Identification of Thermal Springs in Eastern DRC, Case Study of Katanga, Kivu and Ituri Provinces
Total Page：16
File Type：pdf, Size：1020Kb
Proceedings, 8th African Rift Geothermal Conference Nairobi, Kenya: 2 – 8 November 2020 Identification of Thermal Springs in Eastern DRC, Case Study of Katanga, Kivu and Ituri Provinces Deogratias A. Odhipio0, Pacifique S. Mukandala0, Grace N. Kawa0, Georges M. Kasay0,0, Vikandy S.H. Mambo00 1Department of Geology, Université Officielle de Ruwenzori, DRC 2Department of Geoscience, Pan African University of Life and Earth Science, University of Ibadan, Nigeria 3Department of Chemistry, Université de Kinshasa, DRC. Emails:[email protected], [email protected], [email protected], [email protected] Keywords: Thermal spring, Power potential, Geologic formation, Eastern DRC. ABSTRACT The Democratic Republic of Congo (DRC) has a huge and varied renewable and non- renewable energy potential. It consists of hydroelectricity, timber, oil, coal, gas, solar energy, biomass and geothermal energy. Among others, geothermal potential is very common in the Eastern part of the DRC. The substratum of the Eastern DRC consists of a basement complex with an age varying between Archean and middle Proterozoic. It is covered by upper Proterozoic sedimentary rocks in several areas. These geologic formations are folded in a general northeast direction which, from Kiambi, bends to take a north-south direction. Besides these orogenic movements caused by tangential pressures, the East of the DRC is a beautiful illustration of relatively recent vertical movements, giving raise to the rift valley which is filled up by Phanerozoic sediments. The fractures are often lined by surface and subsurface geothermal manifestations. Hot springs are the most common surface manifestations. They are located in many places of the western branch of the rift in the DRC. Some of them are relatively very hot for the most part and their chemical composition is dominated by the abundant presence of sulphide and salt minerals. They are located in the valley of Lake Albert, Lake Edward, in the Semliki river basin, in the Lowa, Ulindi, Ruzizi, Elila, Lualaba, Luama, Luika, Lukuga, Luvua, Lufira, between the Lomami and Luembe stream, in the western part of the South of Lake Tanganyika and finally in the volcanic region around Lake Kivu. 1. Introduction The DRC has a huge and varied energy potential which can be exploited from hydroelectricity, wood, proven oil reserves, proven coal reserves, methane gas in the Odhipio et al. lake Kivu, solar energy, agricultural biomass, wind, nuclear and geothermal energy (Makuku, 2019). Energy potential is very high but still underexploited. With the growing number of the population and eager need of development of many aspects of life, the energy demand is also increasing. This has to be addressed by exploiting the potential which is already known and explore the unknown. The DRC is one of the first African countries to learn about geothermal energy. Indeed the first geothermal installation in Africa was born in the country in 1952 and had a production of 0.2 MW at the geothermal site of Kiabukwa with a temperature of 91°C in the province of Katanga. This production did not last long after independence perhaps because of Belgian colonial paternalism, or because of the bankruptcy of the second republic. (Mambo and Mahinda, 2012). However, there is much work to be done before exploitation. All starts from a good and correct assessment of the energy potential of the country. The influence of geothermal energy in the DRC tends to be positive mainly due to the prevention and protection of environmental pollution impacts related to the use of fossil fuels and woodfire. Preservation of dense forest is a key to the climate change and global warming disasters. Another aspect is that the DRC is a vast country and energy supplies are always far from remote villages and towns. Considering the cost of energy transportation from the supply center to the consumption area, it is always good to think of local energy supply for small communities in villages or towns. Some of the potential energy sources which can fit this demand are most of them renewable such as wind, solar and geothermal energy. The last one is mostly concentrated in the East part of the country which is located within the western branch of the African Rift System. The presence of geothermal energy potential is evidenced by the presence of surface manifestations with the most common being hot springs. Several hot springs are located in the East of the DRC within the rift. Some of them have been well studied and others are still unknown to the scientific community (Makuku et al., 2019; Mambo et al., 2008; Mukandala et al., 2018; Luse and Makonga, 2019). A recent study was done by Makuku (2019) and gave an inventory of thermal springs in the DRC and their development plans for the electrification of rural areas. It focused on the important contribution of