Energy and Exergetic Analysis of a Proposed Olkaria I Binary Geothermal Power Plant, Naivasha, Kenya

Abstract

Olkaria I geothermal power plant in Kenya has an installation capacity of 45 MWe. This single-flash power plant has exergy waste of about 6 MWe in the separated brine. To maximize the geothermal resource, a binary unit using isobutane as a working fluid was developed and optimized using Engineers Equation Solver code. The paper presents the design and energy and exergy analysis of the proposed binary unit for the Olkaria I power plant. The designed binary plant has the potential of generating net turbine work of 2281 kW with plant efficiency of 10.81%, cycle efficiency of 9.87%, and overall utilization efficiency of 31.70%. The temperature of brine reinjected into the reservoir was set at 85 C with exergy of 1763 kW. A Grassmann exergy flow diagram shows that exergy destruction is greatest in the condenser (12.08%) and least in the evaporator (8.99%). Energy and exergy analysis of a plant help to optimize available geothermal resources for maximum energy production.