Integrated CO2 Capture and Thermoelectric Waste-Heat Recovery in an ENF-SOGI-Controlled Hybrid PV–Battery System

Abstract

The efficacy of low-carbon power systems is reduced by the high energy demand of conventional CO2 capture processes, the loss of recoverable thermal energy, and power-quality disturbances associated with variable renewable generation. This study suggests an integrated framework that integrates membrane-assisted CO2 capture, thermoelectric waste-heat recovery, photovoltaic generation, battery energy storage, and a grid-connected converter to address these issues. During the capture of CO2, the waste heat is converted into electrical energy using a thermoelectric generator and integrated with the photovoltaic and battery outputs through a common DC link. A conventional phase-locked loop is not necessary for reference-signal extraction, DC-offset rejection, harmonic compensation, and power management, as an Enhanced Notch Filter-Based Second-Order Generalized Integrator (ENF-SOGI) controller is employed. The effectiveness of the proposed system is demonstrated by simulation and experimental studies conducted under variable irradiance, nonlinear loading, distorted-load, and distorted-grid-voltage conditions. The membrane unit achieves a CO2 capture efficiency of approximately 92%, with a specific energy consumption of 1.2 GJ/tCO2. The controller reduces the source-current total harmonic distortion from 24.3% to approximately 1.2–1.3%, limits its experimental variation to ±5 V, and maintains the DC-link voltage at approximately 600 V. Consequently, the proposed architecture is designed to facilitate low-carbon grid operation by integrating a unified energy-management system that includes high-efficiency CO2 separation, the productive recovery of waste heat from the capture process, increased renewable energy utilization, and IEEE-compliant source-current quality.