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In both Sweden and Finland, water law has traditionally provided strong protection for hydropower operations by issuing permanent environmental licences. This national protection has started to erode as a result of the requirement of the European Union (EU) Water Framework Directive (WFD) for permit reviews to improve the ecological status of rivers. In the light of this dynamic between European and national frameworks, this article compares the Swedish and Finnish implementation of the WFD regarding existing hydropower operations. Whereas Sweden has adopted comprehensive legislative and policy reforms that embrace a systemic perspective on reconciling hydropower with the current societal and ecological circumstances, Finland has relied on bottom-up collaborative processes at the grassroots level. The article shows that both approaches are problematic in so far as they push the boundaries of proper implementation of the WFD and, by extension, the achievement of the ecological objectives of the WFD in waters affected by hydropower. Our comparison highlights tensions between EU law requirements for formal legal effectiveness in national implementation, and the WFD's aspirations for adaptive river basin-based governance. [ABSTRACT FROM AUTHOR]

Unnatural changes in river flow patterns resulting from peak‐operating hydropower plants adversely impact freshwater ecosystems. In particular, the rapid dewatering of shoreline habitats during artificial flow down‐ramping puts early fish life stages at a high risk of becoming stranded if they fail to follow receding water levels in time. While extensive research has been conducted on the effects of hydropeaking on salmonid species, there is limited knowledge on the diverse cyprinid family, particularly on vulnerable early life stages. Hence, this study aims to compare the larval stranding of two cyprinid species, the common barbel (Barbus barbus L.) and common nase (Chondrostoma nasus L.), in response to bank dewatering. We conducted larvae experiments in near‐natural mesocosms, simulating single flow down‐ramping events with varying down‐ramping rates (0.3–1.8 cm·min−1) during the day and at night to quantify stranding rates, also including water temperature and fish development. Our results reveal distinct diurnal patterns for both species, with higher stranding rates during the night than during the day in all experimental scenarios. The data also show higher stranding rates at faster down‐ramping, with interaction effects between down‐ramping rates and time of day. The stranding rates between the two species are similar across most of the scenarios. Scenarios with colder water temperatures show that nase larvae tend to strand more frequently than with warmer temperatures. In conclusion, the study results contribute to the ongoing discourse on hydropeaking mitigation by providing new perspectives on flow‐reduction effects on early cyprinid life stages. Mitigation measures should prioritize the periods during early larval development and factor in prevailing water temperatures. Lowering down‐ramping rates, especially during nighttime, will help minimizing negative impacts on aquatic ecosystems, particularly when combining flow rules and habitat restoration measures. [ABSTRACT FROM AUTHOR]

Hydropeaking mitigation based on down‐ramping thresholds is crucial to avoid stranding of fish and ensure sustainable hydropower production. However, the risk of stranding is influenced by several biotic and abiotic factors that interact with the ramping rate, including river morphology and baseflow magnitude. Also, at the river bar scale, the lateral or horizontal down‐ramping velocity may be of even greater importance than the vertical one as the prior integrates bar morphology. This study investigates the connection between ecologically relevant hydraulic parameters (vertical and lateral ramping velocity, dewatered river bar width) and the stranding of young‐of‐the‐year European grayling (Thymallus thymallus) due to down‐ramping, based on field observations of stranded fish at the hydropeaked Drava River in Austria combined with hydrodynamic–numerical modelling. We also examine the interplay between baseflow conditions and river topography in the dewatered areas. Stranding observations in spring and summer found a median rate of 90 individuals per 100 m, ranging from 50 to 500 fish per 100 m shoreline. Stranding rates were three times higher at night than during the day. Our data revealed a positive relationship between stranded fish and down‐ramping hydraulics, with higher intensity resulting in more stranded fish. This association was stronger for the lateral than the vertical ramping velocity, presumably because the former accounts for bar morphology, suggesting that the lateral dewatering velocity is a better indicator to assess fish stranding at the bar scale than the vertical velocity. We also found a negative relationship between the extent of the dewatered area and baseflow magnitude, indicating that the stranding risk is higher during down‐ramping at low flow conditions. [ABSTRACT FROM AUTHOR]

Integrating Green Renewable Energy Sources (GRES) as substitutes for fossil fuel-based energy sources is essential for reducing harmful emissions. The GRES are intermittent and their integration into the conventional IEEE 30 bus configuration increases the complexity and nonlinearity of the system. The Grey Wolf optimizer (GWO) has excellent exploration capability but needs exploitation capability to enhance its convergence speed. Adding particle swarm optimization (PSO) with excellent convergence capability to GWO leads to the development of a novel algorithm, namely a Grey Wolf particle swarm optimization (GWPSO) algorithm with excellent exploration and exploitation capabilities. This study utilizes the advantages of the GWPSO algorithm to solve the optimal power flow (OPF) problem for adaptive IEEE 30 bus systems, including thermal, solar photovoltaic (SP), wind turbine (WT), and small hydropower (SHP) sources. Weibull, Lognormal, and Gumbel probability density functions (PDFs) are employed to forecast the output power of WT, SP, and SHP power sources after evaluating 8000 Monte Carlo possibilities, respectively. The multi-objective green economic optimal solution consisted of 11 control variables to reduce the cost, power losses, and harmful emissions. The proposed method to address the OPF problem is validated using an adaptive IEEE bus system. The proposed GWPSO algorithm is evaluated by comparing it with PSO and GWO optimization algorithms in terms of achieving an optimal green economic solution for the adaptive IEEE 30 bus system. This evaluation is conducted within the confines of the same test system using identical system constraints and control variables. The integration of a small SHP with WT and SP sources, along with the proposed GWPSO algorithm, led to a yearly cost reduction ranging from $ 19,368 to $ 30,081. Simulation findings endorsed that the proposed GWPSO algorithm executes fruitfully compared to alternative algorithms regarding a consistent convergence curve and robustness, proving its potential as a viable choice for achieving cost-effective solutions in power systems incorporating GRES. [ABSTRACT FROM AUTHOR]

Knowledge of the compatibility of various types of renewable energy infrastructure (REI) with tourism can help avoid conflicts between the energy and tourism sectors and facilitate the energy transition. This study aims to investigate the attitudes of tourism service providers operating in Iceland towards three types of REI—wind, hydro, and geothermal power plants—and identify the factors that shape their perceptions regarding the compatibility between REI and tourism. Mixed research methods were employed to achieve that, which included an online questionnaire survey and semi-structured interviews. The study revealed that tourism service providers were the most positive towards geothermal power plants, followed by hydropower plants, and the most negative towards wind farms. The identified factors that shape their perceptions regarding REI's compatibility with tourism included landscape and environmental impacts of REI, impacts on tourist attractions, potential of REI as a tourist attraction, perceived reversibility, and the image of REI. These factors help to identify locations where each type of REI is likely to be the most compatible with tourism. Thus, considering them in spatial energy planning is likely to reduce foreseeable conflicts between REI and tourism. [ABSTRACT FROM AUTHOR]

