Efficiency And Cost Benefit Analysis Of Combined Heat And Power In Geothermal Energy Utilization: A case study of a low enthalpy fluids from the Menengai Geothermal Field-Kenya

After successfully drilling a productive geothermal well, various parameters are evaluated to establish its energy potential as well as other factors that may affect the well outputs during exploitation. The energy potential of a geothermal well depends on the fluid’s thermodynamic characteristics and quantity. The fluids can either be dry steam, two-phase or just hot water. Geothermal energy can be used both for electricity generation and direct use applications. While high enthalpy fluids are best suited for electricity generation, low enthalpy fluid is mostly used for direct applications. Hot geothermal brine, separated from high enthalpy resources is also a good candidate for direct applications such as industrial processes, agro-processing and for leisure. Such applications can be cascaded to various applications depending on the energy requirements. GDC has done production drilling at the Menengai geothermal field and proved about 170MWe equivalent of steam. The field produces predominantly high enthalpy fluids with an average dryness fraction of 70%. Also, a few of the drilled wells have low wellhead pressure and cannot, therefore, be connected to the steam gathering system. The separated brine, as well as fluids from the low enthalpy wells, have a substantial amount of energy which can be used to generate power using binary technology and thereafter cascaded to direct applications. This paper analyses the energy potential of the low enthalpy fluids at the Menengai geothermal field and the potential for utilizing the energy for combined heat and power. A cost benefit analyses of the proposed development is also evaluated.

Keywords: Integrated Energy Systems, Cascaded Uses, Direct Use