Search

Literature shows that only 56% of Kenyan households had access to electricity, with rural areas having the lowest access rate at percent. The high cost of extending the power grid to remote areas and power losses on distribution are significant challenges facing rural electrification. In addressing power accessibility problems, especially in rural areas, there is a need for tapping hydropower generation through the invention and implementation of in‐duct turbines to maximize the utilization of already existing pressurized water ducts that supply water in various parts of Kenya for hydropower generation. Makueni County is endowed with gravity‐fed water ducts with high potential for hydropower which can innovatively be produced by application of in‐duct turbines. This paper focuses on the assessment of energy needs and applications in rural areas. The research design was exploratory and experimental in nature. It was exploratory because, through an assessment, it sought to explore and identify the potential areas within the water supply lines for the production of hydropower to supply hydropower in Makueni County. It was experimental because the researcher developed (designed and fabricated) a hydro turbine for use in the production of hydropower from gravity water ducts of a diameter raging 100 mm. The research revealed that 62% (98) used solar power for lighting their homes, while 17% (28), 12% (20), and 8% (12) used lanterns, electricity, and kerosene lamps, respectively. Among the fuels assessed was firewood which was identified as the most used fuel at 89% (140). This was followed at a distance far by paraffin at 6% (9) of respondents. The households at 100% (158) identified electricity as a potential source of lighting for their household. The study recommends harnessing hydropower to enhance reach to 100% of the rural communities. The energy availability will provide opportunities for communities and institutions in rural areas to open their minds to business development and engage in income‐generating activities like the rearing of poultry and the development of light industries like the gridding of maize and other cereals. [ABSTRACT FROM AUTHOR]

Micro hydropower power generates electrical energy to meet connected electrical demand, that normally fluctuates causing imbalances. Electronic load controller is then used to balance power system by diverting surplus generated power to the dump load commonly resistive load such as bulk water heater. This study investigated use of oil heating system as a replacement for conventional resistive dump load. In comparison to water, oil has high thermal retention therefore can serve as good thermal media. Dump load range ranged between 17 kW to 78 kW. A 6-kW electrical heater was used for laboratory oil heating system from which heated oil attained about 10,791 MJ in 31.5 minutes. Thermal stratification between upper layers and the lower layers of oil in storage tank decreases from 3.8° to 3.4° as oil temperature increases from 100° to 200°, respectively. Energy dissipated through dump load from micro hydropower plants is sufficient for domestic energy consumption including cooking. [ABSTRACT FROM AUTHOR]

The small hydroelectric power plants (SHPP) are implemented in non-interconnected zones (NIZ) of developing countries. In which, the provision of electrical energy from the national interconnected system is not economically feasible. Therefore, in the literature, hydroelectric generation technologies have been implemented taking advantage of the energy available in the rivers. One of these technologies is the Michell-Banki type cross-flow turbines (MBT), which, despite having lower efficiencies than turbines such as Pelton and Francis, maintain their efficiency although fluctuations in site conditions. For this reason, different studies have been made to increase the efficiency of the MBT by making geometric modifications to both the nozzle and the rotor. The purpose of this study is to determine numerically the effect of the geometry of the blades that form the runner on the efficiency of Michell-Banki Turbine (MBT). For this, two (2) geometries were studied corresponding to a circular sector of a standard tubular profile and an airfoil NACA 6512 modified in curvature profile and chord length, according to the profile of the standard tubular blade. For this study, transient simulations for multiphase water-air flow were implemented using a k--ε turbulence model in the Ansys 2020R1® CFX software. The two (2) turbine models were configured to the same hydraulic conditions of head and volumetric flow corresponding to 0.5 m and 16.27 L/s, respectively. Variations in rotational speed were configured between 100 and 200 RPM with 20 RPM steps. It was found that using the modified 6512 hydrodynamic profile, at 140 RPM increased efficiency by 6 %, compared to the conventional tubular type blade geometry. [ABSTRACT FROM AUTHOR]

