Small Hydropower Systems Research Articles

Potential for small hydropower development on the Pumpum River of Ghana using Remote Sensing and Soil Water Assessment Tool

This study focused on identifying potential locations for the implementation of Small Hydropower Systems to enhance the existing energy infrastructure in the Pumpum River Basin (PRB). Utilizing remote sensing and the Soil and Water Assessment Tool, basin parameters were generated and simulated for hydropower analysis. The energy potential of suitable sites was assessed through flow duration curves and power duration curves. The findings reveal that the PRB exhibits potential for small hydropower development, identifying nine sites along the river. The results of the model indicate power capacities of 1,521 kW for the Run of River and 2,290 kW for the dam sites respectively. The most promising hydropower sites were identified as dam site 1, river of run site 1, and dam site 6 with corresponding firm power of 2356.2 kW, 1567 kW and 264 kW, resulting in estimated firm energy production of 12.07 GWh, 8.03 GWh, and 1.35 GWh, respectively. Considering the suitable spacing of more than between 12 km among dam site 1, river of run site 1, and dam site 6 and a combined annual energy production of 21.65 GWh, a recommended approach involves establishing a cascade hydropower arrangement at sites dam site 1, river of run site 1, and dam site 6 along the Pumpum River. With a plant capacity of 65% to 90% dependability range, incorporating an installed Francis turbine, the total annual firm energy that can be produced from the nine (9) (Run of river and dam) projected sites ranges between 0.69 and 12.07 GWh.

Real-time operating decision support system for reservoir operation using weather forecast and a hydrological model

This paper presents the application of a real-time decision support system (DSS) for power generation and flood control at the Thac Xang hydropower plant in Lang Son province, Vietnam. The DSS consists of three key components: real-time operation and visualization, forecast, and optimized decision modules. The real-time operation and visualization module provides operators with a graphical interface that displays real-time data on the plant's status, such as water levels, reservoir levels, and power output. The weather forecasting module provides information about future precipitation. This information is used as input data for the inflow forecasting model. The real-time computing module takes into account current conditions, such as the water level in the reservoir to compute relevant variables such as current inflow rate or outflow rates from the reservoir. The simulation module is used to test different operating scenarios taking current and future inflow rates into account. This helps the plant operators to understand the impact of their decisions on the plant's performance. The simulation module can also be used to identify potential problems and develop contingency plans. Therefore, a mathematical model is developed. Particularly, this model uses real-time information of dams. The main objective is to maximize economic value over the time horizon by producing electricity when it is most valuable. An approach of a simulated annealing algorithm is used to solve this model. We also present a decision support software tool for small hydropower systems that provide hydropower equipment operators with the information required to optimize the dam's performance in terms of power efficiency and effectiveness.

Small hydropower development potential in the Densu River Basin, Ghana

The study investigated potential sites for the development of Small Hydropower Systems (SHP) to augment the existing energy supply in the UDRB. Remote sensing and the Soil and Water Assessment Tool (SWAT) were employed to generate and simulate basin parameters for the hydropower analysis. The energy potential of suitable sites was evaluated using flow duration curves (FDC) and power duration curves (PDC). Results indicate that the upper DRB has potential for small hydropower development with nine sites along the river having an estimated combined firm power of 7.89 MW. The highest hydropower potential sites were located at HP1, HP7, and HP4 with corresponding firm energies of 13.39 GWh, 7.94 GWh, and 6.83 GWh and estimated annual energy production of 28.68 GWh, 14.36 GWh, and 12.68 GWh respectively. Given the adequate spacing distance between sites HP1 and HP4 (11.38 km) and HP4 and HP7 (11.31 km) with a combined annual energy production of 55.72 GWh, a cascade hydropower arrangement of sites HP1, HP4, and HP7 is recommended along the Upper section of the Densu River. However, based on the analysis, these hydropower sites could be developed as a cascade storage hydropower with a 50% or 75% dependability with an installed Francis turbine.

