Techno-economic analysis of a novel hybrid wind-wave floating platform concept: The OctaPlat

This work focuses on the techno-economic analysis of a novel floating offshore hybrid wind-wave platform. Floating multi-purpose platforms can potentially reduce costs associated with floating offshore wind. This work is based on the OctaPlat, a barge-type hybrid wind-wave floating platform designed at Instituto Superior Técnico, University of Lisbon. The paper presents the concept and numerical model of the floating wave platform, comprising five oscillating water column (OWC) wave energy converters, which was implemented in the object-oriented non-causal Modelica language. The OctaPlat configuration investigated here was equipped with the 15 MW IEA reference wind turbine, whose power output was computed using OpenFAST©. A sensitivity analysis of the geometry was performed, and the best performer design reached an average annual wave turbine power of 2.5 MW and a total wind-wave power of about 10.75 MW for a selected site off the west coast of Portugal. The levelized cost of energy (LCOE) was determined for a farm in the selected location. Various scenarios were assessed, and a Monte Carlo approach resulted in a probable value of LCOE of 135 €/MWh, with LCOE P90 and LCOE P10 values of 99 and 180 €/MWh, respectively. Experimental tests of the wave energy conversion systems were performed on a scale of 1:100, and comparisons with numerical results showed good agreement, with a coefficient of determination (R 2 ) of approximately 0.94 and relative differences were less than 20%, except for a few peak deviations. These results reveal the potential competitiveness of wind-wave multi-purpose platforms in floating offshore renewable energy projects. • A novel hybrid wind-wave floating platform is presented and analyzed techno-economically. • Wind turbine and oscillating water column were modeled to prove the concept. • The floating wave platform was modeled using the Modelica language. • The results show the potential competitiveness of the multi-purpose platform. • Wave energy output of OctaPlat is in the order of Mega-watts.