Agriculture is one of the most energy intensive activities within the European Union. The common absence of electric infrastructure in these rural settings has led to the need for in situ generation in many cases. The existing excess pressures in large pressurised irrigation networks makes the generation of micro hydropower here a possible alternative renewable energy source. Pump-as-turbines have been proposed as a cost-effective technology for such purposes, taking advantage of the excess pressure in pipe networks to produce energy. This paper presents a methodology for the design of a plant for micro hydropower generation in an agricultural farm and outlines the predicted benefits of the installation. These predicted benefits were also compared with the measured performance of the plant for the 2019 irrigation season. The main aim of the plant was to replace a diesel generator that supplied energy to the farm. The excess pressure found in the pipe network varied between 0m and almost 60m. The nominal power of the pump-as-turbine was selected to supply the maximum energy requirements of the farm. The predicted operation time of the plant was estimated at up to 3199 h concentrated between April and September. An annual savings of approximately €2950 and 11 t eCO 2 were also estimated. The measured results showed an actual operation time of 2443 h between May and September, as in April the monitoring system was not operational. For this operation time, the savings were €2258 and 8.4 t eCO 2. Considering the April theoretical irrigation time obtained, the savings raised up to approximately €2434 and 9.1 teCO 2. The return on investment of the installation was computed to be recovered in less than ten years. • Real pilot PAT installation operating during an entire irrigation season. • Electricity was brought to remote places with no access to grid connection. • Diesel energy source was fully replaced by micro hydropower technology. • Solar and micro hydro hybrid solution was used for self-consumption. • More than 9 tCO 2 and €2400 were saved during the 2019 irrigation season. [ABSTRACT FROM AUTHOR]

Undershot water wheels are hydropower converters for head differences between 0.5 and 1.5 m. The Zuppinger and Sagebien types are the most used and efficient. Optimal rotational speeds depend on the head difference and on the flow rate: hence, in variable flow rate applications, the variable rotational speed is needed to optimize the performance, requiring expensive power take-off systems. In light of this, the use of adjustable inflow weirs was tested on Zuppinger and Sagebien wheels. Different flow rates were tested, each one with an inflow weir height chosen to maintain the upstream water level constant through the tests. The first aim was to increase the power at very low flows. The second aim was to maintain the range of optimal rotational speeds as narrow as possible over the flow rate range. The maximum acceptable weir height ranged between 1:15 and 1:10 of the wheel's radius. [ABSTRACT FROM AUTHOR]

In recent years, pump-as-turbines (PATs) have been highlighted for their potential benefits as an application of micro-hydropower (MHP) in water distribution networks. However, PATs come with disadvantages of relatively low peak efficiencies, which can be reduced further with large flow fluctuations. MHP and PATs in particular applied in irrigation networks is a relatively new area of research focus for these devices, and one that poses significant opportunities for energy saving as well as significant challenges due to variations in flow rate. This paper discusses the validation of a statistical methodology to estimate the flow and head variability in a network, and to select PATs whose best efficiency point (BEP) returns the lowest payback period. A comparison between the predicted and actual occurrence probabilities for different flow rates was carried out at nine potential points for MHP installation identified within a real network in Southwestern Spain. For the flow occurrence probability, the coefficient of determination (R2) of 0.804. A total of 281.0 MWh were obtained from the flow prediction and PAT selection methodology, in contrast to 230.5 MWh using the actual measured data. An overall difference of 0.2% was obtained when both PATs were simulated under actual conditions. • The validation of a methodology for flow prediction and pump as turbine selection was carried out. • An average coefficient of determination of 0.804 was obtained for flow occurrence probability. • Difference of 22% on the energy recovery potential with predicted and actual conditions. • Difference of 0.2% was found when predicted pump as turbines were tested under real conditions. • In comparison to alternative approaches, this methodology represents a 7.4 and 38% improvement in accuracy. [ABSTRACT FROM AUTHOR]

This work aims to identify a cost-effective solution for improving the energy performance of a grid-connected prosumer, possibly equipped with electric vehicle chargers. The solution is based on a small-scale energy system based on renewable energy sources (RES). The system is equipped with an Archimedes Screw Turbine (AST) and photovoltaic panels. Energy storage in batteries is also considered. A simple yet efficient method for sizing the AST is proposed. A cost-benefit analysis of the small-scale energy system is performed for six case studies covering different combinations of energy consumers. Three economic scenarios are considered for each case study. The results suggest that the AST-based solution leads to reasonable costs for the prosumer and less impact of energy price fluctuations. Also, if EV chargers are used, their consumption can be covered directly by RES. [ABSTRACT FROM AUTHOR]

