Role Of Hydropower Research Articles

Effect of the leakage flow through guide vanes on the erosion pattern and performance of Francis runner

Abstract The role of hydropower as a renewable energy source is well understood. However, due to the geological characteristics of certain regions, hydropower systems there are facing a unique challenge of excessive sedimentation in rivers. A significant number of research works were performed in the past, which focused on the effects of sediments on the turbine components, that includes reduction in efficiency of the turbine and increase in the erosion wear. Experimental studies of erosion in laboratory conditions are usually limited by several characteristics that affect erosion and complications of handling sediments. As a result, these investigations are normally carried out in a simplified apparatus. This study focuses on using a non-recirculating type of sediment erosion test rig, where a model of Francis turbine is used for experimental investigations. Previous studies have shown that in the case of Francis turbines, erosion occurs in the clearance gap of guide vanes, which increases the size of the gap. The flow from the pressure side of the guide vane is driven into the suction side due to the pressure difference between the two sides. This leakage flow ultimately develops into a vortex filament and hits the runner blades towards the hub and shroud. In this study, the erosion pattern of the runner blades towards these locations are studied by using color coatings. A clearance gap of 4 mm has been created in the guide vane and the consequent impact on the erosion and efficiency of the turbine are studied. The objective is to isolate the effects of leakage flow on erosion in the runner inlet, as well as the overall performance of the Francis turbine. The effect has been observed in terms of increased flow rate, decreased efficiency and erosion in the leading edge of the runner.

Reimagining hydropower in the United States

AbstractIn this Perspective, we review the clashing narratives around the role of hydropower in the United States' (US) energy future. In doing so, we reveal how hydropower is regarded as a keystone for the renewable energy transition but also viewed as a harmful technology with significant negative environmental and social impacts. These narratives can be seen in the contrasting future renewable energy visions of US government agencies, the hydropower industry, NGOs, and Tribal governments. We review critical lessons learned from past dam‐ and hydropower‐related challenges to reimagine a just energy future for the US that bridges diverse sectors, jurisdictions, and values. We conclude by highlighting some key paths forward that might result in more resilient and adaptive water and energy systems as the country strives to decarbonize.This article is categorized under: Human Water > Human Water Human Water > Water Governance Science of Water > Water and Environmental Change Engineering Water > Planning Water

Hydropeaking mitigation with re‐regulation reservoirs

AbstractThe role of hydropower as a renewable and balancing power source is expected to increase in a Net Zero Emissions by 2050 scenario. As a common phenomenon in hydropower plants, hydropeaking will become more prominent, resulting in additional stresses on the ecological status of rivers. Here we propose a novel approach to design and operate auxiliary reservoirs called re‐regulation reservoirs (RRR) that aim to mitigate the adverse impacts of hydropeaking on rivers. A re‐regulation reservoir aims at smoothing flow fluctuations caused by hydropeaking by diverting and retaining parts of high flows and returning them back to river corridors during low flows. Using actual data from a hydropeaking‐influenced river system, the operation and efficiency of potential reservoirs have been investigated. An open‐access algorithm was developed to analyze the influence of the reservoirs to mitigate hydropeaking, considering peak and minimum flow and up‐ and down‐ramping rates. The findings illustrate that, in most cases, the required reservoir volume increases as the flow thresholds become more stringent. Nonetheless, several exceptions were observed, where larger reservoir volumes were required compared with cases with more stringent thresholds. These findings highlight the importance of understanding the impact of flow adjustments, while carefully considering the river regime, sub‐daily flow patterns, and unique characteristics of the river's ecosystem. Our approach shows theoretical possibilities for regulating hydropeaking and provides a basis for optimizing re‐regulation reservoirs, contributing to practical and adaptable strategies for sustainable hydropower management without increasing the operational cost of power systems.

