We investigated proposed design of a double-flash system and compared it to the existing single-flash power plant in Dieng, Indonesia, which uses waste brine from a high pressure separator. The performance of the double-flash system was evaluated using the second law of thermodynamics, and this was based on energy and exergy analyses. The Engineering Equation Solver (EES) was used to solve the relevant mathematical equations. Our results indicate that the double-flash design is interesting for application in Dieng since the power output would increase by 19.97%. Moreover, the precipitation system to avoid silica deposition in the injection well does not have to change much. Therefore, the building costs associated with the new double-flash system would be minimal. The available exergy from the reservoir is 66,204 kW based on the enthalpy determined by TFT (Tracer Flow Test) measurements. The single-flash power plant has a net power output of 23,400 kW with a second law efficiency of 36.7%. In the double-flash design, components such as a LPS, a second purifier and an HPT would be added to the plant. Furthermore, our calculations indicate that the power plant's output and second law efficiency would increase to 29,155 kW and 44.04%, respectively. The waste brine disposed of using this precipitation system would decrease by 8.22% at 5443 kW. (C) 2015 Elsevier Ltd. All rights reserved.