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This paper develops a methodology to determine the installation costs of a floating wind farm installed offshore, the value of which depends on the type of floating offshore wind platform installed. In this context, several costs in the installation process have been defined: installation of the offshore wind generators, installation of the floating offshore wind substructures, installation of the anchoring and mooring, installation of the electric systems and the commissioning or start up of the floating offshore wind farm. Furthermore, several installation scenarios have been taken into consideration regarding the shipyard surface and draught, the number of lifts, the transport, the mooring strategy and the substation configuration. The method, tested for the region of Galicia and for three sorts of floating substructures: spar, semisubmersible and tensioned leg, allows to compare different alternatives of installing a floating offshore and the most important aspects of the costs proposed. It can be useful for investors who decide to use this type of offshore renewable energy in the future. [ABSTRACT FROM AUTHOR]

Abstract The present paper proposes a Computational Fluid Dynamics model to analyze the operation cycle and exhaust gas composition in a four-stroke marine diesel engine, the Wärtsilä 6L 46. Once validated, the numerical model was employed to study the influence of several pre-injection parameters such as pre-injection rate, duration, starting instant and number of pre-injections. The purpose is to reduce consumption and emissions, especially nitrogen oxides, due to the current increasingly restrictive legislation. It was found that the fuel injection is a critical factor influencing combustion and emission characteristics. Important nitrogen oxides emission reductions were obtained for the parameters analyzed. Particularly, a 31.9% nitrogen oxides reduction was obtained using 20% pilot injection, 65.7% advancing 4° the pre-injection start angle, 20.1% shorting 4° the pre-injection duration and 36.7% using 4 pre-injections. A slight increment of hydrocarbons, carbon monoxide and consumption was obtained, lower than 5% for almost all the cases analyzed, and a negligible effect on carbon dioxide emissions. Highlights • A CFD model was developed and validated using experimental data at different loads. • Several NOx reduction mechanisms were compared. • The effect of pre-injection rate, duration, starting instant and number was evaluated. • NOx, CO, HC and CO2 emissions as well as consumption were analyzed. [ABSTRACT FROM AUTHOR]