Numerical study on the influence of hybrid pumped-storage power station on outflow water temperature

YU Dan; YANG Shiwei; CHEN Junguang; LIANG Ruifeng

doi:10.13522/j.cnki.ggps.2023505

Abstract：[Background and Objective]As renewable energy is expanding,complementary energy storage solutions such as pumped-storage power stations have been developed.By the end of 2020,the total installed capacity of pumped-storage power stations in China had surpassed 30 million kW.Differing from conventional hydropower stations,pumped-storage power stations operate under distinct thermal and dynamic conditions,which can affect the environment as the temperature of water discharged from these reservoirs is closely linked to river ecosystems.Low-temperature discharges not only delay or prevent fish spawning,but also adversely affect crop growth,leading to crop yield reduction.Despite these concerns,research on the change in outflow water temperature of hybrid pumped-storage power stations is limited.This paper is to bridge this knowledge gap.[Method]Taking the Jinshuitan Reservoir as an example,we simulate outflow water temperature under different inlet-outlet elevations and pumping rates using used the MIKE3 water temperature model.This allowed us to assess the impact of hybrid pumped-storage hydropower stations on outflow water temperature.[Result]Compared to the outflow water temperature without pumping and storage,pumping-storage reduced the outflow water temperature from May to September and increased it during the other month;the maximum decrease and increase in temperature were less than 0.7 ℃ and 0.8 ℃,respectively.Specifically,at a pumping rate of 110 m3/s,raising the outlet elevation from 130 m to 150 m led to the reduction in the outflow water temperature to decrease from 0.4 ℃ to 0.1 ℃ between May and October,and the rise in temperature to decrease from 0.5 ℃ to 0.02 ℃ during the remaining months,compared to conditions without pumping-storage.When the outlet elevation was maintained at 139 m,increasing the pumping rate from 50 m3/s to 70 m3/s only affected decrease in the outflow water temperature between May and September,with the decrease increasing from 0.1 ℃ to 0.2 ℃.Further increases in the pumping rate,while keeping the outlet elevation at 139 m,had no significant impact on the outflow water temperature.[Conclusion]The elevation of the inlet and outlet significantly affects the outflow water temperature;a lower elevation results in a greater temperature difference.While the pumping rate does influence the temperature difference,the effect is less pronounced,though the temperature difference does increase with pumping rates.To minimize the adverse impacts of pumped-storage operation on downstream ecosystems,it is advisable to position the inlet and outlet at the highest feasible elevations.