Investigation of the Configuration of Small Hydropower using a Novel Smoothed Particle Hydrodynamics Method

A novel Computational Fluid Dynamics (CFD) method utilizing Smoothed Particle Hydrodynamics (SPH) has been developed and applied to a simulation of flows in small hydropower systems. The simulation of the flow through a gravitational vortex turbine (GVT) small hydropower system where the flow is directed to a circular basin with a vertical-axis turbine, harnessing the rotational energy of the vortex formed to drive the turbine. Two modes of Fluid-Structure Interactions (FSI) were tested with identical flow conditions to evaluate the potential of this method to simulate complex FSI scenarios. It was found that simulation results for both one-way and two-way interactions produced reasonable results. The two-way interaction result proved to reflect more accurate FSI scenarios, but more studies are needed to provide validation.

Transient study of series-connected pumps working as turbines in off-grid systems

In the current world economic environment where reducing energy costs is a high priority, it is not surprising that sustainable water and energy management are key topics among the water and electric industry. Specifically, water suppliers, pump manufacturers, and operatives of small hydropower systems, all recognize that pumps working as turbines can be an efficient, simple, and economic approach to generating power and recover the excess of energy in water pressurized systems. In both, variable operating flow rate conditions (ex: presence of different water users) impose the need to augment the range of a proper pump as turbine system. One solution is to associate several pumps as turbines in series to increase the recovered energy. In that context, this work assesses their reliability at transient off-grid conditions by two pumps as turbines connected in series. Each one has an identical self-excited induction generator feeding a three-phase and balanced resistive load. Changes (increase/decrease in values) were applied to the resistive loads and the bank of capacitors at one group only, which allowed examining how changes affect the overall two-group system dynamics. Results show that one change in the first pump as turbine group will significantly affect the other group dynamics. For example, a decrease in load of the first group will affect the flow and head of the other system, until reaching a new equilibrium point. However, as both groups are not mechanically connected, they can achieve different equilibrium speeds. Furthermore, the highest impact occurred in the group where no changes were imposed. The first group maintained its global efficiency value, while the second had its efficiency decreased by about 8%. Similarly, an increase in the capacitance value caused a reduction in its efficiency (lesser but around 2%). Finally, a numerical model was developed and validated through experimental tests to be an applicable prediction model.

Development of a Hydropower Turbine Using Seawater from a Fish Farm

Discharge water from fish farms is a clean, renewable, and abundant energy source that has been used to obtain renewable energy via small hydropower plants. Small hydropower plants may be installed at offshore fish farms where suitable water is obtained throughout the year. It is necessary to meet the challenges of developing small hydropower systems, including sustainability and turbine efficiency. The main objective of this study was to investigate the possibility of constructing a small hydropower plant and develop 100 kW class propeller-type turbines in a fish farm with a permanent magnet synchronous generator (PMSG). The turbine was optimized using a computer simulation, and an experiment was conducted to obtain performance data. Simulation results were then validated with experimental results. Results revealed that streamlining the designed shape of the guide vane reduced the flow separation and improved the efficiency of the turbine. Optimizing the shape of the runner vane decreased the flow rate, reducing the water power and increasing the efficiency by about 5.57%. Also, results revealed that tubular or cross-flow turbines could be suitable for use in fish farm power plants, and the generator used should be waterproofed to avoid exposure to seawater.

Advances in the Definition of Needs and Specifications for a Climate Service Tool Aimed at Small Hydropower Plants’ Operation and Management

The operation feasibility of small hydropower plants in mountainous sites is subjected to the run-of-river flow, which is also dependent on a high variability in precipitation and snow cover. Moreover, the management of this kind of system has to be performed with some particular operation conditions of the plant (e.g., turbine minimum and maximum discharge) but also some environmental flow requirements. In this context, a technological climate service is conceived in a tight connection with end users, perfectly answering the needs of the management of small hydropower systems in a pilot area, and providing a forecast of the river streamflow together with other operation data. This paper presents an overview of the service but also a set of lessons learnt related to the features, requirements, and considerations to bear in mind from the point of view of climate service developers. In addition, the outcomes give insight into how this kind of service could change the traditional management (normally based on past experience), providing a probability range of the future river flow based on future weather scenarios according to the range of future weather possibilities. This highlights the utility of the co-generation process to implement climate services for water and energy fields but also that seasonal climate forecasting could improve the business as usual of this kind of facility.

