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Pumped hydro energy storage system: A technological review
... It is clear that intermittent and fluctuating renewable energy generation requires the support of other technologies [11]. Large-scale energy storage presents itself as a great alternative since it both increases energy storage and the hydraulic synchronous generators can provide inertia to the system [11][12][13]. ...
... Nowadays, the most common and proven energy storage technology applied at utility grid scale is pumped hydro storage [13]. It utilizes the natural elevation differences present in mountainous regions to store surplus grid electricity generation as potential energy, by pumping water to an elevated reservoir. ...
... Furthermore, one respondent detailed the storage scales for batteries and hydrogen: "short-term storage with battery systems" or "seasonal storage could be done via hydrogen". Hydrogen could compete with large scale seasonal storage, however the conversion from electricity into hydrogen and then again into electricity has a low round-trip efficiency (around 54% [83]) compared to conventional PHS systems (around 80% [13]) which is similar to the roundtrip efficiency the current development team for LH PHS aims to achieve (around 80%). Nevertheless, LH PHS could still be used together with hydrogen. ...
Background
The share of renewable energy feeding the European grid has been growing over the years, even though the intermittency of some renewable energy sources can induce electric grid instability. Energy storage has proven to be an effective way of reducing grid instability. Various solutions for large-scale energy storage are being researched nowadays. This study focusses on the innovative low-head pumped hydro storage (LH PHS) technology, a large-scale energy storage scheme suitable for shallow seas (5 – 30 m depth). Implementation of renewable energy technologies, such as wind farms in Europe, Asia and North America, has faced public opposition which has delayed or even cancelled the implementation of renewable energy projects. Literature about public perception of projects highlights the importance of involving stakeholders from the early stages of project planning. Considering this, the present study aims to collect stakeholder opinions (via an online survey) to determine what is necessary for a smooth implementation of LH PHS in the North Sea, both from technical and policy points of view.
Results
Stakeholders from commercial parties, government authorities and local groups recognized the potential of LH PHS as a means to increase the share of renewable energies within the European power grid. Economics, bureaucratic burden, and structural safety have emerged as primary aspects of concern respecting the implementation of LH PHS. The impression of the respondents is that a low-head pumped hydro station would not have negative effects on their organizations. Furthermore, most of the engineering firms participating in the study communicated that their knowledge and resources could be involved in the construction of such an energy storage facility.
Conclusion
As identified stakeholder concerns such as economics and structural safety are currently being researched, effective communication of the findings of this research is paramount to keep stakeholders informed of the ongoing progress. Two-way communication between researchers and stakeholders is recommended to enhance public acceptance of future technologies. Furthermore, is it advisable to undertake an examination of the available energy policies relevant to LH PHS.
... While PHS as a technology had been known since the 1890s and was utilized in the region of and Italy and Switzerland, it came into renewed attention under the emergence of renewables [24]. Globally, the first commercial PHS system was the Pedreira Elevatory Plant, located in Cubató/SP, Brazil, and initiated its operations in 1939 [25]. ...
... It is also important to ensure that overflow from the upper reservoir is directly fed to lower reservoir so as to conserve water. PHS is informally classified into four groups based on size: large (>10 MW), small (<10 MW), micro (<100 kW) and pico (<5 kW) as presented in Fig. 10.10 [24]. Significant advantages of micro and pico PHS include the ability to store solar and wind energy, which can then be used for small and remote communities with exceptionally low power demands. ...
... 10 Classification of PHS[24] ...
The ever-increasing demand for energy in the background of environmental concern is paving the way for replacement of fossil fuels with renewable energy sources. While hydropower is one of the most significant contributors in this sector for a long time, recent growth in renewables is coming from solar energy and wind energy. Despite their strong position of sustainability, a major problem of these sectors is the intermittent nature of energy supply. Hence, to suppress such fluctuations, energy storage is essential. Pumped hydro storage (PHS) in this context is one of the most attractive choices due to high efficiency, reliability and low cost. This paper discusses the use of PHS for removing the intermittency in supplies from solar and wind energy. The current state-of-art indicates that PHS shall be increasingly used in coming decades for energy generation in renewable and hybrid renewable sectors.
... A well-designed energy storage system plays a key role in both mitigating and adapting energy systems to climate change. Effective energy storage solution can help balance energy supply and demand, reduce greenhouse gas emissions, and enhance the use of renewable energy sources [1][2][3][4][5]. One promising technology is Seasonal Pumped Hydropower Storage (SPHS), which has several advantages over other types of large-scale storage systems [6][7][8]. ...
... By 2100 an increasing vulnerability of the poorest regions, a reduction in biofuel and electricity production in these regions may also suffer [A2 and B2]. 2 Lucena et al. [32] Wind Increase in average wind velocities in the coastal regions in general and in the north/northeast regions. ...
... The Inter-Annual Variations IAV is a parameter that allows for identifying fluctuations in climate from year to year, and it can indicate the physical risk of a resource, calculated by Eq. (2). 1 All appendixes are available at https://github.com/natiweber/BESMM. 2 All the python documents are available at https://github.com/natiwebe r/BESMM. ...
Since Brazil's major energy resources are renewable and directly related to climate factors, it is among the countries most likely of being affected by climate change. Given Brazil's high hydropower storage capacity and the strong seasonal patterns of its renewable resources, introducing Seasonal Pumped Hydropower Storage (SPHS) can help mitigate these challenges. To this end, a methodology is proposed that links the dynamic system-optimization model-MESSAGEix-to regional climate model simulations, called the Brazilian Electricity System MESSAGEix Model (BESMM). This model, with its detailed hydropower representation, is capable of integrating data from three climate change scenarios with the country's energy system. Climate change introduces a new dimension to this approach, as there is evidence of increasing the seasonal imbalance of variable renewable resources in Brazil. BESMM results suggest that SPHS can play a fundamental role in achieving a 100 % renewable matrix by 2100 in RCP 2.6 scenario, as well as enhancing the renewable energy endowment in scenarios RCP 4.5 and RCP 8.5. A reduction of up to 68 % of CO 2 emissions is predicted in scenarios incorporating SPHS, compared to scenarios without SPHS.
... A good alternative to increase the efficiency of power generating plants is to adjust the energy generated to demand. Energy storage systems align production with consumption needs as they allow the surplus energy to be captured during periods of low demand, storing it for later use when demand increases (Rehman et al., 2015). ...
... It can be considered that a PSH emerge as a possible solution with advantages arising from their low environmental impact and cost savings in their generation/storage. This approach has been widely adopted in different regions of the world, as seen in Rehman et al. (2015) and (Guittet et al., 2016). Currently, the installed capacity of PSH in the world is 161.6 GW, which represents 94% of all electrical energy stored in the world (IHA, 2022). ...
This work presents a proposal for the transformation of mining-degraded areas into renewable energy installations, converting deactivated mine pits, in the Quadrilátero Ferrífero (QF) region in state of Minas Gerais (MG), Brazil, into reservoirs for Pumped Storage Hydropower (PSH). Additionally, it proposes the alteration of adjacent areas impacted by mining extraction process, through their conversion into Photovoltaic Power Plants (PV). This measure has the potential to turn mining liabilities into sources of energy with lower environmental impact and sustainability for society. This process allows energy to be stored in the form of hydraulic batteries, which can mitigate the effects of intermittency of photovoltaic generation in the electrical grid. The presented methodology involves mapping deactivated mines, calculating the energy potential of the coupled PSH and PV systems, and conducting an economic feasibility study for PSH implementation. The work includes a case study discussing potential local environmental impacts and the energy potentials of this solution. The case study resulted in identifying a suitable pair of mine pits for a PSH in the QF, capable of supplying the electrical grid with approximately 234.3 MW, with the generated energy cost ranging between U$112.26/MWh to U$167.22/MWh. It is concluded that utilizing inactive mines as PSH reservoirs and installing PV in adjacent mining-degraded areas are innovative and technologically feasible strategies. Economically, their implementation will depend on the market price of energy.
... If an effective storage system is coupled to intermittent renewable energy, the power supply can be consistent and this will add considerable value to the system and make it sustainable [2]. There are a number of energy storage systems in use, such as Pumped Hydro Storage (PHS) [3], Compressed Air Energy Storage (CAES) [4], Battery Energy Storage (BES) [5], Capacitor Storage (CS) [6], Super Capacitor Energy Storage (SCES) [7], Thermal Energy Storage (TES) [8], Hydrogen Storage System (HSS) [9] and Flywheel Energy Storage System (FESS) [10] Energy storage devices can be grouped into four classes which are electrical based, electrochemical based, thermal, and mechanical systems. Currently, the most widely used energy storage system is the chemical battery. ...
