What is managed on a floating basis

Floating wind turbines are facing sharp cost reductions

The commercialization of floating wind turbines is key to unlocking the potential of wind turbines in deep waters offshore where more constant and stronger winds prevail. New technological advances offer the possibility of using this abundant wind resource in great water depths more cheaply.

Offshore wind turbines are among the most promising and most environmentally friendly technologies for generating energy. Based on the levelized cost of electricity (LCOE), however, offshore wind turbines - especially floating wind turbines - still appear to be more costly than more ubiquitous sources of electricity such as onshore wind and solar systems. The EU-funded TELWIND project has taken a big step towards making offshore wind turbines in deep waters more competitive. The revolutionary floating platform leads to a qualitative leap in the lowering of the costs of manufacture and construction, which increases the chances of a broad industrial establishment of floating wind turbines in the future. Improved floating construction The floating substructure from TELWIND combines two main breakthrough systems into one affordable integrated system that can be installed easily, quickly and inexpensively: an advanced support configuration with floating ballast and a self-erecting telescopic tower. The suspended ballast of the girder configuration acts as a counterweight. More precisely, a float is connected via tendons to a heavy ballast tank below, which lowers the center of gravity of the system in order to stabilize the substructure. The platform integrity depends directly on the reaction of the tendons. It was therefore imperative to check whether the performance met the project requirements. The floating telescope tower consists of tubular tower segments consisting of precast concrete parts as well as a steel profile and an erecting device with heavy-duty strand jacks for the telescope tower. “Tubular towers made of precast concrete parts are a cost-effective alternative to tubular steel towers. The flexibility of the construction as well as the increased fatigue strength and longevity are decisive for the increase in production output and the industrialization of floating wind turbines ”, explains José Serna, CTO of Esteyco. Water channel test The project partners created an innovative model on a reduced scale in order to test their concept for wind turbines floating in the offshore sea with the help of a water channel test. The focus was on the investigation of the complex interaction between the floating substructure and the wind turbine under the influence of wind and waves. Based on the results, the project partners were able to validate control strategies for the wind turbine. This model was equipped with a complete set of sensors. The data acquisition should provide enormous amounts of information for numerical models that are used to optimize a realistic concept for offshore wind turbines with a 12 MW turbine. The experiments were supplemented by theoretical simulations. In particular, the project partners used a multicopter to simulate the wind loads to which the substructure at sea is exposed in a test basin. “This is the first time drones have been used to mimic high winds,” notes Serna. The increasing capacity and efficiency of wind turbines have an impact on both capital expenditure (CAPEX) and operating expenses (OPEX). Detailed CAPEX and OPEX analyzes have confirmed the assumption that the TELWIND platform concept could reduce the electricity production costs of wind turbines floating in the distant sea. “The TELWIND technology is around 30% cheaper than current ground-based foundation structures at water depths of more than 40 meters,” adds Serna. “The on-site assembly of the floating substructure platform saves considerable time in contrast to the transport with heavy lift ships.” The market for wind turbines floating in the distant sea continues to develop, but floating foundations have always been costly. TELWIND has spawned new advanced technologies that provide a better understanding of how to reduce costs.

key terms

TELWIND, offshore wind turbine, floating wind turbine, wind turbine, floating substructure, LCOE, carrier configuration, ballast tank, telescope tower