How Big Is Too Big for an Offshore Wind Turbine?

Source: By Ed Ballard,. Wall Street Journal • Posted: Wednesday, May 3, 2023

Offshore-wind farms, like this one in the Baltic Sea off the coast of Germany, need to become a lot more common for governments to hit their renewable-energy targets.

The offshore wind industry’s pursuit of scale could be storing up problems for the future, according to a study of insurance claims that found larger turbines are failing earlier.The blades of Vestas Wind Systems’ largest turbine, currently in testing, are nearly 380 feet long. Each turbine towers more than 900 feet and can generate up to 15 megawatts of electricity—enough for a town. Turbines that were state-of-the-art a decade ago had around a fourth of that capacity.Vestas’s rivals, General Electric and Siemens Gamesa, are introducing similarly large turbines, and Chinese suppliers are designing even larger models.

Analysts see these giant machines playing an important role in governments’ clean-energy plans.But GCube, a renewable-energy insurer owned by Japan’s Tokio Marine HCC, sees a downside. It found that component failures in turbines with 8-megawatt capacity or greater occur on average after just over a year. That compares with over five years for turbines of 4-to-8 megawatts.Vestas and Siemens Gamesa have been selling 8-megawatt models for several years.

GE doesn’t yet have turbines that large in commercial operation. The companies declined to comment.Christoph Zipf, a spokesman for industry organization WindEurope, pointed out that customers are ordering suppliers’ newest designs.”This clearly shows that developers continue to be interested in big turbines,” he said. The U.S. Department of Energy says the cost of offshore-wind power has fallen by more than 50% since 2014, thanks largely to increasing scale.