Effects of tidal range on mooring systems of wave energy converters

Wave energy converters are currently proposed to be deployed near coastal area for the closeness to the infrastructure and for ease of maintenance in order to reduce operational costs. The motivation behind this work is the fact that the deployment depths during the highest and lowest tides will have a significant effect on the mooring system of WECs. In this paper, the issue will be investigated by numerical modelling (using ANSYS AQWA) for both catenary and taut moorings to examine the performance of the mooring system in varying tides. The case study being considered is the ¼- scale wave energy test site in Galway Bay off the west coast of Ireland where some marine renewable energy devices can be tested. In this test site, the tidal range is macro-tidal with a range of approximately 6 m which is a large value relative to the water depth. In the numerical analysis, ANSYS AQWA suite has been used to simulate moored devices under wave excitation at varying tidal ranges. Results show that the highest tide will give rise to larger forces. While at lower depths, slackening of the mooring occurs. Therefore, the mooring lines must be designed to accommodate both situations.

A demonstration of wireless sensing for long-term monitoring of water quality

At a time when technological advances are providing new sensor capabilities, novel network capabilities, long-range communications technologies and data interpreting and delivery formats via the World Wide Web, we never before had such opportunities to sense and analyse the environment around us. However, the challenges exist. While measurement and detection of environmental pollutants can be successful under laboratory-controlled conditions, continuous in-situ monitoring remains one of the most challenging aspects of environmental sensing. This paper describes the development and test of a multi-sensor heterogeneous real-time water monitoring system. A multi-sensor system was deployed in the River Lee, County Cork, Ireland to monitor water quality parameters such as pH, temperature, conductivity, turbidity and dissolved oxygen. The R. Lee comprises of a tidal water system that provides an interesting test site to monitor. The multi-sensor system set-up is described and results of the sensor deployment and the various challenges are discussed.