Hydropower Technologies Research Articles

Preface of the proceeding of 12th International Symposium on Current Research in Hydropower Technologies

Current Research in Hydropower Technologies, CRHT-XII conference is taking place at Kathmandu University every year since 2012. It is an annual event of Turbine Testing Lab, where researchers and students in the field of hydraulic turbines and hydropower technologies share their experiences and research outcomes in a common platform. The event used to take place among the Masters and PhD students of Kathmandu University and Norwegian University of Science and Technology. However, there has also been an active participation from researchers and students around the world who are engaged in the similar fields in recent times. The conference has now taken an international recognition, as the selected papers from this conference will be published in journal proceedings. This year in the conference, 37 papers were presented in the topics of hydraulic turbines and pumps, computational and experimental techniques, hydropower and other renewable energy technologies, as well as the problems of erosion and cavitations. This year, we also saw many papers in the field of fish migration, fish passing technologies in hydropower, tunnel engineering and EV technologies, which show the broad topics covered within the hydropower. After receiving comments from the presentations and a peer review process, 24 papers have been selected for publication in this proceeding. We hope that the papers will be beneficial for the researchers and students involved in the sector of hydropower. We would like to thank all the participants, organizing team and the technical committee for the valuable contributions to make this a successful event. Editors Sailesh Chitrakar, PhD (sailesh@ku.edu.np) Prajwal Sapkota (prajwal.sapkota@ku.edu.np)

The new role of sustainable hydropower in flexible energy systems and its technical evolution through innovation and digitalization

Hydropower has played an important role in Europe in recent decades, offering a unique combination of safe, low-cost, and clean power generation. Today, it is still one of the largest renewable energy sources (RES), accounting for about 35 % of RES electricity generation. However, grid stability is threatened by the increasing amount of undispatchable RES. Flexibility and dynamics such as energy storage and rapid response are urgently needed to achieve EU policy goals. In such a context, hydropower can play a key role, not only as a provider of regulated renewable energy but also due to its ability to balance a renewable energy system in the short term and the medium/long term by pumped storage technology. All these aspects underline the new role of hydropower, which aims to strengthen grid stability and power supply resilience and to enable higher penetration of volatile RES. In this context, the aim of this paper is to demonstrate the role of hydropower at the European level as well as the needs and opportunities of modernization to fully exploit its potential. In particular, this study provides, the assessment of the today flexibility offered by hydropower to the power system at the European level by leveraging a database of information collected through the participants to the working groups of the COST Action Pen@Hydropower which includes stakeholders in the hydropower sector of 34 European countries. The study confirms the key role of hydropower in future energy scenarios with 30 % of the flexibility demand at all time scales met by hydropower. Furthermore, the paper presents a review of the digitalization solutions and innovative technologies that support the growth of a new generation of sustainable hydropower together with the modernization opportunities for existing hydropower plants. The results of this work have practical implications for stakeholders in the hydropower sector and policymakers as it provides evidence at the European scale of the role of hydropower technology in balancing the power system and the need to have supportive frameworks and adequate markets to fully exploit the European hydropower potential to achieve the energy transition goals.

Hybrid Solar-Hydropower Systems for Green Energy Production: A Comprehensive Analysis

This paper presents a detailed analysis of hybrid energy systems combining solar photovoltaic (PV) panels and hydropower technologies. Focusing on the increasing popularity of Archimedes screw generators for low head sites, we examine the efficiency and environmental benefits of such systems, particularly in reducing greenhouse gas emissions as part of global efforts like the Paris Agreement. We explore the integration of solar and hydropower systems in the context of Brazil’s renewable energy hybridization and discuss the challenges of their stochastic nature on power grid integration. The paper delves into the theoretical foundation, mathematical simulations, and optimization models that enable these hybrid systems to maintain energy and irrigation balance. The paper also investigates the use of photovoltaic-battery energy storage systems in building power supply and the potential of micro-grids featuring an array of renewable energy technologies. Ultimately, we present a novel approach to off-grid hybrid system deployment contributing to sustainable development goals.

