Thermoeconomic Modeling, Analysis, and Comparison of Single Flash Cycle and Organic Rankine Cycle for Geothermal Power Generation in Montelago, Philippines

The Philippines has abundant geothermal resources because of its advantageous location in the Pacific Ring of Fire. To address the country's increasing electricity demand, the Department of Energy is considering developing low-temperature resources for power generation. One of these resources is the geothermal field in Montelago, Mindoro, which has an average geothermal fluid temperature of 180°C - 200°C. Thermoeconomic analysis was applied to a single flash cycle and two configurations of organic Rankine cycle with various working fluids to evaluate the resource. The simulation of the cycle was done using the Engineering Equation Solver. Having the same operating conditions, the single flash cycle generates the highest power output of 5393 kW with a thermal and 2nd law efficiency of 4.86% and 23.77
^%
, respectively. The simple organic Rankine and organic Rankine cycles with an internal heat exchanger can produce a power of 4916 kW and 5106 kW, respectively. However, there are negative exergy rates in the organic Rankine cycle because of the low operating conditions for the two pressure sides of the cycle. A parametric study was conducted to determine the effect of the variation of the high-pressure side of the cycle on the plant's performance. Based on the result, the cycle that can produce the maximum power output is the organic Rankine cycle with an internal heat exchanger using isopentane, which can reach up to 9980 kW with a thermal and 2nd law efficiency of 14.56% and 53.27%, respectively.