Session: 09-09-01: Advances in Wind and Ocean Energy

Paper Number: 166354

Parametric Control-Oriented Framework for a Coastal-Structure Integrated Wave Energy Converter Powered Reverse Osmosis Desalination System 

With the increasing demand for freshwater in underdeveloped and water-scarce areas, cost-effective desalination powered by renewable energy has emerged as a critical research focus. Offshore Wave Energy Converter (WEC) systems present challenges due to their remote location and complex maintenance requirements. These complexities are evident in power transmission and specialized maintenance procedures. Power transmission over long distances requires robust subsea cables, and grid integration solutions, which contribute to high installation and operational costs. Additionally, maintenance often can require specialized diving operations to inspect and repair submerged components, which further increases logistical difficulties and expenses.  To help address these issues, this study provides a framework for integrating a Coastal-Structure Integrated Wave Energy Converter (CSI-WEC) to power onshore applications, such as Reverse Osmosis (RO) desalination. This approach allows the WEC to leverage existing coastal infrastructures such as breakwaters, piers or seawalls to serve a dual purpose by enhancing energy capture while providing protection from harsh marine environments. Using pre-existing structures can help minimize the cost and maintenance of the system due to its close proximity to the shore. A wall-mounted heave (WMH) is used for this work. The system architecture is developed following the ARCADIA methodology, a model-based systems engineering (MBSE) approach designed to support the design, analysis, and validation of complex systems. The ARCADIA method provides a structured framework for capturing operational needs, functional requirements, and system components while ensuring traceability throughout the design process. This work details the design of the proposed integrated CSI-WEC-RO system, including component sizing and specification. A hydrodynamic model is also created using the WEC-Sim software and coupled with a MATLAB/Simulink-based RO desalination system, where the CSI-WEC and RO desalination system are connected via a rectifier circuit, filter circuit, and battery system with a charge controller.  The integrated model’s performance is validated via representative simulation-based case studies.  To highlight real-world performance, a case study is also conducted for two coastal locations (i.e., Rockland, Maine, and Nags Head, North Carolina) to assess regional impacts on system efficiency. Site-specific wave conditions influence energy harvesting potential, but control strategies such as a Proportional-Integral (PI) controller can help mitigate variability and optimize desalination performance.  The implemented flow controller is compared to a baseline system without active control to showcase the effectiveness of the proposed control framework. In the proposed control architecture, the concentrate flow serves as the manipulated variable, which is adjusted by changing the position of the concentrate (reject) valve. The permeate flow rate is the controlled variable (i.e., regulated) and the feed pressure is maintained by the pump. This control architecture helps to optimize the performance of the CSI-WEC-RO system. Finally, integrating the wave energy converter with desalination using existing coastal infrastructure presents a viable and scalable approach to addressing coastal water scarcity. This study provides a validated framework for future developments in coastal structure integrated wave-powered desalination, emphasizing the importance of system integration, and control optimization for sustainable freshwater production.

Presenting Author: David Koffi UNC Charlotte

Presenting Author Biography: David Koffi is a graduate student in the Applied Energy and Electromechanical Engineering (AEEE) program at UNC Charlotte.

Authors:

David Koffi UNC Charlotte
Maciej Noras UNC Charlotte
Wesley Williams UNC Charlotte
Michael Smith University of North Carolina at Charlotte