Offshore renewable energy technologies

Offshore Renewable Energy Technologies

Design of Offshore renewable energy technologies

Specific Research and Development expertise aimed at the development of innovative technologies for accelerating the placing on the market of devices and components for offshore renewable energy. The objective of this area of expertise is to identify technologies which are viable from an economic perspective while guaranteeing standards of reliabity and safety, according to the rules of the most well-known classification companies (DNV-GL, Bureau Veritas, etc). The technical assessment of the technologies is done using in-house software coupled with commercial alternatives and experimental testing of scaled models under different wave conditions in an experimental long 2D flume.

The main activities in this field include:

  • Design of floating support structures for offshore wind and floating wave energy converters: the design of the floaters is done in order to improve the hydrodynamic behaviour according to the functionalities that must be guaranteed. Moreover, the structural local design will identify criticalities in terms of mechanical stresses and deformations, floating stability, resonance oscillation response or passive and active ballast for trim control. The definition of the design load cases will follow the most advanced offshore standards, taking into account ultimate conditions, as well as fatigue and operational cases that may affect the safety of the structure. Experience has been achieved while designing, among other concepts, the semisubmersible support structure and the platform trim system (PTS) for the offshore wind platform NAUTILUS.
  • Design of mooring systems: innovative mooring systems have been designed for several kinds of structures in order to guarantee the station keeping of the devices. The innovations include the use of multimaterials as well as innovative layouts (i.e. for example the “Karratu”, in which the mooring lines are shared among more devices in an array) or the use of shared anchors. The numerical tools used for the assessment of the mooring system consist in a finite element time domain commercial option (Orcina Orcaflex) as well as inhouse software. Moreover, routines in the frequency domain, as well as using quasi static approaches have been developed for the evaluation of the technologies at a conceptual stage. An experimental campaign with scaled models in the wave flume of these concepts is currently under preparation.
  • Design of dynamic cables: an efficient methodology has been developed for the design of umbilical dynamic cables for exporting the electrical power generated to the substation. The methodology allows to evaluate different concepts (lazy wave, catenary, etc…), providing a safe design taking into account the limits for the mechanical integrity of the cable (bending radii, tension, etc…).
  • Tools for ocean energy array design: within the framework of the European funded projects DTOcean and DTOceanPlus, a toolset for the design of ocean energy arrays has been developed. The toolset developed in DTOcean, which already takes into account several subsystems (hydrodynamics, electrical connection, moorings and foundations, logistics, installation and operation and maintenance) and several assessments (economics, reliability, environmental impact), will be further improved within the framework of the project DTOceanPlus, including more subsystems (site characterization, control) and other tools for the Structured Innovation and the Stage Gate assessment.

Contact and more information: Vincenzo Nava