In developing countries, electricity and water supply are strategic challenges arising from growing demand due to increasing populations and modernization of households. This review paper focuses on Iran as a dryland country that has strived to maintain water resources, generate electricity for domestic purposes and even export electricity. It addresses a scientific gap in the existing literature that has paid limited attention to the intertwined geographical, geopolitical, infrastructure and workforce elements in Iran's development of electricity generation. This review also seeks to link domestic energy production to politically focused regional considerations. It highlights the factors and policies enabling Iran to export its generated electricity. Water conservation and energy generation/electricity can be viewed as complementary when considered within the scenario of hydropower which depends on the presence of large dams. Iran's emphasis on economic advancement in earlier years involved the development of water and energy infrastructure which, decades later, provided opportunities for exporting electricity to neighboring countries. The earlier sole focus on economic development has gradually shifted toward a greater concern for sustainable economic development. Both environmental and political issues are relevant if Iran wants to continue maintaining its water resources, generating hydropower, and exporting its electricity in the region [ABSTRACT FROM AUTHOR]

Although the movement of people from rural to urban areas has caused the increased use of energy, the abundance of water resources can be made into a form of renewable energy known as hydroelectricity. As European countries are ranked as the first users and exporters of hydropower, the production of renewable energy in developed countries such as the Nordic region has caused great impacts on economic growth and human development. The importance of this paper is to investigate the relationship between hydroelectricity and the Human Development Index by depending on some variables such as urbanization, rule of law, corruption, trade openness, and GDP per capita from 2002 to 2021 in Nordic countries. The results were estimated depending on impulse response function after conducting the Vector autoregressive model (VAR) model and Granger causality test. Results showed a negative impact from hydro plants in the short run but a significant positive impact in the long run in Nordic countries. The long-term sustainment of Human Development Index (HDI) is due to policies limiting the immigration of labor as well as protection of energy use. Water batteries are gaining popularity across Europe and their implementation is near mandatory. [ABSTRACT FROM AUTHOR]

The wide-ranging adverse changes caused by hydropower in freshwater ecosystems call for implementing environmental responsibility on the part of the hydropower sector. This article analyses the interplay between the two key EU legal instruments in this respect: the revision of out-dated hydropower permits required under the EU Water Framework Directive and operator liability for water damage under the Environmental Liability Directive. To complement this analysis, the article provides a concrete example of the two directives' combined framework, or at least its multiple implementation challenges, using the specific case of one Member State; Finland. The article concludes that, although the two instruments have the potential to offer a rather powerful framework for environmental responsibility, realising this policy aspiration may be seriously undermined by problems in implementation. The insights presented call attention to the applicable means on both national as well as EU levels to rectify the situation. [ABSTRACT FROM AUTHOR]

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The value of seasonal streamflow forecasts for the hydropower industry has long been assessed by considering metrics related to hydropower availability. However, this approach overlooks the role played by hydropower dams within the power grid, therefore providing a myopic view of how forecasts could improve the operations of large‐scale power systems. With the aim of understanding how the value of streamflow forecasts penetrates through the power grid, we developed a coupled‐water energy model that is subject to reservoir inflow forecasts with different levels of predictive performance. We implement the modeling framework on a real‐world case study based on the Cambodian grid, which relies on hydropower, coal, oil, and imports from neighboring countries. In particular, we evaluate the performance in terms of metrics selected from both the reservoir and power systems, including available and dispatched hydropower, power production costs, CO2 emissions, and transmission line congestion. Through this framework, we demonstrate that streamflow forecasts can positively impact the operations of hydro‐dominated power systems, especially during the transition from wet to dry seasons. Moreover, we show that the value largely varies with the specific metric of performance at hand as well as the level of operational integration between water and power systems. Plain Language Summary: Forecasts of river streamflow are regularly used by water system operators to plan the operations of large‐scale infrastructures, such as hydropower dams. To date, research has focussed primarily on how the predictive performance of forecasts translates into added performance of reservoir systems, thereby overlooking the potential benefits for other interconnected infrastructures that depend on water availability. Here, we focus on the case of national power grids, whose performance is partially controlled by hydropower production. We show that the use of streamflow forecasts could bring benefits that "trickle down" to power system operations, reducing, for instance, power production costs and CO2 emissions during specific periods. Key Points: The benefits of streamflow forecasts trickle down from the water to the power systemForecasts are particularly useful during the transition from wet to dry seasonsThe relationship between forecast predictive performance and value is controlled by the level of operational integration between the two systems [ABSTRACT FROM AUTHOR]

To satisfy the electricity needs of a village in Tangi, northwest Pakistan, the present research can design and evaluate the environmental and economical aspects of an optimal hybrid photovoltaic-biogas-hydropower-battery energy sustainable system (PV-BG-HP-BESS). This framework integrates various renewable energy sources, delivering a modern, efficient approach to sustainable energy solutions. The HOMER Pro software is utilized to optimize the most economical and effective hybrid energy system. The results showed that the proposed hybrid system comprising 91.4 kWp PV modules, 19.6 kW hydropower, a 50 kW biogas generator (BG), 36 batteries, and a 60.6 kW converter was the most economical choice. This system, which used the cyclic charging (CC) method, had a cost of energy (COE) of 0.0728 $/kWh and a total net present cost (NPC) of $152,242. The suggested hybrid energy system for rural areas of Pakistan includes photovoltaic (PV), biogas (BG), hydro, and battery components to provide a dependable and sustainable power supply. This system minimizes the need for expensive fossil fuels while simultaneously minimizing environmental impact by lowering pollutants and greenhouse gas emissions. The system's annual electricity production is 294,782 kWh, with PV leads at 59.4%, BG at 6.02%, and hydro at 34.6%, ensuring uninterrupted power generation even in remote areas. The unmet load, extra electricity, and capacity shortage illustrate the reliability of the system and make it possible to address rural electrification challenges while supporting sustainable development and economic growth. Moreover, the outcomes of the proposed hybrid system dominate the previous studies in multiple objectives, including cost and sensitivity analysis, when compared.

Brazil has faced severe droughts in recent decades, significantly affecting agriculture, water supply, and hydropower generation, among other sectors. The Paraná River Basin, a major hub for hydropower, has been particularly affected, posing challenges for water management. To address this, we conducted a study to provide tailored climate information for the Brazilian hydroelectric sector. Given the complexity of hydrometeorological processes, involving hydrological, meteorological and climatological processes and anthropogenic factors, a multivariate approach is essential for drought assessment. We assessed the effectiveness of a Two-variate Standardized Index (TSI) in characterizing hydrometeorological droughts on large-scales basins and its potential as an operational decision support index. The TSI was compared with the Standardized Precipitation Index and the Standardized Streamflow Index, and we examined the correlation between TSI and Terrestrial Water Storage from GRACE and reservoir volumes, at different time scales. We used the HAND model and water table depth to gain a comprehensive understanding of drought conditions. The results show that the TSI outperforms the univariate indices SPI and SSFI in characterizing drought events in terms of severity and duration. The correlation analysis showed that time scales of 12 and 24 months are the most suitable for hydrometeorological drought monitoring. Overall, the study highlights the potential of TSI as an operational index for monitoring drought conditions and can be applied in basins with different climate regimes.

