Small Hydropower Research Articles

Renewable energy: A way out for South Sudan’s electricity crisis

South Sudan is one of the least electrified countries in the world, despite having abundant renewable energy resources that could be exploited to generate electricity. The country relies on imported diesel for electricity generation, besides having limited focus on renewable energy development. This policy brief sheds light on the potential of renewable energy as a solution to South Sudan’s ongoing electricity crisis. It examines the key factors hindering the development of renewable energy resources for electricity generation in the country. The brief also provides recommendations to the Government of South Sudan, policymakers, experts, and funding institutions on how to improve electricity access in the country. It is stressing on the importance of prioritising the development of diverse renewable energy resources, such as solar, wind, and small hydropower, as an immediate solution to the electricity access challenges in the country.

Fish community dynamics following the low-head dam removal and newly installed fish passage in a headstream tributary of Jinsha River, Southwest China

Low-head dams and small hydropower developments are widely distributed in global rivers because of their high cost-efficiency and smooth implementation. However, these installations have great ecological impacts on native fish communities due to the loss of longitudinal river connectivity. Although dam removal and fishway construction are effective measures to mitigate river fragmentation, research on their effects on fish communities remains limited to date. In this study, we investigated fish community dynamics in a mountainous tributary of the Jinsha River–Heishui River following dam removal, fishway construction, and fishway renovation. Our fish sampling data from 2018 to 2023 yielded 6137 fish belonging to 25 species, 12 families, and 3 orders. The native fish community predominantly represented the typical fish fauna of the Qinghai-Tibetan Plateau, primarily including the genus Schizothorax and the families Sisoridae and Nemacheilidae. Representative fish species in the Heishui River demonstrate notable adaptations to cold water, high altitude, and rapid flow environments. After removing the Laomuhe Dam, upstream fish abundance increased sharply, but species richness slightly decreased in the short term. Fishway construction significantly enhanced species richness and abundance and reduced the difference between the upstream and downstream fish communities from the Songxin Dam. However, the subsequent fishway renovation altered the dominance of fish species, with marginal changes in community structure and abundance. Variations in fish community dynamics in the river channel and fishway structure can be attributed to differences in ecological guilds (e.g., flow preference and thermal regime) and environmental factors (e.g., flow discharge, water temperature, and water depth). The present study provides insight into the significance of mitigation measures for the impact of dams on mountainous rivers in southwest China through ecological assessment and guides for decision-making in the conservation and restoration of specific fish communities.

Investment cost analysis in small hydropower plants in terms of efficiency and a case study in the Euphrates and Tigris basins

Flow rate is the basic parameter for calculating the energy capacity and investment costs of small hydropower plants. Because energy costs are directly related to energy capacity. While the energy capacity increases, the investment cost of the hydropower plant increases also. However, if the energy capacity is high, the energy production will be high and the investment cost will be amortized in a short time. In this study, small rivers in the Euphrates and Tigris Basins with previously determined hydropower capacities were selected, and the investment costs of small hydroelectric power plants to be designed on these rivers were analysed. For this analysis, 10 streams were selected from the Euphrates and Tigris Basins, and only Baskoy and Celebiyan streams have flow observation stations. The flow values of the remaining 8 streams were found by regression analysis using the basin and flow values of Baskoy and Celebiyan streams. Therefore, cost–benefit analyses were carried out separately for these flows in this study. In this study, because it includes the most effective hydrological parameters as well as many technical and economical parameters, the SMART Mini Hydro Tool Program was used.

An assessment of run of river hydropower potential in Great Britain

In the UK, hydropower produces 1.65 GW of energy, only 2% of the national capacity. With most large-scale storage-based hydropower potential sites already utilised in the UK, further development is minimal due to financial, environmental and construction time concerns. However, run of river (RoR) is a type of hydropower that has the potential for further development. While there are studies that estimate different ranges of RoR hydropower potential, the last UK-wide study was undertaken in 1989, meaning it is outdated. In this study, a methodological framework was created to assess the potential of RoR hydropower in Great Britain (GB) (Northern Ireland was omitted from this study due to a lack of river flow data). The hydrological, technical, financial and realisable potentials for pico, micro, mini and small RoR hydropower were determined. The results show that the total hydrological potential is 20 GW, the technical potential is 11 GW, the financially viable potential is 320–420 MW and the realisable potential is 290–320 MW. Most realisable schemes are either mini or small, situated in the west and north-west parts of GB. This study adds to the understanding of the RoR potential in GB and offers a reliable estimate of RoR hydropower that can be produced alongside suitable RoR scheme locations.

