Researchers at the Department of Civil and Environmental Engineering of the Universitat Politècnica de Catalunya (UPC) have designed and patented a prototype floating platform for offshore wind turbines that they say can reduce energy costs to 12 euro cents per kilowatt hour (kWh) through a more efficient design and less expensive, more durable building materials.

Climent Molins displays the prototype structure for offshore wind turbines. Image credit: Universitat Politècnica de Catalunya.Climent Molins displays the prototype structure for offshore wind turbines. Image credit: Universitat Politècnica de Catalunya.The prototype, WindCrete, is a cylindrical structure with a large float and a ballast base that make it self-stabilizing. According to the researchers, Climent Molins and Alexis Campos of UPC’s Department of Civil and Environmental Engineering, the innovations of this model are the monolithic structure and the use of concrete.

Insert image here: Using a concrete design rather than the more commonly used steel structure reduces construction costs 60%, they say. In addition, concrete is more resilient in the marine environment, so the structure has fewer maintenance requirements and an expected life of about 50 years. In particular, the absence of joints in the platform avoids damage that normally occurs in transition areas.

The WindCrete includes a 5 megawatt (MW) wind turbine that can carry rotors of up to 15 MW with minimum increase in cost. The system generates power at approximately half the price, 12 euro cents/kWh, of windpower units in the Canary Islands off the coast of Morocco, where this form of energy is being promoted.

Given what the researchers say is the long useful life of this prototype, the possibility of replacing the turbine with a more powerful and profitable machine may be an option.

The prototype was developed as part of the Alternative Floating Offshore Substructure for Offshore Wind Farms project, carried out under the framework of KIC-InnoEnergy in collaboration with Stuttgart Wind Energy at the University of Stuttgart and Gas Natural Fenosa.

A preliminary design was carried out to ensure technical and economic feasibility. In order to check the behavior of the platform and its anchoring system in an environment that simulates the sea, trials were held in the wave flume of the UPC's Maritime Engineering Laboratory using a WindCrete prototype with a scale of 1:100.

Partially submerged offshore platforms of this type require a minimum depth of 90 meters. However, there is no technical maximum depth at which they can be installed, the researchers say. In the Gulf of Mexico, for example, oil platforms of this type are anchored at depths of up to 2,300 meters.

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