Geothermal development in Tanzania

Abstract

Tanzania is among East African countries that are traversed by the East African Rift System. The geological settings for the occurrences of geothermal resource in Tanzania is variable and include potentials that are likely to be associated with typical young volcanic provinces in the north, intersection of eastern and western arms (triple junction) in the south west, faulted granites areas in central Tanzania (craton), and intrusive in young coastal sedimentary formation. This makes the occurrence of geothermal resource in Tanzania quite different from other countries. In addition the eastern arm and western arms tend to have different geological conditions that need to be differently considered during the exploration of geothermal energy resources in Tanzania. Tanzania’s power system has for decades relied on hydro and oil based generation mix. As a result, the power supply has been prone to variability and uncertainty due to frequent drought spells and oil price fluctuations. As a short term remedy, the government has resorted to emergency fuel oil based power plants to bridge the supply gap. This solution is not only expensive but also environmentally unfriendly. Knowing that energy is vital for economic, social, and human development, Tanzania has determined to develop a sustainable energy mix that will ensure that households, communities, businesses and industries receive supply that is adequate, available when needed, reliable, convenient, healthy and safe for supporting the county’s development agenda.

Geothermal resource studies in Tanzania date back to 1949 but have been limited to surface studies mainly, measurements of surface temperature, water and gas sampling and analyses of the hot springs. The only study that has gone beyond preliminary surface studies is on Ngozi and Songwe geothermal fields that was undertaken between 2006 and 2012 by the Ministry of Energy and Minerals (MEM) in collaboration with the Geological Survey Tanzania (GST), Tanzania Supply Company Limited (TANESCO) and the Federal Institute for Geosciences and Natural Resources (BGR) of Germany. This study comprised geological, geochemical and geophysical investigations and culminated in locating three sites for drilling of temperature gradient wells. However, the geoscientific data has been reviewed and seen gaps as a measure of reducing the drilling risk. As such, more work to fill the identified gags started in June-July 2015 done by GDC in collaboration with TGDC, this continued to September 2016 with technical assistance from UNEP/ARGeo, aiming at defining of the conceptual model and location of drilling sites. This paper presents geothermal development in Tanzania covering the geology of geothermal potential sites, developments goals and strategies, institutional arrangements, new projects and future development plans for accelerating geothermal development and utilisation.