Although China remains one of the world’s largest emitters of greenhouse gases, it is also making notable progress in its ongoing efforts to move toward cleaner alternatives like wind and solar power. In a significant move that further boosts its green credentials, the country recently installed the Sanxia Linghang, or Three Gorges Pilot, which has been described as the world’s largest single-unit operational floating offshore wind turbine, both in terms of capacity and rotor diameter.
Located in the waters off southern China, the turbine, built by Wuhan-based China Three Gorges Corporation (CTG), is a 16-megawatt unit with a rotor diameter of nearly 830 feet and a blade height of more than 885 feet above the water. Unlike conventional turbines installed on the seafloor, the massive structure, which began testing last month, floats on a platform in 164-foot-deep water and is meant to be sturdy enough to withstand 65-foot waves and winds of up to 164 mph, equivalent to a Category 5 hurricane, the most severe classification.
CTG’s design could potentially be a game-changer, as it shows that floating wind turbines can be built on a record scale for a single turbine. At the same time, this opens up deep water sites that fixed wind turbines cannot use.
Making the massive turbine a reality
To make its massive turbine a reality, CTG developed a new mooring system, with the 79,000 square foot floating platform held in place using nine suction anchors and an automatic ballast system to ensure stability. To transfer the generated energy to earth, the facility uses a dynamic 66-kilovolt cable designed to withstand extreme temperatures, wave motion, saltwater corrosion and mechanical stress, among other challenges.
With an estimated annual output of 44.65 gigawatt hours, the Three Gorges pilot project could provide enough electricity for around 24,000 three-person households for a year. During the testing phase, engineers will likely gather performance data, monitor the platform to ensure the stability mechanisms are working as intended, and confirm the effectiveness of the power transfer technology.
Beyond its record size, CTG’s efforts are expected to demonstrate how multiple systems can work together to keep a large floating turbine both stable and productive, with this ambitious project offering a model for how future floating wind projects could be deployed in even deeper and more turbulent waters. The company can then decide whether the design can be extended to future offshore wind farms in the ocean.
Big wind technology, even bigger challenges
Deep-water floating wind farms already exist, including Hywind Scotland in the UK, WindFloat Atlantic in Portugal, Hywind Tampen in Norway and Provence Grand Large in France. But the turbines in these projects are smaller in size and capacity than the 16-megawatt turbine tested by CTG.
The larger CTG unit could help reduce costs by reducing the number of turbines and associated components needed for an offshore project, which could simplify installation and maintenance. Its larger rotor sweep also allows a single turbine to capture more wind and generate more electricity, providing another advantage over smaller installations with more turbines. Large floating turbines could also help countries with limited offshore space. In areas where, for example, shallow water for conventional turbines is rare, a larger floating unit can provide more power with a smaller footprint than many smaller turbines spread over the same area.
It is important to note, however, that these larger floating turbines pose many challenges. For example, they are more difficult to transport and install, not only because of their size but also because working in deep water is more precarious. Additionally, if one of these turbines fails, a large portion of the capacity is destroyed in one fell swoop. Technical problems with smaller turbines are less likely to disable them all at once, allowing electricity to continue to be produced. Despite the challenges, this is undoubtedly an exciting time for wind energy, and as technology advances and reliability improves, it looks set to play an ever-increasing role in the shift away from fossil fuels to clean energy sources.