Preface of the proceeding of 11th International Symposium on Current Research in Hydropower Technologies

The international symposium on Current Research in Hydropower Technologies (CRHT) aims to bring the researchers and students from the field of hydropower around the world in a common platform to share their research experiences. Since 2018, we have also been publishing papers from this conference in IOP Journal of Physics.This year in the symposium, we received 41 papers from Kathmandu University (KU), Tribhuwan University (TU), Norwegian University of Science and Technology (NTNU), École Polytechnique Fédérale de Lausanne (EPFL), Indian Institute of Technology (IIT-Roorkee), IIT-Delhi and Gujarat Technological University, Uka Tarsadia University and CK Pithawala, Gujarat.In the symposium, the overall event was divided into three sessions. The first group of sessions contained hydraulic turbines as well as hydropower and other technologies. We had presentations related to computational and experimental techniques related to the turbines, as well as civil and environmental aspects of the power plants, including sediment traps, tunnels and finding solutions for fish friendly and sustainable power plants. In the second group, there were sessions related to other forms of renewable energies as well, such as fuel cells, hydrokinetic turbines as well as seismic assessment of structures in hydropower. In the third group, we witnessed presentations related to condition monitoring of turbines, erosion and cavitation problems and some interdisciplinary aspects of the sustainable development.After receiving comments from the presentations and a peer review process, 36 papers have been selected for publication in this proceeding. We hope that the papers will be beneficial for the researchers and students involved in the sector of hydropower.

Ecological assessment of the world's first shaft hydropower plant

Efforts to increase the share of renewable energies and to reduce the negative ecological impacts of hydropower use are driving the development of novel hydropower technologies. Innovative hydropower concepts and turbine types should cause less fish damage and be more ‘eco-friendly’ than conventional hydropower plants. In this study, extensive ecological monitoring at the world's first innovative shaft hydropower plant (SHPP) was carried out. The monitoring included the assessment of the corridor usage of downstream moving fish, turbine-related fish injuries and mortality, as well as changes in aquatic community and habitat associated with hydropower plant construction in a before-after comparison. A large proportion of downstream moving fish was not prevented from turbine passage by the installed physical barrier, resulting in mortality rates up to 44% that can be similar to those at conventional Kaplan turbines. Strike and pressure changes (decompression rate up to 377 kPa/s) during turbine passage were identified as a major cause of mortality. In addition, significant differences in the aquatic community and abiotic habitat characteristics between upstream and downstream sides of the dam could be detected, indicating an interruption of the river continuum. The findings of this study indicate that the theoretical advantages of the SHPP concept of optimal fish protection from turbine passage and a low disruption of the serial continuity could not be realized in practice. Further research is needed to optimize this concept to better prevent fish from turbine entrainment, improve bypass efficiency and reduce the effects of the disruption of serial continuity.

The effect of runner installation and design on the performance of gravitational vortex water turbine

ABSTRACT Development in hydropower technology leads to modern and efficient technology. The emergence of gravitational vortex water turbine (GVWT) is a promising invention. It is suitable for harnessing energy from low head and flow rate water sources, ranging from approximately 0.7–2 m and 0.03–5 m3/s. A series of experimental studies had been conducted to develop the GVWT with a propeller runner. The objective of this study is to analyze the effect of runner design, including the number of blades, runner diameter and runner installation position, on the GVWT’s performance. A preliminary study on a dual-stage GVWT was carried out to increase the single-stage GVWT performance. The experimental result shows that 4-blade and 5-blade runners provide better performance than 3-blade runner and 6-blade runner. For a 5-blade runner, the optimal installation position is between 60% and 70% of depth. Installing a runner in the basin produces a blockage effect, which increase the runner performance. An extremely large blockage ratio causes stoppage which is undesirable. The maximum allowed blockage ratio is 0.8. The preliminary study on the dual-stage GVWT proves that it increases the GVWT’s performance. The efficiency of GVWT ranges from 25% − 50%.

