GIS-Aided Prediction of H2S Emission Dispersion from Geothermal Power Production for the Menengai Geothermal Power Project

Abstract

In an effort to decrease reliance on carbon based energy, power production from geothermal sources is increasing in countries with the resource such as Kenya. This owes to its clean and relatively sustainable production cycle compared to fossil fuels. Its development however has some environmental impacts, with air pollution especially from hydrogen sulphide emissions being key. These impacts if foreseen early can be prevented or mitigated. This paper presents the results of a study conducted to develop prediction modeling of H2S dispersion in the surrounding atmosphere from a planned 105 MWe geothermal power plant at the Menengai geothermal field, Kenya. An EIS aided prediction of gas dispersion is used to envisage future concentrations of environmental emissions on a range of geographic scales. Key parameters used in control of the dispersion type for the gas and its average removal rate include meteorological conditions such as wind direction, wind speed, precipitation, atmospheric stability, relative humidity, and surface roughness and topography. Environment Information System (EIS) aptitudes were run for quality visualization of the model outputs and presentation of an accurate numerical model of the study area. Results showed that the area is dominated by SSE and NNW winds and thus long term air quality impacts will be expected as most significant to the NNW and SSE of the proposed power plants. Further, the concentration trends after power production will be similar to the background conditions with minimal changes indicating that the H2S concentrations will be within acceptable Occupational Safety and Health (OSH) guidelines. Nonetheless, routine air quality monitoring within the project area is emphasized.