Search

Given the currently changing climate conditions it is of primary importance to optimise the management of hydropower resources. This paper proposes a framework in a dynamic setting to determine the water outflow that maximises the value of a water resource for a given reservoir. The model includes two sources of uncertainty, the water inventory determined mainly by the water inflow and the electricity prices. It is implemented under the stochastic optimal control approach and calibrated using monthly data of reservoir characteristics from ResOpsUs. The results indicate that the inventory dynamics are specially important in valuing reservoir resources. The application of optimal management policies guarantees the long-term sustainability of the reservoir. The possible effects of climate change are considered in a sensitivity analysis to changes in the price and water inventory dynamics. [ABSTRACT FROM AUTHOR]

As both the population and economic output of India continue to grow, so does its demand for electricity. Coupled with an increasing determination to transition to net zero, India has responded to this rising demand by rapidly expanding its installed renewable capacity: an increase of 60% in the last 5 years has been driven largely by a quintupling of installed solar capacity. In this study, we use broad variety of data sources to quantify potential and realized capacity over India from 1979 to 2022. For potential capacity, we identify spatiotemporal patterns in solar, wind, hydro and wave power. We show that solar capacity factor is relatively homogeneous across India, except over the western Himalaya, and is highest during the pre‐monsoon. Wind capacity factor is highest during the summer monsoon, and has high values off the southern coast, along the Western Ghats, and in Gujarat. We argue that wave power could be a useful source of renewable energy for the Andaman and Nicobar Islands, which are not connected to the main Indian power grid. Using gridded estimates of existing installed capacity combined with our historical capacity factor dataset, we create a simple but effective renewable production model. We use this model to identify weaknesses in the existing grid—particularly a lack of complementarity between wind and solar production in north India, and vulnerability to high‐deficit generation in the winter. We discuss potential avenues for future renewable investment to counter existing seasonality problems, principally offshore wind and high‐altitude solar. [ABSTRACT FROM AUTHOR]

Purpose: This study aims to investigate the noise-inducing characteristics during the start-up process of a mixed-flow pump and the impact of different start-up schemes on pump noise. Design/methodology/approach: This study conducted numerical simulations on the mixed-flow pump under different start-up schemes and investigated the flow characteristics and noise distribution under these schemes. Findings: The results reveal that the dipole noise is mainly caused by pressure fluctuations, while the quadrupole noise is mainly generated by the generation, development and breakdown of vortices. Additionally, the noise evolution characteristics during the start-up process of the mixed-flow pump can be divided into the initial stage, stable growth stage, impulse stage and stable operation stage. Originality/value: The findings of this study can provide a theoretical basis for the selection of start-up schemes for mixed-flow pumps, reducing flow noise and improving the operational stability of mixed-flow pumps. [ABSTRACT FROM AUTHOR]

Abstract As both the population and economic output of India continue to grow, so does its demand for electricity. Coupled with an increasing determination to transition to net zero, India has responded to this rising demand by rapidly expanding its installed renewable capacity: an increase of 60% in the last 5 years has been driven largely by a quintupling of installed solar capacity. In this study, we use broad variety of data sources to quantify potential and realized capacity over India from 1979 to 2022. For potential capacity, we identify spatiotemporal patterns in solar, wind, hydro and wave power. We show that solar capacity factor is relatively homogeneous across India, except over the western Himalaya, and is highest during the pre‐monsoon. Wind capacity factor is highest during the summer monsoon, and has high values off the southern coast, along the Western Ghats, and in Gujarat. We argue that wave power could be a useful source of renewable energy for the Andaman and Nicobar Islands, which are not connected to the main Indian power grid. Using gridded estimates of existing installed capacity combined with our historical capacity factor dataset, we create a simple but effective renewable production model. We use this model to identify weaknesses in the existing grid—particularly a lack of complementarity between wind and solar production in north India, and vulnerability to high‐deficit generation in the winter. We discuss potential avenues for future renewable investment to counter existing seasonality problems, principally offshore wind and high‐altitude solar.

The environmental awareness and rising costs of marine fuel led research activities to focus on eliminating the dependence on fossil fuels as a traditional source of energy. Clean and renewable energies, such as hydro energy for instance, could be used onboard to enhance the ship energy efficiency.In this research, a novel type of capturing energy is used. By exploiting the water flow that is​ generated around the ship hull while sailing overseas, and putting turbines to face this flow, the turbines will spin, and consequently generate a useful energy that may be used to cover a part of needed power onboard. An innovative system of array of turbines integrated to the second version of Kriso Very Large Crude Carrier (KVLCC2)’s hull was modeled, and the numerical investigations, using computational fluid dynamics (CFD), were carried out to analyze the effect of this link on the propulsion hull power and the hull resistance. The gross generated power was calculated, then the additional hull resistance converted to resistance power was estimated to find out the net power of the system which could be used later.To calculate the excess resistance added to the hull resistance, the flow simulations were conducted on the hull itself and its resistance was numerically calculated and validated with the experimental calculations found in literature. Also verification & validation were carried out on the turbines before their integration to the hull to assure their computerized three-dimensional 3D model design. Using the characteristics of KVLCC2 hull in this study, with the attachment of an array of 10 spherical vertical axis turbines to each side of the hull. An excess net power of about 15%–17% of the required effective power of the ship was obtained. Thus, the study presents a new solution for utilizing the renewable hydro-power onboard which limits the great dependence of the fossil fuel.

