Impact of adaptive water-saving and phaseout strategies on water withdrawal in China's coal-fired power industry under carbon constraints

Coal-fired power generation occupies a dominant position in China's power sector and is known for its high water requirement. Limited research exists on how water withdrawal for coal-fired power generation responds to policy and technical factors, as well as spatial variations in the future. To address this gap, this study utilizes a geospatial dataset at the coal-fired power unit level and an improved calculation method for water withdrawal to investigate the evolving trend of water withdrawal in coal-fired power generation, considering the influences of carbon emission reduction, adaptive water-saving measures, and phaseout strategies. The results demonstrate that the improved water withdrawal calculation method yields superior simulation outcomes compared to existing approaches. The study reveals substantial variations in coal-fired power generation under different carbon emission reduction scenarios. Despite the business-as-usual (BAU) scenario where coal-fired power generation continues to dominate the power sector, implementing various adaptive water-saving scenarios results in national water withdrawal estimates ranging from 42.9 to 59.4 billion m³ in 2050. In contrast, water withdrawal is reduced by 37.6% to 42.9% under the 2.0℃ target scenario and by 86.5% to 97.5% under the 1.5℃ target scenario. Technological advancements play a crucial role in reducing water withdrawal for coal-fired power generation, particularly in northwest China. The transformation of cooling systems significantly decreases water withdrawal nationwide and in the regions that predominantly relied on once-through cooling. The deployment of carbon capture and storage (CCS) technology in coal-fired power plants in the northwest region creates short-term pressure on regional water resources. Under strict carbon emissions constraints, adopting the phaseout strategy with guaranteed lifetime results in relatively higher water withdrawal for coal-fired power generation, and the variations in coal-fired power plants configuration across provinces lead to different responses in water withdrawal changes when facing the same unit retirement strategy.