Analysis of hydropower development in China

With the environmental destruction becoming more and more serious, all the countries on earth pool their minds to solve the environmental problems. The use of carbon is one of the most serious problems causing environmental pollution. The country's rapid development leads to excessive carbon emissions. To solve this problem, the country is researching and developing new energy sources. For China, water resources are part of the solution. If reasonable development and good use of water resources, can properly relieve the pressure brought by environmental pollution. This paper summarizes China's previous hydropower generation, and puts forward some suggestions in order to improve China's hydropower technology and reduce the damage to the environment.

Bio-inspired water-driven electricity generators: From fundamental mechanisms to practical applications

Harvesting water energy in various forms of water motion, such as evaporation, raindrops, river flows, ocean waves, and other, is promising to relieve the global energy crisis and reach the aim of carbon neutrality. However, this highly decentralized and distributed water energy poses a challenge on conventional electromagnetic hydropower technologies that feature centralization and scalization. Recently, this problem has been gradually addressed by the emergence of a myriad of electricity generators that take inspiration from natural living organisms, which have the capability to efficiently process and manage water and energy for survival in the natural competition. Imitating the liquid–solid behaviors manifested in ubiquitous biological processes, these generators allow for the efficient energy conversion from water–solid interaction into the charge transfer or electrical output under natural driving, such as gravity and solar power. However, in spite of the rapid development of the field, a fundamental understanding of these generators and their ability to bridge the gap between the fundamentals and the practical applications remains elusive. In this review, we first introduce the latest progress in the fundamental understanding in bio-inspired electricity generators that allow for efficient harvesting water energy in various forms, ranging from water evaporation, droplet to wave or flow, and then summarize the development of the engineering design of the various bio-inspired electricity generator in the practical applications, including self-powered sensor and wearable electronics. Finally, the prospects and urgent problems, such as how to achieve large-scale electricity generation, are presented.

Wasted and excess energy in the hydropower sector: A European assessment of tailrace hydrokinetic potential, degassing-methane capture and waste-heat recovery

Hydropower is the giant of the renewable energy sector, and a well-established source of energy. In order to reduce the impacts of new barriers in rivers, the retrofitting of existing facilities with new technologies is deserving a great attention, especially when hydropower technologies are hybridized with other energy devices. In this study a European-scale assessment is carried out to quantify the potential associated to the exploitation of the excess (and wasted) energy sources in existing hydropower facilities. Three sources of energy are assessed: 1) the hydrokinetic energy of the tailrace water flow and the potential energy associated to the unexploited head below Pelton units, 2) the thermal energy of the cooling system of the electric generators and 3) the chemical energy of the degassing methane. Considering the available technology, 5.0 TWh/y of heat could be generated by exploiting the thermal energy of the cooling system. 2.4 TWh/y of electricity could be generated by harnessing the hydrokinetic energy at the tailrace; this would correspond to thousands of micro hydropower plants 100 kW each), and would avoid new installations in natural freshwater systems. Degassing methane is relevant at the global scale, especially in tropical reservoirs. In Europe 5,950 tons/year of degassing methane could be theoretically captured, since minor methane emissions from reservoirs occur. R&D activities are ongoing to overcome the current technological limitations and high installation costs. Different novelties are included in this study: for the first time, a continental assessment is carried out on this topic, establishing methodologies that could be implemented at any regional scale. For each technology, a literature review is carried out to collect data and case studies. Data to estimate the number of units and the operating range of Francis, Kaplan and Pelton turbines in Europe, and equations to estimate the degassing methane emissions, are provided. These data can be used for similar large scale assessments.

