Abstract

SALGUEIRO, D. V.; PABLO, H. de; NEVES, R.  and  MATEUS, M.. Modelling the thermal effluent of a near coast power plant (Sines, Portugal). RGCI [online]. 2015, vol.15, n.4, pp.533-544. ISSN 1646-8872.  https://doi.org/10.5894/rgci577.

The present work is focused on the dispersion of a thermal effluent, produced by the Sines power plant, Portugal, along coastal waters. This facility intakes a yearly average around 40 m³/s of seawater, for the required cooling process, which is subsequently discharged back to the ocean at a 10 ºC increase in temperature. A three-dimensional hydrodynamic local model was nested into a regional model and set up to simulate the transport of the thermal effluent during two distinct periods, August and October 2013, respectively featuring dominant north and south wind. The simulations were performed for both situations, with and without the thermal discharge, where the later provides baseline scenarios. Obtained model results closely followed the existing field data. The temperature increase is shown to decay from 10 ºC near the outlet vicinity to 2 ºC at a distance of 2 km from the outlet for both scenarios. Even though the main driving force of this phenomenon is the wind, tidal conditions also have additional influence on thermal plume dispersion near the discharge area. In the north wind scenario the plume extends away from the coast while under south wind dominance the plume is contained near the coast, extending towards the inlet. As a consequence there is a positive feedback under south wind dominance, which is caused by the intake of already warm water from the thermal plume itself. Consequently, south wind dominance is the most unfavorable scenario for both coastal environment and the operational efficiency of the power plant.

Keywords : Thermal discharge; Three-dimensional model; Coastal hydrodynamics; Water temperature.

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