Can a wind turbine handle hurricane speed winds?

Can a wind turbine handle hurricane speed winds?

Wind turbines have become an increasingly popular alternative source of energy for many countries. However, the impact of hurricanes or typhoons, which are some of the most powerful forces of nature, has been a cause of concern for operators and developers. As a result, companies are adopting new technologies and designs to ensure that wind turbines can withstand these storms’ ferocious winds.

MingYang Smart Energy, a Chinese manufacturer, recently developed a “typhoon-resistant” floating wind turbine. This 7.25-megawatt turbine can survive wind speeds of up to 134mph for ten minutes. It is installed at a facility 136km off the coast of the island province of Hainan. The MingYang turbine is not the first to be designed to face the onslaught of hurricane-level winds. In 2021, GE’s Halide-X turbine received typhoon certification. It is fixed, not floating, and has a capacity of up to 13MW.

Tropical cyclones, known as typhoons or hurricanes, are a familiar threat in certain parts of the world, including the Gulf of Mexico and much of Southeast Asia. Such storms can produce wind speeds of more than 100mph. The expansion of wind energy is expected in these regions in the coming years and decades.

Today’s turbines are rated to cope with wind speeds of up to 50mph or so, says Simon Hogg at Durham University, who holds the Ørsted chair at the university, funded by energy firm Ørsted. Wind turbine blades are generally made from strong but lightweight carbon fibre composites, and automated manufacturing processes help ensure the uniform placement of fibres, which is crucial for the blades’ robustness, says Leon Mishnaevsky of the Technical University of Denmark.

Wind turbine manufacturers also perform stress tests on blades to ensure they are up to scratch. This can include attaching large “exciters” to the blades that simulate the repeated stresses of winds on the structure. Giant blades are also sometimes bent to the point of breaking, which helps confirm the maximum loads they can bear.

However, the fallibility of turbines, especially the largest ones, is becoming more apparent over time. Insurer GCube notes that offshore wind losses rose from £1m in 2012 to more than £7m in 2021. Machines with capacities larger than 8MW can suffer component failures within two years of installation, twice as fast as 4-8MW devices.

The biggest challenge for wind turbines is torsion or twisting loads that can cause difficult-to-spot fractures. Find Mølholt Jensen, chief executive of Bladena, a firm that specializes in diagnosing and repairing large turbine blades, says repeated twisting of blades can induce such fractures. Jensen argues that current testing and industry standards are insufficient to prove that the largest turbine blades can withstand these stresses.

New designs could help address this challenge. For instance, in Japan, Challenergy is developing a turbine with tall, vertical blades that spin around a central tower. While the device is currently much smaller and less powerful than traditional, three-bladed turbines, it is intended to cope with high winds. When a powerful typhoon called Hin Nam No struck the Philippines and Japan in 2020, it passed over two of the company’s turbines. One of the devices, at Ishigaki City in Okinawa, recorded wind speeds of around 64mph. The turbine continued to operate without any problems, according to Challenergy.

In the US, a research team has designed a turbine with flexible blades that face downwind. The University of Colorado’s turbine is intended to be more resilient than traditional turbines that must face upwind. By doing so, the blades can absorb gusts.

The turbine’s flexible blades also reduce the stress on the tower and the foundation, as they bend with the wind instead of resisting it. This design is particularly useful for areas prone to sudden gusts of wind, such as coastal regions or mountainous areas. In addition, the downwind-facing blades eliminate the need for a yaw mechanism, which is used to adjust the turbine’s angle to face the wind. The researchers hope that their design will lead to more efficient and reliable wind turbines in the future.