A spatially explicit techno-economic framework for assessing co-located floating wind-wave energy farms

The global transition toward sustainable and low-carbon energy systems is driving increasing reliance on renewable energy sources. Offshore wind and wave energy are expected to play an increasingly important role in this transition due to their large untapped resource potential. Co-locating floating offshore wind turbines with wave energy converters can reduce costs, enhance power stability, and improve the spatial efficiency of offshore renewable energy developments. However, most existing studies assess hybrid systems at single sites or without accounting for long-term variability, spatial constraints or techno-economic interactions across broad marine regions. This work introduces a spatially explicit techno-economic assessment framework for co-located floating wind–wave energy farms that integrates multi-decadal metocean hindcasts, multi-criteria site selection, device-scale operational modelling, hybrid variability metrics, and cost modelling. The framework is demonstrated using a 510 MW hybrid farm evaluated across the mainland Portuguese offshore region, drawing on 45 years of SWAN- and ERA5-derived wave and wind conditions. At each feasible location, the method computes annual energy production, capacity factor, non-operational time, complementarity indicators, levelized cost of energy (LCoE), and a composite variability index. These metrics are synthesized using K-means clustering to identify spatial regimes of hybrid performance, variability reduction and economic feasibility. Results show that wave energy provides near-continuous availability, substantially reducing zero-generation events, while wind contributes most of the variability and downtime. Offshore areas off central Portugal (P3–P5), and to a lesser extent parts of the north, achieve the strongest hybrid performance, with high CCF and the lowest LCoE values (≈80–100 €/MWh). The clustering analysis identifies three techno-economic hybrid classes that capture the interplay among resource quality, complementarity and cost of energy. Beyond the case study, the methodology offers a transferable framework for early-stage planning of hybrid offshore renewable energy systems, supporting marine spatial planning, technology selection and strategic investment.