... The moment of inertia of a flywheel is calculated as a function of its shape. In steel solid cylinder flywheel rotors, the inertia is calculated as shown in equation 3 ...
This study gives a critical review of flywheel energy storage systems and their feasibility in various applications. Flywheel energy storage systems have gained increased popularity as a method of environmentally friendly energy storage. Fly wheels store energy in mechanical rotational energy to be then converted into the required power form when required. Energy storage is a vital component of any power system, as the stored energy can be used to offset inconsistencies in the power delivery system. The energy crisis, mainly in developing countries, has had an adverse effect on various sectors, resulting in a resort to various energy storage systems to cater for the outages that are experienced. Solar systems have been the preferred backup system to use. However, the high cost of purchase and maintenance of solar batteries has been a major hindrance. Flywheel energy storage systems are suitable and economical when frequent charge and discharge cycles are required. Furthermore, flywheel batteries have high power density and a low environmental footprint. Various techniques are being employed to improve the efficiency of the flywheel, including the use of composite materials. Application areas of flywheel technology will be discussed in this review paper in fields such as electric vehicles, storage systems for solar and wind generation as well as in uninterrupted power supply systems.
... However, the growing share of new energy linked to the grid has resulted in additional issues and obstacles for the system's safe and stable operation. Due to the advantages of sensitive regulation and fast response, using hydropower units to guarantee the stable operation of the grid is an inevitable choice for the long-term development of the power system [2]. ...
It has become a general trend for new energy to be connected to the power grid, and the tasks of peak and frequency regulation undertaken by hydropower units are tough. Inevitably, the Francis turbine operates under a transient process, which brings serious pressure fluctuations and instability problems. In the present study, a three-dimensional simulation of Francis turbines with the water pipeline system during the load rejection process is carried out. Results indicated that when a straight line is used to close guide vanes, the Francis turbine generates significant rotational speed, which poses a threat to system safety and stability. Based on this, the sinusoidal closing law proposed in the present study can effectively reduce the maximum rotational speed by 2.6%. After the end of load rejection, the difference in rotational speed between the two closing laws is 5.15%.
... While wind and solar power have many advantages, in practice, they are variable or intermittent sources of energy that depend greatly on weather conditions [1][2][3]. Their variability can pose challenges to grid stability and the energy supply [4]. ...
Pump–turbine units with high heads are subjected to strong pressure pulsations from the unsteady transient flow in fluid channels, which can produce severe vibrations and high stresses on the pump–turbine structural components. Therefore, reducing transient flow-induced stresses on prototype reversible pump–turbine units is an important measure for ensuring their safe and efficient operation. A high-head prototype reversible pump–turbine with a rated head of 440 m was used to investigate the transient flow characteristics and the flow-induced-stresses in this study. First, the flow passages of the pump–turbine unit and the structure of the reversible pump–turbine runner were constructed with CAD tools. Next, CFD simulations at the full load were performed to investigate the pressure pulsation characteristics of the pump turbine in both the time domain and the frequency domain. After this, the pressure files calculated by the CFD were exported and applied to a finite element model of the pump–turbine runner to calculate the transient flow-induced dynamic stresses. The results show that the pressure pulsations in the flow passage are closely related to the rotational speed, the guide vane number, and the runner blade number of the pump–turbine unit. The maximum flow-induced stresses on the pump–turbine runner at the full load were below 2 MPa and lower than the allowable value, which reveals that the designs of the pump–turbine runner and the flow passage are acceptable. The conclusions can be used as a reference to evaluate the design of high-head pump–turbines units. The approaches used to carry out the transient flow-induced stress calculations can be applied not only to pump–turbines units but also to other types of fluid turbomachinery such as pumps, turbines, fans, compressors, turbochargers, etc.
... In this case, the existence of the hydrogen reservoir offers the possibility of generating electricity when needed [39,45]. Pumped hydro storage power plants can be considered as energy-intensive ESSs that have been used in the power system for decades [37,[46][47][48]. The flywheel energy storage system, FESS, is an electromechanical ESS that stores electrical energy in mechanical form. ...
Isolated water and energy microgrids (IWEMGs) serve as vital solutions for enhancing the well-being of remote and rural communities, particularly in areas where water and energy resources are scarce. This has spurred research into the interdependence between the water and energy sectors (water–energy nexus), a field that has grown in response to technological advancements. Through a systematic optimization framework, this review critically evaluates the integration of various technologies within IWEMGs, encompassing infrastructure, management, and strategic planning, while considering economic and social impacts. IWEMGs incorporate diverse technologies for the infrastructure, management, and strategic planning of water and energy resources, integrating economic and social considerations to inform decisions that affect both immediate and long-term sustainability and reliability. This article presents an exhaustive review of the literature on IWEMG management, employing an approach that synthesizes existing studies to enhance the understanding of strategic IWEMG management and planning. It introduces a structured taxonomy for organizing research trends and tackling unresolved challenges within the field. Notably, the review identifies critical gaps, such as the lack of comprehensive data on water demand in isolated locations, and underscores the emerging role of game theory and machine learning in enriching IWEMG management frameworks. Ultimately, this review outlines essential indicators for forthcoming research, focusing on the optimization, management, and strategic planning of IWEMG resources and infrastructure, thereby setting a direction for future technological and methodological advancements in the field.
... The main types of mechanical energy storage systems are pumped hydro, flywheel, and compressed air. The pumped hydro storage uses two reservoirs with one at a higher elevation than the other and currently is the most widely used large-scale mechanical energy storage system [7]. ...
... Several models of PAT performance prediction methods are presented in the literature, but very few are able to reconstruct the entire part load and overload performance curves. Note that the entire performance curves are very useful for PAT applications such as Pumped Hydro Energy Storage (PHES) or energy recovery in water distribution networks [19][20][21][22][23][24][25]. PAT performances prediction can be classified into three manners; theoretical, experimental and CFD methods, but the lack of accuracy within the individual approaches are generally caused by the weak interaction between the flow physics and the machine body [18]. ...
... ESSs can be classified into several types based on the mechanism used to store and release the energy, such as mechanical, thermal, electrical, and electrochemical storage devices [1]. Mechanical storage devices include, among others, pumped hydro storage, where energy is stored by pumping water to a higher elevation and released by allowing it to flow downhill through turbines to generate electricity [2,3]; gravity energy storage, where water is used to lift and drop a certain mass moving a turbine [4,5]; and flywheels, where kinetic energy is stored in a rotating mass and released as electricity when needed [6]. Thermal energy storage includes, among others, sensible heat storage, where thermal energy is stored or released by changing the temperature of a material without undergoing phase change, and latent heat storage, where energy is stored or released by changing the phase of a material (e.g., solid to liquid) without changing its temperature [7]. ...
Currently, the urgent needs of sustainable mobility and green energy generation are driving governments and researchers to explore innovative energy storage systems. Concurrently, lithium-ion batteries are one of the most extensively employed technologies. The challenges of battery modeling and parameter estimation are crucial for building reliable battery management systems that ensure optimal battery performance. State of charge (SOC) estimation is particularly critical for predicting the available capacity in the battery. Many methods for SOC estimation rely on the knowledge of the open-circuit voltage (OCV) curve. Another significant consideration is understanding how these curves evolve with battery degradation. In the literature, the effect of cycle aging on the OCV is primarily addressed through the look-up tables and correction factors applied to the OCV curve for fresh cells. However, the variation law of the OCV curve as a function of the battery cycling is not well-characterized. Building upon a simple analytical function with five parameters proposed in the prior research to model the OCV as a function of the absolute state of discharge, this study investigates the dependency of these parameters on the moved charge, serving as an indicator of the cycling level. Specifically, the analysis focuses on the impact of cycle aging in the low-, medium-, and high-SOC regions. Three different cycle aging tests were conducted in these SOC intervals, followed by the extensive experimental verification of the proposed model. The results were promising, with mean relative errors lower than 0.2% for the low- and high-SOC cycling regions and 0.34% for the medium-SOC cycling region. Finally, capacity estimation was enabled by the model, achieving relative error values lower than 1% for all the tests.
