Water use in thermal power plants equipped with CO2 capture systems

Addition of a CO2 capture system to an existing power station has some impact on water consumption. CO2 capture systems require additional water for cooling and process make-up, which can be of concern, particularly in areas of water scarcity. During the past decade, a number of relevant studies have been published that estimate the increase in water use when a capture system is added to Pulverised Coal (PC), Natural Gas Combined Cycle (NGCC) and Integrated Gasifier Combined Cycle (IGCC) power production facility. The report, authored by the Institute’s capture experts Guido Magneschi, Ron Munson and Tony Zhang, provides insights about how adding a CO2 capture system to a power plant impacts the volume of water withdrawn and consumed. The results of this analysis serve to dispel myths about the use of water in CCS systems. Specifically, they challenge the misleading assertion that CCS systems will double water consumption, which is often reported in papers and articles. On the contrary, analyses of available data indicate that for power plants using wet-recirculating cooling systems, the increase in actual water consumed varies from approximately 20 per cent to 60 per cent, depending on the capture technology. For once-through cooling systems the increase can be negligible, or even negative when water recovery options are implemented. Water use estimates cannot be generalised, and are very dependent on the power plant type, the CO2 capture technology and the cooling system used.

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