Energy systems modelling plays a pivotal role in understanding and optimizing complex energy systems. By integrating various factors such as energy demand, supply, infrastructure, and environmental considerations, energy systems modelling provides valuable insights for policymakers, industry stakeholders, and researchers. This can be key to informing stakeholder and policy decisions and facilitate the mobilisation of capital and market development to support the development of the energy sector. This article presents the data, assumptions, and related calculations used for the development of a national scale power system model for Sierra Leone. The focus of the model was a techno-economic analysis of specific hydropower expansion plans. Where possible, this data has been collected from publicly available sources such as scientific literature, feasibility studies, international databases, data from existing modelling efforts in Sierra Leone, and local stakeholders. The collection of the data, development of the model, and creation of scenarios was done in collaboration with the Ministry of Energy in Sierra Leone and verified by a broad range of stakeholders.The following paper outlines the key data presented in the full database which can be accessed through the link found in the Specifications Table. The link also contains the Reference Energy System (RES) used in this study.

Examination of livelihood assets is crucial for displaced people as it informs effective resource allocation and support. This study investigates the livelihood decisions of households displaced by Nepal's Tanahu Hydropower Project using multinomial logistic regression to evaluate how different assets affect their choices. Data were obtained using questionnaires, with a total of 185 questionnaires used for the analysis in this study. Descriptive and inferential statistics were used for data analysis. This study finds that physical assets substantially influence livelihood strategies, promoting diversification and nonfarming activities. Interestingly, social assets have a negative impact, whereas natural, financial, and human assets exert no significant effect. The study highlights the community's focus on economic stability, balancing immediate financial needs with long-term goals such as children's education. However, it reveals ongoing financial struggles, with an average daily income of only 1.962 USD and many households remaining in poverty, particularly those dependent on farming. The study also reflects on the mixed perceptions toward government policies, influenced by factors such as skill gaps and family aspirations. These findings provide essential insights for targeted support and resource allocation to displaced populations.

The hydrological dynamics of the Bagmati River downstream from Kathmandu have transformed due to rapid urbanization, impacting regional water projects. Declining open land and groundwater levels have reduced winter base flow and increased summer peak discharge, challenging sustainable energy generation. This study quantifies Land Use and Land Cover (LULC) impact on downstream hydropower. Using LULC data and a calibrated hydrological model in SWAT, it introduces change scenarios, analyzing their influence on river runoff and energy generation. Results reveal varied runoff curve numbers and seasonal discharge due to LULC shifts. Annual mean flow sees a 1.3% increase, while lean flow decreases by 3.45%. Consequently, dry, wet, and total energy generation drops annually by 0.68%, 0.31%, and 0.38%, respectively. The Flow Duration Curve (FDC) notably shifts upwards at its top and downwards at the bottom compared to the base simulation, defining the most sustainable installed capacity. Additionally, the study presents a regression equation based on LULC changes for simplified analysis. It underscores the crucial role of LULC modifications in river runoff, profoundly impacting energy generation and water resource projects' sustainability. Neglecting these changes could severely affect project success.

This research explains the geopolitics of renewable energy from Laos as a country that has potential in water-based energy (hydropower) in the Southeast Asia region, with the main focus analyzing the mapping of the geopolitics of Laos renewable energy in the development of hydropower energy in Southeast Asia. The authors use the concept of Renewable Energy Geopolitics, which aims to map the geographic and technical characteristics of renewable energy systems and analyze energy relations between countries. The research method used is descriptive qualitative with literature study techniques in data collection. This research shows that Laos is taking advantage of competitive market conditions, thereby triggering investment in the water-based energy sector. Laos also focuses on producing water-based energy by implementing decentralization policies and community involvement in national development to minimize energy poverty, as well as organizing cooperation in technology to produce water-based energy with developed countries both from inside and outside the region.

To combat climate change, societal pressure to develop fossil-free hydroelectricity is growing. There is a great need, however, for environmental assessment tools that can predict the effects of streamflow regulation on biodiversity in hydropower-regulated rivers. Ecological modelling lets practitioners: 1) set broad bounds on population-level responses of key species and 2) identify knowledge gaps and prioritize research needs. Individual-based models (IBMs) are powerful tools for assessing relative benefits of alternative management actions, and therefore help to develop more sustainable hydropower solutions. We applied the inSALMO 7.3-SD IBM for populations of brown trout (Salmo trutta) and Atlantic salmon (S. salar) in the lower Gullspång River, Sweden. We simulated the effects of various minimum hydropeaking flow releases (from 9 to 21 m3/s) on outmigration production. We found that the number of age-1 outmigrants of both species decreased with increasing minimum flow release of the hydropeaking scenarios. The number of age-2 trout outmigrants did not change considerably with increasing the minimum release, but decreased sharply at the highest flow. The most age-2 salmon outmigrants were produced by flow scenarios with minimum releases of 15 and 18 m3/s. The model predicts, therefore, varying species- and life stage-specific effects of flow regulation. Moreover, increased flow caused juveniles to stay in the river longer and outmigrate at larger size, which exposes them to simulated predation longer but could increase post-outmigration survival. By providing insights into mechanisms driving population dynamics, IBMs can help promote the sustainability of high-conservation-value fish species.

Stricter environmental regulations (e.g. the EU’s Water Framework Directive) will entail many environmental improvement measures in waters that have been affected by hydropower, and dam removals are becoming a more common measure. This paper reviews economic evaluations of dam removals, primarily drawing on studies in the USA, and identifies key, frequently recurring, issues that future evaluations will likely need to consider. The paper also reports on an ex-ante evaluation of the recent removal of the Marieberg Hydropower Plant in the Mörrum River in Sweden. An environmental valuation survey carried out as a key part of this evaluation was conducted as a replication of a previous study, where the policy context was different but the expected ecological outcome similar. The replication study produced comparable results to those of the previous study.