... The demand for energy storage systems has immensely increased due to the enhancement of renewable energy sources like solar and wind. Among the various energy storage systems available, the pump turbine system is the most preferable for a large amount of energy storage, which swiftly switches between modes and assists in balancing intermittent disturbance of renewable sources on the power grid (1) . Furthermore, the pump turbine can operate in generation and consumption modes depending upon the electricity demand. ...
... Pumped hydro storage (PHS) is generally acknowledged as the most cost-effective and mature energy storage device, comprising 90.3% of the world's energy storage capacity in 2020. Most PHS are confined to the high-head terrain, where hydropower resources have been fully developed [2]. Nevertheless, the potential of the widespread virgin land characterized by the low head is tremendous but still locked [3]. ...
... Pumped hydro energy storage (PHES) supports essential functionality in the energy system, helping to balance load, regulate frequency, and generate reserve over short and long periods [11,12]. Although PHES systems, for example, in the US, have historically been used in conjunction with nuclear power plants, they are now widely used together with naturally intermittent renewable energy sources such as wind and solar power plants as well [6,13,14]. Developing such energy facilities can significantly increase the share of renewable energy in the global energy mix, which is one of the United Nations' Sustainable Development Goals before 2030 [15]. ...
Future global sustainability depends heavily on the development of renewable energy. The object of this study is a system of two plants (Kaunas hydropower plant (HP) and Kruonis pumped-storage hydropower plant) and upper and lower reservoirs. A possible dam failure accident in such an important system can endanger the population of Kaunas City. The methodology for estimating dam-failure-induced flood wave uncertainty included scenarios of the upper reservoir embankment failure hydrographs, modeling flood wave spreading (MIKE 21 hydrodynamic model), and estimating wave heights. The GRS methodology was selected to assess the uncertainty of flood wave modeling results and the sensitivity of hydrodynamic model parameters. The findings revealed that the discharge values of the Nemunas inflow and outflow through the HP outlets are the most important parameters determining the greatest height of the flood wave. Therefore, by correctly managing the amount of water in the upper reservoir, it would be possible to prevent the lower reservoir dam from breaking.
... The system model is configured to simulate an induction motor driving a mechanical pump that feeds water into a reservoir. This example, although very simple, can be used to mimic the fundamental functioning of a motor pumping water into a reservoir, similar to the pumping operation in a pumped storage hydro-power plant after its energy generation stage [38]. The component SOURCE is an infinite source of water, the pump component represents a centrifugal water pump, and the pipe and reservoir components represent the piping and water storage, correspondingly, inherited from the MSL Fluid library [39]. ...
This paper introduces an innovative method for characterizing, implementing, and validating both three-phase and single-phase induction motor models, accompanied by a variable speed drive model. The primary goal is to investigate interactions between the electrical power grid and other dynamic domains (e.g., thermofluidic) that impact motor/load drive behavior. Our approach involves establishing a mechanical interface based on a physically meaningful equation linking motor torque/speed to the electrical model in the phasor domain. This allows seamless integration of diverse domain subsystems into a unified multi-domain model using Modelica v4.0.0 and the OpenIPSL library v3.0.1, overcoming co-simulation limitations. The proposed model, which requires only one Modelica-compliant tool for simulation, introduces additional dynamics through the mechanical interface, enabling explicit simulation of load disturbances based on constitutive physics. This deepens our understanding of dynamic interactions between the electrical power domain and other subsystems connected through the motor. We detail the modeled components using mathematical equations and textual descriptions, emphasizing the Modelica modeling approach. Simulation examples validate the implementation, demonstrating the multi-domain modeling capabilities of the newly developed components.
... The storage devices used for the hybrid systems of renewable energy will have a substantial effect on the overall cost and dependability of the system. Today's market offers a variety of storage technologies, including ultra-capacitor, battery storage, fuel cell, flywheel storage, and pump hydro storage [13][14][15]. The PHS is the most attractive storage technology now in use because of its fast startup time and the fact that it is scalable, sustainable, and economically viable for large-scale HRES. ...
... Pumped storage stations, the most developed flexible energy source with outstanding peak shaving and valley filling capabilities [9], can flexibly manage energy supply and demand [10], which is essential for addressing the issue of wind and solar absorption and guaranteeing the secure and reliable functioning of the power system [11]. The study of the optimal scheduling of a combined power generation system (CPGS) with participating pumped storage stations is now a hot topic [12]. ...
With large-scale grid-connected renewable energy, new power systems require more flexible and reliable energy storage power sources. Pumped storage stations play an important role in peak shaving, valley filling, and promoting renewable energy consumption. This paper presents the reasonable energy-abandonment operation of a combined power generation system (CPGS), in which a pumped storage station is the core control power, with an ultra-high proportion of renewable energy. Firstly, based on the seasonal characteristics of wind, solar, and load demand, typical days are selected through improved clustering analysis algorithms. Then, a daily optimal scheduling model for combined power generation systems (CPGS) is developed with the goals of economy, low-carbon, and stable operation. Finally, the correlation between the energy-abandonment rate and pumped storage station peak shaving and system optimization operation indicators is obtained by a reasonable energy-abandonment calculation method considering source-grid-load coordination. Taking the operation data of an energy base in the western region of China as an example, when the penetration rate of renewable energy is 60–70% in the future, the operating cost on the power side is greatly affected by the construction of the source side. When the system operates at a planned reasonable energy-abandonment rate of 2%, electricity regulation, load tracking, and daily operating costs all show better performance.
... Due to a lack of effective markers, research on variation within filamentous fungi has been restricted [7,8]. It was suggested that RAPD markers could help identify mushroom strains and be useful in protecting elite strains when they were used to discriminate between different cultivars of mushrooms [9,10]. The present study was conducted with the aim to analyze genetic diversity within five button mushroom strains and determine genetic relationship by DNA fingerprinting using RAPD markers. ...
The investigation was conducted for DNA fingerprinting and genetic diversity analysis of five button mushroom strains (Agaricus bisporus-6, Agaricus bisporus-2, Agaricus bisporus-3, Agaricus bisporus-8 and Agaricus bisporus-5) using eight decamer RAPD primers (OPA01, OPA02, OPA03, OPA04, OPA07, OPB17, OPB12 and OPA10). A modified CTAB technique was used to isolate DNA. RAPD analysis resolved 152 scorable bands, 89 bands were monomorphic and 63 bands were polymorphic. The primer OPB17 amplified the highest number of band (30) and OPA01 amplified the lowest number of bands (09). The primer OPA04 produced the 8 polymorphic bands. Thus, it showed higher level of polymorphism (80%). Dendrogram based on linkage distance using Unweighted Pair Group Method of Arithmetic Means (UPGMA) indicated segregated of five button mushroom strains into two main clusters. Only Agaricus bisporus-6 (V1) grouped in cluster 1 (C1) while the major cluster C2 included all other strains, as well as V2 (Agaricus bisporus-2), V3 (Agaricus bisporus-3), V4 (Agaricus bisporus-8) and V5 (Agaricus bisporus-5). At the linkage distance of 50.5, the major cluster C2 formed sub-cluster C2A (Agaricus bisporus-3) and C2B (Agaricus bisporus-2, A. bisporus-8 & A. bisporus-5). Overall results from the dendrogram indicated that the V1 (Agaricus bisporus-6) button mushroom was shown to be outliers in the dendrogram, that is different from other strains because of its unique genetic makeup and high yields of this starin. The present work revealed that the DNA fingerprinting of five button mushroom strains based on RAPD showed significant different among the strains.
... By storing and releasing energy during surplus or deficit conditions, these systems alleviate the intermittent nature of renewable energy. Various energy storage methods are accessible, including thermal [21][22][23][24][25], supercapacitors [26][27][28][29], batteries [30][31][32][33], thermochemical [34][35][36][37], compressed air [38][39][40], hydrogen [34,41], flywheel [42,43], and pumped energy storage [44]. Among these, thermal energy storage systems (TESS) play a crucial role in effectively managing and conserving thermal energy, holding significant potential across various thermal applications [45][46][47]. ...
