Technical Cooperation Geothermal Energy East Africa - Regional Project
Report of the project:
BGR supports partner institutions in Eastern Africa in the exploration of selected geothermal fields as well as in the general advancement of geothermal development in the regional project Geothermal Energy East Africa
Background
Geothermal exploration area North Ghoubbet in Djibouti
Source: BGR
A continental rift system extends through the countries in eastern Africa, the East African Rift System (EARS). The main rift splits south of Tanzania into a western and an eastern branch. Many volcanos are associated with the East African Rift System, with some of them being active. Hydrothermal springs accompanied with high heat flows can be found along the rift system. This indicates a high geothermal potential in these areas. Currently only Kenya is utilizing this potential with the geothermal power stations Olkaria. The geothermal development in other countries along the rift system is often limited by the financial risk that is associated with the exploration phase of geothermal prospects, as well as by the lack of experienced technical staff, and limited knowledge about the subsurface at potential geothermal sites.
Geological and geochemical investigations of water, gas, and rock samples are undertaken to identify chemical and thermic interactions between those and potential hydrothermal systems in the subsurface. Geophysical methods like magnetotellurics (MT) and transient electromagnetics (TEM) are applied as well for exploring the deep subsurface. They are applied to map the distribution of the electrical conductivity in the subsurface and can indicate the existence of a geothermal reservoir. All methods are used together in the geothermal assessment of potential sites.
Project description:
The regional project Geothermal Energy East Africa is the continuation of the GEOTHERM programme which lasted from 2003 to 2017.
The current project focuses on the aim to provide training for technical staff of the partner institutions through joint feasibility field campaigns and through short courses. Selected sites are investigated for enabling the application of financial support for drilling at the „Geothermal Risk Mitigation Facility (GRMF)“.
The Office Djiboutien de Développement de l’Energie Géothermique (ODDEG) ) is the partner institution of BGR in Djibouti for the current project.
The approximately 120 km² large area North Ghoubbet at the north western end of the gulf of Tadjoura was investigated by several methods, operated by ODDEG, BGR and members of the Leibniz Institute for Applied Geophysics.
Geophysics
Transient electromagnetic measurement in Djibouti
Source: BGR
At the begin of 2020, training lessons for Transient electromagnetics (TEM) and Geoelectrics were undertaken as well as field measurements with TEM. For yielding a greater investigation depth, the TEM equipment was consolidated with a stronger transmitter moment. More surveys with TEM and MT for deeper exploration are planned, covering the area with a spacing of measurement points in the kilometre range.
Geology / Geochemistry
Field investigation in Djibouti in January 2020
Source: BGR
In January and February 2020 a geological and geochemical reconnaissance campaign was undertaken in the area of North Ghoubbet. The area was investigated for geothermal surface manifestations. 25 water samples of hydrothermal springs as well as reference samples of groundwater and sea water were collected. At about 10 fumaroles gas samples were taken. Numerous samples of fresh and alterated rocks close to hot springs and fumaroles were collected.
The samples will be analysed in BGR´s laboratories in cooperation with the project partners from Djibouti.
