Racing to Complete a Floating Wind Demo

Kai-Tung Ma, Professor, National Taiwan University

Glib Ivanov, Doctoral Student Researcher

In 2009, the first Floating Offshore Wind Turbine (FOWT) demo was installed by Statoil (now Equinor). Since then, there have been at least 13 demo projects (over 2MW) with designs from 7 countries: Norway, the USA, Japan, France, China, Denmark and Spain. New designs developed in Taiwan, such as DeltaFloat and TaidaFloat, will require a prototype demo project to complete the technology development. This article summarizes the demo projects worldwide; it also provides ideas for planning a project in Taiwan.

1st Achiever: Hywind by Norway in 2009

It is a breakthrough that Norway completed the very first demo project as far back as 2009. It provided confidence that FOWT can work and empowered Norway to become a leader in FOWT. The project was founded by Statoil, an oil company, as part of its efforts to pursue clean energy. The demo led to the current implementation of the world’s largest floating wind farm, Hywind Tampen. The farm has 11 spars which supply electricity to oil and gas platforms.

2nd Achiever: WindFloat by USA in 2011

Perhaps the most important demo project is WindFloat, as it became a role model to many others. During 3 years of demo operation offshore Portugal, the prototype encountered storms of 17-meter waves, which was higher than the design wave. After 5 years, it was sold and placed at Kincardine, Scotland. The demo led to the successful implementation of two pre-commercial wind farms, WindFloat Atlantic with 3 semis offshore Portugal and WindFloat Kincardine with 5 semis offshore Scotland. According to the designer, Principle Power, $25M was raised for the design, fabrication and installation of the prototype offshore in Portugal. Funding for the project came from the Portuguese government and a joint venture consisting of electricity and oil companies, manufacturers, and government innovation funds.

3rd Achiever: Mirai and Goto by Japan in 2013

Fukushima Mirai with a 2MW turbine was the first project among the four Fukushima Forward platforms. Fukushima Forward has seen the largest number of different institutions pooling their money and efforts together to make it the largest scale and longest demo project. Data from Fukushima Hamakaze, with a 5 MW turbine, was used to validate software predictions. Shinpuu with a 7 MW turbine and the largest displacement of 26,000 tons has a special hull shape. Total decommissioning works for Mirai, Hamakaze and their offshore power substation amounted to $48 mil. The lesson learned is that the decommissioning cost can be quite high, and it should be included in the initial cost assessment. Also in Japan, a spar-type platform Goto has withstood two typhoons without loss of stability, and no structural damage was found. The construction of the 16.8 MW Goto wind farm is scheduled to start soon, and the wind farm is expected to be commissioned in 2024.

4th Achiever: Floatgen by France in 2017

A French company Ideol believes in concrete as the construction material because it is cheaper, but the Japanese think otherwise. In 2018, they simultaneously launched two sister projects: concrete Floatgen in France and steel Hibiki in Japan. Curiously, a steel barge in Japan seems to still cost less to build than a concrete barge in France. The project in France is supported by the European Union, the French government as part of the national investment, and the regional government. In 2023, Floatgen reported achieving a 60% capacity factor throughout the year, promising better efficiency than the planned 40%.

5th Achiever: SanXia by China in 2021

SanXia was installed and connected to the grid in the South China Sea in 2021. The project "Sanxia" (meaning Three Gorges) is China's first FOWT, with a capacity of 5.5 MW. In 2022, another FOWT, FuYao, was installed, which is also a large platform with a displacement of 15,600 tons. The 6.2 MW platform is planned to serve as a technology demonstration before the bigger turbines are built for commercial use in China. Both of them are deployed in the South China Sea.

6th Achiever: TetraSpar by Denmark in 2021

 The inventor of the Danish Wind Turbine concept, Henrik Stiesdal came back from retirement with a 3.6 MW TetraSpar. Launched in 2021, it is designed to be small and mass-produced with its unique floater shape made from the same tubes as fixed turbines’ towers. Updated variants such as TetraSub are being developed with the experience gained during TetraSpar’s field test off the Norwegian coast.

7th Achiever: Sath by Spain in 2022

Sath is a concrete twin-hull barge structure. The project was started by a Spanish design company in 2020. The 2MW unit was installed in a test field offshore Spain in 2022. The Sath design uses pre-fabricated concrete components and a single-point-mooring system that allows the floating structure to yaw around its mooring and passively align itself to the wave and current direction.

Could DeltaFloat and TaidaFloat by Taiwan be the next?

DeltaFloat and TaidaFloat semi-submersibles have been designed in Taiwan with sponsorships from two government agencies, the Ministry of Economic Affairs and the National Science and Technology Council, respectively. A prototype based on the two designs is currently being planned for a demo project off the northern coast of Taiwan.

LEARNINGS

After summarizing the past demo projects, a few key points may be learned:

1.       Semi-submersible type floaters are in the majority, with 6 out of 13 belonging to this category. While 4 are spar type, another 3 are barge type. No TLP (except a very small one with 0.08 MW in Italy).

2.       2 MW demos were the norm mostly for these projects. An increase in MW can be seen, as new demos have to face smaller turbines being phased out of production.

3.       Government funding is helpful for a successful demo. The Japanese government is willing to spend a large amount of money. European projects are usually private-government partnerships.

4.       The average project cost amounts to roughly USD 35 million ($600-$1000 million NTD). The newer projects may become cheaper due to the experience gained from the past.

5.       Most projects had academic collaboration. Professors and student researchers from the University of Tokyo, Massachusetts Institute of Technology, Danish Technical University, Centrale Nantes, and others were directly involved in the designs.

WHAT IS THE PROGRESS ON TAIWAN's DEMO?

Read the free full version of the technical paper presented at the World Conference of Floating Solutions 2023, Tokyo to learn:

• Technical and financial details of the demo projects around the world
• Design Challenges for a Taiwanese demo and solutions
• Recommendations for a demo floater design

(PDF) Overview of FOWT Demo Projects Cost and Analyses of Hull Design Features (researchgate.net)