Design Optimization of a Run-Of-River Small Hydropower Plant: A Case Study of Mabula Kapi Site

Prior to construction, small or large hydropower plants undergo feasibility studies, which involve technical, economic, financial, social, and environmental aspects. Technical studies, particularly, include various engineering disciplines. This study sought to conduct a component of technical feasibility studies, focused on design optimization of the turbine-plant capacity size for a run-of-river case study called Mabula Kapi, on Kaombe River, Serenje, Zambia. The study method used computational modelling, simulation, and optimization techniques, and used secondary data from previous site. A prefeasibility study conducted earlier had underestimated the turbine-plant capacity owing to underestimated discharge data, owing to lack of site gauging station. A less accurate discharge estimation method involving transposition from a gauged similar catchment had been used. A later feasibility-level site hydrological study found improved discharge data. Riding on the improved discharge data, this study found the following optimised plant design parameters based on plant design discharge of 6.20 m3/s: Installed capacity of 10.20 MW; Annual energy production of 42 GWh; Capacity factor of 47.1%; 3 x Pelton wheel of 272 rpm speed, 2.1 m diameter, 2-nozzles of diameter 0.16 m each, 21 buckets of 0.58m width each; and 3 x 4 MVA generators of 50Hz, 22-poles, and 11kV.

Assessing the sustainability of small hydropower sites in the Citarum Watershed, Indonesia employing CA-Markov and SWAT models

ABSTRACT This study investigates the sustainability of potential small hydropower sites within the Citarum Watershed in West Java, Indonesia. The Citarum River, with a catchment area of 6,090 km2, plays a crucial role in regional water supply and hydroelectric power generation. However, environmental challenges such as deforestation, land use changes, and sedimentation pose significant risks. We employed the CA-Markov model integrated with IDRISI TerrSet software and the Soil and Water Assessment Tool to predict future land use changes and assess water supply, soil erosion, and sedimentation impacts for 2030 and 2040. The analysis revealed diverse trends in water yield across different catchment areas, with some regions showing increased water availability and others facing declines. High erosion and sedimentation rates were identified as critical issues affecting hydropower efficiency. The study highlights the need for comprehensive watershed management strategies, including reforestation, sustainable land management practices, and sediment management, to enhance the sustainability of small hydropower projects. Our findings underscore the importance of integrating environmental considerations into hydropower development to ensure the ecological integrity of the Citarum Watershed.

Community energy and socio-technical infrastructure resilience: analysis of mini/micro hydro power projects in Khyber Pakhtunkhwa, Pakistan

Abstract In 2014–15, Pakistan’s provincial government of Khyber Pakhtunkhwa (KPK) launched a decentralised power generation initiative, installing over 356 small hydro power units to provide electricity to over 2.5 million people in its mountainous regions. This initiative built on the foundation of prior community-based mini/micro hydro-power projects (MHPPs) deployed in the region since the 1980s that have experienced mixed success; by 2020, over 150 units were non-operational. This paper investigates the socio-technical factors influencing the success and failure of these projects, focusing on outcomes and processes integral to community MHPPs. The study analyses the critical implications of MHPPs for socio-economic welfare, gender equity and democratic governance through extensive primary research including field observations at 40 sites, questionnaire surveys with community residents in three in-depth case-studies, and expert interviews with local policymakers and project developers. Analysis shows that electricity provision from MHPPs has had positive outcomes for the communities in terms of improved education, poverty alleviation and economic growth, alongside enhanced access to information and gains in women’s entrepreneurship and health. Nonetheless, the study also identifies significant shortcomings in the processes involved in community MHPPs related to inadequate technical assessments, monitoring, and evaluation, as well as challenges arising from undemocratic governance mechanisms and inequitable participation. By teasing out the multiple socio-technical dimensions that shape infrastructure resilience of MHPPs in KPK, this paper contributes to the broader discourse on sustainable community energy projects and informs policy for decentralised energy transitions that ensure democratic alignment and inclusive design.

