Abstract
Ocean wave energy is one of the most abundant renewable energy sources on earth. However, deploying commercial-scale ocean wave energy harvesting devices has a high cost, which is the main challenge addressed in the proposed work. Breakwaters are frequently constructed for shoreline protection, coastal restoration, or harbor installation. A dual-functional wave-power plant integrated with slotted barrier breakwater is proposed to reduce costs and facilitate wave energy commercialization. The fixed oscillating water column (OWC) type wave energy converter is chosen for its simplistic pre-castable manufacturing capabilities and electrical power generation components out of water. A slotted barrier breakwater allows for the water quality near the shore to be maintained while reducing the amount of wave energy transmitted to the shore. Previous experiments have been conducted using a small scale wave flume for a slotted barrier OWC design consisting of a hollow rectangular prism air chamber with circular orifice and slotted barrier with varying porosities of 10%, 15%, 20%, and 25%. Data was collected from four capacitance type wave gauges, differential pressure sensor, and single axis force balance. The wave gauges were installed in two pairs adjacent to the OWC slotted barrier model to determine the amount of wave energy reflected and transmitted by the model after conducting Goda-two point wave separation. The differential pressure sensor was installed to the air chamber to determine the efficiency. The force balance was installed behind the slotted barrier to determine the amount of wave loading for different wave conditions. The wave conditions that were tested at three water depths of 0.16 cm, 0.17 cm, and 0.18 cm, varying wave period from 0.7 to 1.4 seconds on a 0.1 second interval with a fixed wave amplitude of 1.0cm, and a fixed 1.0 second wave period with a varying amplitude from 0.5 to 2.0 cm on a 0.5 cm interval. Results showed the lower porosity had a greater efficiency, wave loading, and wave reflection. The small change in water depth yielded negligible change in observed parameters. The purpose of the proposed study is to extend this design to deep water applications. In the literature, an OWC solid barrier with a bottom plate experimentally tested for 2 cm and 3 cm wave amplitudes, period ranging from 1 to 1.6 seconds on a 0.1 second interval, period ranging from 2.0 to 2.6 seconds on a 0.2 second interval, and fixed water depth of 40 cm. The results show that the lengthened bottom-plate can effectively increase the energy dissipation and lead to lower reflection and transmission coefficients. These results are limited to a solid barrier and do not report on the effects on the wave loading of the structure. Therefore we plan to modify our existing shallow water OWC slotted barrier design for a deep water application by affixing a bottom plate which we anticipate will increase efficiency, wave loading, and reduce wave transmission.