Hydropower is often required to adjust the load in the multi-energy complementary system, due to the strong volatility, intermittency, and instability of new energy power generation. Therefore, the turbine is forced to operate in a low-load area with the low efficiency and severe vibration over a long time. The operating conditions vary frequently to threaten the stability and operating life of the unit. It is necessary to optimize the overcurrent components of the turbine for the hydroelectric unit in the multi-energy complementary system. The hydraulically unstable flow can be suppressed to broaden the high-efficiency operation range of the turbine. In this study, a multi-operating optimization of the runner was implemented to consider the weight coefficient in the operation of the turbine under the condition of multi-energy complementation of wind, solar and water. The runner of turbine was obtained suitable for the multi-energy complementary condition. The unsteady numerical analysis and comparison were also carried out on the turbines before and after optimization. The research results show that: An appropriate increase in the weight coefficient of the operating conditions in the low-load area was effectively improved the cavitation performance and the efficiency of the turbine after the multi-condition optimization, particularly with the operational performance of the turbine in the high-load area. There was an increase in the inlet and outlet placement angles of the optimized runner blades, leading to effectively reduce the attack angle of the heading edge of the blade and the flow angle of the tailing edge of the blade under low-load conditions. The vortex was better restrained from the heading edge to the back of the blade. There was an increase in the flow separation area at the tailing edge of the blade, and the inflow conditions of the draft tube. The strength of the vortex band in the draft tube was significantly reduced. Under the low load conditions, the pressure pulsation in the draft tube was mainly the 0.2fn low-frequency pressure pulsation that caused by the vortex, and the low-amplitude pressure pulsation with the blade passing frequency at the inlet of the draft tube that caused by the rotation of the runner. The pressure pulsation in the runner was mainly the 0.8fn pressure pulsation that caused by the flow separation area at the tailing edge of the blade, while the 24fn high-frequency pressure pulsation was caused by the dynamic and static interference between the guide vane and the runner near the band. The 0.2fn low-frequency pressure pulsation was passed up from the draft tube. The pressure pulsation amplitudes of different frequencies in the runner and the draft tube were effectively reduced after optimization of the runner blade, indicating the particularly outstanding improvement of pressure pulsation in the draft tube. The amplitudes of pressure pulsation were reduced by 45% and 40%, respectively, in the draft tube with the frequency of 0.2fn and 14fn under the low load condition (OP1). There was no pressure pulsation with the frequency of 0.2fn in the draft tube under rated condition (OP4). The amplitude of pressure pulsation of 14fn was reduced by 31%. The operation stability of the turbine was better improved in the low load area. The finding can provide a strong reference to optimize the operation of the turbine runner in the multi-energy complementary system. [ABSTRACT FROM AUTHOR]

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

The application of Self-Excited Induction Generator (SEIG) for micro/mini hydro power generation running under standalone mode is an emerging topic for research. Therefore, investigation of parallel operation for two or more SEIGs imitating two separate generating units under standalone mode is highly needed. This paper presents a hardware-based new approach for running two SEIGs in parallel without considering any constraints and without use of any power electronic components. Separate excitation capacitor banks are required for two differently rated machines while sharing of loads has been discussed, along with simple and novel parallel steps using starting resistive load are also being presented. Three phase 2.2 kW and 5.5 kW SEIGs of the same number of poles are being used for this experiment. Results are observed in a power analyser (Tektronix PA4000) and are being advocated with graphs which showcases load sharing between these two machines. In the proposed method, separate excitation capacitor banks are used for individual machines to overcome the unwanted disadvantages of existing method of paralleling, and, it is observed that the proposed method performs better, provided an individual starting resistive load must be connected. The hardware result indicates that there is a decrease in load sharing current for 2.2 kW machine by 78% and increment in load sharing current by 19.79% for 5.5 kW machine when compared with the existing method.

Integration of a grid with an under-developed remote hilly area faces various technical and geographical challenges. Thus, generation of power from renewable resources in off-grid conditions has become one of the most cost-effective and reliable solutions for such areas. The present research deals with the possible application of an integrated solar/hydro/biomass/battery-based system to generate power in autonomous mode for a remote hilly town of a northeastern Indian state. Four different cases of the integrated energy system (IES) were designed using the hybrid optimization model for electric renewable (HOMER Pro), examining the performance of each case. The best combination of the integrated system was chosen out of several cases depending upon the optimized solution that can meet the load demand of the proposed hilly town sustainably, reliably and continuously. The simulation results show that the integrated battery/biomass/hydro/solar-based system is the best optimized, cheapest and most suitable solution to generate renewable-based power for the specified location, having the lowest net present cost (NPC) of USD 644,183.70 with a levelized cost of energy (COE) of 0.1282 USD/kWh. Further, the result also indicates that the optimized configuration reduces the emission of CO2 gas in the environment compared to the battery/biomass/hydro system having the worst emission rate. A sensitivity study was also carried out with variation in load, hydro stream flow and solar irradiation, respectively that may largely affect the technical as well as economical aspect of an integrated energy system. [ABSTRACT FROM AUTHOR]

