| Hydraulic machinery


combining social, ecological, economic, and technical dimensions. According to the authors, this study provides valuable methodological models for the evaluation of small hydropower turbines, particularly relevant in decentralised contexts. The involvement of stakeholders in the definition of specific indicators allows the approach to be adapted to local characteristics, minimising estimation errors and biases. The model provides a comparative framework applicable to other similar micro projects in South Asia or Africa


Another case study, this time in Portugal, is the Alviela River Micro-Hydropower Project which offers a rigorous methodological model for assessing hydropower potential in water supply systems where the available drop is low (~2.5 m), but the flow is constant. This case study highlights the importance of an integrative analysis, which combines technical effectiveness with clearly defined financial indicators. It can be extended to the application of eco-efficiency and life cycle assessment, providing a solid framework for decisions in the context of mini- and micro-hydropower plants with low environmental impact.


Described as an innovative project, the City of Fribourg


in Switzerland has harnessed residual hydraulic energy from the drinking water distribution system, based on the use of microturbines integrated directly into urban networks. In terms of performance, the system produces


approximately 1GWh of electricity annually and contributes to avoiding emissions of approximately 258 tons of CO2/year. According to the authors these values are remarkable, considering that the installation uses existing infrastructure and does not require additional space or major ecological modifications. Furthermore, maintenance costs are reduced due to the simplicity and reliability of the equipment, and the amortisation of the investment takes place in the short term, due to the reduction of energy costs and ecological benefits This case could also be replicable in other European cities with drinking water distribution networks operating under pressure, constituting a viable and sustainable alternative to expanding conventional energy production capacities.


Holistic vision According to Lakatos et al, these case studies highlight


how integrated operational, techno-economic, and lifecycle-oriented approaches can support sustainable turbine management and hydropower modernisation. Based on the analysis carried out, they believe turbine performance cannot be assessed exclusively from the perspective of technical efficiency, but must be integrated into a holistic vision that includes the complete life cycle of the equipment, the environmental impact, and the contribution to regional socio-economic development. In this regard, the application of circular economy principles provides a viable framework for optimising the operation of hydropower plants. Strategies for remanufacturing, reusing, and recycling turbine components contribute to extending the life of equipment, reducing the consumption of critical raw materials and limiting industrial waste, they add.


On Impulse Due to its unique structural design, the impulse turbine


unit achieves high efficiency in utilising high-head,


low-flow hydropower resources. China, despite its vast hydropower potential, faces more challenging conditions for impulse hydropower development. Resources suitable for impulse turbines are often located in high- altitude regions and zones of high seismic intensity, where the construction conditions are relatively poor. Therefore, while conventional medium and low-head hydropower has been developed rapidly in China, the construction of impulse hydropower stations remains limited. According to recent research by Li et al, the flow and


interference mechanisms within the components of impulse hydro-turbines in China are still insufficiently understood, and relevant industry standards require further refinement. Although international companies such as Andritz Hydro have achieved notable success, domestic manufacturers reportedly still lack substantial practical experience in these areas, the authors claim. Consequently, a significant gap persists between China’s impulse hydropower engineering capabilities and top international standards. If collaboration among enterprises, design institutes, universities, and research institutions can be enhanced, particularly through greater sharing of design parameters for the distributor, injector, and bucket profiles, the authors believe impulse hydro power technology will undoubtedly enter a new phase of unprecedented development. Future research could be helped further


through strengthening operational experience and technological optimisation. A systematic review of operational data and experience from existing impulse power stations is considered essential. While continuously integrating insights from real-world engineering challenges will facilitate the optimisation and advancement of impulse hydropower technology, thereby propelling China’s hydropower sector to new levels. The authors also recommend that there should be


more of a focus on enhancing turbulence modelling and achieving high-fidelity, full-flow-path simulations. By optimising simulation details, more precise analysis of local flow features - such as jet dynamics, sediment erosion mechanisms, and secondary flow structures - can be achieved, thereby further elevating impulse hydropower technology.


The case study of a micro hydro plant on the Alviela River in Portugal, highlights the importance of an integrative analysis Jan Hospodka/Shutterstock.com


References


The Role of Hydraulic Turbines in the Energy Transition: A Systematic Review of Methods for Evaluating and Optimising Hydropower Plant Operation by Gheorghe Daniel Lakatos, Roxana Maria Albu (Druta), Andreea Loredana Rhazzali, Sára Ferenci, Lucian Ionel Cioca, Radu Adrian Munteanu and Loránd Szabó. Processes 2026, 14, 841 https:// doi.org/10.3390/pr14050841


Advances in research on impulse hydro-turbine technology by Xiaochao Li, Ye Zhou, Hao Zhang, Guanglei Xiao, Yanwei Li, Zhongxin Gao, Zhiyang Lu, Shangqi Li. RIVER. 2026;1–22. DOI: 10.1002/rvr2.70040


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