Emergy evaluation of ladder hydropower generation systems in the middle and lower reaches of the Lancang River

Ladder hydropower systems can improve hydropower stability by dispatching the load among each station. However, the impact to ecosystem brought by the stations is obvious. In order to study the ecological and economic performance of ladder hydropower systems, this paper conducts an emergy evaluation on the ladder hydropower system of the Lancang River in Yunnan Province, China. Based on the input and output data of each station, the emergy indices under separate and combined operation modes are calculated. The ecological service losses show that the impact of hydropower stations on environment is mainly reflected in the sediment loss, followed by soil erosion and non-endangered biodiversity loss. The results of other emergy indices for the separate operation mode show good sustainability of the hydropower stations. As for the combined operation mode, the sustainability index of the system will finally be 8.88, which means a good utilization efficiency and sustainability. The fair price of the system is 0.205 yuan/kWh when the seven stations are operated, which is higher than the grid connected hydroelectricity price in Yunnan province, demonstrating that the system is unprofitable. Considering the results of economic and emergy analysis, a better economic benefit and sustainability could be achieved when Jinghong and Gongguoqiao hydropower stations are cancelled. (C) 2021 Elsevier Ltd. All rights reserved.

Automated summary

The emergy evaluation of ladder hydropower system in Yunnan Province, China, shows that the impact on environment mainly includes sediment loss, soil erosion, and non-endangered biodiversity loss. The system demonstrates good sustainability in separate operation mode and a sustainability index of 8.88 in combined operation mode, with a fair price higher than the grid connected hydroelectricity price locally.