Integrating Green Renewable Energy Sources (GRES) as substitutes for fossil fuel-based energy sources is essential for reducing harmful emissions. The GRES are intermittent and their integration into the conventional IEEE 30 bus configuration increases the complexity and nonlinearity of the system. The Grey Wolf optimizer (GWO) has excellent exploration capability but needs exploitation capability to enhance its convergence speed. Adding particle swarm optimization (PSO) with excellent convergence capability to GWO leads to the development of a novel algorithm, namely a Grey Wolf particle swarm optimization (GWPSO) algorithm with excellent exploration and exploitation capabilities. This study utilizes the advantages of the GWPSO algorithm to solve the optimal power flow (OPF) problem for adaptive IEEE 30 bus systems, including thermal, solar photovoltaic (SP), wind turbine (WT), and small hydropower (SHP) sources. Weibull, Lognormal, and Gumbel probability density functions (PDFs) are employed to forecast the output power of WT, SP, and SHP power sources after evaluating 8000 Monte Carlo possibilities, respectively. The multi-objective green economic optimal solution consisted of 11 control variables to reduce the cost, power losses, and harmful emissions. The proposed method to address the OPF problem is validated using an adaptive IEEE bus system. The proposed GWPSO algorithm is evaluated by comparing it with PSO and GWO optimization algorithms in terms of achieving an optimal green economic solution for the adaptive IEEE 30 bus system. This evaluation is conducted within the confines of the same test system using identical system constraints and control variables. The integration of a small SHP with WT and SP sources, along with the proposed GWPSO algorithm, led to a yearly cost reduction ranging from $\$$19,368 to $\$$30,081. Simulation findings endorsed that the proposed GWPSO algorithm executes fruitfully compared to alternative algorithms regarding a consistent convergence curve and robustness, proving its potential as a viable choice for achieving cost-effective solutions in power systems incorporating GRES.

Egypt’s geographic location and natural resources make it an ideal candidate for Renewable Energy (RE) projects. The government has implemented initiatives and policies to promote RE development, resulting in notable projects such as the Benban Solar Park and wind farms in the Gulf of Suez. These endeavors aim to combat climate change, reduce greenhouse gas emissions, and foster sustainable development. Multicriteria decision making techniques are increasingly favored due to their ability to accommodate diverse criteria for selecting RE sources. This paper evaluates numerous RE options in Egypt, including solar, wind, hydropower, and biomass energy, and proposes a hybrid strategy for classifying RE sources for power generation based on criteria such as finance, environment, technology, and community. The study utilizes four multicriteria decision making methods: the analytical hierarchy process, the Technique for Order Preference by Similarity to an Ideal Solution (TOPSIS), Fuzzy Technique for Order Preference by Similarity to an Ideal Solution (FTOPSIS), and fuzzy analytical hierarchy process. The key findings indicate that solar and wind energy are the most viable options for Egypt’s renewable energy strategy, with the fuzzy technique for order preference by similarity to an ideal solution method proving to be the most effective for ranking these sources by providing a comprehensive evaluation framework that aligns well with related studies. These findings have significant implications for policy and investment, as they provide a robust decision-making framework that ensures balanced consideration of financial, environmental, technological, and social factors. The study underscores the value of using advanced multicriteria decision making techniques to guide RE development in Egypt, contributing to the global effort to combat climate change.

Knowledge of the compatibility of various types of renewable energy infrastructure (REI) with tourism can help avoid conflicts between the energy and tourism sectors and facilitate the energy transition. This study aims to investigate the attitudes of tourism service providers operating in Iceland towards three types of REI—wind, hydro, and geothermal power plants—and identify the factors that shape their perceptions regarding the compatibility between REI and tourism. Mixed research methods were employed to achieve that, which included an online questionnaire survey and semi-structured interviews. The study revealed that tourism service providers were the most positive towards geothermal power plants, followed by hydropower plants, and the most negative towards wind farms. The identified factors that shape their perceptions regarding REI’s compatibility with tourism included landscape and environmental impacts of REI, impacts on tourist attractions, potential of REI as a tourist attraction, perceived reversibility, and the image of REI. These factors help to identify locations where each type of REI is likely to be the most compatible with tourism. Thus, considering them in spatial energy planning is likely to reduce foreseeable conflicts between REI and tourism.

Despite consistent maintenance and monitoring equipment installed in pumped storage hydropower (PSH) facilities, many shafts and electrical component failures are reported, possibly resulting from undetected sources. These sources include undetectable vibrations or, in certain conditions, high-frequency mechanical or electrical harmonics. This paper presents a direct method for plotting Campbell diagrams of large motors supplied by variable frequency drives (VFDs) for torsional analysis purposes in PSH systems. These diagrams display the precise locations where torsional stress components induced by VFDs can interfere with shaft resonance modes. The method simplifies the determination of the magnitude of stimulus forces in the motor airgap that may threaten the shaft. The method has been successfully applied to two-level, three-level neutral-point clamped, and seven-level cascaded H-bridge multilevel inverters, which are commonly used industrially available VFD topologies for pumped PSH plants. The paper also discusses the theoretical motor-pump voltage, current, and torque spectra when driven by a cascaded H-bridge multilevel converter operating with bypassed and faulty cells. The accuracy of the theoretical developments is supported by selected simulations results at different operating points and different fault conditions. Hybrid experimental-numerical VFD-induced harmonic stress analysis is also performed to demonstrate the relevance of the proposed study.

Hydrological alterations by dams and climate change can reduce aquatic biodiversity by disrupting the life cycles of organisms. Here, we aimed to evaluate and compare the hydrological alterations caused by dams and climate change throughout the Omaru River catchment, Japan, using a distributed hydrological model (DHM). First, to assess the impacts of dam and climate change independently, we performed runoff analyses using either dam discharge or future climatic data (two future periods, 2031–2050 and 2081–2100 × three representative concentration pathways). Subsequently, we derived indicators of hydrologic alterations (IHA) to quantify changes in flow alterations by comparing them to IHA under natural conditions (i.e., without dam or climate change data). We found that dams altered IHAs more than climate change. However, on a catchment-scale standpoint, climate change induced wider ranges of flow alterations, such as a further decrease in low flow metrics along the tributaries and uppermost main stem, suggesting a catchment-level shrinkage in important corridors of aquatic organisms. We also observed that the altered flow by water withdrawals was ameliorated by the confluence of tributaries and downstream hydropower outflows. Our approach using a DHM captured the various patterns of flow alterations by dams and climate change. HIGHLIGHTS The hydrologic model is used to assess flow alterations by dams and climate change.; Compared with climate change, dams altered most environmental flow metrics.; Climate change decreased low flow metrics in upland streams and tributaries.; Ameliorations of the natural flow regime by hydropower outflows remained insufficient.; Prediction of spatial patterns of flow regime alterations is useful to river managers.;

Hydropower as a flexible regulation resource is a rare choice to suppress the ever-increasing penetration of wind power in electrical power systems. The complementary characteristics and performance improvement of a hydro–wind hybrid power system based on a mathematical model of the hybrid power system is studied in this paper. This established model takes into account the stochastic variation in wind speeds in the wind power subsystem and the hydraulic–mechanical–electrical coupling characteristics of the hydropower subsystem. The complementary analysis is conducted based on the evaluation variables outputted by the established model, such as the wind power, hydro-regulation power, hydraulic power, and frequency. To make full use of the regulation capability of the hydropower system, the optimization of parameter settings is also carried out to improve complementary performances of the hybrid power system. The results from the complementary analysis show the detailed characteristics of hydro–wind coordinated operation under different types of real wind speeds. Here, 95% of installed hydro-capacity is used to complement the power shortage of the intermittent wind energy under the low wind speed. Alternatively, only around 66% of the installed hydro-capacity can be utilized to cope with the fluctuation in wind power under the medium and high wind speeds before the optimization of parameter settings. The recommended values and change rules of the control, hydraulic, and electrical parameters for the hydropower system are subsequently revealed from the analysis of parameter settings to contribute to a stable and safe hybrid power system. The results show that the optimized parameter can increase the maximal regulating capacity of the hydropower system by nearly 9 MW, approximately a sixth of the total installed hydropower capacity. The method and results obtained in this paper provide theoretical and technical guidance for the safe and economical operation of power stations.