Hydropower Hegemony: Examining Civil Society Opposition to Dams in Cambodia

As the urgency of addressing the climate crisis gathers pace, the role of hydropower is likely to attract increased interest for its claimed sustainability, despite fragmenting fragile river systems and evidence of significant emissions when constructed in tropical contexts. Building upon existing post-development, political ecology and civil society literature, this paper examines civil society opposition to hydropower projects in Cambodia. The paper introduces the term ‘hydropower hegemony,’ as an analytical tool for examining not just the tactical dimensions of civil society opposition to hydropower, but also the importance of ideological contestation. This analysis is applied to two case studies, Lower Sesan 2 and the Areng Valley in Cambodia, but with relevance for populations in peripheral areas and countries facing the expansion of hydropower projects. The case studies illustrate a spectrum of approaches to contestation, from reform to confrontation, and their intersections with the rapacious Cambodian state. The analysis also challenges reductionist characterizations of civil society in Cambodia. Despite the presence and success of confrontation with the state, we suggest that civil society’s increasingly reformist approaches are ultimately reinforcing hegemony, hydropower and otherwise, rather than challenging it, by inadvertently taming and domesticating burgeoning opposition to dispossession.

The role of hydropower in the renewable energy industry in reducing CO2 emissions in COVID-19

Become a necessary strategy for curbing a fast rise in infections because of the Coronavirus 2019 (COVID-19) social pandemic distance. However, the government's strategy has had an effect on the life and socio-economic activities of citizens because the pandemic had to be coping with new adaptive measures. The study therefore explores the links between the existing COVID-19 hydropower pandemic and the reduction of CO2 emissions in the power sector. This paper examines the COVID-19 pandemic trend in the hydropower and energy sector in relation to reduction of CO2 emissions by systematically reviewing secondary information from document reports and existing literatures. Findings from this article provide empirical evidence for the COVID-19 effect of a CO2 emission reduction during a pandemic on the hydroelectric and energy sectors. More importantly, the findings of the study examine COVID-19's energy relations, its influence on the hydroelectricity sectors as compared to other renewables, COVID-19's impact on energy and oil demand as well as COVID-19's lock-up relationship on CO2 emissions reduction. Finally, policymakers are led to choose to produce sustainable energy and to reduce CO2 emissions.

Numerical Simulation and Experimental Validation of a Kaplan Prototype Turbine Operating on a Cam Curve

The role of hydropower has become increasingly essential following the introduction of intermittent renewable energies. Quickly regulating power is needed, and the transient operations of hydropower plants have consequently become more frequent. Large pressure fluctuations occur during transient operations, leading to the premature fatigue and wear of hydraulic turbines. Investigations of the transient flow phenomena developed in small-scale turbine models are useful and accessible but limited. On the other hand, experimental and numerical studies of full-scale large turbines are challenging due to production losses, large scales, high Reynolds numbers, and computational demands. In the present work, the operation of a 10 MW Kaplan prototype turbine was modelled for two operating points on a propeller curve corresponding to the best efficiency point and part-load conditions. First, an analysis of the possible means of reducing the model complexity is presented. The influence of the boundary conditions, runner blade clearance, blade geometry and mesh size on the numerical results is discussed. Secondly, the results of the numerical simulations are presented and compared to experimental measurements performed on the prototype in order to validate the numerical model. The mean torque and pressure values were reasonably predicted at both operating points with the simplified model. An analysis of the pressure fluctuations at part load demonstrated that the numerical simulation captured the rotating vortex rope developed in the draft tube. The frequencies of the rotating and plunging components of the rotating vortex were accurately captured, but the amplitudes were underestimated compared to the experimental data.

Hydropower as a catalyst for the energy transition within the European Green Deal Part I: urgency of the Green Deal and the role of Hydropower

The European Union has the ambition to be the first carbonneutral continent by 2050. To fulfil this objective and integrate into the grid the large amount of power from solar and wind, Europe can rely upon the high storage and flexible capacity of hydropower. Thus, new reservoirs and innovative use of current reservoirs will be needed to provide an effective contribution to this unprecedented European Green Deal. The project Hydropower Europe, funded by the H2020 research programme, is tasked with identifying innovative uses of reservoirs and prioritizing the associated innovation actions targeting an energy system with high flexibility and renewable share. The project deliverables are a Research and Innovation Agenda (RIA) listing the top strategic research and innovation directions and a Strategic Industry Roadmap (SIR) addressing non-technical actions and requests for the hydropower sector. This paper describes the vision of the project: “Hydropower as a catalyst for the energy transition”. In this paper (Part I), the Green Deal and the role of hydropower are outlined and discussed. In Part II of the paper, after highlighting the complex environment that hydropower is situated within in Europe, and the challenges of biodiversity, the main innovation and research directions (extracted from the RIA) and the main steps for combining multipurpose hydropower, in a sustainable, efficient and cost-effective manner (extracted from the SIR), are presented.