Identifying the Links Among Poverty, Hydroenergy and Water Use Using Data Mining Methods

Water is fundamental to human well-being, social development and the environment. Water development, particularly hydropower, provides an important source of renewable energy. Water development is strongly affected by poverty, but only few attempts have been made to understand the links between water development and poverty from a global water development point of view. In this work, this linkage was explored using reservoir construction, hydroenergy and water use data along with six derived indicators. We used association rule mining and classification and regression trees (CART) to identify the links. Random forests were employed to search for factors sensitive to poverty. This study shows that the reservoir density is significantly related to poverty, and reservoir densities are lower in countries with higher poverty rates. Countries with a higher use of small hydropower (SHP) systems are generally more prosperous as follows: an SHP utilization rate above 27% corresponds to a poverty rate below 4.9%. The ratio of water utilization, water availability per capita (WAPC) and reservoir density were essential for the prediction of the poverty class. All three ratios could be related to poverty alleviation as they enable the identification of the potential for water resource development and their constraints. This study concludes that water development in poor countries needs to receive more attention.

Computational Analysis of a Double-Nozzle Crossflow Hydroturbine

The crossflow turbines commonly used in small hydropower systems have a single nozzle. We are unaware of any studies of double-nozzle crossflow turbines which could have twice the power output of the single-nozzle design by doubling the flow through the same runner, with a high maximum efficiency. We present a computational analysis of a double-nozzle crossflow turbine, to determine the turbine efficiency and fundamental flow patterns. This work was based on a single-nozzle crossflow turbine with a maximum efficiency of 88%, one of the highest reported in the open literature through extensive experimental measurements. Previous numerical studies on this turbine have shown that the water flow in the runner was confined to less than half the runner periphery, implying that the other half could be used to double the runner power output by employing a second nozzle. We show that adding a second, identical nozzle without making any other changes to the design achieves a doubling of the power output. The dual-nozzle turbine, therefore, has the same efficiency as the original turbine. We also investigate the use of a slider to control the flow at part-load and show that part-load efficiency of the double-nozzle is very similar to that of the original turbine. This demonstrates the feasibility of using two nozzles for crossflow turbines.

The place of small hydropower electrification scheme in socioeconomic stimulation of Nigeria

The World Bank reported that approximately 55% of Nigeria’s population have no access to the national electricity grid and most of these people live in the rural areas. The national grid capacity is hovering between 4500 MW and 6000 MW for a population of about 186 million. However, this is contrary to the enormous energy that abounds in Nigeria, both conventional and renewable energy sources. Nigeria is ranked 13th largest crude oil producer in the world and 1st in Africa, with current crude oil reserves of 37 billion barrels and gas reserves of 192 trillion cubic feet. The supply of adequate and affordable power by Nigeria to her citizens is further compounded by the global energy trends coined as energy trilemma. This involves the global pursuit of energy equity, energy security and environmental sustainability. Emission of CO2 in Nigeria has risen from 0.0 Kt in 1960 to 82 634.2 Kt in 2016 mainly due to the use of fossil fuels. This study sees small hydropower (SHP) systems as an alternative source of energy that satisfies the modern energy attributes of low CO2 emissions with environmentally friendly flow, and a renewable energy source. Only about 64.2 MW out of the 3,500 MW estimated SHP exploitable potential distributed across Nigeria has been tapped. Adequate development and utilization of SHPS will substantially add to the supply capacity of clean and affordable power in Nigeria. This study recognizes SHP systems as the cornerstone to rural electrification and socioeconomic activity stimulation in Nigeria.

Rural utility to low-carbon industry: Small hydropower and the industrialization of renewable energy in China

Small hydropower (SHP) is a renewable energy that provides electricity for many rural areas in the Global South that lack national grid access. In China, however, SHP has transformed from a community-focused rural utility into to a privatized low-carbon industry that earns revenues from the sale of electricity to the grid. This paper analyzes the policies that enabled this transformation of SHP in China, and the profit motivations and political incentives that shape plant construction and operation. I argue that privatizing and framing SHP as ‘low-carbon’ makes it more amenable to industrialization, because its value is based on the amount of electricity it generates, not its contribution to poverty alleviation and conservation. Data were collected from interviews with government officials, private investors, and farmers in Xinping county, located in Yunnan province in China’s southwest. I find that investors and officials are incentivized to build and operate large-scale SHP systems that have a high installed capacity, are situated in multiple-plant cascades, and that attempt to operate year-round, including during the dry season. Some of these plants reduce streamflow and irrigation water access for farmers. This case thus exposes the inequalities of privatizing and deploying rural renewable energy for low-carbon industrial growth in the absence of strong local environmental and social safeguards.

