, they are susceptible to earthquakes, tsunamis, or tidal waves caused by typhoons, so there is a justifiable concern about the impact on stable power supply because Japan is an earthquake- and typhoon-prone country. Also, because the areas where bottom-mounted wind turbines can be installed are limited to only shallow seabed locations, the scale of wind farms possible would be limited, as well.

On the other hand, floating wind turbines do not require a dedicated installation ship or a large amount of seabed construction work. As marine areas with a depth of 50 meters or deeper are found common in the waters around Japan, it is possible to establish large-scale wind power generation facilities. Also, since they are not fixed to the seabed, the impacts from earthquakes, tsunamis, or tidal waves can be better avoided.

As for floating offshore wind power generation itself, however, pilot studies were started just a few years ago in Norway and Portugal, with only one floating offshore wind turbine constructed for each of those studies. Also, in order to realize a large-scale floating offshore wind farm in the future, there are still technical challenges remaining to be solved, such as the establishment of the technology for a floating power transmission and transformer system.

Floating Offshore Wind Power
Copyright Fukushima Floating Offshore Wind Farm Consortium
All Rights Reserved.

Efforts by the Fukushima Offshore Wind Consortium

In an effort to maximize the advantages of floating offshore wind farms, the Fukushima Offshore Wind Consortium was created by ten companies and one university, with Marubeni Corporation, one of Japan's major general trading firms, as the project integrator, and the University of Tokyo as technical adviser. The consortium is implementing the floating offshore wind farm project off the coast of Fukushima Prefecture.

The aims of this demonstration project are to overcome various technical challenges, ensure collaboration with the fishing industry, secure marine navigation safety, and establish a method for environmental impact assessment -- all of which are essential to create large-scale offshore wind farms in the future. Furthermore, the project also has its eyes on developing floating offshore wind farms into one of Japan's main export industries, by accumulating expertise and transferring that expertise to projects overseas.

In this demonstration project, producing results in a short period of time has been the absolute top priority. The project has so far successfully developed a floating power transformer facility, which is both durable and unsusceptible to motion, and a large-capacity, waterproof riser cable with high fatigue resistance. In the first phase of the construction work, the world's first floating grid integration system was established, consisting of a 2-MW down-wind offshore turbine, a 66-kilovolt floating substation, and undersea cable connecting floaters.

These were the results of only 18 months after the project was first commissioned to the consortium by the Ministry of Economy, Trade and Industry. The operation of the floating offshore wind farm started in the demonstration waters, about 20 kilometers offshore Fukushima Prefecture, in November 2013. From now on, as a demonstration, the project will focus on evaluating the safety, reliability, and economic feasibility of the floating offshore wind farm by collecting and analyzing meteorology data, oceanography data, and operation data. At the same time, it will try to establish the operation and maintenance practices.

In the second phase of construction work, two of the world's largest hydraulic-drive floating offshore wind turbines, each with 7-MW outputs and a height of almost 200 meters, are scheduled for installation at the facility in fiscal 2014. This will increase the total facility output to 16 MW, making it the world's largest floating wind farm. The consortium intends to demonstrate the economic feasibility of large-scale floating offshore wind farms, including the cost-reduction effect of construction of larger wind turbines.

Floating Offshore Wind Power
Copyright Fukushima Floating Offshore Wind Farm Consortium
All Rights Reserved.

This experimental study project also has an aspect of contributing to post-earthquake reconstruction, in that it will create new industries, particularly manufacturing related to the floating offshore wind turbines because they require many parts, which will lead to the creation of a wider variety of industries. Currently, German-made blades are being used for these wind turbines, but studies are currently examining the potential for producing windmill blades domestically.

Challenges and Prospects

To commercialize floating offshore wind farms, several challenges must be overcome. Here, we outline the current situation and future perspectives in regard to three relatively large, challenging issues: construction cost, maintenance, and collaboration with the fisheries industry.

The target construction cost at an early stage of the project was 800,000 yen ($7,768) per kilowatt (kW), while the actual cost for the first phase of construction was 2 million yen ($19,417) per kW. As for the second phase, using larger wind turbines is expected to help reduce the cost to around 1.5 million yen ($14,563) per kW. Making the entire wind farm larger by using expertise accumulated through these experimental studies is expected to help achieve the targeted construction cost.

Maintenance is essential for a stable energy supply, but access to the floating offshore turbines will be a major challenge, since they are not fixed to the ground. The consortium therefore plans to demonstrate methods currently adopted in Europe, such as the introduction of dedicated maintenance ships and the use of helicopters. At the same time, it is also considering the introduction of training centers dedicated to maintenance of the unstable floating offshore turbines.

Offshore wind turbines are usually built in waters also used as fishing grounds; thus, collaboration with the fishing industry is also an important issue. That is why various measures are being investigated to help make fishing grounds richer and eventually revitalize fisheries, by making use of the floating facility to create marine farms, build marine culture facilities for seafood and algae, and gather fish through marine fertilization and the use of culture rafts.

To achieve collaboration with the fishing industry, efforts to build mutual trust and deepen mutual understanding continue to be made, by frequently visiting local fishermen and having dialogue with them.

The first phase of construction of this project was completed in only one-and-half years, as a result of prioritizing the quickness of development. How can this effort lead to overcoming the challenges and advancing to the second phase of construction in order to put floating offshore wind turbines into practical use? We will keep our eyes on future developments.

Written by Nobuhiro Tanabe

See also:
Fukushima Floating Offshore Wind Consortium (Fukushima FORWARD) 


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