Hydropower as a catalyst for the energy transition within the European Green Deal Part II: The complex environment for hydropower, biodiversity challenges and the main innovation and research directions

The European Union has the ambition to be the first carbonneutral continent by 2050. To fulfil this objective and integrate into the grid the large amount of power from solar and wind, Europe can rely upon the high storage and flexible capacity of hydropower. Thus, new reservoirs and innovative use of current reservoirs will be needed to provide an effective contribution to this unprecedented European Green Deal. The project Hydropower Europe, funded by the H2020 research programme, is tasked with identifying innovative uses of reservoirs and prioritizing the associated innovation actions targeting an energy system with high flexibility and renewable share. The project deliverables are a Research and Innovation Agenda (RIA) listing the top strategic research and innovation directions and a Strategic Industry Roadmap (SIR) addressing non-technical actions and requests for the hydropower sector. This paper describes the vision of the project: “Hydropower as a catalyst for the energy transition”. In Part I of this paper, the Green Deal and the role of hydropower were outlined and discussed. In this Part II, after highlighting the complex environment for hydropower in Europe, and the challenges of biodiversity, the main innovation and research directions extracted from the RIA and the main steps of the SIR for combining multipurpose hydropower, in a sustainable, efficient and cost-effective manner, are presented.

Bhutan’s Hydropower: the Economy Sector and One of the Foundations of the State's Foreign Policy

The small Himalayan Kingdom of Bhutan, located in South Asia between China and India, is constrained in the alternatives of means for development. The most optimal natural resource for exploitation is the system of mountain rivers and the energy received from them. At the same time, this sector of the country's economy faces several development difficulties. Those often include the technical complexity of project implementation, the national debt burden, the impact of hydroelectric power plants on wildlife preserved in the Kingdom, deep dependence on New Delhi solutions and limited alternatives for partnership in the industry. The article is based on the comprehensive approach. The author explores the natural resources available to the country, the peculiarities of their use and analyzes the hydropower facilities implemented in the Kingdom, as well as those at different stages of construction. The article also studies the national regulatory and structural fundamentals of the sector’s organization in a small state. The role of hydropower in foreign trade and in ensuring the welfare of the Himalayan country is determined on the basis of actual data, as well as the conditions and main schemes of project implementation and sources of financing for energy initiatives in the country. The importance of the Bhutan's hydropower industry in forming its foreign policy course is considered. Hydropower gave an impetus to the growth of the Kingdom's economy, but also it determined the long-term prospects for its development.

The nature of our mistakes, from promise to practice: Water stewardship for sustainable hydropower in Sub‐Saharan Africa

AbstractThe role of hydropower in the renewable energy mix for Africa's green development is widely recognised and underpinned by respective government and development partner funded initiatives. However, the growing demand for energy must be balanced with considerations for resource protection and benefit sharing of water resource developments with vulnerable human communities. An international conference on water stewardship for sustainable hydropower brought together key stakeholders in Nairobi, Kenya. This paper aims to synthesise the key messages of experts who attended the conference, presents the emerging body of good practice policies, plans and action in developing sustainable hydropower in Sub‐Saharan Africa, and provides recommendations for the way forward. Outcomes of the conference include considerations, planning for sustainable resource development, resource protection considerations, sharing of resource development benefits, and putting the promise into practice. This discussion describes the nature of our planning and management mistakes in the past, presents good practice options and how to implement sustainable hydropower in the future.

