Economic Optimisation of Cooling Systems for Geothermal Power Stations

Abstract

The power output of a geothermal power plant using an atmospheric cooling system is dependent on the design wet bulb temperature selected to size the plant and the prevailing ambient wet bulb temperature. Selection of a design wet bulb temperature which is not exceeded by the ambient wet bulb temperature will ensure full power output but will require a large and costly cooling system which will at well below its design capacity for the majority of the time. Alternatively, selection of a design wet bulb temperature which is exceeded by the ambient wet bulb temperature for a percentage of the time will require a less costly cooling system but will result reduced power outputs and consequently a loss of power generation revenue. Thus, final selection of the design wet bulb temperature is essentially an economic compromise between the high capital cost associated with cooling systems designed for high ambient wet bulb temperatures and the loss of power generation revenue associated with cooling systems designed for low ambient wet bulb temperatures. This paper summarises the procedures for optimising the selection of the design wet bulb temperature and the cooling system approach to minimise the direct and indirect generation costs associated with an atmospheric cooling system for a geothermal power plant.