Thermal energy storage (TES) plays a pivotal role in a wide array of energy systems, offering a highly effective means to harness renewable energy sources, trim energy consumption and costs, reduce environmental impact, and bolster the adaptability and dependability of power grids. Concurrently, artificial intelligence (AI) has risen in prominence for optimizing and fine-tuning TES systems. Various AI techniques, such as particle swarm optimization, artificial neural networks, support vector machines, and adaptive neuro-fuzzy inference systems, have been extensively explored in the realm of energy storage. This study provides a comprehensive overview of how AI, across diverse applications, categorizes, and optimizes energy systems. The study critically evaluates the effectiveness of these AI technologies, highlighting their impressive accuracy in achieving a range of objectives. Through a thorough analysis, the paper also offers valuable recommendations and outlines future research directions, aiming to inspire innovative concepts and advancements in leveraging AI for TESS. By bridging the gap between TES and AI techniques, this study contributes significantly to the progress of energy systems, enhancing their efficiency, reliability, and sustainability. The insights gleaned from this research will be invaluable for researchers, engineers, and policymakers, aiding them in making well-informed decisions regarding the design, operation, and management of energy systems integrated with TES.
... At present, only pumped storage technology and compressed air energy storage technology can match the grid and realize large-scale energy storage. The single unit power of compressed air energy storage power station can reach more than 350MW, and the maximum capacity of pumped storage power station can reach 2.1GW [19]. Although the technology of pumped storage power station has matured, and the cycle efficiency is high and the cycle is long, the site selection of pumped storage power station has strict requirements: it must be a reservoir with a large drop and a corresponding dam. ...
Compressed carbon dioxide energy storage (CCES) offers several benefits over other existing energy storage systems, including ease of liquefaction, high energy storage density, and environmental friendliness. As a result, the research progress, economic and technological feasibility, and system operation of the CCES system are all discussed in depth in this study. The system evaluation method is summarized and the compressed carbon dioxide storage is analyzed, and the performance optimization direction of the compressed carbon dioxide energy storage technology is discussed. When the overall performance of a transcritical CCES system, a supercritical CCES system and a liquid CCES system are compared, it is discovered that the supercritical CCES system has better thermodynamic characteristics and a simpler system configuration, making it suitable for large-scale development and use. The goal of the CCES system's future development is to create a design with an optimum compression and expansion ratio, a more precise analysis and system model, and multi-field coupling. This review's discussion serves as a guide for the best design and use of the CCES system.
... Moreover, their operational characteristics differ considerably from today's battery energy storage. For instance, LNG storage incurs consistent fuel costs, while pumped hydro operations must account for environmental and water supply constraints [23]. Hence, given the associated modeling complexity and the limited impact in practice, the paper concluded that perhaps the most realistic option is to "exempt them (energy limited resources) from the no economic or physical withholding standard". ...
Problem definition: Economic withholding in electricity markets refers to generators bidding higher than their true marginal fuel cost, and is a typical approach to exercising market power. However, existing market designs require storage to design bids strategically based on their own future price predictions, motivating storage to conduct economic withholding without assuming market power. As energy storage takes up more significant roles in wholesale electricity markets, understanding its motivations for economic withholding and the consequent effects on social welfare becomes increasingly vital. Methodology/results: This paper derives a theoretical framework to study the economic capacity withholding behavior of storage participating in competitive electricity markets and validate our results in simulations based on the ISO New England system. We demonstrate that storage bids can reach unbounded high levels under conditions where future price predictions show bounded expectations but unbounded deviations. Conversely, in scenarios with peak price limitations, we show the upper bounds of storage bids are grounded in bounded price expectations. Most importantly, we show that storage capacity withholding can potentially lower the overall system cost when price models account for system uncertainties. Managerial implications: Our paper reveals energy storage is not a market manipulator but an honest player contributing to the social welfare. It helps electricity market researchers and operators better understand the economic withholding behavior of storage and reform market policies to maximize storage contributing to a cost-efficient decolonization.
... Due to the inherent intermittency and volatility presented by wind, solar, geothermal, among others, the quality of produced power is poor, even worse, their large-scale integration into the power grid will impact the stability of power grid, resulting in the oscillations of power system and splitting of the power generator. Confronted with this challenge, the fast peak and frequency regulation provided by hydropower has been given full play, that is, main tasks that hydropower performs have been substituted by being a regulatory energy source, including pumped storage and cascade hydropower stations in various basins [3,4]. During the normal operation of hydro unit, the turbine is usually operated with the highest efficiency under rated conditions, thus the stability of hydropower station can be guaranteed. ...
Various countermeasures including geometry optimization have been proposed and proved to have a huge impact on flow filed within the draft tube in order to mitigate the vortex rope and the induced pressure fluctuations for Francis turbine under part load operation. However, the effect of these approaches on the hydro-dynamics in upstream region still remains unclear, which is of great significance for the overall performance of the unit. This study aims to explore the influences of modified draft tube with inclined conical diffuser on the pressure fluctuations in whole flow passage. The results reveal that Generation-1 and Generation-2 draft tubes are effective in alleviating pressure fluctuations resided in the draft tube, but the former one would trigger a low-frequency pressure fluctuation with higher amplitude in the runner zone. In addition, the modified draft tube has a very limited effect on the high-frequency pressure fluctuations in the guide vane and vaneless areas. To eliminate the adverse effect of inclined conical diffuser, a design with a transitional section is put forward to smoothly connect the runner zone and inclined conical diffuser. This further developed Generation-2 draft tube presents a reasonably good performance in terms of improving flow stabilities, i.e. alleviating the pressure fluctuations not only in draft tube but also in upstream region such as runner zone. This study provides reference for obtaining a better mitigating effect on pressure fluctuations in the whole turbine flow passage.
... Pumped-Hydro Storage system (PHS) is an extensively deployed mechanical energy storage system worldwide. This technology is known for its large energy storage capacity, long lifetime, and interesting efficiency of storage [93]. The typical form of a PHS system includes two huge water reservoirs which are positioned at different elevations and a powerhouse. ...
Integrating renewable energy systems into the grid has various difficulties, especially in terms of reliability, stability, and adequate operation. To control unpredictable loads, one potential approach is to incorporate energy storage systems (ESSs) into the power network. The implementation of an ESS is dependent on its technical properties, the implementation site, the electrical energy source (conventional or renewable energy types), and its related costs. Therefore, an up-to-date database with technical and economic properties, cost data, and applications is necessary for decision-making purposes. Moreover, the integration of ESSs with renewables should be based on an optimal sizing analysis that incorporates system modeling and proper formulations of technical and financial design criteria. This paper provides an overview of recent developments in the field of energy storage; combining a comprehensive assessment of the technical and economic characteristics of the various types of energy storage systems, and creating a pertinent database with the technical specifications and cost figures of both established and newly developed energy storage systems. The reviewed research works present all metrics that affect the performance of each type of storage and discuss their future directives and innovations. Moreover, recent analyses of integrating energy storage systems with hybrid photovoltaic/wind power systems are also discussed in terms of system modeling, performance analysis indicators, and optimization methods. By combining all these aspects, our research significantly contributes to the existing literature and offers a holistic understanding of energy storage systems and their role in hybrid power plant applications.
Forecasting future wind electricity generation requires diverse methods and tools to estimate potential output at specific locations. This study utilizes historical meteorological data and simple models at particular sites, along with past electricity production records from selected wind farms. The interannual and decadal oscillations of wind energy production at the grid level are computed. The large‐scale, long‐term energy storage needed to achieve dispatchable electricity, addressing generation variability is assessed. For the continental United States, the estimated storage requirement is approximately 1300 GWh per GW of installed capacity. The inclusion of solar power generation and the round‐trip efficiency of energy storage positively or negatively impact this estimation.
This review article explores the critical role of additives in enhancing the performance and durability of thermochemical energy storage (TCES) materials, particularly in limestone-based systems. It evaluates various strategies, including hydration and the use of fine particles, along with additives like Al2O3 and ZrO2, to address challenges like performance degradation and sintering over multiple cycles. Additionally, the review examines how multicyclic stability and material activity toward CO2 are related. It emphasizes the importance of selecting support materials that optimize both stability and reactivity. Furthermore, it highlights the need for systematic investigation into the selection, synthesis methods, and additive percentages to identify optimal formulations for improved multicyclic stability. Finally, it underscores the importance of understanding the mechanisms of interaction between additives and CaO/CaCO3 matrices to guide the design of effective additive-integrated systems. This comprehensive analysis provides valuable insights into current methodologies, emerging trends, and future directions for advancing sustainable energy storage technologies.
