MSc defence by Christine Katana
Christine Katana from Kenya, MSc Fellow in Geology at University of Iceland will present her MSc project on Thursday 15th of May at 15:15-15:27 at University of Iceland, Askja building, room 131. The presentation will be a part of the UI series "Open seminar at Masters-day of Natural Sciences".
The title of the project is:
Geochemical and Petro-physical Characteristics of the Kenyan Rift Basalts for CO2 Mineralization Potential - Case Study Olkaria Geothermal Field
Christine's supervisors are:
Guðmundur H. Guðfinnsson, Research Scholar, University of Iceland
Iwona M. Galeczka, Laboratory supervisor in geochemistry, University of Iceland
Her external examiner is Helga Margrét Helgadóttir, geologist, ÍSOR
Abstract
This thesis presents the findings of a study of the chemical and petrophysical characteristics of Olkaria basalts with respect to CO2 mineralisation. The motivation for the study is the urgent need for mitigation of the geothermal-related CO2 emissions within the Olkaria geothermal area. The Olkaria geothermal field has an installed capacity of 799 MW, which is a huge step towards Kenya’s renewable energy generation goals. However, geothermal production is not entirely emission-free. The geothermal power plants in Olkaria emit ~68,916 tCO₂e/yr. Although much lower emissions than fossil fuel alternatives, this still contributes to greenhouse-gas accumulation and global warming. This study aims to improve the understanding of the subsurface lithostratigraphy, specifically the Olkaria Basalt unit, for CO2 mineralisation potential. The study involves carrying out binocular, petrographic, whole rock analysis and porosity volume estimations. Rock cuttings from four reinjection wells, OW-204, OW-723A, OW-739 and OW-R12, were used to investigate the variation in chemical composition, porosity distribution and width, and ultimately to estimate the theoretical CO2 storage capacity. Results indicate that the Olkaria Basalt unit is comprised of layers of basalts intercalated with layers of tuff, rhyolite, basaltic trachyandesite, trachybasalt and trachyandesite. The unit varies in thickness from 70 m in OW-723A to 250 m in OW-204. Total concentration of divalent cation oxides ranges from <10 to 27%, in the rhyolites and basalts, respectively, and porosity values range from 1.3-3.8 %. The theoretical storage capacity is estimated to be 23-89 Mt, which is sufficient for mineralisation of the local CO2 emissions within Olkaria.