In light of challenges like climate change, pollution, and depletion of fossil fuel reserves, governments and businesses prioritize renewable energy sources such as solar, wind, and hydroelectric power. Renewable energy forecasting models play a crucial role for energy market operators and prosumers, aiding in planning, decision-making, optimization of energy sales, and evaluation of investments. This study aimed to develop machine learning models for hydropower forecasting in plants integrated into Water Distribution Systems, where energy is generated from water flow used for municipal water supply. The study involved developing and comparing monthly and two-week forecasting models, utilizing both one-step-ahead and two-step-ahead forecasting methodologies, along with different missing data imputation techniques. The tested algorithms—Seasonal Autoregressive Integrated Moving Average, Random Forest, Temporal Convolutional Network, and Neural Basis Expansion Analysis for Time Series—produced varying levels of performance. The Random Forest model proved to be the most effective for monthly forecasting, while the Temporal Convolutional Network delivered the best results for two-week forecasting. Across all scenarios, the seasonal–trend decomposition using the LOESS technique emerged as the most successful for missing data imputation. The accurate predictions obtained demonstrate the effectiveness of using these models for energy planning and decision-making.

Water system management models represent different purposes, such as water supply, flood control, recreation, and hydropower. When building large-scale system models to represent these diverse objectives, their most appropriate time steps for each purpose often do not coincide. A monthly time step is usually sufficient for water supply modeling, but it can be too coarse for flood control, hydropower, and energy operations, where hourly time steps are preferred. Large-scale water management and planning models mostly employ monthly time steps, but using monthly average energy prices underestimates hydropower revenue and overestimates pumping energy cost because these plants tend to operate during times with above- or below-average energy prices within any month. The approach developed here uses hourly varying prices depending on the percent of monthly operating hours. This paper examines an approach that approximately incorporates hourly energy price variations for hydropower and pumping into large-scale monthly time-step water system model operations without affecting water delivery results. Results from including hourly varying energy prices in a large-scale monthly water supply model of California (CALVIN) are presented. CALVIN is a hydroeconomic linear programming optimization model that allocates water to agricultural and urban users with an objective to minimize total scarcity costs, operating costs, and hydropower revenue loss. Thirteen hydropower plants are modeled with hourly varying prices, and their revenue increased by 25 to 58% compared to revenue calculated with monthly average constant energy prices. Hydropower revenue improvements are greater in critically dry years. For pumping plants modeled with hourly varying prices, the energy use cost decreased by 10 to 59%. This study improves system representation and results for large-scale modeling. [ABSTRACT FROM AUTHOR]

This paper presents a method to quantitatively assess the impact of ice-affected hydraulics on hydropower operations using the widely used Hydrologic Engineering Center River Analysis System (HEC-RAS) hydraulic model. The model was used to identify historical periods where downstream river ice growth reduced the net head on a US Army Corps of Engineers dam on the Pend Oreille River in Idaho, USA. The model was used to create curves of projected stage impacts based on border-ice and continuous bank-to-bank ice formation scenarios. The temperature modelling capabilities in HEC-RAS were used to hindcast ice formation periods on the river that were validated with shore-based webcam data. These results provide a framework that can be applied to other rivers with hydropower generation, particularly sites where an open-water HEC-RAS model exists. [ABSTRACT FROM AUTHOR]

This article draws on findings of long-term field research in upland central Laos, examining the rapidly changing dynamics of language among multilingual Indigenous communities in the upper reaches of Laos's massive Nam Theun 2 Hydropower Project. The case study of sudden language shift in the context of new transport infrastructure finds disruption of distributional flow at multiple levels, from natural forces to built networks to the circulation of communicative norms and social encounters. This is understood in terms of layered infrastructures, which are distinguished at three main, interarticulated levels: natural (e.g., river systems), technological (e.g., transport networks), and institutional (e.g., language ecologies). A key finding is that linked infrastructures are causally interdependent through mechanisms of flow piracy (intercepting flows and transforming them for new purposes) and percolation (denuding networks and critically reconfiguring them). The case study from Laos of rapid change in the context of a hydropower dam not only refines our conception of infrastructure, but the idea of language itself as an infrastructure helps us to better understand its spatialized dynamics, foregrounding language as a new empirical domain in the study of infrastructure and other socially spatialized networks. [ABSTRACT FROM AUTHOR]

Habitat fragmentation due to dams is a well‐known threat to freshwater fish. Yet, the global consequences of fragmentation for the viability of freshwater fish populations are unknown. Here, we provide the first global assessment of the threats of dams to the persistence of freshwater fish species. We developed a global macroecological relationship between freshwater fish range size and body size and used this relationship to assess whether isolated range fragments are too small to support a species. Our assessment includes 7369 freshwater fish species and considers the effects of 31,780 dams globally. Furthermore, we performed a more detailed analysis of the threats of dams in Brazil, the greater Mekong region and the United States, using complementary national and regional data sets. Globally, more than half of the species analysed face extirpation in a part of their geographic range, with an average potential range loss of 3.3% (95%‐range: 0%–31.8%) across all species analysed. For 74 fish species, occurring in Brazil, China, India, the Mekong basin, the United States, South‐Africa and the East Adriatic Coast, more than 50% of their range is potentially lost. This includes 18 species threatened with extinction across their whole range. Our complementary regional analysis revealed that the potentially lost range increases by a factor of 2–4 when considering both large and small dams compared with considering only large dams (≥15 m), highlighting the need to establish more comprehensive global dam inventories. Our novel approach and global analysis identifies species at risk of extirpation as well as geographic hotspots of extirpation threat by dams, which can aid in establishing more effective strategies for global hydropower development and barrier removal efforts to optimise the trade‐offs between biodiversity conservation and the socio‐economic benefits of dams. [ABSTRACT FROM AUTHOR]

Despite the reliability and flexibility of hydropower, the operation of hydroelectric power plants may have significant impacts on the downstream river system, including its water stage, sediment transport, and water temperature, ultimately affecting the ecology. To address these challenges, there is a need to identify water scheduling patterns that improve both hydropower economics and the environment relative to current operations. This paper presents a new methodology to explore promising operational criteria/rules that can achieve such improvements. Typical environmental impact statements and relicensing processes generally perform detailed site-specific analyses of a few alternatives that focus on reservoir water release operating rules and their associated environmental impacts. In contrast, the methodology presented in this article uses a widely applicable approach that explores a much larger solution space. This large set of potential alternatives can be represented in a multidimensional space for which one axis represents the economic value and the other axis quantify individual environmental impacts (e.g., sediment transport and fish growth), and they are explored via two approaches: a Monte Carlo simulation that identifies "win–win" alternatives and a multi-objective optimization problem that identifies Pareto-optimal alternatives. [ABSTRACT FROM AUTHOR]