The role of hydropower installations for sustainable energy development in Turkey and the world

Abstract Hydropower has the largest share among renewable energy sources in the world, supplying more than 16.6% of total global electricity to over 160 countries around the world. Global hydropower capacity increased to approximately 1096 GW with the addition of 25 GW of new hydropower capacity in 2016. With a 216 TWh per year generation capacity, Turkey’s hydropower potential is the largest in Europe. The increased rate of installed capacity in Turkey was ranked 7th in the world in 2016 with an annual installed hydroelectric capacity of 0.8 GW. The main objective of this paper is to review the developments of hydropower installations around the world and in Turkey with an emphasis on the potential of small scale hydropower systems such as waterwheels in utilizing low head water flow for household electricity usage. In the first part of this study, the growth of worldwide hydropower capacity is reviewed and the countries with the largest installed and new built hydropower capacities are reported. In the second part of this study, the current status of Turkey’s hydropower plants is discussed in detail with respect to annual regional rainfall, gross water mass flow and potential of Turkey’s major water basins to demonstrate the potential energy output that can be harnessed from small-scale systems implemented in low-head water sources. In addition, the most recent information on Turkey’s electricity generation and consumption rates are reported.

Small Hydropower Development in Rwanda: Trends, Opportunities and Challenges

The Rift Valley region of Sub-Saharan Africa represents a promising area for the development of small (<5MW) hydropower resources. This study compiles data from government and UN agency reports to analyze different development outlooks. The study found that there has been a rapid deployment of small hydropower in the last 10 years. From the current total deployed small hydro of 47.5 MW, 16.5MW (35%) were deployed from 1957 to 1984 while the remaining 31 MW (65%) were deployed from 2007 to 2017. While all systems constructed prior to 1985 are grid-connected, one third of the 24 facilities constructed after 2007 are connected to off-grid systems. The study provides an overview of the economic incentives for developing small hydropower systems in Rwanda and the potential contribution of that development to Rwanda’s electrification goals.

Smart Design and Development of a Small Hydropower System and Exploitation of Locally Sourced Material for Pelton Turbine Bucket Production

Small hydropower (SHP) systems are known to be an environmentally friendly, cost-effective and simple form of renewable energy production, appropriate for rural and standalone electrification. Greater access to power in sub-Saharan Africa (SSA) can be facilitated through domestic design and development of SHP components and systems. Domestic participation in the design, manufacturing of SHP components and application of SHP systems can be promoted through SHP capacity building and the use of locally sourced materials. This study, therefore, involves the design of both civil and mechanical aspects of SHP, and the use of locally sourced materials and manufacturing processes, in the design and production of Pelton turbine buckets. The study succeeded in the coding of a SHP system design and the development of design charts using MATLAB. A390 and A390-5 Mg cast aluminium alloys were selected and investigated as Pelton bucket materials using Solidworks modelling and simulation software. The performance of the materials as measured by von Mises, displacement and strain results were outstanding: the probe maximum stress was 6.7 × 107 N/m2, located along the splitter; the FOS was 4.5; fatigue damage and load safety for fully reversed loading at 106 cycles were 0.001 and 2.03, respectively.

Experimental investigation and performance prediction modeling of a single stage centrifugal pump operating as turbine

In small hydropower systems, Pumps as Turbines (PaTs) represent a cost-effective alternative to conventional turbines as long as the turbine mode performance can be predicted before their installation. A closed-loop test rig for experimental studies on hydraulic pumps and turbines has been built at the Department of Mechanics, Mathematics and Management of the Polytechnic University of Bari, in order to experimentally support the theoretical studies on PaTs. A single stage centrifugal pump has been tested in both direct and reverse mode. Furthermore, a literature survey of PaT models has been conducted and a new model, with a more general applicability, has been proposed.

