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A prospective assessment of scale effects of energy conversion in ultra-low-head pumped hydro energy storage units

Hao Wang, Fujun Wang, Chaoyue Wang, Benhong Wang, Chenfeng Li Orcid Logo, Dianji Li

Energy Conversion and Management, Volume: 315, Start page: 118798

Swansea University Author: Chenfeng Li Orcid Logo

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DOI (Published version): 10.1016/j.enconman.2024.118798

Abstract

Ultra-low-head pumped hydro energy storage (PHES) is an attractive solution to the intermittency of sustainable energy in lowland countries and regions. For the development of large-scale ultra-low-head PHES units, tubular pump-turbine is the core equipment, but a comprehensive understanding of the...

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Published in: Energy Conversion and Management
ISSN: 0196-8904
Published: Elsevier BV 2024
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URI: https://cronfa.swan.ac.uk/Record/cronfa69489
Abstract: Ultra-low-head pumped hydro energy storage (PHES) is an attractive solution to the intermittency of sustainable energy in lowland countries and regions. For the development of large-scale ultra-low-head PHES units, tubular pump-turbine is the core equipment, but a comprehensive understanding of the technical and economic aspects of its scale effects of energy conversion is still lacking. In this paper, taking the East Route of the South-to-North Water Diversion Project in China as a prospective case, a comprehensive technical assessment of scale effects of energy conversion in ultra-low-head PHES units is conducted, and then a generalized economic analysis considering both benefits and stability is performed. The following valuable results are obtained: (1) For energy performance, special scale effects are observed in the head, power and hydraulic efficiency in both pump and turbine modes, suggesting more attention should be paid to the energy conversion similarity failure induced by the variations of geometric scale. (2) For hydraulic stability, the rotor force moment and pressure fluctuations increase with the geometric scale in both pump and turbine modes, while the pump mode plays a crucial role in restricting the limit size for safe bidirectional operation. (3) For internal flows, partial flow separation is observed in the guide-vane region in pump mode and in the draft tube in turbine mode, respectively. The fundamental path to improving project technicality lies in controlling the energetic vortices. (4) For generalized economy, the adverse effects caused by the deterioration of stability with the increase of geometric scale must be considered, and the 7 ∼ 9 m runner size is recommended for ultra-low-head PHES units from the perspective of optimal generalized revenue. These findings can provide a comprehensive guidance for the selection, optimization and development of ultra-low-head PHES units with different capacities, and can help the decision-makers effectively avoid technical and economic problems caused by the scale effects during the project design phase.
Keywords: Ultra-low-head; Pumped hydro energy storage; Tubular pump-turbine; Energy conversion; Scale effect; Generalized economy
College: Faculty of Science and Engineering
Funders: The authors would like to acknowledge the financial supports given by the National Natural Science Foundation of China (No. 52209117, U22A20238, 51836010), the National Key Research and Development Program of China (No. 2022YFC3204604), the China Postdoctoral Science Foundation (2021M703516) and the 2115 Talent Development Program of China Agricultural University.
Start Page: 118798

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