Continuous and reliable power supply plays an important role for water leakage monitoring systems used in urban water supply pipes. Renewable energies powered water leakage monitoring system is becoming a promising way to reduce the dependence on traditional chemical batteries. In this study, an inline vertical cross-flow turbine was developed to harvest the potential hydropower inside water supply pipes for supplying power to the water monitoring systems. Specifically, numerical investigations are carried out on the block shapes of a water turbine system to determine an optimal model. The effects of tip clearance on the turbine performance are conducted and it is found that a smaller tip clearance can reduce the reversing torque on the returning blades and increase the pressure drop through the runner for improving the turbine performance. Besides, a self-adjustable vane is designed to avoid excess water head loss. The simulation results show that the proposed self-adjustable vane is effective to limit the water head loss at high flow velocities (1.5–2.0 m/s) to 5 m. Finally, the turbine prototype is fabricated and tested on a lab test rig. The experimental results indicate that the numerical method adopted in this research is accurate enough for such micro water turbine performance prediction. A month-long test shows that the daily electricity generation of the proposed turbine is about 600 Wh and the water head loss is always below 5 m, which means that the proposed turbine can provide sufficient power for any general water leakage monitoring system without influencing normal water supply. [ABSTRACT FROM AUTHOR]

Highlights • A novel design method for inline cross-flow turbine used in water mains was proposed. • Effects of different block design on turbine performance were investigated. • The influence mechanism of block shape on turbine performance was studied by numerical methods. Abstract Cross-flow turbines offer a promising, cost-effective solution to harvest hydropower from water mains to supply power to water monitoring systems. However, the design and performance of cross-flow turbines in water mains have not been fully investigated. In this paper, an inline cross-flow turbine configuration with two blocks is proposed and a block design method is presented. Specifically, numerical investigations are carried out to verify the proposed method and study the effect of different block designs on turbine performance. Flow velocity analysis shows that the proposed block can improve the flow attack angle at the runner inlet and significantly increase the flow velocity through the runner. In addition, the pressure distribution indicates that the blocks can increase the pressure difference through the runner and thus improve turbine performance. A comparison of three models with different guide block orientation angles reveals that the model with the largest conversion block orientation angle performs best, because the blocks from this model not only function better in terms of flow separation and negative torque reduction at the first stage, but also convert more water head into kinetic energy. Numerical results show that the inline turbine can achieve its maximum efficiency of 42.4% with a power output of about 1500 W and that the water head reduction is limited within an acceptable range. [ABSTRACT FROM AUTHOR]

The inline cross-flow turbine is a promising and reliable device to harvest hydropower in an urban water supply pipeline for power supply to its water supply monitoring system. However, investigations about the influencing factors on the performance of inline cross-flow turbines are still rare and this paper focuses on the effect of their runner inlet arc angle for improving the device's performance. Firstly, a mathematical design method for the turbine's blocks is developed. With the proposed method, four models with different runner inlet arc angles are developed. The turbine's performance, function of conversion block, flow velocity characteristics, pressure distribution and blades torque output of the models are then analyzed. Results indicate that a smaller runner inlet arc can increase the flow velocity at runner inlet and pressure difference between the upstream and downstream of the runner, resulting in a higher output power but also a higher overall water head reduction through the turbine. Besides, it is found that the runner inlet arc angle has a significant influence on the power output of runner second stage. With the increase of runner inlet arc angle, the torque output at the second stage encounters a gradual decrease. To achieve a good balance between turbine efficiency and water head reduction, the suggested runner inlet arc angle is 105°. Numerical results showed that the model with 105° runner inlet arc angle could produce a maximum power generation efficiency of 42.6% with about 1.6 kW power output. [ABSTRACT FROM AUTHOR]

The objective of the study has been to determine the river discharge by measuring the river flow velocity using two different measurement methods together with the area method and compare the accuracy of the results. Two river flow velocity measurement methods were used, the floating method and the use of current meter. In floating method a floating object was used to determine the water flow velocity on the surface by allow a float to move a distance of 1 m along the river and record the time it takes to travel that distance in seconds. Ten readings were taken and manually recorded and the flow velocity was determined by taking the distance travel by the float (1 m) divide by the time taken by the float (in seconds). On the other hand, the current meter method measure directly the average flow velocity across the river depth, twenty readings were taken and recorded manually and the average velocity were calculated. The use of current meter display flow velocity directly without the need of calculations. The result shows that both methods produce very close value, but the floating method have displayed higher value of around + 2% than current meter method which is a good value, despite the fact that floating method measures the surface velocity and the use of calculation. Many literature highlighted the accuracy of flow velocity measurement using current meter due to the fact that it measures the average velocity across the river, but from the findings when the floating method flow velocity measurement is properly applied it will produce as accurate results as the current meter with a fraction of cost in terms of instrument cost and expertise requirement in measurements. The floating method flow velocity measurement method could be applicable as alternative to current meter in micro hydropower projects river flow measurements in rural areas of developing countries with limited funding and local expertise. [ABSTRACT FROM AUTHOR]