Development of a Machine learning assessment method for renewable energy investment decision making

The aim of this study is to develop a hybrid methodology based on statistical approach and machine learning algorithm to structure the investment decisions in renewable energy industry. Six main criteria including GDP rate, inflation rate, electricity demand, electricity generation from Renewable Energy Technology (RET), electricity price, and CO2 emissions are used to classify and structure the decision-making algorithm. The risk related to each feature is calculated through using standard deviation of their historical data collected from each country. The Machine Learning (ML) algorithms such as Artificial Neural Network (ANN), Logistic regression (LR), Support Vector Machine (SVM), Decision Tree (DT), Naive Bayes (NB), k-Nearest Neighbors (k-NN), Random Forest (RF), and Ada Boost (AB) have been applied on the dataset related to each RET to classify the countries from the lowest risk (best country) to the highest risk (worst country) in terms of RET investment alternatives. LR, SVM, ANN, and DT showed the best performance among other ML algorithms. The highest accuracy was 0.94 and the lowest accuracy belonged to AB with the value of 0.24 for biomass technology. The minimum and maximum MSE was obtained 0.058 and 0.771 by LR for biomass technology and AB for hydropower technology, respectively. Moreover, the electricity generation risk from RET and electricity price risk in each country are the most important criteria for decision making in RET investment.

Current status, prospects, and implications of renewable energy for achieving sustainable development goals in Nepal

AbstractThe energy mix in Nepal is currently dominated by the traditional and inefficient use of biomass (66.54%) and fossil fuels (27.24%), and energy poverty remains extremely high. This paper reviews relevant literature to provide an overview of the current renewable energy status and energy mix in Nepal, and to discuss prospects for the country to achieve a sustainable energy transition. Nepal‐specific papers from peer‐reviewed sources and other agency and academic reports were included insofar as these discussed renewable energy and provided recommendations for policy‐making on sustainable energy and related development goals. Despite the rapidly falling cost of solar photovoltaic, the share of modern renewable energy in Nepal is currently less than 3%. On this basis, and given the country's sustainable energy goals, we conclude that favorable and aggressive policies and strategies are needed to support adoption of clean energy in Nepal, comprised of a high share of solar generation equipped with battery storage, and balanced with storage such as off‐river pumped hydropower technology.

31st IAHR Symposium on Hydraulic Machinery and Systems

Hydropower is one of leading sources of energy used to meet the primary, secondary and territory ancillary services to balance the energy demand. Hydraulic turbine is essential component of a hydro power plant to generate electricity. The IAHR symposium on hydraulic machinery and systems provides unique opportunity to the academic and industrial research teams to exchange the stat-of-the-art knowledge and ideas on the development of the next-generation of hydropower technology. 31st Symposium on Hydraulic Machinery and Systems was organized by Norwegian University of Science and Technology, Trondheim, Norway, during 26 June – 01 July 2022. This preface describes the overall summary of the symposium, including the parallel sessions, scientific and cultural tours. For more specific detail, please visit the symposium website www.ntnu.edu/iahr2022. Scientific manuscripts reviewed by the experts, accepted and presented during the symposium are published in a proceeding at IOP Science EES conference series.

Runner optimal position in a gravitational water vortex hydraulic turbine with spiral inlet channel and a conical basin

A gravitational water vortex hydraulic turbine (GWVHT) is a low head hydropower technology with a vertical runner for extracting energy from the water vortex. To determine the optimal position (h) of the runner for the hydropower plant efficiency to be increased, a runner in three different positions was compared using computational fluid dynamics (CFD). The position of the runner was a function of the basin height (H). The maximum efficiency (44.15%) was established when the runner was located at 60% of H. The angular velocity associated with the maximum efficiency was 14 rad/s.