Trends in Hydropower

With a global focus on reducing carbon dioxide emissions, hydro power has come to the fore as an effective means of balancing other forms of electricity production from renewable sources (wind, photovoltaics and biomass).
 The role of hydropower in the modern mix of energy has led to favorable climatic conditions for development in the construction of new plants and upgrading with the renovation of existing hydroelectric power plants.
 Especially reversible hydropower plants with modern equipment with the so-called variable speed technology have a special role, which enables stability in the primary and secondary energy regulation system.
 A noteworthy trend is the construction of new facilities with low falls with the installation of highly efficient Kaplan and Tubular turbines.
 The already built projects in the fifth and sixth decades of the previous century, especially in northern Europe, are rapidly revamped and prepared for use in the next 40 to 50 years.
 Modern and sustainable approach to designing and preparing documentation for the construction of new or renewable power plants requires the use of modern information technology with 3D design and BIM (Building information Modeling) approach. In this way, young generations of engineers and consultants are easier to communicate with each other and reduce the possibility of errors in all phases of project realization.
 Key to the realization is the contracting of projects, the big dilemma whether to have EPC (Engineering, Procurement, and Construction) contracts (turnkey) a responsibility in one place or to deal with separate lots and engage their employees to control realization in order to minimize risk.
 Special attention is given to model research and development of turbines with reciprocal tests both on the model and prototype turbines.

The role of hydropower in South Asia’s energy future

ABSTRACT With rising energy demand in Asia, the high potential for hydropower development and the need for low-carbon energy development, hydropower would seem to have a significant role in South Asia’s energy future. However, the extent of hydropower development will depend on several risk factors, including the cost of alternative energy sources, the environmental sustainability of hydropower and social issues of equitable development. Using a risk-analysis framework, it is concluded that the future of hydropower will depend on how well policies and institutions manage the risks, facilitate efficient financial markets, and promote fair and friendly cross-border electricity trade.

Credit crunch: Chinese infrastructure lending and Lao sovereign debt

AbstractLao PDR's push for large infrastructure‐led economic growth has been delivered through a significant amount of financial leverage and a build‐up of sovereign debt obligations. The government now finds itself in danger of a sovereign default. This article traces the roots of this debt crisis over the past decade, focusing particularly on the role of hydropower. A significant share of infrastructure lending to Laos has been through Chinese policy banks. We argue that over‐lending to dam projects focused on the domestic energy market has been at the core of Laos' debt situation. Through 2020 the Lao Government has undertaken a series of restructuring measures, including privatisation of state assets, engaging in debt renegotiations with China, and attempts to secure new short‐term credit. We outline a range of other options Laos has to reschedule or restructure their sovereign debt, and offer policy targeted recommendations focusing on reforms in the energy sector.

Experimental investigation of theoretical stability regions for ultra-low frequency oscillations of hydropower generating systems

With the increasing momentum towards flexible power systems based on renewables, the role of hydropower has great importance, especially for providing balancing power. In this paper, a fundamental study on the operating stability of hydropower generating systems is conducted to reveal the practical characteristics for the newly emergent issue of ultra-low frequency oscillations. A unique study methodology is adapted by combing the theoretical analysis and the physical model experiment. In this paper, first, the set-up of the integral experiment platform for the transient processes of the pumped storage plants is presented. Second, a mathematical model of hydropower generating systems is built, and the theoretical stability analysis is conducted based on the Routh-Hurwitz criterion and the stability margin region. The model experiments related to the frequency stability of hydropower generating systems were conducted with reference to the stability region from theoretical analysis. The results demonstrate the sustained ultra-low frequency oscillations and frequency instability of hydropower units in experiments for the first time. Attenuation characteristics of the oscillations are theoretically derived based on the stability margin region, and then quantitatively identified by experiments. The experiment accorded with theoretical stability region within a reasonable tolerance that corresponded to the ±0.1 stability margin.

The role of hydropower in visions of water resources development for rivers of Western Nepal

ABSTRACT Water resources can play significant roles in development pathways for water-endowed, low-income countries like Nepal. This article describes three visions for water resource development in the Karnali and Mahakali Basins of Western Nepal: state-led development, demand-driven development and preservation of ecosystem integrity. The analysis calls attention to water use trade-offs, including those resulting from national priorities such as infrastructure-based hydropower and irrigation, from local drinking water demand, and from environmental conservation concerns. While these visions of water resources development do diverge, common trends appear, including acknowledgment of water management’s role in expanding energy access and increasing agricultural productivity.

