Type Classification for Horizontal Axis Tidal Turbine (HATT): An Important Step Towards Commercialisation

Abstract

One key aspect of serial production is to define a set of parameters that can define the limits and conditions that product can be used. Type certification is applied to serial production such as wind turbines when the matching of the site characteristics and the turbine design conditions is summarised in a short description of the site parameters that fundamentally describes the wind conditions (energy and turbulence). This easy matching is used by all stakeholders in assessing the suitability of different turbines to a specific project development. However, type classification is also important to optimise the design, manufacturing, installation and maintenance costs by setting key parameters to production of turbines with same characteristics (scale factor). The same applies to tidal turbines. Although, at the present phase of development, serial production is not yet a main driver and designs are mainly carried out with specific sites in mind, it is useful to develop a type classification now to support generic design parameters and that can be tested for future serial production and matching sites with serial products. While for wind turbines, the set of key parameters is reasonably simple [1], for tidal there are a number of environmental conditions (for example waves, astronomical tide, current turbulence, water depth, etc), and parameters (such as hub height related to the seabed and sea surface) which must be considered within the design of a HATT, parameters which may also be utilised in the construction of generic type classes for Tidal Turbines. Thus, the identification of generic type classes for HATTs is dependent upon the ability (by conjunction of assumptions, formulations, etc.) to distil the existing extensive list of site / HATT parameters down to a minimum number of key parameters upon which a simple but robust set of generic type classes could be based. Whilst it is recognised that adjustments of type classes may be required in the future, a first approach will be presented in the DNV GL Standard for Certification of HATT developed under the ReDAPT project and it is described in detail in this paper. The ReDAPT project is commissioned and co-funded by the ETI (Energy Technologies Institute).

Identification of the Uncertainties for the Calibration of the Partial Safety Factors for Load in Tidal Turbines

“…Another objective of ReDAPT was the preparation of a standard for certification of HATTs, which overall background philosophy for risk can be seen in [23]. A type classification similar to the International Electrotechnical Commission wind turbine classes is proposed in [24] that are in accordance with what has been discussed in the sections above. Finally, the partial safety factors in the standard are calibrated for HATTs.…”