Savonius hydrokinetic turbine is one of the prominent vertical axis turbines for tapping hydro potential available in flowing streams in rivers or canals. In spite of their simple design, Savonius turbines have the problem of poor performance. This study aims to enhance the performance of turbine through modification in the blade shape. Under the present study, geometrical parameters namely blade arc angle and blade shape factor are considered to modify the blade shape of Savonius hydrokinetic turbine. A commercial unsteady Reynolds-Averaged Navier-Stokes (URANS) solver in conjunction with realizable k-ε turbulence model has been used for numerical analysis. Using CFD analysis, blade arc angle and blade shape factor are optimized on the basis of coefficient of power. Fluid flow distributions found around the rotor has also been analyzed and discussed. Based on the present investigation, the maximum power coefficient value of 0.426 is obtained for blade arc angle of 150° and blade shape factor of 0.6 corresponding to TSR value of 0.9 at flow velocity of 2 m/s. [ABSTRACT FROM AUTHOR]

Feasibility study of the renewable energy resources is usually employed as a primary step in the design of Hybrid Renewable Energy System (HRES), to highlight the most potential sources and the best combinations obtained by using HOMER software. Thus, the main objective of this study is to identify the potential areas in Malaysia utilize solar, the wind and Micro Hydropower (MHP) sources. For this purpose, the results of a study accomplished by Ibrahim Hussein in 2010 are considered to obtain sites with the greatest hydropower potential in Malaysia. Then, a renewable energy resource assessment for these sites was performed to identify the sites that have the greatest solar, wind and hydropower potentials based on total Net Present Cost (NPC) comparison. Based on the historical data, a daily pattern emerged in electricity consumption among rural residents in Malaysia. The results of this study indicate Langkawi is the most potential region for the solar/wind combination by the significant difference with other regions (total NPC of 696,083 USD). After Langkawi, Tioman Islands has the second rank (total NPC of 818,931 USD), while villages in Tioman are the most appropriate sites for installing hybrid renewable energy system with the current specifications. In terms of the premiered locations for solar and hydropower potential, four sites at Lawas in Sarawak and Ranau in Sabah were identified as the greatest potential (total NPC of 354,000 USD). These findings demonstrate that Tioman Islands and Malaysian Borneo Island (Sabah and Sarawak) can be considered as the most attractive regions for the solar/wind/MHP and solar/MHP, respectively. [ABSTRACT FROM AUTHOR]

Rural electrification in developing countries is often hampered by major information gaps between local communities and urban centers, where technical expertise and funding are concentrated. The tool presented in this paper addresses these gaps to support the implementation of off-grid micro hydropower infrastructure. Specifically, we present a method to site, size and evaluate the potential for micro hydropower based on remote sensing data. The method improves on previous approaches by (i) incorporating the effect of hillslope topography on the optimal layout of the infrastructure, and (ii) accounting for the constraints imposed by streamflow variability and local electricity demand on the optimal size of the plants. An assessment of the method’s performance against 148 existing schemes indicates that it correctly identifies the most promising locations for hydropower in Nepal, but does not generally reproduce the specific design features of constructed plants, which are affected by site-specific constraints. We develop a proof-of-concept computer tool to explore the potential of webGIS technology to account for these constraints by collecting site-specific information from local users. [ABSTRACT FROM AUTHOR]