Planned decommissioning of coal-fired plants in Europe requires innovative technical and economic strategies to support coal regions on their path towards a climate-resilient future. The repurposing of open pit mines into hybrid pumped hydro power storage (HPHS) of excess energy from the electric grid, and renewable sources will contribute to the EU Green Deal, increase the economic value, stabilize the regional job market and contribute to the EU energy supply security. This study aims to present a preliminary phase of a geospatial workflow used to evaluate land suitability by implementing a multi-criteria decision making (MCDM) technique with an advanced geographic information system (GIS) in the context of an interdisciplinary feasibility study on HPHS in the Kardia lignite open pit mine (Western Macedonia, Greece). The introduced geospatial analysis is based on the utilization of the constraints and ranking criteria within the boundaries of the abandoned mine regarding specific topographic and proximity criteria. The applied criteria were selected from the literature, while for their weights, the experts' judgement was introduced by implementing the analytic hierarchy process (AHP), in the framework of the ATLANTIS research program. According to the results, seven regions were recognized as suitable, with a potential energy storage capacity from 1.09 to 5.16 GWh. Particularly, the present study's results reveal that 9.27% (212,884 m2) of the area had a very low suitability, 15.83% (363,599 m2) had a low suitability, 23.99% (550,998 m2) had a moderate suitability, 24.99% (573,813 m2) had a high suitability, and 25.92% (595,125 m2) had a very high suitability for the construction of the upper reservoir. The proposed semi-automatic geospatial workflow introduces an innovative tool that can be applied to open pit mines globally to identify the optimum design for an HPHS system depending on the existing lower reservoir. [ABSTRACT FROM AUTHOR]

This article presents an isolated microgrid which combines two renewable power generators: a Hydraulic-Turbine-Generator (HTG) and a Wind-Turbine-Generator (WTG) with a Li-ion battery-energy-storage (BES). Depending on the generator(s) which supply active power, the microgrid can operate in three modes: Hydro-Only (HO), Wind-Hydro (WH) and Wind-Only (WO). In WH mode, the HTG supplies the difference between the power demanded by the consumers and the power supplied by the WTG. This net demanded power can be negative when the WTG power is greater than the load and this situation can lead to a microgrid collapse. This article shows by means of simulations how the BES is controlled to consume the WTG power excess guaranteeing the microgrid stability. Additionally, when the negative net demanded load is persistent the microgrid must transition from WH mode to WO mode, where only the WTG supplies active power, and this WH-WO transition is also simulated. In the simulations in WO mode, the BES is controlled to regulate the microgrid frequency. The needed controls to command the BES in WH and WO modes and in the WH-WO transition are also explained. The simulations show the effectiveness of using the BES since the microgrid stability and reliability is improved. [ABSTRACT FROM AUTHOR]

Summary: Since the depletion of fossil fuels, the world has started to rely heavily on renewable sources of energy. With every passing year, our dependency on renewable sources of energy is increasing exponentially. As a result, complex and hybrid generation systems are being developed to meet the energy demands and ensure energy security in a country. The continual improvement in the technology and an effort toward the provision of uninterrupted power to the end‐users is strongly dependent on an effective and fault‐resilient Operation & Maintenance (O&M) system. Ingenious algorithms and techniques are hence been introduced aiming to minimize equipment and plant downtime. Efforts are being made to develop robust prognostic maintenance systems that can identify the faults before they occur. To this aim, complex Data Analytics and Artificial Intelligence (AI) algorithms are being used to increase the overall efficiency of these prognostic maintenance systems. This paper provides an overview of the predictive/prognostic maintenance frameworks reported in the literature. We pay a particular focus to the approaches, challenges, including data‐related issues, such as the availability of quality data and data auditing, feature engineering, interpretability, and security issues. Being a key aspect of ML‐based solutions, we also discuss some of the commonly used publicly available datasets in the domain. The paper also identifies the key future research directions to further enhance the prognostics maintenance procedures. [ABSTRACT FROM AUTHOR]

The paper analyses the coordinated hydro-wind power generation considering joint bidding in the electricity market. The impact of mutual bidding strategies on market prices, traded volumes, and revenues has been quantified. The coordination assumes that hydro power generation is scheduled mainly to compensate the differences between actual and planned wind power outputs. The potential of this coordination in achieving and utilizing of market power is explored. The market equilibrium of asymmetric generation companies is analyzed using a game theory approach. The assumed market situation is imperfect competition and non-cooperative game. A numerical approximation of the asymmetric supply function equilibrium is used to model this game. An introduced novelty is the application of an asymmetric supply function equilibrium approximation for coordinated hydro-wind power generation. The model is tested using real input data from the Croatian power system.