Optimizing the Layout of Run-of-River Powerplants Using Cubic Hermite Splines and Genetic Algorithms

Despite the clear advantages of mini hydropower technology to provide energy access in remote areas of developing countries, the lack of resources and technical training in these contexts usually lead to suboptimal installations that do not exploit the full potential of the environment. To address this drawback, the present work proposes a novel method to optimize the design of mini-hydropower plants with a robust and efficient formulation. The approach does not involve typical 2D simplifications of the terrain penstock layout. On the contrary, the problem is formulated considering arbitrary three-dimensional terrain profiles and realistic penstock layouts taking into account the bending effect. To this end, the plant layout is modeled on a continuous basis through the cubic Hermite interpolation of a set of key points, and the optimization problem is addressed using a genetic algorithm with tailored generation, mutation and crossover operators, especially designed to improve both the exploration and intensification. The approach is successfully applied to a real-case scenario with real topographic data, demonstrating its capability of providing optimal solutions while dealing with arbitrary terrain topography. Finally, a comparison with a previous discrete approach demonstrated that this algorithm can lead to a noticeable cost reduction for the problem studied.

Balancing smart irrigation and hydropower investments for sustainable water conservation in the Indus basin

Indus River Basin (IRB) region of South Asia is severely water-stressed with irrigation receiving 90–95% of total surface water allocations and depletion of fossil groundwater reserves of more than 30 km3/year. Simultaneously, many supply-driven hydropower reservoirs, are planned in the basin. The reservoirs constructed upstream inflict severe environmental damages and reduce water availability for irrigation downstream. Policymakers promote smart technologies as a demand-based solution to reduce water consumption in irrigation. However, the effects of such technologies are not yet well understood, and unintended consequences (such as irrigation efficiency paradox and other nexus externalities) have recently begun to appear. Therefore, we use an integrated assessment model to analyze the proliferation of smart technologies in the IRB. The analysis suggests that if the Indus countries adopt a demand-based approach and irrigate their land completely using smart technologies, surface and groundwater withdrawals are indeed reduced. However, this reduction comes with a 33% increase in total expenditures, an increase in consumption across water and energy sectors, and higher withdrawals from fossil groundwater reserves. On the other hand, we find that if the countries were to balance their investments between smart and hydropower technologies it would not only reduce the increment in expenditure to 28%, but would also conserve irrigation water while avoiding the increased multi-sectoral consumption and environmental degradation. Thus, balancing investments between smart irrigation and hydropower projects can significantly reduce the economic and environmental (including conservation of water resources, meeting environmental flow targets, among others) costs of multi-sector water conservation in the IRB.

Hydropower development, policy and partnership in the 21st century: A China-Nigeria outlook

Regardless of the challenges facing renewable energy development in today’s world, hydropower is still the most broadly patronized source of renewable energy, with a global installed capacity of 1330 GW in 2020. Hydropower contributes the largest share of the total installed renewable energy globally, accounting for more than 54% of renewable energy generation capacity worldwide. In this 21st century, the quest for a global shift to a carbon-emission-free future has been epitomized by China through its way of overcoming some crucial challenges to becoming the number one hydropower producer in the world. China is currently the top exporter of its hydropower technology and expertise to a reasonably significant number of countries across the globe. Due to failed energy policy implementation, Nigeria, on the other hand, has been languishing in air pollution from fossil fuel energy generation due to poor and erratic electrical energy supply from the grid, despite its enormous hydropower potential. However, a resurgence of Nigeria’s National renewable energy and Energy Efficiency Policy in 2015 resulted in a consortium signed between China and Nigeria, placing China at the helm of reviving Nigeria’s hydropower industry, yielding some positive outcomes so far. A partnership between technologically advanced and undeveloped countries, particularly Africa, is required to overcome significant avoidable hydropower constraints towards attaining their full hydropower output potential. In this way, the imperative to guaranteeing a globally cleaner and more sustainable energy future is more reassuring.

