Life cycle water consumption for oxyfuel combustion power generation with carbon capture and storage

Abstract

To fulfill its commitment to carbon emission reduction and peak carbon emission in 2030, China is expected to conduct large-scale carbon capture and storage deployment in future decades, considering the dominant role of coal-based energy for power generation. As an important carbon emission mitigation technology, oxy-fuel combustion will play a significant role in this process. Meanwhile, the water scarcity in China is also worthy of attention, especially in coal-rich areas which are usually water-scarce. The development and implementation of coal-based carbon capture and storage technology may exacerbate the water shortage situation in these regions. Considering this background, a correct analysis of the water use of oxy-fuel combustion power plants is of great importance, before implementing the large-scale deployment of carbon capture and storage. Therefore, this study aims to assess the life-cycle water consumption of a 600 MW oxy-fuel combustion power plant, retrofitted from a typical 600 MW coal-fired power plant in China. Based on a tiered hybrid method, the direct and indirect water consumption of a typical oxy-combustion CCS project is evaluated. Results show that 4.63 L of water is used for capturing 1 kg of carbon dioxide, while the calculated water intensity for power generation is 3.79 L/kWh. The operation and maintenance processes dominate the total water consumption, in which the cooling mode exerts a great influence on life cycle water consumption. Once-through cooling has lower water consumption than recirculating cooling in the retrofitted oxy-combustion power plant. If we compare water consumption with other power generation technologies, the water intensity of oxy-combustion carbon capture and storage power production is lower than that of bio-power, but beyond that of solar photovoltaic and wind power. Moreover, based on the thermal power production in China in 2017 and the water use calculated in this study, transforming all the thermal power plants to oxy-combustion systems is hardly feasible as the induced water withdrawal will account for 17.26%–827.19% of the total industrial water budget in 2030. Further regional analysis indicates that even to achieve 10 Gt of carbon dioxide abatement, Shanxi province will encounter great difficulties due to reduced water availability.