Utilizing the thermal stratification of reservoirs to obtain cold water for cooling green data centers (GDCs) is a new mode of energy conservation and emission reduction. However, global warming is expected to alter this phenomenon in deep reservoirs and thus may affect the digitalization process. While the frequency and intensity of extreme climate (EC) events are increasing under a changing climate, the impacts of these highly destructive events on thermal stratification and the related cascading effects on GDC cold-water supplies are still unclear. A two-lateral-dimensional thermohydrodynamic model was established to determine the characteristics of reservoir thermal stratification changes and its potential water environment impacts based on the heat extreme experienced by the Jinshuitan Reservoir, a large, pumped storage power station (PSPS) with a GDC in southeastern China. Fourteen different PSPS inlet/outlet schemes under 2 climate scenarios were designed, and two new indexes, namely, the risk index of cold-water shortage and the index of thermal stratification, were proposed to explore the impact of extreme climates on GDC water extraction. The results showed that compared to the present climate conditions, the reservoir experienced stronger thermal stratification with a 20.6 % average increase in thermal stability, a longer thermal stratification duration with a transitional trend from seasonal to permanent stratification, and a thinner cold-water layer with a 15-m average decrease. Changes in the thermal stratification of reservoirs under EC conditions will benefit some species, such as diatoms (except for early July and the period from mid-August to early October), green algae and cyanobacteria and the migration of warm-water fish, but adversely impact dissolved oxygen, diatoms and cold-water fish. Furthermore, the risk of cold-water shortages under EC conditions was consistently greater than that under average climate (AC) conditions (traditional assessment) when the elevation of pumped storage intake/outlet was less than 145 m. According to the traditional assessment method, the intake/outlet elevation of pumped storage reservoirs resulted in a 60.27 % increase in the risk of cold-water shortages during climate extremes. Furthermore, the demand for green cold-water withdrawal and optimal pumped storage power generation benefits were met when the PSPS intake/outlet elevation was 145 m. Beyond solving this specific case, this study elucidates the importance of linking the thermal stratification and data center of cold-water withdrawal to ECs. These findings provide new insights for increasing climate change resilience.
In order to reach the goal of reducing emissions by at least 55% by 2030 and achieving decarbonization by 2050, the increasing emphasis on net-zero energy buildings/districts encourages the development of advanced modelling tools to better design and manage district energy systems. This paper presents a critical review of such tools, considering the different detail level of building data and analysing the reliability of obtainable results. Initially, it elaborates on the characteristics of data resources and formats, energy demand representations of individual buildings, and the interconnection between individual buildings and districts, which are subsequently used to analyse the accuracy level of case studies. Then, the most used evaluation criteria for comparing tools arerevised. Five categories are defined: (i) input data and representation of buildings, (ii) district energy system components (i.e., generation, distribution, storage), (iii) outdoor environment, (iv) user behaviour and mobility,and (v) validation and licencing. 29 tools suitable for district energy systems modelling are critically analysed with a focus on accuracy and validation, as well as on their application and future perspectives. The results highlighted the importance of data reliability in modelling approaches and results. Difficulties in achieving accurate results included robust data acquisition, interconnection among individual buildings, outdoor environment, and modelling approaches. The results also emphasized that, although no tools can cover all the possible features at the current stage, this study can support the selection of the most suitable tool for specific applications at the district scale.
Repurposing groundwater-filled mine cavities for thermal energy storage has demonstrated promising potential to buffer the imbalance of energy supply and demand. Fractured formations are widespread in old mines due to previous excavation activities, which dominates the performance and efficiency of the mine thermal energy storage (MTES) system. Therefore, understanding the mechanisms of fluid flow, heat, and solute transport in fractured reservoirs in the MTES system is essential for its application and the assessment of environmental impact. In this study, fluid flow, heat, and solute transport in a 3D fracture-matrix MTES system are modeled simultaneously based on site-specific data in Freiberg, Germany. The simulations are conducted with a coupled Hydro-Thermo-Component process newly developed in the open-source software OpenGeoSys (OGS). To stabilize the simulation in the fracture-matrix hybrid system, a flux-corrected transport scheme is specifically implemented and applied in the model. Thus, heat and mass exchange between the embedded fractures and the matrix in the formation of MTES can be accurately simulated on the basis of the conforming mesh. In a hypothetical short-term scenario of a 15-day heating and cooling cycle of the MTES operation, the solute is transported faster than the heat in the fractured formation, indicating that disturbance of mineral compositions in the original mine water can affect a larger region than heat. The embedded fracture network in the surrounding formation is also found to increase the thermal energy storage capacity by 44%, while decreasing the recovery ratio by 14% compared to those of the unfractured formation. More energy will be transported and stored in the more fractured formation from heated mine water, but less energy can be recovered. The behavior of the MTES system strongly depends on local geology and hydraulic conditions and therefore needs to be evaluated in a site- and application-specific manner. This study provides preliminary insights into the performance and efficiency, as well as the environmental impact of the MTES operation in the short term.
The impacts of climate change, combined with the depletion of fossil fuel reserves, are forcing human civilizations to reconsider the design of electricity generation systems to gradually and extensively incorporate renewable energies. This study aims to investigate the technical and economic aspects of replacing all heavy fuel oil (HFO) and light fuel oil (LFO) thermal power plants connected to the electricity grid in southern Cameroon. The proposed renewable energy system consists of a solar photovoltaic (PV) field, a pumped hydroelectric energy storage (PHES) system, and an ultra-capacitor energy storage system. The economic and technical performance of the new renewable energy system was assessed using metrics such as total annualized project cost (TAC), loss of load probability (LOLP), and loss of power supply probability (LPSP). The Multi-Objective Bonobo Optimizer (MOBO) was used to both size the components of the new renewable energy system and choose the best location for the solar PV array. The results achieved using MOBO were superior to those obtained from other known optimization techniques. Using metaheuristics for renewable energy system sizing necessitated the creation of mathematical models of renewable energy system components and techno-economic decision criteria under MATLAB software. Based on the results for the deficit rate (LPSP) of zero, the installation of the photovoltaic field in Bafoussam had the lowest TAC of around 52.78 × 10⁶€ when compared to the results for Yaoundé, Bamenda, Douala, and Limbe. Finally, the project profitability analysis determined that the project is financially viable when the energy produced by the renewable energy systems is sold at an average price of 0.12 €/kWh.
The objective of this paper is to assess the techno-economic performance of different cycle configurations for pumped thermal energy storage (PTES), including the effects of charging electricity cost. Reversible turbomachinery was employed to reduce the capital cost of the system. Brayton cycles with different working fluids and a subcritical Rankine cycle operating with ammonia were compared. Both liquid and packed bed thermal storage were investigated. A new cost correlation for turbomachines, initially established for the turbines of organic Rankine cycles, was developed for compressors and reversible machines. This correlation is based on the number of stages and physical size of the machine, which were estimated considering thermodynamic as well as mechanical limitations. The results indicate that for a plant size of 50 MW and a discharge duration of 8 hours, the Brayton system with liquid storage and helium as a working fluid has the lowest levelized cost of storage at 0.138/$kWh, mainly due to the high thermal conductivity of the fluid. Packed bed thermal energy storage systems were found to be more expensive than liquid storage systems due to the large cost of the pressure vessels, with cost parity reached at a discharge duration of 4 hours. However, at this duration lithium-ion batteries are likely to be cheaper. The results suggest that the levelized cost of storage for the Rankine cycle based system is slightly higher at 0.151/$kWh.
In this paper, the CFD analysis for the design of centrifugal pumps is assessed particularly with respect to the calculation of pump efficiency and head. Some directions of how to improve its usage in future are also offered. The study adopts a 3-D numerical CFD tool to simulate the complicated flow field inside pump machinery. Pressure contour, velocity contour, and streamlines of the fluid flow are visualized, and interaction effects are predicted. Useful pump performance metrics can be evaluated employing this simulation framework, which is supported by ANSYS CFX and integrated commercial CFD codes such as CPD Vista, BladeGen, and TurboGrid. This research continues to guide centrifugal pump design optimization, employing CFD simulations to understand difficult-to-quantify fluid dynamics and maximize performance. Finally, the paper includes a critical review and future prospects on CFD analysis applied to centrifugal pump design. It indicates good agreement between experimental test results and numerical predictions across various operating conditions. The study concerns itself with three main impeller geometric parameters (blade thickness, number of blades, blade outlet angle), and the design and modeling of the centrifugal pump exhibits efficiency and head have both increased for the optimized pump over its original design. This is a complete analysis, which forms an excellent reference for advancing the understanding of centrifugal pump performance and future improvements in centrifugal pump design.