This paper proposes a novel 1D-3D approach for the stability characteristics of the hydropower generation system (HGS) in transition processes. First, a 1D-3D coupling model was established for the HGS in the load-reduction process. Second, a sensitivity analysis of the HGS's parameters to the rotation speed and discharge was conducted. Third, the pressure pulsation characteristics of the HGS with three typical guide vane openings were analyzed during the load-reduction process. The results show that with the closure of the guide vane, the discharge gradually decreases and it is sensitive to the change in hydraulic parameters. The rotation speed fluctuates at the early stage of the transition process and is easily affected by mechanical parameters. In addition, the pressure pulsation inside the Francis turbine is more intense under small openings than large openings, and the primary frequency of pressure pulsation under three opening degrees is the blade frequency. The 1D-3D coupling model successfully integrates the advantages of traditional methods and provides a reference for predicting system stability and exploring the stability mechanism. [ABSTRACT FROM AUTHOR]

The recovery of excess energy in water supply networks has been a topic of paramount importance in recent literature. In pressurized systems, a pump used in inverse mode (Pump As Turbine, PAT) demonstrated to be a very economical and reliable solution, compared to traditional energy production devices (EPDs). Due to the large variability of flow rate and head drop within water distribution networks, the operation of PATs could be performed by a series-parallel regulation system based on an electronic or a hydraulic principle. Despite the low cost of the PATs and of regulation and control systems, a great barrier to the diffusion of a small hydro power plant in water distribution is represented by the necessity of additional civil works to host the whole plant. Based on laboratory and numerical experiments, the present paper proposes a new low-cost technology, overcoming most of the limitations of the present technologies when low energy is available and high discharge variation occurs. The operating conditions of the plant are properly optimized with reference to the working conditions of a case study. Despite the laboratory prototype having exhibited a significantly low efficiency (i.e., 16%), due to the use of small centrifugal pumps suitable for the analyzed case study, in larger power plants relying on more efficient semi-axial submersed pumps, the energy conversion ratio can increase up to 40%. The results of this research could be useful for network managers and technicians interested in increasing the energy efficiency of the network and in recovering energy in the peripheral branches of the network were a large variability of small flow rates are present. [ABSTRACT FROM AUTHOR]

The Snowmelt-Runoff Model (SRM) was used to evaluate the impact of climate change on hydrological aspects of Lidder River Catchment of the Himalayan Region. It was observed that the river has an average discharge of 1082.49 cusecs. The coefficient of determination (R2) was varies in the range 0.90-0.95 during model validation period (2013-2018). The average coefficient of determination 0.926 and average seasonal volume difference (Dv) was obtained (-) 0.83%. The snow melt runoff harvested water can be used to bring 10 per cent more area under irrigation and water use efficiency which can be increased to an extent of 12-15 per cent for sustainable agriculture production in the Himalayan Region. [ABSTRACT FROM AUTHOR]

In July 2012, the Feed-in Tariff (FIT) scheme for all renewable energy was introduced in Japan to promote renewable energy generation. Under the FIT scheme, the installation of photovoltaic power increased exponentially as previous studies reported. Although hydropower is one of the most important sources of renewable, clean, and stable energy, few studies analyzed the trend after the FIT started in Japan. The purposes of this study were to clarify the trend of the small and medium hydropower (SMHP) installation under the FITs scheme and examine the effectiveness of FIT to SMHP. Before the FIT scheme started for SMHP in June 2012, total amounts of existing hydropower were 9,600 MW, and the only 100 MW was introduced as new introduction power for eight years. Under the FIT system, there were 140 cases on average certificated every year in the first 4years (2011–2015). On the other hand, after 2016, the number of certifications decreased obviously. The power grid limitation in high voltage connection by power companies might influence this change. We concluded that the present FIT scheme mainly contributed to the renewal or maintenance and power upgrading of existing large hydropower. If the installation pace does not change, the 2030 target will be achieved in 2100. That is because SMHP has various problems that cannot be solved by the FIT system, such as difficulty in estimating suitable sites, construction costs, and consensus-building with residents who generally have the water right.

Wind power production is uncertain. The imbalance between committed and delivered energy in pool markets leads to the increase of system costs, which must be incurred by defaulting producers, thereby decreasing their revenues. To avoid this situation, wind producers can submit their bids together with hydro resources. Then the mismatches between the predicted and supplied wind power can be used by hydro producers, turbining or pumping such differences when convenient. This study formulates the problem of hydro-wind production optimization in operation contexts of pool market. The problem is solved for a simple three-reservoir cascade case to discuss optimization results. The results show a depreciation in optimal revenues from hydro power when wind forecasting is uncertain. The depreciation is caused by an asymmetry in optimal revenues from positive and negative wind power mismatches. The problem of neutralizing the effect of forecasting uncertainty is subsequently formulated and solved for the three-reservoir case. The results are discussed to conclude the impacts of uncertainty on joint bidding in pool market contexts.

