Efficiency of Geothermal Binary Power Plants: a Worldwide Review Update

Abstract

Estimation of efficiency of a geothermal power plant is a subject of debate with regards to the best method that should be applied. In Zarrouk and Moon, (2014) [1] the conversion efficiency of geothermal plants (dry-steam, single and double flash, binary and hybrid steam binary) was analyzed and correlations developed. In this paper, focus is made on binary power plants to further develop the correlation in Zarrouk and Moon, (2014) [1] so as to get a more accurate estimation formula that can be used during prefeasibility studies by taking into consideration the estimated rejection temperatures from the chemical composition of the geothermal fluid. Different methods for efficiency measurements are described and are shown to be dependent on the objective of calculation. During geothermal project development, it may be necessary to use conversion efficiency to get a realistic estimate of electricity production from a given estimate of the reservoir capacity for geothermal systems. Optimization of power plant operations on the other hand may require the use of utilization efficiency to achieve maximum benefit for the power plant operations. Published data from thirty-five (35) binary power plants are used to compare existing correlations and develop a new correlation that can be used to estimate production output from a reservoir during pre-feasibility studies. The results show more accurate conversion efficiency can be generated when the effect of reinjection temperature is taken into account