Risk-benefit comparative analysis of different control methods for reservoirs under the water to electricity mode

Abstract For some small hydropower stations that are not under the control of power dispatching department, there are many ways to implement the reservoir operation scheme formulated under the premise of determining power by water. This paper respectively selects the output, flow and water level process as the control conditions, explores the risks and benefits of reservoir operation with different control variables, and selects the optimal operation scheme through comprehensive comparative analysis. Simulation results of a hydropower station in the Han River Basin show that when the output is taken as the control condition, the waste water is small, the power generation benefit is high, and the risk of the water level outside boundary is within the acceptable range. Considering the risk and benefit of reservoir operation and taking output as the control condition, it has significant advantages over water level and flow.

Identifying a Self‐Sustaining Population, Spawning Site and Population Size of the Danube Salmon Hucho hucho Using the Citizen Science Approach

ABSTRACTThe last populations of Danube salmon (Hucho hucho) in Croatia are found in the Kupa and Una rivers. However, the size of the suitable area that could serve as the best spawning ground for the remnant Danube salmon population in these rivers is not known. This study aimed to leverage anglers' experiences to determine the sections of the Una and Kupa rivers where the last populations of Danube salmon (Hucho hucho) in Croatia are most abundant, identify potential spawning sites and assess threats that could impact the species' existence. The Kupica river emerged as a tributary of the Kupa river with a large Danube salmon population in Croatia. Experienced divers conducted three dives along a 350‐m transect in the Kupica river, estimating a total of 13 Danube salmon individuals ranging from 50 to 115 cm in total length, in pool and run mesohabitat types. In the Kupa and Kupica rivers, the survey identified 25 Danube salmon spawning sites. The primary local threats identified for the Danube salmon population include small hydropower plants, the construction of a radioactive waste disposal site, water abstraction, the removal of riparian vegetation, overfishing and climate change. Based on the results of this study, we strongly recommend the implementation of protective measures against these threats and the establishment of an ichthyological reserve specifically for Danube salmon in the Kupica river. This recommendation aligns with the EU Biodiversity Strategy, emphasizing the need to identify designated areas by 2030.

Nun of the river: The material and spiritual economies of small hydropower in rural Tanzania

This article examines the significance of hydroelectric mini-grids owned and operated by Catholic sisterhoods in rural Tanzania, situating them within a broader context of energy transition and environmental justice. The Tanzanian state is betting that mini-grids can effectively supplement the national grid’s limited reach; since 2010 it has invested considerable effort in developing a regulatory framework that streamlines licensing procedures and specifies feed-in tariffs. Today, the field is wide open and a range of ownership models – community, private, state-owned – are unfolding on the ground with variable results regarding their financial sustainability, environmental impact, and developmental outcomes. Though often overlooked in this discourse, missions, churches, abbeys, and convents have a history of operating run-of-the-river power stations and other off-grid systems that stretches back into the colonial era. Such infrastructures anchor material and spiritual economies of rain, care, and cash that straddle both community and commercially oriented modes of provisioning. Their continued presence suggests that in some ways this new paradigm of decentralized energy provision builds upon long-standing historical logics of patronage and political authority in marginal areas.

Integrating Flood Early Warning System (FEWS) for Optimizing Small Hydropower Sites: A West Java Case Study

Integrating Flood Early Warning System (FEWS) for Optimizing Small Hydropower Sites: A West Java Case Study

Assessing the Sustainability of Small Hydropower Potential in the Threats of Natural Disasters: an Analytic Hierarchy Process-Based Approach

Assessing the Sustainability of Small Hydropower Potential in the Threats of Natural Disasters: an Analytic Hierarchy Process-Based Approach

Rehabilitation or Demolition of Small Hydropower Plants: Evaluation of the Environmental and Economic Sustainability of the Case Study “El Cerrajón”

During the 1950s, numerous small-capacity hydroelectric power plants were built in Spain. Seventy-five years on, it must now be decided whether to continue their operation or demolish them. In order to provide a valid answer, it is necessary to have access to decision-making tools that enable sustainable economic and environmental decision making. The present work proposes a methodology that employs an economic indicator of life cycle cost and environmental indicators of carbon footprint and embodied energy by means of life cycle data analysis. Quantification of the impacts was carried out with the support of construction cost databases and the PREDICE software tool for the quantification of environmental impacts incorporated into maintenance tasks. The case study of the “Cerrajón” power plant was analyzed, where historical hydrological cycles were considered. A life cycle scenario was evaluated in which renovation extended the life of the power plant by a further 75 years. The results show savings in environmental impacts with respect to the impacts of the Spanish energy mix of up to 175 kgCO2 per MWh produced, although no economic benefit was found. It was also shown that in climate change scenarios, the profit price breakeven increases. Rehabilitation appears to present the best choice when combining the two criteria.