Integration of a grid with an under-developed remote hilly area faces various technical and geographical challenges. Thus, generation of power from renewable resources in off-grid conditions has become one of the most cost-effective and reliable solutions for such areas. The present research deals with the possible application of an integrated solar/hydro/biomass/battery-based system to generate power in autonomous mode for a remote hilly town of a northeastern Indian state. Four different cases of the integrated energy system (IES) were designed using the hybrid optimization model for electric renewable (HOMER Pro), examining the performance of each case. The best combination of the integrated system was chosen out of several cases depending upon the optimized solution that can meet the load demand of the proposed hilly town sustainably, reliably and continuously. The simulation results show that the integrated battery/biomass/hydro/solar-based system is the best optimized, cheapest and most suitable solution to generate renewable-based power for the specified location, having the lowest net present cost (NPC) of USD 644,183.70 with a levelized cost of energy (COE) of 0.1282 USD/kWh. Further, the result also indicates that the optimized configuration reduces the emission of CO2 gas in the environment compared to the battery/biomass/hydro system having the worst emission rate. A sensitivity study was also carried out with variation in load, hydro stream flow and solar irradiation, respectively that may largely affect the technical as well as economical aspect of an integrated energy system.

Planned decommissioning of coal-fired plants in Europe requires innovative technical and economic strategies to support coal regions on their path towards a climate-resilient future. The repurposing of open pit mines into hybrid pumped hydro power storage (HPHS) of excess energy from the electric grid, and renewable sources will contribute to the EU Green Deal, increase the economic value, stabilize the regional job market and contribute to the EU energy supply security. This study aims to present a preliminary phase of a geospatial workflow used to evaluate land suitability by implementing a multi-criteria decision making (MCDM) technique with an advanced geographic information system (GIS) in the context of an interdisciplinary feasibility study on HPHS in the Kardia lignite open pit mine (Western Macedonia, Greece). The introduced geospatial analysis is based on the utilization of the constraints and ranking criteria within the boundaries of the abandoned mine regarding specific topographic and proximity criteria. The applied criteria were selected from the literature, while for their weights, the experts’ judgement was introduced by implementing the analytic hierarchy process (AHP), in the framework of the ATLANTIS research program. According to the results, seven regions were recognized as suitable, with a potential energy storage capacity from 1.09 to 5.16 GWh. Particularly, the present study’s results reveal that 9.27% (212,884 m2) of the area had a very low suitability, 15.83% (363,599 m2) had a low suitability, 23.99% (550,998 m2) had a moderate suitability, 24.99% (573,813 m2) had a high suitability, and 25.92% (595,125 m2) had a very high suitability for the construction of the upper reservoir. The proposed semi-automatic geospatial workflow introduces an innovative tool that can be applied to open pit mines globally to identify the optimum design for an HPHS system depending on the existing lower reservoir.

Ethiopia is a land locked country, located in Horn of Africa. The country power generation does not meet the national demand of the people. The aim of the paper is to review a current status, future potential and barriers on development of renewable energy for power generations in Ethiopia. The approaches would be use of primary and secondary data. The structural question is developed and data collected from experts. Secondary data were also collected from national published report, ministries brief and policy guides. The study used predominate renewable energy resource for power generation such as solar, wind, hydro, geothermal and waste to energy. Based on the result, the country utilization of the resources like solar, wind and geothermal with less than 1% with respect to the potential except hydro power which is less than 9% from the national reserve. The paper found that finical, technical, policy and regulation are the main barriers that faced on the development renewable energy. Key measurements are strengthened finical institution, establishing capacity building center, initiation active community participation, organizing institution to support development of renewable energy. This proposed measurements and policy issues were based on the evidence faced the country.

Hydro screw is an axial micro hydro turbine of Archimedean origin. Due to ever-increasing need for clean fuel based and environmentally clean electric power, a research project was undertaken at IROST. In this study, the effect of spiral variable pitch on hydro screw turbine has been studied numerically. Based on the results, it was found that the turbine had the best efficiency with a spiral pitch of 1.5. Accordingly, the small model of this turbine was made and tested in the laboratory. The results indicate that the numerical results of the calculations are in good agreement with experimental result, and therefore they can be used safely in the course of subsequent turbine studies. In summary, the results indicate that the maximum turbine output is between 62% and 68% which is about 30% higher than the constant pitch blade turbine.

This article presents an isolated microgrid which combines two renewable power generators: a Hydraulic-Turbine-Generator (HTG) and a Wind-Turbine-Generator (WTG) with a Li-ion battery-energy-storage (BES). Depending on the generator(s) which supply active power, the microgrid can operate in three modes: Hydro-Only (HO), Wind-Hydro (WH) and Wind-Only (WO). In WH mode, the HTG supplies the difference between the power demanded by the consumers and the power supplied by the WTG. This net demanded power can be negative when the WTG power is greater than the load and this situation can lead to a microgrid collapse. This article shows by means of simulations how the BES is controlled to consume the WTG power excess guaranteeing the microgrid stability. Additionally, when the negative net demanded load is persistent the microgrid must transition from WH mode to WO mode, where only the WTG supplies active power, and this WH-WO transition is also simulated. In the simulations in WO mode, the BES is controlled to regulate the microgrid frequency. The needed controls to command the BES in WH and WO modes and in the WH-WO transition are also explained. The simulations show the effectiveness of using the BES since the microgrid stability and reliability is improved.

