THE ROLE OF 'STEAMING GROUND' OVER HIGH TEMPERATURE SYSTEMS IN THE KENYA RIFT

Abstract

Several types of geothermal systems occur in the Kenya Rift; the most common type is hosted by young volcanic complexes where almost all discharged heat is derived from shallow vapour with very little liquid discharge. Fumaroles and 'steaming ground' are the prominent manifestations
althrough most (60%) of the heat discharged at Olkaria involves conductive transfer. Linear proportionality between various types of thermal ground exists and allows assessment of the Olkaria heat loss (445+70 MW) to be based on a detailed study of a sub-area. A poorly understood quasi-conductive mechanism controls the heat transfer of steaming ground which accounts for c. 30% of the Olkaria natural losses. Extending the proportionality concept to other prospects it was found that the heat loss of the Evurru prospect is of the order of 160+50MW. The output of all systems characterised by steaming ground is of the order of 1200 MW; the natural heat ourpur of Olkaria is by far the largest of all geothermal systems in the Kenya Rift.