ABOUT SOME PROBLEMS OF THE ELECTRIC ENERGY SECTOR OF GEORGIA

In the article - "About some problems of the electric energy sector of Georgia" - the issue of the country's electricity production potential and how it is used is discussed. The article mentions that out of all the energy resources, Georgia has the most electrical energy resources. These are hydropower (water resources), wind and solar resources. A retrospective analysis of both total and individual production and consumption of electricity in the period 1990-2023 concluded that a 47.5% increase in individual consumption was caused by the catastrophic population decrease in Georgia during the same period. The article also mentions that the average consumption of electricity in Georgia is half of the corresponding indicator of Germany, the USA - Mesa-Med, and Norway - one-sixth. The electricity balance of Georgia is negative. A significant part of electricity is imported from Russia and Azerbaijan. Among the problems faced by the electrical energy system, the article discusses the possibility of causing danger by depending on external sources of electricity, giving preference to the construction of large hydroelectric power plants (the construction of which destroys wild nature) and less attention to the study of the issue of regional production and consumption of electricity. The article provides conceptual solutions to each of these problems. Keywords: electric energy; hydropower; wind and solar energy; large and small hydropower plants; Electrical energy balance.

Comparing feed-in tariff and renewable portfolio standard in South Korea: Cost reduction impact on non-photovoltaic renewable electricity

Renewable energy (RE) electricity plays a crucial role in addressing climate change but has limitations, such as intermittent production, high costs, and site constraints. South Korea transitioned its RE support system from a feed-in tariff (FIT) to a renewable portfolio standard (RPS) in 2012. This study evaluates the impact of the FIT-to-RPS transition on cost reduction for non-photovoltaic RE technologies (RETs), i.e., onshore wind power, bioenergy power, small hydropower, and fuel cell power, using a learning curve model. The results indicate that the FIT-to-RPS transition did not have a significant positive impact on cost reduction for onshore wind power, bioenergy power, or small hydropower, as the results show negative learning rates (LRs) during both FIT and RPS periods. The analysis suggests that the positive learning effect was hindered by the gradual depletion of sites favourable to RE power plants as more RE power plants were installed. However, fuel cell power, which is not affected by land availability, increased the LR from 1.4 % to 3.5 %.This study has policy implications, such as improving excessive regulations and procedures that hinder the installation of RE power plants on sites with good condition.

Macroinvertebrate response to run‐of‐river hydropower tailrace inflow: Spatial assessment of community and traits

AbstractRun‐of‐river (R‐O‐R) hydropower dams introduce two discontinuities in the river: the dam and the tailrace. Discontinuities can lead to changes in the water quality that may affect the survival of aquatic macroinvertebrates, depending on their traits. We investigated the invertebrate assemblage and community‐level traits in an urban river influenced by a small hydropower tailrace in Hokkaido, Japan. As a result of the tailrace inflow to the main channel, the bypassed reach was warmer, and the areas below the confluence were colder. Temperature was a consistent factor affecting the distribution of indicator taxa and of the five major taxa that contributed the most to dissimilarity, but other environmental factors also showed significant effects. At the community level, the weighted mean of taxa with warm preference showed a significant positive relationship with temperature, but taxa with cold preference did not appear to be filtered by the cold water delivered by the tailrace. However, sensitive taxa such as Ephemerella have already started showing negative responses to temperature. The observed distribution of cold‐preferring scrapers could negatively affect the energy transfer from primary producers to higher consumers in the bypassed reach. Appropriate mitigation of climate change effects in hydropower systems can be achieved by increasing the flow in the bypassed reach, especially during the summer months, to maintain a temperature regime that is adequate for the survival of macroinvertebrate populations and maintenance of ecosystem functions.

Optimization and reconstruction of pelton buckets based on statistical techniques, artificial neural networks and CFD modelling

During operation Pelton turbines suffer from erosion and cavitation wear, which decreases the hydraulic efficiency. Welding repair is a cost-effective method for recovering the original bucket geometry but requires templates to ensure proper results. However, those templates may be unavailable for Pelton units with decades of operation. This is the case of one of the 2.8 MW Pelton units at Nima II, a small hydropower plant in Colombia that began operation in 1942. This paper presents the redesign and optimization of the bucket. First, the bucket is rebuilt following both, technical recommendations, and Design of Experiments (DOE) to verify the effects of the basic dimensions on the hydraulic efficiency. Experimental measurements on the eroded turbine validate the two-phase computational fluid dynamics (CFD) modelling to be applied in the optimization process. Second, the best inner surface is found by using a multi-objective optimization based on Artificial Neural Networks trained by the previous DOE and a genetic algorithm. At the end, the CFD results suggest a total hydraulic efficiency recovery of 8 %. Further experimental tests on the optimized runner showed a difference of 0.7 % from the predicted value.

