Noise assessment and H2S dispersion at Olkaria geothermal power plant, Kenya

Abstract

The goal of this study was to characterise noise levels and hydrogen sulphide (H2S) dispersion at Olkaria geothermal power stations in Kenya. Noise levels due to the exploitation of geothermal resources at Olkaria were assessed both in space and time, and the measured levels were compared with the standard limits set by the Kenyan National Environment Agency and the World Health Organisation. H2S dispersion at Olkaria was modelled and predicted using AERMOD, which is a steady-state Gaussian model. Two modelling scenarios were assessed, scenario one considered H2S emissions from the existing Olkaria I and Olkaria II power stations, whereas scenario two considered predicted concentrations in light of the addition of Olkaria IV to the existing power stations. One, eight and twenty-four hour averaging periods were selected for the study. Modelling results showed that no significant health and environmental impacts were expected outside the powerplant boundaries due to the existing or proposed power plants. However, it was found likely that odours would be detectable over a wide area. In general, averaged gas concentrations were high close to the emission sources and rapidly diluted depending on weather conditions. The behaviour of the plume was also considered; it was noted that gas emissions through cooling tower plumes achieved better plume rise than gas discharged through gas ejectors.