I. K. Duah, C. K. K. Sekyere, F. Kemausuor, K. A. Amaning
This review offers a dual-staged evaluation of micro-hydropower (MHP), integrating a technical synthesis of over 150 of the most relevant papers with a bibliometric analysis of 918 peer-reviewed studies from 2014 to 2024. It provides a map of publishing trends, keyword development, and leading universities that describe global research patterns and identify research gaps in the field. Key advancements in turbine design, including impulse, reaction, low-head, and pump-as-turbine configurations, as well as the use of GIS-driven site-selection methodologies, have been synthesised. Thirteen real-world MHP initiatives are analyzed to contextualize the outcomes by examining the influence of design choices, financing strategies, and community engagement on results. Africa possesses around 25 GW of hydro energy potential, although it exhibits notably poor research output according to the findings. Context-sensitive engineering, robust governance, and adaptable implementation strategies also facilitate long-term success, extending beyond the mere adoption of technology. Overall, this study offers pragmatic recommendations for researchers, practitioners, and legislators aiming to expand MHP for sustainable rural electricity by integrating macro-level bibliometrics with micro-level design insights.
The development of micro-scale renewable energy power generation systems, such as micro-hydropower (MHP), often needs more consideration for sustainability during the planning stages. Many small-scale renewable energy systems have shorter-than-expected lifespans, jeopardizing Indonesia's Net Zero Emission Target for 2060 or earlier. Despite this, only some studies have examined the long-term viability of installed renewable energy generation projects, particularly MHP plants not managed by state-owned companies or PLN (Pembangkit Listrik Negara). The primary objectives of this research are to evaluate the feasibility of retrofitting and assess the potential sustainability of a decommissioned MHP in Banjarnegara, Central Java. A cash flow analysis was performed to assess techno-economic indicators. Additionally, the social-institutional dimension was analyzed through in-depth interviews with 15 stakeholders. Sustainability was evaluated using a framework of 15 indicators across technical, economic, environmental, social, and institutional dimensions. The findings revealed that among the four sustainability aspects, the social-institutional dimension scored the lowest potential sustainability at 26.67%. In contrast, the technical and environmental dimensions showed higher potential sustainability, scoring 83.7% and 87.5%, respectively. The economic dimension was deemed feasible only when the financing model accounted solely for retrofitting costs. It is crucial to consider all dimensions comprehensively. Furthermore, engaging multiple stakeholders and fostering local community awareness is vital to ensure the long-term sustainability of decentralized energy systems. This study enhances the understanding of the sustainability potential of abandoned decentralized energy systems and explores how reusing abandoned MHP facilities can support stakeholders in revitalization efforts, contributing to an increased share of renewable energy in the overall energy mix.
A gas or vapor bubble moving in translation in a liquid and varying its volume propels itself by a rocket effect, which occurs in foams moving in pressure or temperature fields with a non-zero gradient. It is notably observed in boiling and centrifugal pump operation, which latter features the following two characteristic bubble types : __ 1. Gas bubbles, which are apt to emerge faster from the pump than the liquid; 2. Vapor bubbles (cavitalion). When a bubble in translatory motion implodes, energy is transferred: potential pressure energy is converted info kinetic implosion energy, which in turn becomes kinetic translation energy. The instrument for this energy transfer process is a "micro-jet" following the bubble. It is shown that a considerable increase in kinetic translation energy density occurs, which is converted into potential pressure energy on impact against a solid obstacle. The resulting pressures (10,000 kg/sq.cm) explain the mechanical aspect of cavitation erosion. Several experimental results have confirmed these theoretical considerations. The development of a rotoscope is also described, this being a device enabling a centrifugal pump impeller (for example) to be "stopped" so that only the relative motion of the flow particles remains. Unlike with a stroboscope, time exposures can he taken with this device. With more thorough knowledge of foam mechanisms, and especially of cavitalion bubble behavior, it should be possible to design cavitation erosion-proof impeller blades.