Realistic estimate of water hold-up, circulation and consumption in solar concentrating thermal power plants

This paper presents a comprehensive analysis of water utilization in concentrating solar thermal (CST) thermal power stations (TPS) keeping in mind the experience of operating coal plants. The water utilization is divided into three modes: water hold-up, water circulation and water consumption. The water hold-up and circulation represent the minimum quantity of water required for running a power plant with a few days autonomy. The water consumption represents the extent of replenishment required on a continuous basis. On the basis of quality, the consumption can be classified into: raw water, soft water and demineralized (DM) water. The reserve hold-up in a CST station of 1 GW is around 0.95 to 1.05 million m³ per GW which corresponds to 9-10 days consumption. The working hold-up inside the plant is 0.27 million m³ per GW. The water circulation rate for a 1 GW CST station is 7500 m³/h or 0.18 million m³/day. The major water consumption which is not generally tracked or measured is conveyance loss between the raw water intake source and the power station intake point which can be as high as 30 %. Loss of DM water directly affects the energy efficiency as it mostly represents the high quality steam lost from the system and has a high cost of production.