The role of hydro power, storage and transmission in the decarbonization of the Chinese power system

Deep decarbonization of the electricity sector can be provided by a high penetration of renewable sources such as wind, solar PV and hydro power. Flexibility from hydro and storage complements the high temporal variability of wind and solar, and transmission infrastructure helps the power balancing by moving electricity in the spatial dimension. We study cost-optimal highly-renewable Chinese power systems under ambitious CO2 emission reduction targets, by deploying a 31-node hourly-resolved techno-economic optimization model supported by a validated weather-converted 38-year-long renewable power generation and electricity demand dataset. With a new realistic reservoir hydro model, we find that if CO2 emission reduction goes beyond 70%, storage facilities such as hydro, battery and hydrogen become necessary for a moderate system cost. Numerical results show that these flexibility components can lower renewable curtailment by two thirds, allow higher solar PV share by a factor of two and contribute to covering summer cooling demand. We show that expanding unidirectional high-voltage DC lines on top of the regional inter-connections is technically sufficient and more economical than ultra-high-voltage-AC-connected “One-Net” grid. Finally, constraining transmission volume from the optimum by up to 25% does not push total costs much higher, while the significant need for battery storage remains even with abundant interconnectivity.

The political economy of electricity trade and hydropower development in eastern South Asia

ABSTRACT This article frames the political economy of electricity trade and hydropower development in eastern South Asia. It distils and analyzes four crucial variables in this regard: the health of distribution companies in India; the role of hydropower in India’s ambitious turn to renewable energy; Bangladesh’s power crisis and import dependency; and the governance of regional electricity trading arrangements. It argues that progress in both electricity trade and hydropower development in the region will be incremental in the next decade, hindered by mixed demand signals and the turbulence of geopolitics.

The impact of electricity consumption on CO2 emission, carbon footprint, water footprint and ecological footprint: The role of hydropower in an emerging economy

The primary objective of this paper is to investigate the isolated impacts of hydroelectricity consumption on the environment in Malaysia as an emerging economy. We use four different measures of environmental degradation including ecological footprint, carbon footprint, water footprint and CO2 emission as target variables, while controlling for GDP, GDP square and urbanization for the period 1971 to 2016. A recently introduced unit root test with breaks is utilized to examine the stationarity of the series and the bounds testing approach to cointegration is used to probe the long run relationships between the variables. VECM Granger causality technique is employed to examine the long-run causal dynamics between the variables. Sensitivity analysis is conducted by further including fossil fuels in the equations. The results show evidence of an inverted U-shaped relationship between environmental degradation and real GDP. Hydroelectricity is found to significantly reduce environmental degradation while urbanization is also not particularly harmful on the environment apart from its effect on air pollution. The VECM Granger causality results show evidence of unidirectional causality running from hydroelectricity and fossil fuels consumption to all measures of environmental degradation and real GDP per capita. There is evidence of feedback hypothesis between real GDP to all environmental degradation indices. The inclusion of fossil fuel did not change the behavior of hydroelectricity on the environment but fossil fuels significantly increase water footprint.

Balancing environmental benefits and damages of small hydropower generation in policy-making: assessing the implementation of a contradicting EU policy framework in Austria and Slovenia

ABSTRACTHydropower contributes to a higher share of renewables but is also in conflict with environmental legislation aiming to protect natural habitats, wildlife and endangered species. Analysing two neighbouring European countries with similar topographical and hydromporphological characteristics, Austria and Slovenia, allows assessing to what extent a policies’ national context steers possible policy conflicts of EU legislation. The paper shows that hydropower expansion in examined countries is strongly shaped by factors such as financial concerns of investors, diverging opinions of involved stakeholders, available hydro potential and the role of hydropower in national energy strategies. Addressing issues that lead to a lower effectiveness of national policies already at the level of EU policy design or engaging countries to broadening their national energy portfolio by considering emerging technologies such as PV and wind will enable future energy and climate strategies that are more consistent with other environmental goals.

The role of hydropower in electric power integration of Asian countries

The possible role of hydropower plants in formation and operation of interstate power pools is described based on the generalization of the world experience. Peculiarities of the influence of hydropower on development of interstate electric ties in this part of the world and potential effects are showed on the example of Central and Northeast Asia.