Crisis and care have been paired as complementary terms. The dialectical relationship invests itself within and across planetary biomes that struggle to thrive. China is a land of ancient heritage and abundant rivers, as well as a drive to modernize through hydropower and electricity. This essay focuses on the important case of the Nu River controversy to add to the corpus of care and crisis discourse in environmental communication. This example requires a move outside the over-determination of spaces that involve episodes of immediate stories of protracted engagement. In a study of how Chinese ENGOs and environmentalists fought hard in a 13-year-long battle to save China's last natural river, I illustrate China's ways of working through assertions of crisis, opposition to care, and an outcome opened by new care strategies for creating consensus. [ABSTRACT FROM AUTHOR]

This article aims to extend and deepen our understanding of how emotions figure in experiences of major nature-society disruptions or "rupture." Cambodia's Lower Sesan 2 hydropower dam is an example of rupture, which refers to dramatic, adverse, and disruptive episodes that ripple across scale. Against a historical backdrop of land enclosures and dispossession, the dam sparked significant community and civil society resistance. This emotionally charged campaign emphasized that the dam and associated resettlement would erase the impacted communities' deep customary relationships to the area. Although some community members ultimately refused the resettlement package and moved to customary lands near their flooded village, the majority accepted resettlement. We explore the emotional dimensions of these communities' experiences, finding that rupture is an inherently emotional process, within layered historical processes of change and violence. The intense emotions that such processes evoke can spark action within the "open moment" (Lund, 2016) that episodes of rupture create; yet the outcomes are highly unpredictable within the asymmetrical political and economic settings that underpin nature-society rupture. [ABSTRACT FROM AUTHOR]

In 2015, a 45 MW vertical hydropower machine exhibited excessive vibration after refurbishment. Measurements revealed a substantial bearing clearance at the lower generator guide bearing. Consequently, the bearing was unable to generate sufficient opposing force to drive the rotor toward the bearing center, resulting in more pronounced overall system vibration. Addressing this challenge required a cost-effective and feasible solution for mitigating the vibration problem. To this end, a design modification was implemented wherein the lower generator guide bearing (originally a sleeve bearing) was modified to a four-lobe bearing by offsetting the two halves of the bearing twice in two axes. Numerical simulations and experimentations were conducted, and the dynamics of the machine before and after the design modification were investigated. Both the simulation and experimental results showed that the machine with the four-lobe bearing improved the system stability and reduced the vibration amplitudes. The numerical simulation result demonstrated that, due to the design modification, the first and second critical speeds were effectively eliminated for a speed range of up to three times the nominal speed. Furthermore, for nominal operation with unbalanced magnetic pull, the four-lobe bearing provided a stability advantage in terms of the modal parameters relative to the original sleeve bearing. [ABSTRACT FROM AUTHOR]

This paper addresses the critical need to determine the stable operating limit of modular multilevel converter-based high voltage direct current (MMC-HVDC) systems, particularly concerning the integration of extensive renewable energy sources. To achieve this, the steady-state mathematical model and state-space model of bundled hydropower and photovoltaic integration through MMCHVDC systems are established. A novel methodology considering steady-state and small-signal stability constraints is proposed to compute the stable operating region of the system. The quantitative assessment reveals that diminishing AC system short-circuit capacities amplify restrictions from small-signal stability constraints, thereby reducing the system's stable operating region. Eigenvalue and participation factor analyses shed light on the pivotal factors affecting smallsignal stability in weak AC systems. To expand the system's stable operating region, a supplementary frequency damping control strategy is proposed. The theoretical analysis and calculation results are validated by building a simulation model for the bundled hydropower and photovoltaic integration through MMCHVDC systems in PSCAD/EMTDC. [ABSTRACT FROM AUTHOR]

Alkaline electrolysis systems are currently considered to be suitable for large-scale hydrogen production. Previous research has primarily focused on integrating renewable energy sources such as solar and wind into water electrolysis systems. However, intermittent issues stemming from the sporadic nature of renewable energy sources have led to the introduction of energy storage systems (ESSs) to address these intermittent challenges. Extensive research has been conducted on the efficiency and operational aspects of these systems. In contrast to other renewable energy sources, hydropower offers the advantages of stable output and high utilization, making it a promising solution for overcoming intermittent issues. In this study, we propose the design of an optimized alkaline electrolysis system tailored for small-scale hydropower generation. This approach allowed us to confirm the efficiency of a small-scale hydropower-based hydrogen production facility and the analysis of hydrogen production costs under diverse scenarios. Notably, the optimal selling price per kilogram of hydrogen was determined to be USD 15.6 when the operational time exceeded 20 h, albeit indicating a challenging market supply. Under the consideration of various scenarios and government subsidies, this study revealed that a USD 10/kgH2 subsidy or 24 h of continuous operation achieved break-even points in the sixth and eighth years, respectively. Ultimately, the findings underscore the necessity for essential measures, including government backing and technological advancements in small-scale hydropower facilities, to enhance the economic viability of the green hydrogen market in South Korea. [ABSTRACT FROM AUTHOR]

Hydrogen as an energy vector can provide energy in applications from low to large scale and contributes to the promotion of renewable energies as low-carbon emission alternatives. This paper presents a literature review on hybrid green hydrogen systems. It was found that 23% of the articles review different methodologies and comparisons of hydrogen technologies, 15% present technical, economic and environmental analyses of hydrogen-based systems and projects. Fifty-three percent of the reviewed articles focus on artificial intelligence methodologies and use of commercial software for sizing, energy management and optimization of these models on hybrid renewable energy systems with a high focus on off-grid systems. The potential for simulation models to be developed on this topic is quite large because of the decarbonization brought by hydrogen. The models should consider additional aspects of the entire hydrogen value chain to have a complete vision of its development in Colombia, taking into account the development opportunities in the framework of different energy scenarios. [ABSTRACT FROM AUTHOR]

