The Influence of Ocean Thermal Energy Conversion System Efficiency on Net Power Output

Indonesia has great potential for utilizing Ocean Thermal Energy Conversion (OTEC) due to its strategic tropical conditions. This study analyzes the sensitivity of main parameters on the net power output of a 10 MW OTEC system based on the Organic Rankine Cycle (ORC) using Aspen Plus simulation. Variations on surface seawater temperature, deep seawater temperature, turbine efficiency, working fluid pump efficiency, and seawater pump efficiency were carried out. The simulation results show that turbine efficiency is the dominant factor, where an increase from 92% to 96% raised the net power from 9332 kW to 9958 kW. Seawater pump efficiency also gave a significant contribution by increasing the net power, while the working fluid pump efficiency only produced small improvement on the scale of tens of kilowatts. On the other hand, variations in warm and cold seawater temperatures had a limited effect. This happens because other parameters, such as mass flow rate of working fluid and seawater, were kept constant in the simulation, so temperature increase alone was not enough to influence system performance. These findings confirm that OTEC optimization is more effective through improving the efficiency of main components, especially the turbine and seawater pump.