Geothermal development in Tanzania: status report

Type Report
Title Geothermal development in Tanzania: status report
Publication (Day/Month/Year) 2014
Tanzania is among the East African countries that are traversed by the East African
Rift System (EARS). The different from other countries in the region is that,
Tanzania is traversed by the two arms of the EARS. 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
considered during the exploration of geothermal energy resources in Tanzania.
Tanzania has a total grid installation capacity of 1,490.14 MW. This is from hydro
(37%), gas (33%) and other fossil fuels (30%). 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 renewables being considered are wind and solar.
Several preliminary and one detailed studies have been carried out to assess
geothermal resources for power generation. These studied 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 Lake Ngozi geothermal field 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. The drilling of temperature gradients
wells has been delayed, to allow for third party review as a measure of reducing the
drilling risk. This paper presents geothermal development in Tanzania covering the
geology of geothermal potential sites, developments institutional arrangements,
new projects and future development plans for accelerating geothermal
development and utilisation.

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