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A new solar tower thermal power system integrating the intercooled gas turbine top cycle and the Kalina bottoming cycle is proposed in the present paper. The thermodynamic performance of the proposed system is investigated, and the irreversibility of energy conversion is disclosed using the energy utilization diagram method. On the top cycle of the proposed system, the compressed air after being intercooled is heated at 1000 degrees C or higher at the solar tower receiver and is used to drive the gas turbine to generate power. The ammonia-water mixture as the working substance of the bottom cycle recovers the waste heat from the gas turbine to generate power. A concise analytical formula of solar-to-electric efficiency of the proposed system is developed. As a result, the peak solar-to-electric efficiency of the proposed system is 27.5% at a gas turbine inlet temperature of 1000 degrees C under the designed solar direct normal irradiance of 800 W/m(2). Compared with a conventional solar power tower plant, the proposed integrated system conserves approximately 69% of consumed water. The results obtained in the current study provide an approach to improve solar-to-electric efficiency and offer a potential to conserve water for solar thermal power plants in arid area. (c) 2012 Elsevier Ltd. All rights reserved.