Investigations of organic Rankine cycle with various working fluids on geothermal energy for development of distributed generation in Indonesia

In this study, organic Rankine cycle (ORC) combined with geothermal energy applied for distributed generation (DG) was developed to resolve the problem in Indonesia, especially for remote areas. High investment cost for building traditional power plant in remote areas is a big problem. To increase the utilization of renewable energies, geothermal energy is a great heat source and able to be chosen for resolving energy shortage in Indonesia, in which the useful range of heat source temperature for ORC is between 110 and 180 °C on predictions in this work. The potential energy calculated in Mataloko-02, East Nusa Tenggara, Indonesia, for geothermal was 11,795.57 kW. The predictions of net power generation, net thermal efficiency and exergy were carried out with various heat source temperatures with different working fluids, which were R245fa, R1233zde, R1224ydz, Novec649, R1336mzzz, R1234zez, R141b and Butane. The result showed that R141b has a good performance with the highest net thermal efficiency and exergy. The highest net power generation achieved by using Butane. According to environmental consideration, R141b had high values of Global Warming Potential (GWP) and Ozone Depletion Potential (ODP) compared with other working fluids selected. Based on predictions, R1233zde and R1224ydz presented as potential working fluids to replace the R141b with the best performance in ORC system. In addition, there is an idea proposed to combined ORC and DG to resolve the problem facing of sustainability electricity development and decrease the high investment cost on grid power supply and power losses for the remote areas.