Exploitation assessment of geothermal energy from African Great Rift Valley

Abstract

Countries that are in the Great Rift Valley have one of the lowest average annual electricity consumption per capita in Africa with a value of 164 kWh per inhabitant. Furthermore, the electrification rate is 34% that is more than fifty percentage points below the world average, which is around 86%. One possible solution to improve the electrification rate is to properly exploit the energy resources present in the territory. One of the most significant energy sources of this region is certainly geothermal energy which has a potential of about 15 GWe, mostly concentrated in Ethiopia. Furthermore, it is possible to find the resource in a wide temperature range, not only to produce electricity, which, nonetheless, has a very limited exploitation rate, as only 900 MWe are installed between Kenya and Ethiopia, but also for direct use. In this study, two geothermal power plants for two different geothermal sites, Corbetti and Arus-Bogoria, respectively in Ethiopia and Kenya, have been hypothesized after analyzing the resource potential. For the first, which has been estimated to be of high enthalpy (~300°C), a flash plant configuration was assumed, and the estimated energy production potential was found to be around 50-100 MWe. While for the second, at medium enthalpy (T<200°C), the use of a binary cycle plant was assumed with an obtained production of about 20 MW of electricity. Finally, the possibility of geothermal water exploitation for greenhouse heating, drying of agricultural products, civil sanitary uses, recreational uses (spa), or for industrial purposes has been assessed.