Assessing small hydropower viability in water-scarce regions: environmental flow and climate change impacts using a SWAT+ based tool

Water-scarce regions, like the Mediterranean, face worsening conditions due to climate change, intensifying pressure on key economic sectors such as hydropower. Additionally, environmental conservation policies, particularly the implementation of environmental flows, present challenges for hydropower systems. Certainty regarding the impact of these factors on future hydropower production is crucial for informed decision-making in the transition to sustainable energy. This study introduces S + HydPower, a tool coupled with SWAT+ to assess climate change and watershed management effects on small hydropower plant (SHP) systems. In this study, we used this tool to investigate the consequences of implementing environmental flows and climate change on run-of-river SHPs in the Catalan River Basin District (CRBD), in Catalonia. The results show that applying environmental flows would lead to a significant 27% reduction in SHP production. However, this reduction would represent only 0.25% of the region’s current energy demand. Furthermore, the study reveals a potential 38% to 73% reduction in SHP production by the end of the twenty-first century due to the combined effects of environmental flows and climate change. This suggests a substantial decline in run-of-river SHP’s contribution to the CRBD’s electricity supply. These findings emphasize the need to explore alternative and sustainable energy sources to ensure the long-term reliability and resilience of the region’s energy supply.

Research on Multi-Objective Optimization Scheduling Strategy for Cascaded Small Hydropower Stations Based on Improved HBA

Abstract Effective optimization scheduling strategy is the premise and key to improving the power generation and capacity benefits of cascade small hydropower stations (CSHS). However, the power generation of CSHS is significantly affected by complex hydraulic and electrical constraints. To effectively solve this problem, an improved honey badger algorithm (HBA) is proposed by updating the mutation strategy and introducing non-dominated sorting to achieve the multi-objective optimization scheduling solution of CSHS. The following improvements have been made to the standard HBA: Firstly, the Tent chaotic mapping is applied to the population initialization stage, its strong ergodicity and randomness ensure the randomness of the initialization stage and improve the global search ability of CSHS scheduling. Secondly, the powerful optimization ability and fast convergence speed of the Golden-Sine strategy make updating and mutation more efficient, greatly enhancing the local search ability of CSCH scheduling. And then combining the non-dominated sorting of the non-dominated sorting genetic algorithm-II (NSGA-II), an improved multi-objective Honey Badger Algorithm (IMOHBA) is further proposed to achieve multi-objective solutions for CSCH scheduling. Finally, abundant field experiments were tested for validation. The results expressed that compared to other algorithms, the effect of IMOHBA in CSHS scheduling can further increase power generation, while also improving the peak shaving ability of CSHS.

Importance of Variable Turbine Efficiency in Run‐Of‐River Hydropower Design Under Deep Uncertainty

AbstractWhen less water is available, hydropower turbines are less efficient, or have to stop altogether. This reality is often neglected in recent work on the planning and operations of hydropower systems, despite widespread expected increases in drought intensity, frequency and duration. This paper is the first to integrate variable‐efficiency turbines into a hydropower plant design framework that accounts for design optimization as well as deep uncertainty in climatic and socio‐economic variables. Specifically, this framework focuses on leveraging multi‐objective robust decision making for the financially robust design of run‐of‐river hydropower plants, whose output is highly sensitive to flow variability. Application to five plants in Türkiye challenges two key design assumptions, use of net present value as a design objective and use of identical turbines. Instead, maximizing the benefit‐cost ratio yields plants with better financial viability over a range of plausible futures. They tend to have smaller capacity, and feature a small turbine that is well‐adapted to low‐flow periods. Another key insight is that socio‐economic uncertainties have as much or even more impact on robustness than climate conditions. In fact, these uncertainties have the potential to make many small hydropower projects too risky to build. Our findings are of considerable practical relevance at a time where 140 GW of unexploited small hydropower potential could help power the energy transition. They also highlight the need for similar research in reservoir‐based plants, considering over 3,000 such plants planned or in construction worldwide.