Session: 08-08-02: Design Analysis and Optimization of Energy Conversion Systems - 2

Paper Number: 137732

137732 - Wave Energy Converter for Off-Grid Applications 

The energy sector is steadily moving towards a clean energy future; while solar, wind, and hydropower energy continue to dominate the industry, marine renewable energy research has also proven to be an area of growing interest. Marine energy broadly encompasses a range of marine hydrokinetic energy forms, including tidal energy, current energy, and wave energy. Of these energy forms, wave energy conversion has become a prominent focus of research and development efforts.

For this project, a wave energy converter (WEC) is designed for off-grid applications. The  objective of the project is to build off existing designs to reduce production costs, enhance efficiency, and produce a device that can be readily integrated into off-shore or near-shore power systems. The team aims to do this by creating a point-absorber style WEC prototype, where a flotation device is used to convert the oscillating force of the waves to electricity. Low-cost manufacturing methods have been used to produce the prototype.

This designed convert utilizes the rising and falling motion of a wave to generate electricity. The device uses a stationary rack and a floating buoy that contains a pinion gear, a gear box, and a generator to transmit vertical translational motion of waves into rotational motion of the pinion. The vertical translation movement of the buoy along the rack rotates the pinion shaft. The pinion shaft is attached to a gear box that uses a set of clutches to convert the bidirectional input to a unidirectional output, optimizing the system efficiency. The gearbox also amplifies the rotational speed to ensure the generator receives the necessary RPM. The output of the gear box is then coupled to a generator that charges an internal battery in the buoy. The rack is attached to a frame that guides the buoy and maintains proper alignment with the rack.

After finalizing the design for the WEC and its power-takeoff system, a series of analyses, simulations, and testing protocols were carried out to validate the proposed design elements. The buoyancy of the buoy and WEC frame were optimized under open-water conditions and closed-environment conditions; the results of these calculations were then verified using algorithmic hydrodynamic diffraction tools. Finite element analyses were also employed to characterize the stress propagation through the various gears in the system. To simulate the performance of the system, a system dynamics framework was proposed to numerically represent the characteristics of the translational, rotational, and electrical energy domains considered in the system. Iterative testings of the system electronics and power-takeoff were performed, ultimately culminating in closed-environment testing under moderate wave conditions (1-ft, 0.3-Hz waves).

It is anticipated that the proposed design will provide valuable insight into the development of economical, energy efficient wave energy converter technologies. The development of WEC devices like the one proposed in this paper is extremely relevant in meeting demands for marine renewable energy, with identified applications ranging from aquaculture industry implementation to independent power generation for coastal community microgrids. Overall, this investigation demonstrates potential for future research that will contribute to the advancement of the marine renewable energy industry.

Presenting Author: Francisca Anunobi Saint Martin's University

Presenting Author Biography: Francisca Anunobi is a graduate student in Department of Mechanical Engineering of Saint Martin's University.

Authors:

Francisca Anunobi Saint Martin's University
Quinton Spitler Saint Martin's University
Patricia Mcgarrah Saint Martin's University
Shawn Duan Saint Martin's University