Severe droughts, water-use conflicts, and minimum outflow requirements have caused infeasibilities in modeling large-scale complex hydrothermal systems. This paper presents and discusses a new formulation of objective function and constraints to better represent multiple water uses and deal with infeasibilities in the HIDROTERM model, a nonlinear programming (NLP) model developed to optimize the operation of the Brazilian interconnected hydrothermal system. The system is one of the largest in the world. In the last 10 years, approximately 72% of electricity consumed in Brazil has been supplied by hydropower plants, but with increasing shares from thermal, wind, and, more recently, solar power generation. Because of hydrological changes in recent years and the additional operational constraints imposed by environmental agencies, the use of models for decision making, such as HIDROTERM, frequently encounters the problem of infeasibility. To avoid this problem, a new objective function is proposed in HIDROTERM that incorporates economic penalties when the preset requirements are not met. Based on economic considerations, some hard constraints are removed from the constraint set and added to the objective function as penalty terms. These constraints are tightly linked with multiple water uses, including environmental protection, flood control, consumptive uses, and navigation purposes. The proposed change in the objective function and constraints avoids the problem of infeasibilities and makes it possible to apply the model to extreme conditions. Additionally, this formulation helps identify and minimize the risk, duration, and intensity of unavoidable non-compliance occurrences related to multiple water uses. The presented new version of the HIDROTERM model can be used to study and support decision making in the management and operation of large-scale hydrothermal systems. These systems can be formed by a set of hydraulically connected individual hydropower plants and reservoirs, located within a set of electrically connected subsystems. Each subsystem contains demands and other power plants, including thermal, wind, nuclear, and solar plants, and exchanges. The model has been developed with continued improvements since 2008 and applied to large systems such as the Brazilian Interconnected Power System (BIPS) with over 150 reservoirs. A graphical user interface is provided. The objective function is to minimize the total costs of additional thermal dispatch and exchanges, as well as avoid or minimize deficits in energy supply in subsystems, minimum releases, consumptive uses, and minimum storages in reservoirs. The decision variables are the power and nonpower releases for each hydropower plant and the thermal dispatches and exchanges for each subsystem. Some typical applications include (1) monthly planning operation of the system, considering a planning horizon from 3 to 5 years; (2) diagnostic studies about reliability and resilience of existing systems, processing the same system configuration to a set of different hydrological or energy demand scenarios; (3) impact analysis of changes in operational rules and constraints related to multiple uses of water; and (4) planning and evaluation of expansion alternatives. The model can be applied to a complete hydrothermal system or subsets of it, including subsystems, basins, cascades, or a single hydropower plant. [ABSTRACT FROM AUTHOR]

A new in-pipe hydropower prototype having a novel internal flow separator, denominated as P20, was developed and tested to achieve Technology Readiness Level (TRL) 6. The P20 separates water into main channel where the water flow is uninterrupted and two power generation (PG) purpose channels with nozzle and turbine system, respectively, at each side. The P20 also has valves for turbines maintenance and service work purposes at the PG channels' inlets and outlets. From the performance test, 28.8% of pressure loss is created at the maximum flow condition (0.076 m³s-1 flow rate that produced 1.25 bar of stagnation pressure). At this condition, each turbine produced mechanical power of 55W with 35.9% of turbine efficiency. The highest turbine efficiency recorded in this study was about 42% obtained at a flow rate 59% of the maximum condition, where less water filled the turbine casing as compared to the maximum flow condition. PG channel size also affects the turbine efficiency. Overall, the P20 has been functioning according to the design that allows the majority of water to flow uninterruptedly while concurrently generating in-pipe hydropower. [ABSTRACT FROM AUTHOR]

In high-head Pelton turbines, the injector faces severe erosion due to suspended sediment leading to a reduction in turbine efficiency and higher maintenance costs. Here, the effects of design parameters such as the bend angle of the nozzle pipe, nozzle angle, and needle angle along with an operating parameter stroke ratio on hydro-abrasive erosion of Pelton turbine injector are numerically investigated. The Volume of Fluid (VOF) model was implemented for capturing the interphase between air and water; whereas, the SST k-ω model is used for modelling the turbulence effect. For tracking the discrete phase, a Eulerian-Lagrangian based Discrete Phase Model (DPM) is considered. The bend angles led to flow circulations in the nozzle pipe causing the non-uniform distribution of sediment concentration and uneven erosion patterns. Irrespective of the bend angle, the erosion hotspot in the needle is observed toward the bend side. Further, for larger sediment particles, higher bend angles lead to more erosion rate in both the nozzle and needle and must be avoided to prevent excessive damage. As the needle angle increases from 40° to 60° for a constant nozzle angle, the nozzle erosion rate increases by 70% and the needle erosion rate decreases by 99%. Hence, an injector design can be optimized in hydro-abrasive erosion conditions by selecting a needle angle between 40° and 60°. Further, the operation of the injector at too high and low a stroke ratio results in excessive erosion of the nozzle and needle, respectively. In this study, a stroke ratio of 0.45 is found to be the most suitable for hydro-abrasive erosion conditions. Moreover, the asymmetricity in the erosion pattern of the needle increases with needle angle and stroke ratio resulting in jet quality degradation, one major reason for efficiency reduction in Pelton turbines. [ABSTRACT FROM AUTHOR]

Hydropower can have significant impacts on riverine ecosystems due to hydropeaking (i.e., artificial rapid and short-term fluctuations in water flow and water levels downstream and upstream of hydropower stations) that negatively affect downstream fish. However, when it comes to analyzing species habitat use and availability above and below small hydropower plants (SHPPs), studies conducted at the microhabitat scale are scarcer, particularly in Mediterranean rivers. The goal of this study is to assess the seasonal (early and late summer) and size-related (juveniles and adults) microhabitat use by native fish above and below SHPPs. Fish were sampled by a modified point electrofishing procedure, and a multivariate approach was used to analyze microhabitat use and availability data from sites located upstream (reference) and downstream (disturbed) from two SHPPs in northeast Portugal. Cover and water depth were the most influential variables in the use of microhabitat for all species at both the reference and disturbed sites, although some differences in the variable rankings were found. Leuciscids exhibited similar patterns of non-random (i.e., selective) microhabitat use between the reference and the disturbed sites. Overall, the seasonal and size-related patterns in species microhabitat use were similar, with the majority of species displaying seasonal patterns in microhabitat use from early summer to late summer. This study showed that differences in fish microhabitat use between downstream SHPP and upstream reference sites were negligible. Cover might have had a significant role in tempering the effects of detrimental environmental conditions, namely, peaking flows, by providing hydraulic shelter, highlighting the need to maintain riparian vegetation strips and mosaics of submerged aquatic macrophytes, as well as the provision of coarse substrata that can be critical for fish. Future studies are needed to better clarify how different size classes of fish select microhabitats when facing past and present hydropeaking conditions. [ABSTRACT FROM AUTHOR]

Salmonid repeat spawners are precious individuals for wild populations due to their high fecundity and previous spawning experience, making them important in environmental policy. However, repeat spawners rarely exist above hydropower dams in regulated rivers as the mortality of post‐spawners (kelts) when passing through turbines during downstream migration is very high. To mitigate this problem, there are different technical solutions that potentially guide fish toward available fishways. Bubble barriers represent one alternative to costly physical guiding structures, but the efficiency of bubbles for guiding downstream migrating kelts has not been tested. In this study, we evaluate a 100 m long bubble barrier in guiding salmonids—both smolts and kelts—away from the main current and toward an alternative fishway in Ume River, a large regulated river in northern Sweden. We used both acoustic telemetry and sonar to measure the guiding effect of the bubble barrier for downstream migrating fish. We found that more than twice as many salmonids chose the alternative fishway when the bubble barrier was turned on. This was true both for smolts and kelts, suggesting that bubble barriers can be used to guide salmonids of different life stages in rivers with flow rates over 500 m3 s−1. Indeed, our study indicates that bubble barriers are low‐cost structures that could be rapidly applied in many regulated rivers to support salmonid migration. [ABSTRACT FROM AUTHOR]

