Modeling and optimization of an ocean thermal energy conversion system for remote islands electrification. (December 2020)

• Record Type: Journal Article
• Authors: Vera, D.; Baccioli, A.; Jurado, F.; Desideri, U.
• Is Part Of: Renewable energy. Volume 162(2021)
• Page Start: 1399
• Page End: 1414
• Publication Date: 2020-12
• Subjects: Organic rankine cycle -- Ocean thermal energy conversion -- Working fluid -- Optimization; Renewable energy sources -- Periodicals; Power resources -- Periodicals; Énergies renouvelables -- Périodiques; Ressources énergétiques -- Périodiques; 333.794
• DOI: 10.1016/j.renene.2020.07.074
• Languages: English
• ISSNs: 0960-1481

Abstract

Abstract: Electrification of remote zones is often characterized by high energy costs as a result of the fossil fuels supply and cost associated to its logistic. This study performs a theoretical model and optimization of an ocean thermal energy conversion (OTEC) system coupled to an organic Rankine cycle (ORC) generator for small scale applications in the San Blas archipelago (Panama). The gross electric power has been previously set at 125 kW for the eleven working fluids selected: ammonia, R152a, R1234yf, R1234ze, R125, R134a, R161, propane, isobutene, RE143a and decafluorobutane. Results show R1234yf gets the maximum thermodynamic and net electric efficiency (3.60% and 2.57%, respectively). Ammonia reaches the maximum net electric power (99.3 kW) and, thus, the lowest pumping losses (20.59% of the gross). Besides, despite decafluorobutane shows slightly lower electric power (98 kW) and efficiencies, this fluid does not present environmental hazardous features. Sensitivity analyses show that all performance parameters of the plant are strongly affected by deep and surface seawater temperature variation. Finally, for a surface seawater temperature of 30 °C and deep 5 °C, the net electric power reached is 94.6 kW for R1234yf, 99.3 kW for ammonia and 98.0 kW for decafluorobutane. The net electric efficiency is 2.57%, 2.53% and 2.42%, and the total area required by the heat exchangers is 890 m 2, 940 m 2 and 986 m 2, respectively. Highlights: Theoretical model of a small-scale ocean thermal energy conversion system. R1234yf presents the maximum electric and thermodynamic efficiency. Ammonia reaches the maximum electric power generation and lowest pumping losses. The performance parameters strongly depend on seawater temperature changes.