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. Tanzania’s aspirations to reach the middle income status as enshrined in the country’s Vision 2025 need to support the energy sector to access its agriculture and industrialization potential, and targets. 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.

The country’s current total grid installation capacity is 1,263 MW. This is from hydro (44.9%), natural gas (48.7%), disel (5.6%) and biomass (0.8%). Previously, the national power system was mostly relying on hydropower. Long and frequent periods of drought which might have been due to the climate change between 2003 and 2006; 2009 and 2010 lead to shortfalls in electricity supply from the hydropower stations; thus, the government of Tanzania resorted to thermal based generation sources as a short term solution. As a long term power development strategy the government intends to diversify the country’s energy generation mix and is focusing on increasing the proportion of renewable energy generation, whereby geothermal development is ranked high on the list. Other renewable sources being considered are wind and solar. Mnjokava 2 Geothermal in Tanzania 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. To date, Ngozi geothermal prospect has gone beyond detailed surface study, where drilling of exploration testing wells is planned within one year time. Songwe, Kiejo-Mbaka and Luhoi geothermal fields are next rank to Ngozi. The detailed surface study in the support from ICEIDA/MFA is expected to complete by end of this year (2017). TGDC with ELC consultants undertaking geological, geochemical and geophysical investigations and culminated in locating three sites for drilling of test wells in Kieji-Mbaka and Luhoi geothermal fields. 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.