Evaluation of Current and Feasible Future Use of Geothermal Energy at Chinyunyu Hot Spring, Zambia

Abstract: The main source of geothermal energy is the heat flow from the mantle beneath the Earth’s surface, generated by the gradual decay of radioactive isotopes in the Earth‘s crust. A hot spring is produced by the emergence of geothermally heated groundwater flowing out to the Earth’s surface. The Chinyunyu hot spring is located about 90km east of Lusaka, Zambia. Water from the spring has been artificially channeled into a large excavated pool which is used as a bathing place. Since the undiluted spring water at the source is too hot for comfortable bathing, it is mixed with surface water to reduce the temperature. There is potential for electricity generation from the Chinyunyu hot spring. Even the most recent proposed survey by the Japanese International Corporation Agency (JICA) in conjunction with the Geological Survey Department in the Ministry of Mines, Energy and Water Development (MMEWD), could not progress beyond the planning stage due to lack of funds. Notable among interest groups in geothermal energy was Kalahari GeoEnergy Limited, a private company registered in Zambia. Even though the objective of Kalahari GeoEnergy Limited was to explore and, if viable, develop geothermal energy resources to produce electrical power in Eastern and Southern Africa, the company concluded that the Chinyunyu Hot Spring was not viable for electricity generation without drilling any test wells and reaching for higher temperatures. The overall purpose of this study is to evaluate the benefits of the current use of the geothermal energy from the Chinyunyu Hot Spring, and also to explore some technically and economically feasible future applications. The study recommends electrical power generation by a binary cycle, with the assumption that drilling for larger mass flow and higher temperatures can be done. Results show that a net power capacity of 233 kWe is technically feasible with minimum environmental impact. However, the expected capital cost in the order of USD 3.4 million and specific cost of $14,500/kWe can hardly be justified without support mechanisms.