Determination of Working Fluid on Binary Cycle System Plan for Optimization of Electric Generation on Lahendong Geothermal Field

Abstract

The potential of geothermal energy from medium to low enthalpy in Indonesia very much, if the utilization must use a binary cycle, the electricity potential will be very significant. The reservoir with liquid dominated system, produces enough brine in total fluid. Brine water has separate from separator still in high temperature aroud 170 - 192 0C. So far, the brine is only used as injection fluid, whereas the temperature including medium temperature category that can be used to produce electricity with binary cycle technology. The choice of working fluid in a binary system is very important in order to obtain optimal and safe results for the environment and economically in every electricity produced. For this reason, in this case study we will compare several working fluids, namely propane, isobutane, and refrigerant-12. The comparison is based on the amount of mass of the working fluid, the power produced, and the security for the surrounding environment and economic factors. Of the three working fluids, the most efficient is the isobutane working fluid assuming the minimum heat exchanger area is 20.66 m2, 4,303 kg / s which can produce 233.12 kW (simulation). Isobutane is hydrocarbon product environment friendly compare to thw halocarbon refrigerant-12.