PRARANCANGAN PABRIK PEMBANGKIT LISTRIK TENAGA GEOTHERMAL (PLTP) DENGAN TEKNOLOGI BINARY CYCLE

Abstract

The need for electricity in Indonesia continues to increase throughout the year, so an alternative for energy resources are needed. One of the abundant potential energy sources in Indonesia is geothermal energy. To generate electricity from geothermal energy several kinds of technologies are available, including direct steam, flashing, and binary cycle technologies. The application of binary cycle technology is interesting since it could be applied to low to medium geothermal fluid temperatures. This technology is applied in several types of cycles, but an alternative availble for a lower cost and non-corrosive materials is the Organic Rankine Cycle (ORC). Geothermal Power Plant Design (PLTP) with Binary Cycle Technology has a capacity of 45 MWh and operates continuously 330 days a year with operating hours 24 hours/day. To achieve this capacity, 205.33 kg/s of geothermal fluid is needed as the heating medium of R245fa refrigerant the double stage organic rankine cycle system. This system consists of a High Temperature (HTS) and Low Temperature (LTS) system with a mass flow refrigerant R245fa of 851.2 kg/s and 486.92 kg/s respectively which takes place cyclically. In both systems, the refrigerant flow will enter the evaporator in the form of a kettle reboiler with a demister in a subcooled liquid condition. Then the evaporator outflow will be saturated vapor in conditions of 104.5°C and 13.85 bar (HTS), as well as 69.22°C and 5.9701 bar (LTS). The flow will then go to a steam turbine with a power generating capacity of 34 MW (HTS) and 11 MW (LTS). From the turbine, the temperature and pressure of the flow will decrease significantly and flow to the condenser to be condensed into a subcooled liquid. Before entering back into the evaporator, the flow will first go through the pump and preheater/preheater circuit to increase the pressure and temperature to suit the operating conditions of the evaporator so as to form a closed cycle. The product in the form of electricity produced by this factory is as much as 35640 kW. To meet utility needs, 2291309,6 kg/hour of water, 1064,95 kWh of electricity, and 36.96 m3/minute of instrument air are required. The power plant is located in Beang, Aramaba, Pantar Tengah District, Alor Regency, East Nusa Tenggara with a land area of 31727 m2 and a total of 138 workers. From the economic evaluation, it was obtained Fixed Capital Investment (FCI) of IDR 7,240,470,359,014.58 and Working Capital (WC) of IDR 1,087,551,626,154.88. The factory profitability value was obtained in the form of a Breakeven Point (BEP) of 14.07%, ROIb of 53.12%, ROIA of 39.84%, POTb of 1.88 years, POTa of 2.51 years, SDP of 4.24% , and an IRR of 6.84%. From the results of the economic evaluation, it is feasible to build a Geothermal Power Plant (PLTP) with Binary Cycle Technology with a capacity of 45 MWh. Keywords: Geothermal fluid, Electricity, Organic Rankine Cycle, R245fa