Hydrokinetic Turbine Technology and Its Prospect in Bangladesh: A Review

As a sustainable alternative to fossil fuel, hydropower is becoming increasingly popular since the concern over global warming is growing worldwide. Conventional hydropower technology involves the use of hydraulic turbines, which require a large static head of water created by constructing a dam across the river. This technology, though widely used, has a negative impact on river hydrology and aquatic lives. Hydrokinetic turbine, on the other hand, having a working principle similar to wind turbine doesn’t require a dam or barrier and has negligible impact on the aquatic environment. Bangladesh being the land of rivers can effectively implement hydrokinetic turbine-based technology for supplying electricity in off-grid remote areas. In this article, a review of hydrokinetic turbine technology for extracting the kinetic energy of rivers and oceans has been conducted. The status, merits, and applications of this technology have been briefly discussed. Finally, the prospect of this technology in Bangladesh has been assessed.

A Review of World-wide Advanced Pumped Storage Hydropower Technologies

After the 21st UN Climate Change Conference, Net Zero Emissions (NZE) has become a hot issue in the power industry all over the world. The use of renewable energy for power generation will highly increase in the future. However, renewable energy power generation is limited by the uncertainty of renewable resources, which is easy to cause an imbalance between supply and demand. In order to eliminate the impact of renewable energy generators on the power system, the development of energy storage systems is most important. Pumped storage hydropower (PSH) is very popular because of its large capacity and low cost. The current main pumped storage hydropower technologies are conventional pumped storage hydropower (C-PSH), adjustable speed pumped storage hydropower (AS-PSH) and ternary pumped storage hydropower (T-PSH). This paper aims to analyze the principles, advantages and disadvantages of various PSH technologies, and provide a selection reference for future PSH expansion and replacement. In addition, this paper using a case for explain the T-PSH operating.

Design Guideline for Hydropower Plants Using One or Multiple Archimedes Screws

The Archimedes/Archimedean screw generator (ASG) is a fish-friendly hydropower technology that could operate under a wide range of flow heads and flow rates and generate power from almost any flow, even wastewater. The simplicity and low maintenance requirements and costs make ASGs suitable even for remote or developing areas. However, there are no general and easy-to-use guidelines for designing Archimedes screw power plants. Therefore, this study addresses this important concern by offering a simple method for quick rough estimations of the number and geometry of Archimedes screws in considering the installation site properties, river flow characteristics, and technical considerations. Moreover, it updates the newest analytical method of designing ASGs by introducing an easier graphical approach that not only covers standard designs but also simplifies custom designs. Besides, a list of currently installed and operating industrial multi-Archimedes screw hydropower plants are provided to review and explore the common design properties between different manufacturers. On top of that, this study helps to improve one of the biggest burdens of small projects, the unscalable initial investigation costs, by enabling everyone to evaluate the possibilities of a green and renewable Archimedes screw hydropower generation where a flow is available.

Hydropower Technology for Sustainable Energy Generation in Wastewater Systems: Learning from the Experience

Hydropower is a well-known technology, applied worldwide for electricity generation from renewable sources. Within the current framework, some studies have started to consider its application to existing urban water systems, to harness an excess of energy that otherwise would be wasted. This research sought to determine a methodology to assess the potential of hydropower application to wastewater treatment plants (WWTPs), regarding different aspects of sustainability. Firstly, previously developed methodologies for potential assessment in this sector at a country level were analyzed. Secondly, data from existing real case studies were gathered from publicly available documents and a theoretical analysis of their actual performance was conducted to validate assumptions made in the previous methodologies. As a result, the proposed new approach suggests adapting methodologies for potential assessment at a lower level, considering possible driving factors, other than economic feasibility. To define the study area, the management model scope should be considered. The power to determine the cut-off point for a WWTP to be considered as a potential site, is proposed to be lowered according to technical feasibility. Additionally, bearing in mind the sustainability concept, social or environmental factors should also be introduced in the methodology, tailored to the region being assessed. This novel perspective could provide a closer approach to the most likely decision-making level for these kinds of strategies in the wastewater industry.