Technical Performance of Organic Rankine Cycle (ORC) for Low-Enthalpy Geothermal Power Generation
Abstract
The present study evaluates the performance of low-enthalpy geothermal brine as a heat source for power generation using Organic Rankine Cycle (ORC) technology at the Kiejo-Mbaka hot springs. The Kiejo-Mbaka pilot well brine temperature, pressure, and mass flow rate were measured as 348 K, 1.3 bar, and 1 kg/s, respectively. Besides, five environmentally friendly working fluids with low boiling points and low global warming potential (R600, R123, R245ca, R245fa, and R141b) were selected for this analysis. A thermodynamic investigation of the ORC system was conducted considering the effects of expander inlet temperature, expander inlet pressure, mass flow rate, and condensation temperature. The system performance was assessed using net power output (Pnet) and thermal efficiency (ηth) as key indicators. The results show that the dry fluids R141b and R600 achieved the highest performance, with thermal efficiency reaching approximately 39.0% and net power output of 177.48 kW. Among the tested fluids, R245ca and R141b demonstrated strong performance in terms of thermal efficiency, while R600 and R141b excelled in net power output under the given operating conditions. Overall, R141b emerged as the most promising working fluid for the Kiejo-Mbaka geothermal source, by achieving a thermal efficiency of 42.20% along with consistently high-power output across different conditions.
Downloads
References
Akander, J. (2000). The ORC method. Effective modelling of thermal performance of multilayer building components.
Akorede, M. F., Hizam, H., & Pouresmaeil, E. (2010). Distributed energy resources and benefits to the environment. Renewable and Sustainable Energy Reviews, 14(2), 724-734.
Baral, S. (2019). Experimental and techno‐economic analysis of solar‐geothermal organic Rankine cycle technology for power generation in Nepal. International Journal of Photoenergy, 2019(1), 5814265.
Chikwama, N., Manyuchi, M., & Sukdeo, N. (2022). Techno-economic assessment for geothermal energy in Zimbabwe. Proceedings of the International Conference on Industrial Engineering and Operations Management,
Chitgar, N., Hemmati, A., & Sadrzadeh, M. (2023). A comparative performance analysis, working fluid selection, and machine learning optimization of ORC systems driven by geothermal energy. Energy Conversion and Management, 286, 117072.
Dickson, M. H., & Fanelli, M. (2018). What is geothermal energy? In Renewable energy (pp. Vol1_302-Vol301_328). Routledge.
Gerutu, G. B., Kivugo, R. O., Lujaji, F., & Chombo, P. V. (2023). Thermo-economic performance of organic rankine cycle-based waste heat recovery for power generation at a wide range of operating conditions. Global Journal of Energy Technology Research Updates, 10, 1-23.
Hettiarachchi, H. M., Golubovic, M., Worek, W. M., & Ikegami, Y. (2007). Optimum design criteria for an organic Rankine cycle using low-temperature geothermal heat sources. Energy, 32(9), 1698-1706.
Hijriawan, M., Pambudi, N. A., Biddinika, M., Wijayanto, D., Kuncoro, I., Rudiyanto, B., & Wibowo, K. (2019). Organic Rankine Cycle (ORC) in geothermal power plants. Journal of Physics: Conference Series,
Imran, M., Usman, M., Park, B.-S., & Yang, Y. (2016). Comparative assessment of Organic Rankine Cycle integration for low temperature geothermal heat source applications. Energy, 102, 473-490.
Kajugus, S. I. (2021). Geothermal development in Tanzania–An update. Short Course V on Exploration and Development of Geothermal Resources, Naivasha, Kenya.
Khennich, M., & Galanis, N. (2012). Optimal design of ORC systems with a low-temperature heat source. Entropy, 14(2), 370-389.
Nouman, J. (2012). Comparative studies and analyses of working fluids for Organic Rankine Cycles-ORC. In.
Oyewunmi, O. A., Kirmse, C. J., Pantaleo, A. M., & Markides, C. N. (2017). Performance of working-fluid mixtures in ORC-CHP systems for different heat-demand segments and heat-recovery temperature levels. Energy Conversion and Management, 148, 1508-1524.
Pambudi, N. A. (2018). Geothermal power generation in Indonesia, a country within the ring of fire: Current status, future development and policy. Renewable and Sustainable Energy Reviews, 81, 2893-2901.
Pintoro, A., Ambarita, H., Nur, T., & Napitupulu, F. (2018). Performance analysis of low temperature heat source of organic Rankine cycle for geothermal application. IOP Conference Series: Materials Science and Engineering,
Prananto, L. A., Juangsa, F. B., Iqbal, R. M., Aziz, M., & Soelaiman, T. A. F. (2018). Dry steam cycle application for excess steam utilization: Kamojang geothermal power plant case study. Renewable energy, 117, 157-165.
Rashwan, S. S., Dincer, I., & Mohany, A. (2019). Analysis and assessment of cascaded closed loop type organic Rankine cycle. Energy Conversion and Management, 184, 416-426.
Rizzello, D., Armadillo, E., Pasqua, C., Pisani, P., Principe, C., Lelli, M., Didas, M., Giordan, V., Mnjokava, T., & Kabaka, K. (2022). Assessment of the Kiejo-Mbaka geothermal field by three-dimensional geophysical modelling. Geomechanics and Geophysics for Geo-Energy and Geo-Resources, 8(5), 143.
Thangavel, S., Verma, V., Tarodiya, R., & Kaliyaperumal, P. (2021). Comparative analysis and evaluation of different working fluids for the organic rankine cycle performance. Materials Today: Proceedings, 47, 2580-2584.
Zhang, L., Chen, S., & Zhang, C. (2019). Geothermal power generation in China: Status and prospects. Energy Science & Engineering, 7(5), 1428-1450.
Copyright (c) 2025 Peter Elias Maguha, Gerutu Bosinge Gerutu, Esebi Nyari, Sosthenes Karugaba, Pius Victor Chombo
This work is licensed under a Creative Commons Attribution 4.0 International License.
