Future changes in hydropower energy system in the Yangtze River Basin under different warming levels

In comparison to traditional fossil fuels, hydropower has the potential to significantly reduce greenhouse gas emissions and play a crucial role in promoting a low-carbon energy structure transformation. However, the reliability and stability of the hydropower system in the warming future remain unclear. Here, we evaluate the impact of future climate change on hydropower production, regional electricity demand, and energy system supply-demand balance in the Yangtze River Basin (YRB), which is China's largest hydropower production base. We have utilized two indexes, i.e., Energy Production Drought (EPD) and Energy Supply Drought (ESD), to characterize the changes in the hydropower energy system. EPD refers to a series of days with low hydropower production, while ESD refers to a series of days with mismatched production/demand. We utilize 15 global climate models from CMIP6 to force the Conjunctive Surface-Subsurface Process version 2 (CSSPv2) land surface model with consideration of reservoir regulations, to estimate the generation capacity of 86 mainly hydropower plants in YRB. In addition, an empirical electricity demand model considering socio-economic and climate factors is adopted to evaluate the changes in electricity demand in the receiving areas of southern China. Under climate change, the projected hydropower generation in the YRB is expected to increase throughout the 21st century. However, the future electricity demand will also rise due to GDP growth. Climate change will alter the distribution of seasonal electricity demand, resulting in an increasing mismatch between electricity demand and hydropower supply. Therefore, hydropower EPD and ESD are also being investigated, and the study is crucial for understanding future changes in the electricity supply and demand balance, as well as mitigating the impact of global warming.