In this 3-year funded LiftWEC Project, partners collaborate to determine the economic potential of a new type of wave energy converter using lift forces to convert wave energy into electricity. The LiftWEC consist of two hydrofoils rotating around a horizontal axis interacting with the incident waves. Different configurations of support structures for attaching the rotor and generators have been analysed and evaluated in Deliverable 8.4 using the LiftWEC Levelised Cost of Energy (LCoE) Calculation Tool. Based on these results, and with consensus from the consortium, the Spar Buoy LiftWEC concept shown below on Figure 1 was selected for final optimisation.

The assumptions used for each cost centre are detailed in Deliverable 8.4 and the assumed effect on costs from changing the dimension on Capital Expenditures, Operational Expenditures and Annual Energy Production will be described in this deliverable.

This deliverable describes a methodology and assumptions in which the effect of changing a design parameter effects the system weight, cost and performance and resulting LCoE. If the specified range of parameter change leads to a minimum LCOE value this can be identified as an optimal solution in terms of cost effectiveness. The parameter chosen for demonstrating this methodology is the span of the rotor foils varied from 20 meter to 50 meter.

The general form of the hydrofoil rotor, power take-off system and its pitch control are essentially the same for all dimensions of the span, the difference being increased power rating due to increased foil span, and the structural loads experienced by the foils, support structure and moorings.

By quantifying this relationship and calculating the LCoE for four different spans at three different installation sites, an indication of how much the LCoE is affected not only by span, but also by the given site is obtained and presented. The study shows that the longer the span the lower the LCOE. The optimal dimension of the LiftWEC concept for the chosen location is the LiftWEC with the longest span. The trend shows that the LCOE is lowest at a deployment location with most incident wave power.

The resulting LCoE calculated for 4 different spans and three deployment sites will allow to quantify the project to further detail the relationship between economic cost and structural span.

Results from the LCoE assessment will be fed back into the concept evaluation (WP2) to help identifying the design elements of the configuration that offer the greatest potential for reduction in LCoE with further investigation.