Floating offshore: The next big development in wind power


Norway’s Hywind floating offshore wind turbine

Mention wind turbines to some people and they go ballistic, but fortunately the next big development in wind power is already beginning to appear over the horizon. The idea sounds simple, just stick a wind turbine on a floating platform and sail it further out to sea, where people can’t see it, where the winds are stronger and, given that it’s on a platform, where it doesn’t need lots of costly foundations technology.

Actually, it’s not quite as simple as all that, but fortunately countries such as Japan have been working on such an idea for several years, which means that the technology is already viable and ready to be developed into a market-ready technology.

Floating offshore wind turbines are now increasingly being deployed in various countries around the world. A key advantage is cost reduction. The costs associated with foundations technology for conventional offshore wind farms can be severe but with floating wind turbines, all that is dispensed with. The cost of developing the floating platform in the first place is still quite high but as costs for floating offshore projects fall, it is likely that the majority of offshore wind projects will be of this type, especially after 2030. Although Japan is expected to take the lead in this segment, growth is also expected in other areas, particularly in Europe and the US.

The first viable floating wind turbine was deployed off the coast of Norway in 2009. The Hywind project was located six miles off the coast of Stavanger and was prompted, ironically, by two oil and gas engineers. The project was then developed by Norway’s oil company, Statoil, to the tune of $60 million.

Hywind has a 200 foot tower that sits on a floating platform made of steel which extends 300 feet below the surface. The platform is filled with water and rock which acts as ballast and it is secured to the sea bed by three cables.

Japan has increasingly shifted its emphasis over the last few years away from nuclear and towards renewables, primarily because of the catastrophic Fukushima disaster. A key part of its strategy is the development of floating offshore infrastructure.

A report into the Japanese market by the Carbon Trust is enlightening. Japan has been investing in research focused on floating offshore technology for the past 20 years. Most of this has been funded by the Japanese government, but the Fukushima disaster has motivated a shift towards incentives in order to attract funding from the private sector.

The Carbon Trust report explains other factors in the Japanese development of floating offshore wind technology, besides that of cost. One of these, which is driving the development of renewable energy generally is the high cost of gas. In Japan, this requires a shift to renewables in order to close the gap left by the closure of nuclear plants. Another issue, particular to offshore wind, is geographical constraints and social factors regarding onshore wind. This is a factor that is not uncommon in other countries, particularly the UK and Ireland. As a result of these constraints, the Japanese onshore wind sector is expected to peak before 2030. This in turn has driven a new offshore wind target of 37 GW capacity by 2050, 18 GW of which will consist of floating offshore wind.

One of the main challenges for offshore wind deployment is grid infrastructure. The transmission of electricity requires converters, however the Japanese have established a Basic Policy on Electricity Reform which is aiming to abolish the regional utility monopolies, thus enabling a greater freedom of movement of electricity across the regions. This is particularly important in Japan as the country’s offshore wind farms are often located in areas of low demand, such as Hokkaido, Tohoku and Kyushu.

The cost of deploying offshore wind farms is currently high wherever in the world they are being deployed. In Japan, high base costs and a lack of suitable infrastructure and experience add to the various challenges and so in order to deal with this the Japanese have implemented a strong incentive system in order to attract investment from the private sector. This is largely based on Feed-in Tariffs.

One of the major problems is that Japan has very deep waters close to shore. Furthermore, given that over the long term Japan will need to deploy its offshore wind infrastructure further away from shore, there is a need to develop greater expertise in floating offshore wind. This means that Japan has already acquired a pre-eminent position in the development of this type of technology. It also explains why the Japanese have been so keen to develop their offshore supply chain. The purchase by Marubeni Corporation and the Innovation Network Corporation of Japan of British company Seajacks, which builds bespoke vessels for supporting the offshore industry, was a key part of this strategy.

Installed floating capacity around Japan currently totals 4 MW, all of which consists of demonstration projects. The main floating offshore wind farm project in Japan is the Fukushima Project near Tohuku, but there are two others near Kyushu, one of them at Kabashima Island which was actually the first of the three to be deployed in 2012. It originally consisted of a 100 kW floating spar buoy located 1 kilometre away from the island. This was later replaced in October 2013 by a 2 MW Fuji Heavy Industries turbine which became the first grid-connected floating offshore wind turbine in Japan. One of the big advantages of Kabashima island is that the typhoons in this area are generally more ferocious than those experienced further north, so it is an ideal place in which to test the technology for typhoon resilience.

The Fukushima floating offshore wind project was the next to be installed, in late 2013. When the Japanese government first announced this project in March 2011, the plan was to build the largest offshore wind farm in the Fukushima prefecture, capable of generating more 1 GW of wind power by 2020. This will be far in excess of that generated by the London Array, the UK’s largest offshore wind farm, which generates 630 MW. The Fukushima project is being developed by a consortium consisting of 11 different organisations led by the Marubeni Corporation. These include the University of Tokyo, Mitsubishi Corporation, Mitsubishi Heavy Industries, Japan Marine United Corporation, Mitsui, Nippon Steel, Hitachi, Furukawa Electric Co., Shimizu Corporation, and Mizuho Institute. The next phase of this project is scheduled for completion this year and will consist of turbines located in deep waters of 100 to 200 metres with wave heights of 7-14 metres. It will generate 16 MW, thereby becoming the world’s largest floating offshore wind project so far.

Finally, there is the Windlens Project in Hakata Bay, led by Kyushu University. It was originally launched in 2011 to test a floating platform measuring 18 metres in diameter and equipped with two 3 kW Windlens turbines. This design consists of rotors set within an outer curving ring which increases the pressure as the blades rotate thereby doubling the generated output. The second phase of the project will involve a larger platform located 2 kilometres off the coast which will combine wind with other technologies such as solar PV, tidal and wave energy.

Floating offshore wind infrastructure can also help to remove the visual impact of conventional offshore wind farms, some of which can still be seen from the shore. The passion felt by some people regarding this issue has been demonstrated on numerous occasions, for example in 2011 when a group attempting to fight the US Cape Wind offshore project took its case to the Supreme Court. The argument was that homeowners on Cape Cod would be able to see the wind farm. Floating wind farms can be deployed more than 12 miles out to sea enabling the NIMBY (Not In My Back Yard) problem to be completely eradicated. This will also enable offshore wind farms to be more convenient placed with regard to passing shipping.

Another advantage is that the wind speeds are higher further out to sea, and they are more consistent.

Although Japan is likely to be the most dominant developer of floating offshore wind technology, the US will also be an important market, particularly with regard to its eastern coast. The US has estimated a potential offshore wind resource in that area of 300,000 MW and developers are already operating in coastal regions off Delaware, New Jersey, Maryland and Rhode Island. Meanwhile, developers in Europe are working on high voltage HVDC undersea cabling transmission systems that could cut out the problems of intermittency.

In this way, a whole series of offshore wind farms could be connected into a ‘supergrid’ network and this is indeed already beginning to happen with conventional offshore wind farms in Europe.

There’s an exciting future ahead for offshore wind and it’s certainly something to keep our eyes on as the technology develops.

About Robin Whitlock
I am an experienced freelance journalist with a wide and varied portfolio to my credit including web content, magazine articles, reporting, features, interviews, reviews and blogs. My special interests include environmental issues, particularly climate change, renewable energy, transport, green building and sustainable infrastructure. I have numerous secondary interests ranging from politics and current affairs to social justice, science, technology and innovation, historical topics and lifestyle subjects such as literature, psychology, contemporary spirituality and culture.

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