This paper proposes a novel 1D-3D approach for the stability characteristics of the hydropower generation system (HGS) in transition processes. First, a 1D-3D coupling model was established for the HGS in the load-reduction process. Second, a sensitivity analysis of the HGS’s parameters to the rotation speed and discharge was conducted. Third, the pressure pulsation characteristics of the HGS with three typical guide vane openings were analyzed during the load-reduction process. The results show that with the closure of the guide vane, the discharge gradually decreases and it is sensitive to the change in hydraulic parameters. The rotation speed fluctuates at the early stage of the transition process and is easily affected by mechanical parameters. In addition, the pressure pulsation inside the Francis turbine is more intense under small openings than large openings, and the primary frequency of pressure pulsation under three opening degrees is the blade frequency. The 1D-3D coupling model successfully integrates the advantages of traditional methods and provides a reference for predicting system stability and exploring the stability mechanism.

Hydropower technology is a simple and renewable form of energy that involves the conversion of potential energy due to head and mass flow rate of water into kinetic energy that drives a water turbine connected to a generator. In this paper, the potential of hydropower in the Sultanate of Oman is studied, considering Wadi Dayqah Dam in Quriyat. The following variables of the dam were used in evaluating its potential for electricity generation for the year 2010 through 2018: the amount of water flowing in and out of the dam and the amount of water available in the dam at the beginning and end of the considered years. A recommendation was made for the type of hydro turbine for maximum power extraction from the dam, based on the available water head and flow rate, considering the standard characteristic selection envelope for hydro turbines. Power generation from the dam could be affected as a result of the decline in reservoir water level, the continuous release of water for irrigation purposes, fear of the aftermath of a cyclone, lack of rains for consecutive years, and high evaporation. However, the occurrence of a cyclone increases the reservoir water level of the dam for more power generation. Some long-term scenarios for effective operation of the dam considering water availability and management were discussed. In addition, some ways of mitigating water loss from the reservoir of the dam through evaporation were proposed.

The potential of hydroelectric plants in north-eastern region is very much promising for supplying electricity. But the reservoirs of hydroelectric plants are facing water shortage during the lean season, which results in a very low power generation. Gumti Hydroelectric Plant generates power to diminish the power crisis of Tripura but it remains inoperative during the lean season due to the shortage of water. Therefore, this study proposes an advancement to Gumti Hydroelectric Plant in Tripura by designing a hybrid energy system using renewable energy sources to supply a dependable, continuous and economical power supply. This study includes optimisation analysis by utilising real-time data of renewable energy sources, which help us to understand the extent of power generation and its cost of energy. The results of this study indicate that a hybrid system is a viable option as compared to a single hydroelectric plant in maintaining the continuity of power supply. [ABSTRACT FROM AUTHOR]

The recovery of excess energy in water supply networks has been a topic of paramount importance in recent literature. In pressurized systems, a pump used in inverse mode (Pump As Turbine, PAT) demonstrated to be a very economical and reliable solution, compared to traditional energy production devices (EPDs). Due to the large variability of flow rate and head drop within water distribution networks, the operation of PATs could be performed by a series-parallel regulation system based on an electronic or a hydraulic principle. Despite the low cost of the PATs and of regulation and control systems, a great barrier to the diffusion of a small hydro power plant in water distribution is represented by the necessity of additional civil works to host the whole plant. Based on laboratory and numerical experiments, the present paper proposes a new low-cost technology, overcoming most of the limitations of the present technologies when low energy is available and high discharge variation occurs. The operating conditions of the plant are properly optimized with reference to the working conditions of a case study. Despite the laboratory prototype having exhibited a significantly low efficiency (i.e., 16%), due to the use of small centrifugal pumps suitable for the analyzed case study, in larger power plants relying on more efficient semi-axial submersed pumps, the energy conversion ratio can increase up to 40%. The results of this research could be useful for network managers and technicians interested in increasing the energy efficiency of the network and in recovering energy in the peripheral branches of the network were a large variability of small flow rates are present.

The electricity demand is increasing day by day all over the world. A lot of efforts are made to make the buildings productive and self sustainable. Saving a small amount of electricity can contribute huge to full fill the demand of electricity. Due to this fact it is proposed to get energy from overhead water tanks. Following this approach a 20 m high water tank is considered. Water in the pipeline rotates a mini-hydro turbine with appropriate rotation. The feasibility to generate electricity from the potential energy of water of the pipeline has been founded. The purpose of this system is to find the cost effective and environmental friendly solution of the power generation using low-cost mini-hydro turbine having negligible environmental effects. The experimental system of this idea consists of a mini-hydro turbine having diameter of 0.21 m which is coupled with a dc generator via chain-gear mechanism to obtain desired rotation. Sensor box is designed to monitor the technical parameters. Led bulbs are introduced in the system to indicate and validate the output and results. The calculations and theoretical concepts are presented using basic theory and equations of fluid mechanics and turbo-mechanics. The outputs are validated using numerical and experimental results.