Electricity demand has grown in the Kingdom of Saudi Arabia at a very fast pace and there are large differences between the summer and winter peak loads as well as between morning and evening peak loads. Thus, the predicament facing the Saudi Arabia power sector is how to reduce the requirement and investment for new thermal peak plants in order to meet the rapidly increasing short-term peak demands. To ensure a reliable power supply, the system needs expensive peaking units to operate just for a few hours during the whole year. To reduce the peak thermal generation, the possibility of building pumped storage hydroelectric power plants is being considered. During the off peak generating hours, when surplus generation is available, the pumped storage plant will pump water to an upper reservoir, and then use this stored water for hydro generation during peak load hours.
Wind power, a green energy, has become another primary renewable resource of great value in economic utility and industrialization development, like hydraulic power at the time when comes with the pressure from energy crisis and environmental protection. This paper considers a wind-powered pumped storage system based on an 8 MW wind farm. The effect of pumped storage power station to wind power regulation is calculated, and an economic evaluation model was developed. This paper shows that a significant smoothing of the produced power is realized, dispatchable output power can be offered to the system, whereas extra economic benefit can also be achieved.
Renewable energy sources, such as wind and solar, have vast potential to reduce dependence on fossil fuels and greenhouse gas emissions in the electric sector. Climate change concerns, state initiatives including renewable portfolio standards, and consumer efforts are resulting in increased deployments of both technologies. Both solar photovoltaics (PV) and wind energy have variable and uncertain (sometimes referred to as intermittent) output, which are unlike the dispatchable sources used for the majority of electricity generation in the United States. The variability of these sources has led to concerns regarding the reliability of an electric grid that derives a large fraction of its energy from these sources as well as the cost of reliably integrating large amounts of variable generation into the electric grid. In this report, we explore the role of energy storage in the electricity grid, focusing on the effects of large-scale deployment of variable renewable sources (primarily wind and solar energy).
The transient performance of a small-scale plant consisting of a photovoltaic (PV) and a pumped hydro storage (PHS) system has been evaluated. An indirect field oriented control (IFOC) based state-vector pulse width modulation (SVPWM) drive connects the plant to the distribution system. The drive system includes two six-pulse IGBT converters interconnected through a DC link, to which the PV plant is interfaced via a single-stage bidirectional boost converter. The electrical system of the PHS plant consists of a squirrel-cage induction machine supplied by the machine side converter. The hydraulic system of the PHS plant includes separate turbine and pump units where a scaled linearized model is adopted to represent the elastic water column and surge tank. In the present study, the PV generated power has a control scheme designed to regulate the performance of the overall system. Simulation results are provided that show the transient performance of the plant during pumping and generating cycles of the PHS system.
High penetration of wind power has impacts that have to be managed through proper plant interconnection, integration, transmission
planning, and system and market operations. This report is a summary of case studies addressing concerns about the impact of wind
powers variability and uncertainty on power system reliability and costs. The case studies summarized in this report are not easy to
compare due to different methodology and data used, as well as different assumptions on the interconnection capacity available.
Integration costs of wind power need to be compared to something, like the production costs or market value of wind power, or
integration cost of other production forms. There is also benefit when adding wind power to power systems: it reduces the total
operating costs and emissions as wind replaces fossil fuels.
Several issues that impact on the amount of wind power that can be integrated have been identified. Large balancing areas and
aggregation benefits of large areas help in reducing the variability and forecast errors of wind power as well as help in pooling more
cost effective balancing resources. System operation and working electricity markets at less than day-ahead time scales help reduce
forecast errors of wind power. Transmission is the key to aggregation benefits, electricity markets and larger balancing areas.
From the investigated studies it follows that at wind penetrations of up to 20% of gross demand (energy), system operating cost
increases arising from wind variability and uncertainty amounted to about 14 /MWh. This is 10% or less of the wholesale value of
the wind energy.
With current technology, wind power plants can be designed to meet industry expectations such as riding through voltage dips, supplying
reactive power to the system, controlling terminal voltage, and participating in system operation with output and ramp rate control. The
cost of grid reinforcements due to wind power is very dependent on where the wind power plants are located relative to load and grid
infrastructure. The grid reinforcement costs from studies in this report vary from 50 /kW to 160 /kW. The costs are not continuous;
there can be single very high cost reinforcements, and there can also be differences in how the costs are allocated to wind power.
Wind generation will also provide some additional load carrying capability to meet forecasted increases in system demand. This
contribution can be up to 40% of installed capacity if wind power production at times of high load is high, and down to 5% in higher
penetrations and if local wind characteristics correlate negatively with the system load profile. Aggregating larger areas benefits the
capacity credit of wind power.
State-of-the-art best practices so far include (i) capturing the smoothed out variability of wind power production time series for the
geographic diversity assumed and utilising wind forecasting best practice for the uncertainty of wind power production
(ii) examining wind variation in combination with load variations, coupled with actual historic utility load and load forecasts
(iii) capturing system characteristics and response through operational simulations and modelling and (iv) examining actual costs
independent of tariff design structure.
This paper presents a power production system for the isolated insular power system of the islands Karpathos and Kasos. Karpathos and Kasos are two small islands, located in the South-East Aegean Sea (Dodecanese complex) that are not connected to the main power distribution network. Energy production is based exclusively on an autonomous thermal power plant and a small wind park, installed on the island of Karpathos. The maximum annual power demand has been estimated to exceed 12 MW by 2014. The mean specific annual energy production cost from the existing system has been calculated at 0.249 €/kW h in 2008.
Electricity generation from renewable energy sources (RES) in Greece is regulated by the energy law 2244/94 which provides incentives to attract private investments in the RES sector. The wind energy sector is highly attractive due to the verified large wind potential in many regions of the country. This paper presents the current situation concerning wind energy exploitation, analyses the technical problems following the penetration of wind power into electricity grids, and the consequent technical solutions proposed by the Public Power Corporation (PPC). It also describes the perspectives for high wind power penetration into Greek power system.
Pumped hydroelectric energy storage (PHES) is the largest and most mature form of energy storage currently available. However, the capital costs required for PHES are extremely large and the availability of suitable sites is decreasing. Therefore, identifying the remaining sites available for PHES is becoming vital so that the most beneficial location is chosen: in terms of capacity and economics. As a result, the aim of this work is to develop a computer program that will scan a terrain and identify if there are any feasible PHES sites on it. In this paper, a brief description of the program is provided, including the limitations identified during the initial development. Also, the program was used to evaluate a 20km × 40km area in the South West of Ireland so the results obtained from this study are discussed. Finally, future improvements to advance the program's capabilities are identified. The program has proven to date that it can identify feasible locations for PHES, however, further investigation is necessary to improve the site selection.
Pumped hydroelectric storage (PHES) is the most established technology for utility-scale electricity storage and has been commercially deployed since the 1890s. Since the 2000s, there has been revived interest in developing PHES facilities worldwide. Because most low-carbon electricity resources (e.g., wind, solar, and nuclear) cannot flexibly adjust their output to match fluctuating power demands, there is an increasing need for bulk electricity storage due to the increasing adoption of renewable energy. PHES has been the traditional way of storing energy. This chapter introduces PHES technology, its pros and cons, its historical developments, and its prospects.
This chapter details how pumped storage hydroelectric projects differ from conventional hydroelectric projects. The concept of electrical energy storage has become a controversial issue in recent years. Many questions are raised in the electricity sector: Why is energy storage needed? What are the alternatives? One of the answers is pumped storage hydropower plants, using mainly pump-turbines. In this chapter, details of some remarkable examples of pumped storage power plants are given: Okinawa Seawater in Japan, Goldisthal in Germany, Tianhuangping in China, and Coo-Trois Ponts in Belgium.
