Design and Efficiency Analysis of a Mechanical Wave Energy Converter

Wave energy is the most promising natural energy resource that is gaining momentum in the recent years. Successful attempts are made by several researchers to harness wave energy by heave, surge and sway motion of the devices; however no successful commercial model is launched till date leaving this domain as a research potential. Among the proposed technologies, point absorbers are found to be commercially viable to a greater extent primarily due to its simplicity. The present study discusses a new mechanical wave energy converter (MWEC) using point absorber as a wave energy capturing device. Heave motion of a floating buoy due to incident wave field is harnessed to produce power. The conversion takes place in four different stages namely: i) motion of a gear rack, attached to floating buoy results in heave motion; ii) this vertical reciprocating motion is converted to oscillatory rotation of a shaft by a rack and pinion arrangement; iii) alternative rotary motion is converted in to continuous unidirectional rotation using a unidirectional chain assembly; and iv) unidirectional rotation is converted in to other usable energy form. MWEC employs numerous operating advantages over other systems such as: (i) the rack and pinion gear arrangement enabling the buoy to float in line to the changing water levels automatically. (ii) use of RPM multiplier enables rotation of generator shaft at high RPM even for small displacement of float; (iii) the free wheel sprockets of unidirectional chain assembly enable the gear rack to produce a positive upward stroke and a positive downward stroke for every passing wave impact. Further, rpm multiplier shall be easily adjusted to rotate the generator at desired rpm while the whole operation shall be shut down on emergency. The paper presents a detailed analysis of the mechanical system to arrive at the efficiency of the developed MWEC. Based on the studies conducted, it is seen that the overall efficiency of the MWEC is about 19% while maintaining maximum possible efficiency of the mechanical systems involved in the design.