To make clear the influence of renewable energy on ultra-low-frequency oscillation (ULFO) in a hydro-dominant system via an high voltage direct current (HVDC) transmission system, this paper studies the damping characteristics when wind power is integrated into the sending power system. The damping torque method is applied for the mechanism study and risk evaluation of ULFO. The study of the inner cause and outer performance proves that ULFO belongs to frequency oscillation rather than conventional power oscillation. According to the theoretical analysis, the suggested control mode is identified to reduce the risk of ULFO. Moreover, a robust controller is designed for wind units based on mixed H2/H∞ robust control theory, and the control method makes use of the fast response ability of the converter without compromising the primary frequency regulation ability. Finally, a simulation model of a hydro-dominant sending power system with wind integration is established in PSCAD Version 4.6 software. The simulations verify the proposed control can suppress ULFO effectively. [ABSTRACT FROM AUTHOR]

The reasons (use of fossil fuels as a heat carrier) and consequences (prolonged energy and economic crises) of global warming are analyzed. It is shown that developing countries, using more advanced technologies, particularly in electricity production, are gaining global markets for raw materials and fuel. The vector of technological growth is shifting to Asian and South American countries. The global structure of electricity production by fuel types in countries with the highest electricity consumption is examined. According to the International Energy Agency (IEA) data, in 2019, the majority of electricity production came from fossil sources, a small part from nuclear energy (10.3%), and 26.7% from renewable energy sources (RES). It is demonstrated that half of the world's electricity production is concentrated in three countries: China (30%), the United States (15.5%), and India (6%). Significant contributions are made by EU countries, accounting for 11.2% of global production (including 37.1% from RES). Global renewable energy capacity was 16.7% in 2010, 26.3% in 2019, and 28.7% in 2021. This growth is attributed to the UN's climate policy, aiming at decarbonizing the global economy, and substantial investments in the energy sector. Challenges hindering further growth of renewable energy share in China and other countries are discussed, including the insufficient number of energy storage systems (partly due to high entry costs ranging from 200 to 600 dollars per kWh) and the need for long-distance energy transmission. China, a global leader in renewable energy usage, generates almost 50% of the world's renewable energy capacity. Solar energy, including space projects, is considered the most promising among RES. However, a complete transition to RES is currently impossible due to various reasons. The key problem lies in ensuring an uninterrupted energy supply to consumers. Therefore, there is a need to accelerate the development of powerful energy storage systems and power lines for end consumers. [ABSTRACT FROM AUTHOR]

Water, energy and food are important for human survival and sustainable development. With climate change, investigating climate change impacts on Water-Energy-Food nexus has been a topic of growing interest in recent years. However, there is a lack of a systematic review of the current state and methodologies of Water-Energy-Food nexus studies under climate change. Here, we review research articles investigating climate change impacts on Water-Food, Water-Energy and Water-Energy-Food nexus over last seven years. The existing methods and tools, spatial scales, and future climate scenarios setting in these articles are summarised and analysed. We found that the analyses methods could be divided into four categories (physics-based modelling, statistical methods, supervised learning and operation optimisation), among them, physics-based modelling accounts for the largest proportion. The reviewed studies cover a range of scales from site scale to global, with most studies focusing on the regional scale. Models used for small to middle scale are mainly related to hydrology and water resource, while large-scale modelling is based on interdisciplinary models. Future climate scenarios setting include emission scenarios and global warming scenarios based on Global Climate Models (GCMs). A number of future research challenges have been identified. These include spatial scale and resolution, internal physical mechanism, application of novel artificial intelligence models, extreme climate events, potential competition in nexus systems as well as data and model uncertainty. [ABSTRACT FROM AUTHOR]

The Pelton turbine has been widely regarded as the most efficient hydro turbine for high-head applications. However, the Pelton turbine buckets, especially the area commonly referred to as the 'splitter', are highly susceptible to erosion, drastically reducing efficiency over prolonged periods of time. This paper demonstrates a novel turbine idea that has been validated through both computational and experimental methods. This turbine addresses the issues associated with the erosion of the splitter through a redesign of the Pelton turbine to remove the need for a splitter and therefore potentially reducing downtime due to maintenance. The computational fluid dynamics (CFD) simulation results show that the turbine is capable of efficiencies greater than 82% with room for further improvement. The practical experimental results also show efficiencies within 6% of an optimized Pelton turbine. The results from this study indicate that through further optimization this turbine design could provide a means to produce power outputs similar to conventional Pelton turbines, with the added benefit of lower maintenance costs. [ABSTRACT FROM AUTHOR]

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Hydropower facilities are often remotely monitored or controlled from a centralized remote control room. Additionally, major component manufacturers monitor the performance of installed components, increasingly via public communication infrastructures. While these communications enable efficiencies and increased reliability, they also expand the cyber-attack surface. Communications may use the internet to remote control a facility's control systems, or it may involve sending control commands over a network from a control room to a machine. The content could be encrypted and decrypted using a public key to protect the communicated information. These cryptographic encoding and decoding schemes become vulnerable as more advances are made in computer technologies, such as quantum computing. In contrast, quantum key distribution (QKD) and other quantum cryptographic protocols are not based upon a computational problem, and offer an alternative to symmetric cryptography in some scenarios. Although the underlying mechanism of quantum cryptogrpahic protocols such as QKD ensure that any attempt by an adversary to observe the quantum part of the protocol will result in a detectable signature as an increased error rate, potentially even preventing key generation, it serves as a warning for further investigation. In QKD, when the error rate is low enough and enough photons have been detected, a shared private key can be generated known only to the sender and receiver. We describe how this novel technology and its several modalities could benefit the critical infrastructures of dams or hydropower facilities. The presented discussions may be viewed as a precursor to a quantum cybersecurity roadmap for the identification of relevant threats and mitigation. [ABSTRACT FROM AUTHOR]

Trap‐and‐transport of migratory fish is commonly used to bypass in‐river obstructions. On the River Conon in Scotland, Atlantic salmon (Salmo salar) smolts are transported around two hydropower facilities. Smolt release occurs during daylight, when predation rates can be high. A novel automatic release cage (ARC) was designed to release smolts at night. Smolts were fitted with acoustic tags (n = 99) to compare survival. High post‐release mortality was identified in the day‐release group, with night‐release survival >40% higher. ARCs can provide fishery managers with a cost‐effective and reliable method of improving smolt survival. [ABSTRACT FROM AUTHOR]