Country s location

Transcription

1 GEOTHERMAL EXPLORATION IN BURUNDI Short course III on Exploration for Geothermal Resources organized by UNU-GTP and KenGen Naivasha, Kenya, 24th October - 17 November, 2008 Presented by HUREGE Déogratias & WAKANA Ferdinand

2 Country s location

3 Location and economy Burundi is a landlocked country in central Africa It is borded with RDC in the West, Rwanda in the North and Tanzania in the East and South. Its area is km² Population is about 8 millions The capital is Bujumbura with about The main industry is agriculture Major j products are cotton, rice, tea, sugar and coffee Income from coffee and tea constitutes about 90% of the total t export

4 Energy egysecto sector Biomass: 95% Electricity: 2% Oil: 3% Electricity it Hydro: 95% Thermal: 5% Hydro exploitable potential: 300 MW Hydro install capacity: 32,46 MW Thermal install capacity: :5,5MW

5 .Energy sector Consumption capacity: 45 MW Importation capacity: 15 MW from RDC and SINELAC Demand capacity: 75 MW Deficit capacity: 30 MW

6 GEOTHERMAL RESEARCH IN BURUNDI HISTORY The first description of geothermal manifestations in Burundi was given by Stanley (1878) But the first specific investigation i i of activity in the country was carried out in 1968 by the UNDP following a request from the Burundian Government (McNitt 1969) This study covered eight geothermal locations.

7 PREVIOUS GEOTHERMAL RESEARCH IN BURUNDI (cont..) The geology of the surroundings was described and a geochemical examination of fth the discharges recommended. Deelstra and al. (1972) described 15 hot springs in Burundi, 1 in Rwanda and 3 in RDC Results of chemical analyses of 9 Burundian,,1 Rwandian and 2 RDCian geothermal water samples were reported. Edeline and al. (1981) described 14 geothermal locations and reported chemical analysis of from 13 of them

8 Location of the resources

9 Survey reports All the reports concentrate on descriptions of the thermal sources and their immediate surroundings The geothermal activity is mostly connected with faults in Pre-Cambrian rock or sediments There is no record of a connection between recent volcanism and geothermal activity, even though one of the geothermal locations is in an area of basaltic formations according to the geological map edited by Radulescu (1981).

10 Survey reports (cont..) Little attempt has been made to relate the existence it of geothermal heat to the general geology of the country It is however, clear that all the sources are situated in the westhern or central parts of the country and none in the eastern part where instrusions i are absent and which lies farthest away from the active rift zone

11 Survey reports (cont..) All reported geothermal sources in Burundi are water springs There is no record of surface steam (fumaroles) or mud pools Therefore it seems unlikely that high temperature geothermal areas will be found there The highest temperature is 68 C at RUHWA McNitt (1969), Deelestra et al. (1972), Edeline et al. (1981)

12 Survey reports (cont..) Application of the Quartz geothermometer of Fournier and Rowe (1966) to the results of Deelstra and al.(1973), Edeline and al.(1981) suggests underground source temperatures as high as C Cinat least two places in RUSIZI valley.

13 RECENT SURVEYS (1982) The recent reconnaissance mission of geothermal resources in Burundi was done in 1982 by two scientists from National Energy Authority, Iceland. During D i the mission, i fifteen samples of geothermal water, three of cold ground water and one of gas were collected Eight of the locations are outside the western branch of the East African rift valley, but six inside it.

14 RECENT SURVEY CONCLUSIONS: GEOLOGY The geothermal manifestations in Burundi are found mainly in two types of environment, e.g Precabrian rock, mostly outside the rift valley, and sediments inside the valley. The old age and low porosity of the precabrian rock make the existence of an exploitable geothermal system within it higthly unlikely. The higher porosity of the thick sediment layers, and the recent volcanism in the rift valley constitute conditions which could lead to exploitable geothermal systems.

15 RECENT SURVEY CONCLUSIONS: GEOLOGY There is considerable volcanism around Lake Kivu in whose vicinity geothermal heat has been reported The chemical composition of the Lake water is affected by geothermal heat The northwestern part of Burundi is on the edge of the Thibinde volcanic region of Lake Kivu. Thus from a geological point of view this is the most promising of the geothermal areas in Burundi which were investigated.

16 Principal geological l structures of central Africa

17 RECENT SURVEY CONCLUSIONS: GEOLOGY Six geothermal locations in the rift valley were visited, four in the Rusizi valley, one on the east coast of Lake Tanganyika (Kabezi), and one further south at some distance from the lake (the Mugara springs). In the Rusizi valley and at Kabezi the hot water rises from sediments, but at Mugara from precabrian rock. Thus the former sources are likely to the originate from larger and more open aquifers than the latter.

18 RECENT SURVEY CONCLUSIONS: GEOCHEMISTRY Chemical geothermometers suggest highest source temperatures in the rift vallely and the three highest temperatures t were estimated t at locations in the Rusizi i valley All discharges rising from sediments were carbon dioxide do d rich This could indicate the presence of a poweful heat source. The high carbon dioxide concentrations lead to supersaturation with respect to calcium carbonate in some cases, so that t care would have to be exercised in avoiding calcuim carbonate deposition in the event exploitation

19 Cl distribution

20 Cl/CO 2 distribution

21 F distribution

22 Na/Cl distribution

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25 RECENT SURVEY CONCLUSIONS: GEOCHEMISTRY In summary, an exploitable geothermal source which has temperature in C range, may exist in the Rusizi valley and probably extends well into RDC and Rwanda. This source is thougt to be connected to the Thibinde volcanic area south of fl Lake Kivu. Therefore, an anomalous geothermal gradient may be expected in this region.

26 RECENT SURVEY CONCLUSIONS: GEOCHEMISTRY The base temperature in Burundi is unlikely to be high enough for conventional electricity production, but is suitable for many industrial and domestic uses. Of the existing industries in Burundi, the tea factories, the brewery and the textile factory could benefit from such use, and any new industries especially those in which heating and drying are involved could use such an energy source. The geothermal water in Rusizi valley is carbon dioxide rich, and a minor exploitation might involve its cooling and bottling as mineral water The most chloride rich sources would, however, be unsuitable in this respect The water rising from Precambian rock is unlikely to be exploitable for other than direct uses, such as bathing.

27 RECENT SURVEY RECOMMENDATION It is recommended that further geological, geochemical and geophysical studies be carried out in the whole of the Thibinde region, subject, of source to an agreement between the three government involved (Burundi, RDC and Rwanda).

28 Observations / Recommendations The two previous surveys give the same recommendations More investigations including geological, geochemistry and geophysical studies are involved to define the geothermal potential ti assessement. Establish a policy for an integrated geothermal exploration and development of the resources Mobilize funds both locally and through our development partners to support the above initiatives. Establish a good collaboration with East African s countries in which geothermal exploration is advanced.

29 MURAKOZE THANK YOU MERCI