Energy Recovery in Existing Water Networks: Towards Greater Sustainability

Analyses of possible synergies between energy recovery and water management are essential for achieving sustainable improvements in the performance of irrigation water networks. Improving the energy efficiency of water systems by hydraulic energy recovery is becoming an inevitable trend for energy conservation, emissions reduction, and the increase of profit margins as well as for environmental requirements. This paper presents the state of the art of hydraulic energy generation in drinking and irrigation water networks through an extensive review and by analyzing the types of machinery installed, economic and environmental implications of large and small hydropower systems, and how hydropower can be applied in water distribution networks (drinking and irrigation) where energy recovery is not the main objective. Several proposed solutions of energy recovery by using hydraulic machines increase the added value of irrigation water networks, which is an open field that needs to be explored in the near future.

A Performance Prediction Method for Pumps as Turbines (PAT) Using a Computational Fluid Dynamics (CFD) Modeling Approach

Small and micro hydropower systems represent an attractive solution for generating electricity at low cost and with low environmental impact. The pump-as-turbine (PAT) approach has promise in this application due to its low purchase and maintenance costs. In this paper, a new method to predict the inverse characteristic of industrial centrifugal pumps is presented. This method is based on results of simulations performed with commercial three-dimensional Computational Fluid Dynamics (CFD) software. Model results have been first validated in pumping mode using data supplied by pump manufacturers. Then, the results have been compared to experimental data for a pump running in reverse. Experimentation has been performed on a dedicated test bench installed in the Department of Civil Construction and Environmental Engineering of the University of Naples Federico II. Three different pumps, with different specific speeds, have been analyzed. Using the model results, the inverse characteristic and the best efficiency point have been evaluated. Finally, results have been compared to prediction methods available in the literature.

Facilitating greater energy access in rural and remote areas of sub-Saharan Africa: Small hydropower

Flowing water has hydraulic energy that can be transformed into electrical energy, sub-Saharan Africa has an abundance of hydro resources that are untapped. In this study, various barriers limiting the use of small hydropower to tap the abundant hydro potentials for power generation are discussed. These barriers include insufficient fund; lack of adequate manufacturing infrastructure; lack of adequate power generation and distribution policies; inaccurate hydrological data; insufficient human and power infrastructure capacities; and inadequate domestic and regional participation in design and manufacture of small hydropower component devices and systems. This study sees hydro as a cleaner energy source and small hydropower as the best power system for rural and remote areas and for stand-alone electrification. For power sustainability in the region, public–private partnership, domestication of small hydropower technologies and less reliance on foreign technologies and international support are key factors.

Design and optimization of small hydropower systems in water distribution networks under consideration of rehabilitation measures

Small hydro power systems (SHPSs) are increasingly installed in water distribution systems (WDSs). With only minor adaptations in a WDS, pressure surplus can be utilised. In such systems, a water surplus is also often available. In this work, water consumption data of a real Alpine WDS over one year are used as an input for an Epanet2 long-term simulation model to assess such a SHPS. In addition, the combinations of pressure and water surplus devices in a WDS are investigated. For such a specific investigated case, the yearly profit of 1750 € for a single SHPS could be increased to 3550 € when combining two interacting devices. Further, necessary and upcoming rehabilitation measures are investigated concerning their positive impact on the energy production potential and how additional costs (e.g., higher diameters (200 mm instead of 125 mm)) can be compensated by additional profits from energy production (maximum 5250 € per year).

Review of small hydropower system

Renewable energy resources play an important part in the world's future. Renewable energy sources have the following components: biomass, geothermal, solar thermal, directs solar, wind, tidal and hydropower. Hydropower is still the most efficient way to generate electricity worldwide. Hydropower projects can contribute as a cheap energy source, as well to encourage the development of small industries across a wide range of new technology; furthermore hydropower systems use the energy in flowing and falling water to produce electricity or mechanical energy. Hydropower systems are classified as large, medium, small, mini and micro according to their installed power generation capacity, as do the following components: water turbines, control mechanisms and electrical transmissions. In this article a review of small hydropower systems has been done on the principles surrounding the fundamentals of hydraulic engineering, the fundamentals of hydrology, identification of sites and economic analysis.