Dams are playing a significant role in utilizing the resources of water and have a larger impact on the river ecosystem. It has an enormous deal of positive and negative effects on the environment in addition to their benefits like managing stream regimes, as a result preventing floods, obtaining domestic and irrigation water from the stored water and producing energy. The acute and chronic effects due to the construction of the dam are various and categorized according to the area, the services provided by the dams to the community and also its unsocial impacts, advantageous and detrimental impacts on nearby communities and to the aquatic environment These consequences of the construction of any dam project may be commanded in a rigorous and complicated approach resembling climatic, hydraulic, biological, communal, intellectual, archaeological etc. The role of Dams and their benefits are much more and impact directly in our social and environmental life, but it is also a key point that we have to focus about the negative effects of these developmental activities and major and minor dam construction projects by the way of water resource engineering and sustainable development. Dams have the majority of significant functions in utilizing water resources. All through the history of the world, dams have been used successfully in collecting, storing and managing water needed to uphold civilization. Dams have a great deal of affirmative and pessimistic effects on the environment. The advantages are also varying from modest to many folds to the community like controlling stream regime as a result of preventing floods, obtaining domestic and irrigation water from stored water and generating energy from hydropower. Whereas dam endows with significant benefit to our civilization, their impact on the surrounding includes resettlement and relocation, socioeconomic impact, environmental concerns, sedimentation issue, safety aspects etc. Over and above their incredibly important communal and ecological benefits, it is significant to moderate the negative effects of the dam on the environment regarding sustainable development.

In this study, the thermal stabilization of a water resource together with an energy production optimization in the power plant of the dam–reservoir coupled system is conducted. This coupled dam system is designed to consist of a primary (Włocławek) and secondary (Siarzewo) dam due to the erosion control aspect. The other beneficial aspect of this coupled dam design is to have an additional power plant, with the aim of achieving more efficient renewable energy production. One of the factors to be included in the conditions influencing the energy production is the ice formation in the reservoir and tailwater due to the hydrodynamic and meteorological conditions of the site location. Frazil formation and jam may reduce the power plant efficiency. The concept of thermal stabilization, based on the previous studies, refers to providing the ice cover in the reservoir section of a dam to isolate the water from thermal condition. In this research, the ice cover expansion is triggered by the discharge reduction over a specific time and the entire study site. The optimized discharge for stimulating the ice cover through the night was found based on the results, leading to the desired thermal stabilization. This power loss emerged by reduced water withdrawal in the specific time during the day (nighttime), and will be remedied by the more suitable hydrodynamic condition over winter.

Despite the long history of hydropower technology and rising number of system harvesting energy from alternative sources, the constant research within hydro power sector becoming increasingly important as the power from water was and still is the leading alternative source of green energy generation, capitalized not necessarily within micro-urban structures only. The advantages of hydro systems involve their relatively low acquisition cost against durability, the possibility of gaining energy independence, relatively high flexibility and adaptability for spatial conditions and energy demands of the end users. Nowadays micro hydro systems could capitalize head range starting at 100cm and the efficiency of hydro systems in general ranges between 65-75% in micro and small applications climbing up to 96% in macro designs. It is mostly due to flexibility in applications, adaptability in combinations with other renewable energy systems and the ability to generate clean, stable, thus reliable energy that makes technical development the most vibrant and noticeable in the micro sphere.

Cross-border power trade in the Eastern Africa Power Pool (EAPP) has been very low for nearly 15 years since its inception in 2005. This analysis uses a least-cost generation and transmission capacity expansion model to assess economic and CO 2 emissions reduction benefits from different levels of integration. These benefits are assessed for several policy scenarios around renewable energy, national energy security and CO 2 emission reduction targets. In addition, we have explored if major drought events may significantly alter the benefits of trade. The World Bank Electricity Planning Model (EPM) is used to represent 11 countries in the EAPP, Eritrea, South Sudan (and SAPP as an external system) for 2020–2030 including all existing, committed and planned generation and interconnectors. Our analysis shows encouraging prospects for EAPP to potentially gain $7.6 billion from a "Shallow" level of integration wherein countries retain their national plans and interconnections are limited to existing and already committed transmission links. A "Tight" integration that requires generation and (new) interconnection plans to be optimized at a regional level, would increase benefits to $18.6 billion. Tight integration would be most efficient in meeting a 30% CO 2 emission reduction target by 2030 retaining $11.8 billion of benefits. This CO 2 target can be met at 3.8 times lower cost of $6.6 billion compared to the $25.7 billion needed to meet the target in the Business-as-usual (BAU) scenario of very low trade. We find that imposing a 20% upper limit on imports would still retain 80% of the benefits that allays a large part of the concerns around national energy security. We have also simulated extreme droughts that may reduce benefits of trade due to 20%–30% lower hydro availability from hydro dominated systems like Ethiopia. This indeed affects the benefits of a Shallow integration although more than 60% of base case benefits are still retained. Higher flexibility of a Tight integration, on the other hand, allows for a benefit retention of 89% or more, by adjusting flow volumes and directions of trade. A Tight integration renders a greater ability to the system to reduce the impact of major droughts and meet policy constraints including CO 2 emission and import restrictions at a lower cost, due to the intrinsic flexibility of a stronger and wider network. Since all these issues are very realistic, the additional investments in major cross-border links and institutional challenges should be addressed to achieve significant benefits over the medium term. Overall, our exploration of the key facets of trade in EAPP suggests an overwhelmingly positive case for trade pointing to a rapid increase in trade volume by an order of magnitude over the next decade. • Eastern Africa Power Pool holds significant potential for economic trade where the current trade represents only 0.4% of regional demand. • The analysis conducted for 2020-2030 shows encouraging prospects for EAPP to potentially gain $7.6 billion from a "Shallow" level of integration. • A "Tight" integration that requires generation and (new) interconnection plans optimized at a regional level, would increase benefits to $18.6 billion. • Volume of trade needs to grow 10-fold to 4.1% of demand for a Shallow integration and 11.2% of demand for the Tight integration scenario. [ABSTRACT FROM AUTHOR]

