Preliminary wave energy assessment to setup a breakwater type oscillating water column ocean wave energy converter at Hambantota port, Sri Lanka

Abstract

Oscillating Water Column (OWC) is a type of Wave Energy Converter that transforms the energy of ocean waves into low-pressure pneumatic power. Subsequently, this pneumatic power is taken out by a turbine and converted to electric energy through a generator. The Sri Lankan wave energy resources were assessed and revealed that 12-15 kW/m average wave power can be generated annually and is appropriate to establish large-scale, offshore wave energy converters. The wave climate off the South-East coast of Sri Lanka is encompassed with two different wave types which are long period swell waves and locally wind propagated short period waves due to monsoons. Therefore, Hambanthota Harbor was selected as a research study area and the most appropriate place to fix a breakwater-type OWC. As per the annual and seasonal wave climate of the South East coast of Sri Lanka, this research focuses on extreme wave occurrences in July and August. In this investigation, firstly a directional, roll, and pitch ‘Wave Rider Bouy’ was placed inside the Hambanthota Harbour to collect wave climate data from July to August 2019. Then, the same ‘Wave Rider Bouy’ was placed 4 NM away outside the harbour and wave measurements were obtained. Finally, an analytical study was conducted and revealed that swell wave height and significant wave height were sufficient to generate wave power and feasible to set up a breakwater type OWC ocean wave energy converter at Hambanthota harbour. It is recommended to carry out another study to collect swell wave and significant wave data for continuous three years, to confirm the sustainability of this project.