Hydropower is not only a renewable and sustainable energy source, but its flexibility and storage capacity also makes it possible to improve grid stability and to support the deployment of other intermittent renewable energy sources such as wind and solar power. As a result, a renewed interest in pumped-hydro energy storage plants (PHES) and a huge demand for the rehabilitation of old small hydropower plants are emerging globally. As regards PHES, advances in turbine design are required to increase plant performance and flexibility and new strategies for optimizing storage capacity and for maximizing plant profitability in the deregulated energy market have to be developed. During the upgrading of old small hydropower plants, the main challenges to be faced are the design of new runners, that had to match the existing stationary parts, and the development of optimal sizing and management strategies to increase their economic appeal. This paper traces an overview of the prospects of pumped-hydro energy storage plants and small hydro power plants in the light of sustainable development. Advances and future challenges in both turbine design and plant planning and management are proposed. PHES and hybrid wind/solar-PHES are illustrated and discussed, as well as the limits and peculiarities of the new design strategies, based on computational fluid dynamics, for both PHES and small hydropower plants.
With the rapid development of the Chinese economy and society, differences in the electric power system load between the peak and valley values are increasing, and inefficient small capacity coal-fired plant units must be involved in load adjustment because gas units and pumped storage units that act as peak-load units are lacking. In addition, due to concerns about energy saving and emissions reduction, clean energy sources are rapidly being developed and deployed. This presents a significant challenge for the construction and planning of peaking power solutions in China. Pumped storage plants provide a means of reducing the peak-to-valley difference and increasing the deployment of wind power, solar photovoltaic energy and other clean energy generation into the grid. Pumped storage plants represent the most mature approach among the peaking power sources and thus are one of China's major investments for the future. This paper presents China's current development of pumped storage plants, their role in the electric power system, the management models for pumped storage plants and the electricity price patterns utilising them. Here, we also analyse China's future plans for pumped storage plants, including the influencing factors and related policies.
This paper presents the characteristics of a power plant that combines renewable energy sources (RES), that is, a photovoltaic (PV) power plant and pump storage hydroelectric (PSH), to achieve sustainable production of green electric energy equal to that of conventional energy sources. The proposed solution does not produce CO 2 and does not significantly use freshwater or other resources. The PSH storage is the main element of the proposed power plant system, which provides a continuous and reliable supply of green energy. Its size significantly affects the size of the PV generator and operation characteristics of the hybrid plant. The paper elaborates in detail the functional relationship between the choice of the PV generator power and the PSH upper storage volume and presents the basic mathematical relations. The algorithm of the system development is presented, along with the procedure choice solutions. The results from the case study show that the concept is flexible in design, construction, and operation.
The Renewable Energy Law has been formulated by China government in 2005. During the next few years, there has been dramatic progress in China's renewable energy industries, along with the formation of the policy system of renewable energy in China. It is widely recognized that a reasonable and effective policy system can lay the solid foundation for the development of renewable energy. Regarding the rapid growth of renewable energy With a host of relevant policies issued in China, there is an urgent need to study the policy system of renewable energy in view of the latest situations to further promote the development of renewable energy. This paper is a systematical review about the promotion of China's policy system of renewable energy since Renewable Energy Law issued. Achievements on the policy system of renewable energy in 2011 as of 2005 are discussed. Experiences from recent periods are drawn and factors limiting the policy system of renewable energy are also addressed in details to probe the policy predicament and solutions. The development tendency of renewable energy is presented and the framework is drafted to set the framing constraints for China's policy system of renewable energy. Finally, policy suggestions are proposed for the successful implementation of renewable energy policies within the framing constraints of the policy system and the long-term healthy development of renewable energy in China.
With the integration of increased variable renewable energy generation and advent of liberalized electricity market, much attention has been devoted on the development of pumped hydro energy storage (PHES) as it has many prominent advantages of ensuring the safe and steady operation of power grid. In China, PHES has met a booming periods for the last ten years. Currently, there are 24 PHES stations with an installed capacity of 16.95 GW while government's target of 2020 is 50.02 GW. In this paper we provide an overall review of China's PHES development with a detailed presentation of the installed capacity and distribution of existing and proposed PHES stations, examine 4 typical stations in order to give a good description for the practical functions of PHES in power grid, analyze the management mode and price mechanism of PHES operation and point out the barriers in PHES development in China. State Grid Corporation of China (SGCC), which are making great efforts on China's PHES development, is discussed as a role model. On that basis we suggest PHES in the fast developing period should be temporarily operated and scheduled by grid companies in terms of exertion of its positive effects, while government should also take responsibility to subsidize on the stations' operation to relieve the price pressure of the ever-growing integration of renewable energy.
Pumped storage is generally viewed as the most promising technology to increase renewable energy source (RES) penetration levels in power systems and particularly in small autonomous island grids, where technical limitations are imposed by the conventional generating units. In this chapter, an operating policy is proposed for hybrid wind-hydro power stations (HPS) in island grids, in order to increase wind penetration levels, while at the same time minimizing the impact on the conventional generation system and ensuring the viability of the HPS invest-ment. The proposed operating strategy is applied to different autonomous island systems using a dedicated logistic model, in order to evaluate the effect on the overall operation and economics of the island systems and to assess the feasibility of HPS investments. In addition, the real study case of the HPS in Ikaria island, Greece, which is currently in the construction stage and will be one of the first wind-hydro-pumped-storage hybrid stations in the world, is examined and the ex-pected benefits from its operation according to the proposed policy are presented. The material presented in this chapter is based on publications [36] and [38] avail-able in IET-Renewable Power Generation and IEEE Transaction on Sustainable Energy.
This paper deals with the operation of a hybrid wind/hydro power system aiming at producing low cost electricity. A specific application on the island of Ikaria in Greece is analysed and typical results are presented and compared to the results produced from a simulation program. The simulation program, which is based on the stochastic behaviour of the weather conditions, uses as input data the monthly wind-speed distribution and, to a smaller extent, which is determined from the use of an appropriate weighting factor, the rate of rain water which is stored in the hydro reservoir. Useful conclusions were drawn regarding the feasibility of these applications in Greek islands and the expected electric energy saving.
Lack of electricity and water, the two fundamental resources in modern societies, is still a major issue in many developing countries and remote areas. This paper proposes a standalone renewable power system to solve the energy and water shortage in remote areas with abundant solar energy. The system utilizes a photovoltaic (PV) panel as the main energy source, which is controlled by a maximum power point tracking (MPPT) technique. A battery pack is used as the main energy storage device to smooth the fluctuation of solar power and to mitigate load transients and variations. In addition, a hydro storage system is used for water storage and supply, and also for supplying extra electric power via a hydro-turbine generator. The electricity and water demand of three households are considered for the system. The system modeling, unit sizing, control, simulation studies and the actual hardware implementation are presented and discussed in the paper.
Due to technological advancement, availability of multi-megawatt wind turbines, ease of installation and maintenance, economic compatibility and commercial acceptance, wind power is being used globally for both grid-connected and off-grid applications. The wind power is intermittently available due to the fluctuating nature of the wind and hence needs to be understood well. Its variability was studied in this paper both in time and spatial domain. The present work utilized daily mean values of wind speed from different meteorological stations spread over the Kingdom of Saudi Arabia in conjunction with wavelet transform and fast Fourier transform power spectrum techniques to understand the dynamic nature of the wind at nine stations. The study found that wind speed changed by ± 0.6 to ± 1.6 knots over a long period of about 10 years depending on the locations. The long-term mean wind speed of 5.6, 8.9, 6.25, 8.1, 6.0, 7.1, 6.0, 8.6 and 7.3 knots was obtained at Abha, Dhahran, Gizan, Guriat, Hail, Jeddah, Riyadh, Turaif and Yanbu, respectively.
The growing economy with corresponding increase in power demand causes more challenges in power sector of developing countries. In India, the increase in peak power demand necessitates energy storage schemes over and above the storage-hydro-, oil- and gas-based peak power plants to ensure power system stability. In utility energy storage schemes, the Pumped storage schemes attract more attention even in the developed countries due to its unique operational flexibility over other energy storage systems. In India, the availability of suitable topographies, hydro-thermal ratio imbalance in various regions, and optimal storage capacity for flexible power system operation gives a thought for the planers and executors to implement these schemes to meet peak demands. This paper presents a critical review of the necessity of pumped storage schemes in India. This review reveals that the major constraint for pumped storage operation in India is the deficit of off-peak power available in all the regional grids except north-east region for pumping at present. But the current adversity is likely to be gradually solved by the commissioning of newly proposed power projects. Fixing of a separate operational tariff for pumped storage schemes throughout the country is another requirement for which the government has set up a one man committee to analyze the feasibility for this peak tariff. Non-availability of lower tail pools and irrigation needs also causes poor pumping operations in some cases. However, most of the states in India are evincing interest in pumped storage schemes and proposals are being submitted to central government for securing stations clearance.
