A twin unidirectional impulse turbine topology for OWC based wave energy plants

• Published in: Renewable energy Vol. 34; no. 3; pp. 692 - 698
• Main Authors: Jayashankar, V., Anand, S., Geetha, T., Santhakumar, S., Jagadeesh Kumar, V., Ravindran, M., Setoguchi, T., Takao, M., Toyota, K., Nagata, S.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01-03-2009; Elsevier
• Subjects: Applied sciences; Energy; Energy. Thermal use of fuels; Engines and turbines; Equipments for energy generation and conversion: thermal, electrical, mechanical energy, etc; Exact sciences and technology; Frequency domain; Impulse turbine; Natural energy; OWC; Time domain; Wave energy; Wave to wire model; Asia; India; INW, Japan; Frequency domain; Time domain; Wave energy; OWC; Impulse turbine; Wave to wire model; Ocean energy; Technical progress; Wave power generator; Turbine; Topology; Case study; Energetic efficiency; Electric power production; Performance
• ISSN: 0960-1481; 1879-0682
• DOI: 10.1016/j.renene.2008.05.028

Experimental results from near shore bottom standing OWC based wave energy plants in Japan and India have now been available for about a decade. Historically the weakest link in the conversion efficiency of OWC based wave energy plants built so far has been the bidirectional turbine. This is possibly because a single turbine has been required to deliver power when the plant is exposed to random incident wave excitation varying by a factor of 10. A new topology that uses twin unidirectional turbines (which features a high efficiency spanning a broad range) is proposed. Using the Indian Wave Energy plant as a case study, it is shown that the power output from such a module considerably exceeds existing optimal configurations including those based on a fixed guide vane impulse turbine, linked guide vane impulse turbine or a Well's turbine. A wave to wire efficiency of the order of 50% over the incident range is shown to be feasible in a credible manner by showing the output at all stages of the conversion process. A frequency domain technique is used to compute the OWC efficiency and a time domain approach used for the power module with the turbine pressure being the pivotal variable.