This document constitutes Deliverable “D5.3 Performance function parameterisation” of the LiftWEC project. LiftWEC is a collaborative research project funded by the European Union’s Horizon 2020 Research and Innovation Programme under Grant Agreement No 851885. It is the intention of the project consortium that the LiftWEC project culminates in the development of one or more promising configurations of a Wave Energy Converter operating through the use of one or more rotating hydrofoils that generate lift as the primary interaction with the incident waves.

The report consists of the description of the performance function (PF) and its parametric structure. The presented PF can be used for development of the control methods for the cyclorotor based wave energy converter and its performance assessment in terms of Levelised Cost of Energy (LCoE) [1]. The document is based on the previous deliverable “D5.1 Determination of performance function parametric structure” [2], which was submitted during the early stages of the LiftWEC project and inherits some of its elements and structure. The research of the LiftWEC technology in collaboration with work packages WP6 Structural Design and WP8 Cost of Energy allows us to further clarify and determine elements of capital and operational costs of the device [3,4,5] as well as a structural fatigue which can be caused by a real time control [6].

Ideally, the performance structure should be based on a bulk economic performance indicator, such as LCoE and that performance indicator be expressible as a function of the control actions, so that the control actions can be optimised, maximising the economic performance of the LiftWEC. This ideal presents two difficulties: LCoE is very difficult to enumerate, especially with regard to operational costs, and it is virtually impossible to propagate the effect of control actions all the way through to LCoE. It has been emphasised in the deliverables of our colleagues, the uncertainty level of the LCoE at this stage of development (Stage 1, TRL 3) is in the order of -30% to 80% [4].

The deliverable summarises the performance assessment results which were obtained in the set of authors’ open access publications [7,8,9], where the optimal control strategy has been obtained for a cyclorotor based WEC in terms of mechanical power optimisation. It illustrates the range of cyclorotors’ control effectors and their influence on device mechanical performance. The authors also show how the generated mechanical power is connected with electrical energy production. At the end of the document, the authors present the selected current technology state of LiftWEC performance function 𝑬𝑻𝒐𝒕𝒂𝒍. The PF consists of a combination of the generated electrical power 𝑬𝑬𝒍𝒆𝒄𝒕𝒓𝒊𝒄𝒂𝒍 (articulated in Section 4) and fatigue damage D (Section 3).