| Abstract |
Geothermal energy is the heat from the earth's inner core which is always moving outward to the surface or near the surface. The geothermal heat manifests itself on the surface in form of hot ground, hot springs, geysers and fumaroles. Geothermal mapping using temperature measurements commonly referred to as heat loss measurements, employ the principle of heat transfer to quantify the heat energy lost to the surface naturally. The normal conductive temperature gradient is about 0.03oC per meter but the presence of a hot body, "near" the earth's surface, results in an elevated temperature gradient. Elevated temperature gradient can also result from thinning of the earth's crust as is the case in the floor of the East African Rift Valley. Although geothermal temperature gradient varies from place to place, it averages 25-300C per km. Heat-loss survey methods, together with other geoscientific studies have been used during the geothermal surface exploration stages to map two existing geothermal fields and in other six geothermal prospects within the Kenyan Rift Valley. This paper discusses the use of heatflow measurement during geothermal surface exploration and show some examples of heat-loss survey work done in the Kenyan part of the East African Rift Valley and how this has been used in the development of geothermal conceptual models. |