Advancements of Novel Thermodynamic Cycles in Ocean Thermal Energy Conversion (OTEC) and Their Future Prospects in Malaysia

Abstract

Ocean Thermal Energy Conversion (OTEC) presents a promising renewable energy technology that harnesses the temperature difference between warm surface seawater and cold deep seawater. This study provides a comprehensive review of major thermodynamic cycles developed for OTEC applications, with a focus on their design innovations, working fluid enhancements, and resulting impacts on system efficiency. Traditional cycles like the closed Rankine cycle, commonly using anhydrous ammonia, exhibit efficiency limitations under moderate thermal gradients. In contrast, advanced configurations such as the Kalina and Uehara cycles utilize ammonia-water mixtures and multi-stage expansion techniques to improve thermal performance. Among the newer cycles, the Guo-Hai and reheating-injecting power absorption cycles demonstrate the most promising results, achieving efficiencies above 5%. A MATLAB-based simulation conducted using Malaysian oceanic conditions confirms that the Guo-Hai cycle yields the highest net power output and thermal efficiency. Furthermore, this study explores the feasibility of repurposing Malaysia's decommissioned offshore oil platforms for OTEC deployment. These retrofits offer significant reductions in capital expenditure, deployment time, and environmental disruption. By combining high-efficiency thermodynamic cycles with existing offshore infrastructure, Malaysia is well-positioned to advance the commercial viability of OTEC as a sustainable energy solution.