hydroelectricity in the electrification of urban and rural agglomerations of the DRC in general and of geothermal energy to cover up the lack of energy remote areas of the eastern DRC. Another study did a regional detailed review of hot springs in the East of the DRC (Mambo et al., 2008). Nevertheless, since then, some other hot springs have been identified and the list needs to be updated with some new discoveries. This work aims to identify thermal springs in the East of the DRC and to describe the geology of this part of the country, by including new findings from the recent implemented researches and new discoveries of unreported hot springs. It will constitute a useful new database both for the scientific community and for the government, to make a wise choice on the source of a useful, clean and affordable energy for the Congolese people. 2. Literature review Geothermal manifestations are known in a great part of the East African Rift System and a part of southern Africa (Figure 1). They are located along the rift where they Odhipio et al. have various temperatures depending on their geographic locations. In some places within the rift do not show any surface geothermal manifestations but have huge geothermal potentials which is related to subsurface or deep manifestations. The entire eastern borders of the DRC extend along the western branch of the East African Rift region (Delvaux et al., 2006). In the eastern branch of the rift, in Kenya and Ethiopia, the geothermal power has already been developed (Varet, 2014). In the western branch of the East African rift system, Uganda is at an advanced stage of geothermal energy production (Kato and Kraml, 2000). The East of the DR Congo is dominated by volcanic provinces with two known active volcanoes, Nyiragongo and Nyamulagira (Scoon, 2020). This part of the country has also got several geothermal surface manifestations which are mainly represented by hot springs (Figure 1). They are situated in different locations and provinces and are of various temperatures (Makuku, 2019; Mambo et al, 2008; Mambo et al, 2012). Prospecting and identifying these hot springs could lead to the research of clean and affordable sources of energy. This would allow the government to select the best available energy resources, taking into account not only the cost but also other benefits, including long-term environmental benefits. In this logic, preliminary reconnaissance studies were already carried out in the past, by Belgian researchers on the distribution of thermal springs in Katanga (Cornet, 1906), on the thermal springs of Bas-Katanga (Mathieu, 1913) in the region of Katanga and also the thermo-mineral sources of Kivu. Another research focused later on the relations between hot springs with the great radial fractures and their use from a tectonic point of view (Boutakoff, 1933), and then on the thermal sources of the Orientale Province (Passau, 1933). These studies most likely facilitated the installation of Africa’s first geothermal power plant at the Kiabukwa geothermal site in 1952, with a capacity of 0.2 MW (Mambo et al., 2012). Odhipio et al. Figure 1: Index map of thermal springs in Central, Eastern and Southern Africa (after Gerald et al., 1965). 3. Regional Geology of the East of the DRC The geology of the DRC is characterized by two large structural groups separated by a discrepancy (an important gap): • The metamorphic and basement formations (Precambrian terrains) forming an uninterrupted ring around the Congo Basin; • Non-metamorphosed cover formations (Phanerozoic terrain), generally fossiliferous and of age between the Upper Carboniferous and the Holocene. 3.1.The basement grounds The basement is subdivided into tectonostratigraphic units (Figure 2) which are: a) Archean shields are greater than or equal to 2500 Ma outcropping in northern Congo and Kasai. The northern part includes, in addition to North Kivu and Ruwenzori, the region which extends from the Congo-Nile watershed ridge in the East to the Ubangui watershed in the West. The geologic formations here are crystallophyllian series formed mainly of mica schist, quartzites, graphitic schists and gneiss; b) The lower and middle Precambrian belt (2500 to 1300 Ma) represent the sediments which are deposited in mobile meridian zones located on the eastern and western Odhipio et al. borders of the craton and in transverse intracratonic ditches. Its southern part is the largest part of the province of Katanga as well as a portion of Kasai Oriental; c) The cover of the Upper Precambrian called the Katangian whose sediments are deposited on the epicontinental platforms and in the subsistence areas of the Congo craton (pleated and tabular Katanga). Figure 2: Geological map of the eastern part of the DRC (after Delvaux et al., 2016). This substratum brings together all of the magmatic and metamorphic formations (Figure 2) set up during the period between the Archean and the Neoproterozoic (3.3 and 0.57 Ga): • Cratonic zones : Kasai, W.