Exploitation of small hydropower sources requires the use of small turbines that combine efficiency and economy which can conveniently cater the power needs of rural and small communities. Cross-flow turbines are used widely in such micro hydropower plants due to their simple design, easier maintenance, low initial investment and modest efficiency. Also, because of their suitability under low heads, their efficient operation under a wide range of flow variations and ease of fabrication, cross-flow turbines have been extensively employed. The primary objective of this study is to numerically analyze the characteristics and the fluid flow in a cross-flow hydro turbine and to optimize its performance by geometrically modifying the several parameters. During the process, a base model was chosen, the design was modified simultaneously by varying the nozzle shape, changing the guide vane angle, varying the number of runner blades and simulations were carried out individually. Two phase (air & water at 25 °C), steady state with SST turbulence model was selected in the commercial CFD code ANSYS CFX 13.0 for the numerical simulation. The design parameters included 10 m head, 0.1 m 3 /s flow rate and 642 rpm rotational speed. The results obtained showed that the best efficiency obtained from the base nozzle was 63.67% which was geometrically modified that improved the turbine performance and the efficiency reached 76.60% (increase by 12.93%). Velocity distribution, pressure contours, output torque within the flow domain were also characterized. It was observed that the re-circulating flow region was reduced and also its pattern was varied. [ABSTRACT FROM AUTHOR]

The modern layout and configuration of cities create power generation and storage possibilities through the urban water system. Surplus energy in water and wastewater networks has come to the researchers' attention for exploitation as micro hydropower (MHP). Also, the gravitational potential energy of stored water on highrises makes them a sustainable option for distributed energy storage as micro pumped-storage (MPS). Many studies have investigated technical aspects and estimated capacity of urban micro hydro systems (UMHS) in urban infrastructures. However, there is no systematic review of relevant literature to signify challenges and opportunities of different urban infrastructures as UMHS, from economic, technical, and environmental viewpoints. Therefore, this article applied a reference-by-reference method to provide a systematic assessment and concept review of UMHS, including the characteristics, challenges, and drivers of potential sites for MHP and MPS development. Examining the challenges of real case studies worldwide identifies economic feasibility and energy generation reliability as obstacles in developing MPS and MHP, respectively. Nevertheless, overlooked opportunities are recognised that may accelerate UMHS proliferation. UMHS synergies, such as water saving and peak-load shaving, are introduced as influential factors in the economic feasibility of the UMHS that can be achieved through deploying sustainable stormwater management strategies and considering real-time analysis in the volatile energy market. Furthermore, simulation-optimisation tools are concisely presented for both the design and operation stages. Finally, some future research directions are offered to clarify the role of urban UMHS in addressing water and energy issues as individual systems or integrated into other decentralised energy sources. [Display omitted] • Characteristics and drivers of potential sites for MPS and MHP are assessed. • Economic feasibility is recognised as the main limitation of implemented urban MPS. • Variable head and flow are the main challenges for MHP implementation in cities. • Water saving and load shifting are essential factors in MPS and MHP feasibility. [ABSTRACT FROM AUTHOR]

There is great potential for the expansion of the small or micro scale hydropower network. Of the 43 thousand weirs in the UK there are only 500 consented hydro schemes. Planning applications for such schemes require a noise assessment. Noise evaluation of a proposed renewable scheme is often complicated by the turbine sites having distinct noise characteristics in the first instance, which are often caused by the weirs themselves. Three types of weir were studied: Broad Crest weirs were studied in detail; this is complimented by further studies in Flat V and Crump weirs. Flow data was collected for ten sites from the Environment Agency and the National Rivers Flow Archive to assess the collected Sound Pressure Level (SPL) and calculated Sound poWer Level (SWL) in relation to various river flows. Weir head height, width and meteorological data were also collected. It has been shown that the SPL data collection method used was the right choice, as the greatest amplitudes at the water impact interface at all weir types was recorded. SPL and SWL were found to be within a 36–82 dBz and 45–86 dBz range respectively for all weir types. These values can be used in computer simulations of sound propagation. The mean SPL and SWL difference between the weir types are 6.1 dBz and 6.3 dBz. Head height has the greatest effect on SPLs. Attenuation with distance was found to be similar to that of a free field line source in general. [ABSTRACT FROM AUTHOR]

Low efficiency is the main drawback of a Crossflow turbine, despite the turbine being an important low cost technology for micro hydropower generation. Poor flow profile has been mentioned by other Crossflow turbine performance investigators as one of the reasons for the underperformance. This paper has investigated, using numerical method, the flow profile in the turbine at best efficiency point and at operating conditions that are away from best efficiency point. Numerical method has also been used to calculate and predict the efficiency of the turbine. The flow physics in a Crossflow turbine runner is a two-phase with a movable free surface. Such flow physics is difficult to analyse even numerically. A procedure for numerical analysis was followed and ANSYS CFX® was used to solve the governing equations and to process the simulation results. Actual pictures of the flow were taken so as to compare the actual flow with the numerically determined flow profile. Turbine efficiency results from the previous performance evaluation experiment conducted on the model Crossflow turbine were compared with the numerically obtained efficiency results. It has been observed that the numerically obtained flow profile compare favorably with the actual flow pictures. The numerical analysis over-predicts the efficiency, especially for runner speeds that were more than the best efficiency point speed. Pockets of negative pressures and flow circulation have been observed in the flow profile. At constant head and valve opening, the velocity profile was found to vary more with runner speed than the pressure profile. The numerically obtained flow pattern showed positions where the flow gives maximum efficiency. Therefore, the study has shown that numerical method is a superior design tool for Crossflow turbines. [ABSTRACT FROM AUTHOR]

