The present paper compares in economic terms, four technological alternatives to use offshore renewable energies: floating offshore wind energy technology, floating offshore wave energy systems, floating offshore co-located systems and floating offshore hybrid systems. These alternatives are compared considering different locations and sizes of the farms. Studies such as this can be useful for planning strategies and decision-making, particularly to investors that have to decide if and how to develop and deploy particular technologies in deep waters. The results indicate that the best alternative considering the life-cycle cost and LCOE is the floating offshore wind energy technology. Floating offshore co-located systems have the second best result, being a better alternative than floating offshore wave energy devices or floating offshore hybrid systems. (C) 2017 Elsevier Ltd. All rights reserved.