Exergy Analysis of the Mindanao 1 & 2 Geothermal Power Plants

Abstract

An exergy analysis was made on Mindanao 7 & 2 Geothermal Plants, both based on the MHI tuhine and flash system. A program was used to simulate actual plant operation to calculate exergy, identify exeqy losses and estimate the efficiencies of both plants. A comparative analysis of both plants was made using the same reference environment and their actual operating environment. The exergy analysis shows that at their actual operating environment, M7GP has 8 net plant second law efficiency of 60.4 % while M2GP has 57.2 %. At the same refemnce environment, the efficiency of M7GP dropped to 56.3 %. The analysis showed that the cooling water system, particulariy the condenser and cooling tower and the tuhines need further investigations to improve exegetic eft"rciency. The extraction and utilization of low-pressue steam from M7GP to generate additbnal power for M2G P maximizes the efficient utilization of the available geothermal msoune and resulted to an increase in net plant second law efficiency of 63.32 %. Since exergy analysis expmsses the relationship between the system and the environment, it should be integmted in the design of engineering systems and in life cycle analysis of geothermal systems.