Development in Africa is undergoing an infrastructure turn, no more so than in resurgent dam building. But how are new projects planned and constructed? Are we seeing the repetition of much maligned practices that underestimated economic, environmental and social costs, or have past critiques changed infrastructure building in the twenty-first century? Using the concept of the technician's realm that describes short-sighted and expert-centric twentieth century practices of dam building, this article analyses the incorporation of reformist ideas about knowledge production, mitigation and compensation. It uses a detailed case study of the Rusumo Dam, and examines the decision-making processes of the World Bank and a new dam-building organisation, Nelsap. Significantly, this case involved a marked design revision to reduce impact, but also top–down and depoliticising impact assessment and policymaking. It therefore demonstrates nuanced change in the infrastructure turn, the incorporation of reform and continued relevance of past critiques. [ABSTRACT FROM AUTHOR]

The cost of large scale hydrogen production from electrolysis is dominated by the cost of electricity, representing 77–89% of the total costs. The integration of low-cost renewable energy is thus essential to affordable and clean hydrogen production from electrolysis. Flexible operation of electrolysis and hydro power can facilitate integration of remote energy resources by providing the flexibility that is needed in systems with large amounts of variable renewable energy. The flexibility from hydro power is limited by the physical complexities of the river systems and ecological concerns which makes the flexibility not easily quantifiable. In this work we investigate how different levels of flexibility from hydro power affects the cost of hydrogen production. We develop a two-stage stochastic model in a rolling horizon framework that enables us to consider the uncertainty in wind power production, energy storage and the structure of the energy market when simulating power system operation. This model is used for studying hydrogen production from electrolysis in a future scenario of a remote region in Norway with large wind power potential. A constant demand of hydrogen is assumed and flexibility in the electrolysis operation is enabled by hydrogen storage. Different levels of hydro power flexibility are considered by following a reservoir guiding curve every hour, 6 h or 24 h. Results from the case study show that hydrogen can be produced at a cost of 1.89 €/kg in the future if hydro power production is flexible within a period of 24 h, fulfilling industry targets. Flexible hydrogen production also contributes to significantly reducing wasted energy from spillage from reservoirs or wind power curtailment by up to 56% for 24 h of flexibility. The results also show that less hydro power flexibility results in increased flexible operation of the electrolysis plant where it delivers 39–46% more regulating power, operates more on higher power levels and stores more hydrogen. • Flexible operation of electrolysis and hydro power to reduce lost energy resources by up to 56%. • Low hydro flexibility results in storing more hydrogen to deliver wind power regulation. • Hydro flexibility significantly reduce the cost of hydrogen production in constrained grids. • Obtainable cost of hydrogen from electrolysis at 1.89 €/kg, achieves industry targets. [ABSTRACT FROM AUTHOR]

Indonesia has a target using renewable energy in the national energy mix of 23% in 2025 and 31% in 2050. But, by 2018, the installed capacity of renewable energy power plants 2.13% from the total potential renewable energy in Indonesia. Along with that, with the prediction, the earth will face global cooling instead of global warming in 2020 - 2050 because of the grand solar minimum. Therefore, the utilization plan of renewable energy must align with grand solar minimum phenomena. This paper is developed to find whether the plan to use of renewable energy up to 2050 is appropriate regarding grand solar minimum effect and seek what is renewable energy solution to align with grand solar minimum. In this paper, the author demonstrates using dominance and non-dimensional scaling multiattribute decision making to determine the best option for renewable energy business for Indonesia covers the effect of grand solar minimum, total life cycle cost, availability capacity factor, feed-in tariff, energy supply potential, and Government's regulation. The paper concludes that Geothermal and Hydropower covers most conditions and align with the grand solar minimum. [ABSTRACT FROM AUTHOR]