Micro hydropower station is one of the clean choices for off grid points with available hydropotential. The challenging in this type of energy production is the high capital cost of the installed capacity that is worse for low-head micro hydropower stations. Turbine price is the main problem for this type of energy production. In this research, a simple machine has been introduced instead of conventional propeller turbines. The key is using an axial pump as a propeller turbine. In the present research, a propeller pump was simulated as a turbine by numerical methods. Computational fluid dynamics (CFD) was adopted in the direct and reverse modes performance prediction of a single propeller pump. To give a more accurate CFD result, all domains within the machine control volume were modeled and hexahedral structured mesh was generated during CFD simulation. Complete performance curves of its pump and turbine modes were acquired. For verification of the numerical results, the machine has been tested in an established test ring. The results showed that a propeller pump could be easily run as a low-head turbine. In the next, the goal was to optimize the geometry of the blades of axial turbine runner which leads to maximum hydraulic efficiency by changing the design parameters of camber line in five sections of a blade. The efficiency of the initial geometry was improved by various objective functions and optimized geometry was obtained by genetic algorithm and artificial neural network to find the best efficiency of the turbine. The results showed that the efficiency is improved by more than 14%. Indeed the geometry has better performance in cavitation. [ABSTRACT FROM AUTHOR]

Most renewable energy (RE) studies focus on technology readiness, environmental benefits and/or cost savings. The market permeation, viability and adoption of RE technologies such as micro hydropower (MHP), however, require the alignment of other interrelated factors, such as the socio-technical, institutional and political dimensions. This is particularly the case where the energy recovery potential in decentralised water networks is being explored as part of a wholesome sustainability strategy by and for individual and communal prosumers. This study employs a socio-technical approach to understand factors that influence the perceived viability and adoption of MHP in group water-energy schemes. Methods included a progressive literature review to formulate a conceptual framework for the implementation of MHP systems. The framework was validated using survey data from representative stakeholders from groups schemes in Ireland and Spain. These stakeholders were sampled and surveyed at the stage of considering the adoption of MHP in their water networks. The findings highlight the push–pull factors and discusses the opportunities and barriers to the adoption of MHP systems. It confirms that the market, institutional and policy context, cost and financial benefits, social support and collaborative services combine to influence the adoption of MHP technology. Thus, a framework for evaluating the socio-technical viability of MHP systems based on these more realistic integrated, multi-dimensional criteria is proposed. [ABSTRACT FROM AUTHOR]

Savonius hydrokinetic turbine is considered as an environmentally friendly and cost effective turbine to extract hydrokinetic potential available in flowing streams. However, this turbine has not been fully explored, as the solution for the main problem of low efficiency of Savonius turbine is still being investigated around the globe. In order to study the effect of number of stages, this study aims to analyze the performance of modified Savonius hydrokinetic turbine having twisted blade under different values of number of stages. A commercial unsteady Reynolds-Averaged Navier-Stokes (URANS) solver in conjunction with realizable k-ε turbulence model has been used for the numerical analysis. Pressure and velocity distribution found around the rotor have also been analyzed and discussed. Based on the present investigation, the maximum power coefficient value of 0.44 is obtained for double stage turbine corresponding to tip speed ratio (TSR) value of 0.9 at Reynolds number of 37.53 × 104. Using numerical data obtained, correlation has been developed for power coefficient as a function of number of stages Reynolds number and tip speed ratio. • Effect of multi-stages on performance of Savonius hydrokinetic rotor is studied. • CFD investigation is carried out for Reynolds number ranging from 9.38 × 104 to 37.52 × 104. • Flow distribution around the Savonius hydrokinetic turbine is discussed. • A correlation for power coefficient is also developed. [ABSTRACT FROM AUTHOR]