Pumped storage is generally viewed as the most promising technology to increase renewable energy source (RES) penetration levels in power systems and particularly in small autonomous island grids. Combined wind and pumped-storage “virtual power plants”, called hybrid power stations (HPS), constitute a realistic and feasible option to achieve high penetrations, provided that their components are properly sized. In this paper, the optimum sizing is investigated for a pumped storage HPS operating in an island system. The analysis addresses the sizing of the main HPS components (hydro turbines, pumps, wind farm, reservoirs), adopting either the investor’s perspective, where the objective is to maximize the return on the HPS investment, or a system perspective, where the optimization target is the maximization of RES penetration, along with maintaining the lowest possible generation cost in the system. Genetic Algorithms (GAs) are applied for the optimization and a real isolated island power system is used as a study case. The adopted operating policy and pricing principles, which critically affect the optimal sizing of an HPS project, are based on the existing regulatory framework for storage stations in Greek islands.
This paper studies pumped storage plants (PSPs) operating all over the EU, in which the key statistical indicators can be found in the European Hydropower database (HYDI), administered and managed by the European Small Hydropower Association (ESHA). The main emphasis is on mixed-type PSPs, which generate electricity from natural inflow; however, pure PSP plants are included in this study. Different analysed, independent PSP data sources (e.g., Eurostat, Eurelectric) show a great variation in the main statistical values (installed capacity and power generation) of the EU pumped storage plant fleet. Presented and analysed PSP layouts and a clear methodology for determining renewable electricity generation from mixed pumped storage plants will avoid ambiguities that actually pertain to power databases to clearly separate renewable and non-renewable electricity generation. Most of the National Renewable Energy Action Plans (NREAP) submitted to the European Commission do not correctly account for renewable electricity generation due to natural inflow into upper basins of PSPs. Moreover, renewable and non-renewable electricity generation types are mixed up. The operating mixed PSP installed capacity and electricity generation were determined in the EU countries, which is a type of renewable source, and their projected estimates in 2020 are provided.
Renewable electricity expansion highlights the need for a review of energy storage options. Wind power growth, in particular, is likely to require the support of dedicated fast-start reserve capacity. Moreover, in New Zealand, non-pumped hydroelectricity-based storage has only limited potential to meet seasonal variations of hydro inflows. This constraint has contributed to several ‘dry-year’ events over the last decade. This case study surveys New Zealand electricity sector experts as to the feasibility of meeting reserve capacity needs while reducing carbon emissions through the introduction of pumped hydro and utility-scale batteries by 2025. Most respondents project peak power demand to continue to increase, resulting in new-build centralised (∼150 MW) thermal reserve power sources. Pumped hydro is seen by most as prohibitively costly, but is almost universally viewed as technically capable of providing renewables support and peak power adequacy. Utility-scale batteries are seen as least cost-effective, with very high storage costs per kWh and most likely only to be used in NZ for very high-value applications where there is a strong technical advantage, such as the six-second instantaneous reserve. A price of carbon of around NZ$100/tCO2-e, however, was seen as making these technologies much more competitive, and climate change mitigation was seen as a strong driver of these storage options.
Integrating large amounts of wind power in energy systems poses balancing challenges due to the variable and only partly predictable nature of wind. The challenges cover different time scales from intra-hour, intra-day/day-ahead to several days and seasonal level. Along with flexible electricity demand options, various electricity storage technologies are being discussed as candidates for contributing to large-scale wind power integration and these also differ in terms of the time scales at which they can operate. In this paper, using the case of Western Denmark in 2025 with an expected 57% wind power penetration, wind power impacts on different time scales are analysed. Results show consecutive negative and high net load period lengths indicating a significant potential for flexibility measures capable of charging/activating demand and discharging/inactivating demand in periods of 1 h to one day. The analysis suggests a lower but also significant potential for flexibility measures charging/activating demand in periods of several days. In addition, the results indicate a physical potential for seasonal electricity storage. In the study, a number of large-scale electricity storage technologies – batteries, flow batteries, compressed air energy storage, electrolysis combined with fuel cells, and electric vehicles – are moreover categorised with respect to the time scales at which they are suited to support wind power integration. While all of these technologies are assessed suitable for intra-hour and intra-day/day-ahead power balancing only some are found suited for responding to several days with high/low net loads and even fewer for seasonal balancing.
The new Spanish regulations allow wind farms to go to the market to sell the energy generated by their facilities. In the case of over- or under-supply, other producers must reduce or increase their production to resolve the so-called deviation, thereby incurring financial losses. Faced with this situation, wind farms have several options. In this paper we consider one promising method: the combined optimization of a pumped-storage hydro-plant and a wind park. First, we are going to present the mathematical modelling of the resulting problem. Second, we shall solve the optimization problem using Optimal Control techniques and finally we shall present several examples of the combined optimization and analyse which strategy is the best one possible.
Energy storage constitutes an effective way to manage excess RES production, and pumped storage is a suitable and mature solution for large storage capacities. The present study aims to investigate the performance of a pumped storage unit introduced in a conventional Hydroelectric Power Plant in Greece. At first, the plant operation and the electric grid data for a reference period of one year are used to compute the time variation of water inflow into the dam, and to estimate the RES production rejections depending on the installed power. Next, a pumping station powered by the rejected RES production and raising water from an adjacent downstream reservoir is modeled. Various scenarios concerning the pumping station power rate and feeding program are examined. The operation of the combined system is simulated in detail and the energy results are analyzed. Also, an economic evaluation is carried out based on current financial conditions in Greece. The results showed that a considerable amount of excess RES production can be stored, but the economic viability of the investment depends on some critical parameters, which are identified. Certain guidelines concerning the optimum sizing and operation strategy of the pumped storage scheme are finally extracted.
This paper presents important technical details for the design, construction and operation of seawater pumped storage systems (S-PSS).S-PSS co-operating with wind parks, features as the most promising technology towards maximizing Renewable Energy penetration in insular systems with low annual rainfalls.This article summarises the fundamental points of integrated studies of S-PSS, from the feasibility study to the precise positioning of the systems' components and the selection of the main equipment. Special issues regarding the use of seawater from the PSS (pumped storage system), such as the use of materials for the construction of the penstock, the construction of the upper reservoir, placing the pump station and the hydro power plant on the coast and the selection of pump and hydro-turbine models are presented thoroughly. Indicative results are presented from two S-PSS of small and medium size.The study proves that current technology enables the secure use of seawater in PSS. The electricity surplus from Wind Powered Pumped Storage Systems (WP-PSS) can also be exploited in reverse osmosis desalination plants for producing potable water.Seawater can be pumped directly from the sea, thus construction of a lower reservoir is avoided, compensating higher costs arising from the use of corrosion-resistant materials for certain components.
The electrification of the non-interconnected Greek islands is mainly based on Autonomous Power Stations (APSs) that are characterized by considerably high electricity production cost, whilst, in several cases, problems related with power shortage are encountered. At the same time, the contribution of wind energy is significantly restricted due to electrical grid limitations imposed to “secure” the stability of the local network and thus resulting in significant rejected wind energy amounts. On the basis of sensitivity analysis, the present study evaluates the techno-economic viability of a system that incorporates the simultaneous operation of existing and new wind farms (WFs) with pumped storage and hydro turbines, which are able to provide the electrical grid of a remote island with guaranteed energy amounts during the peak load demand hours on a daily basis. The performance of the system is simulated during a selected time period for various system configurations and an attempt is made to localize the optimum solution by calculating various financial indices. Emphasis is given on the conduction of an extensive sensitivity analysis considering three main variables (i.e. produced energy selling price, the percentage of state subsidization and the price of the wind energy surplus bought from the already existing WFs) taking also into account several constraints of the national legislation. Based on the most economically viable (payback period quite less than 10 years) configuration derived (24 MW WFs, 15 MW water pumping system, 13.5 MW hydro turbines), the contribution of renewable energy increases by almost 15% (in absolute terms) compared to current conditions, reaching about 25% of the island’s energy consumption pattern. The proposed analysis may be equally well applied to every remote island possessing remarkable wind potential and appropriate topography.
Since the main problem of continuous energy supply from photovoltaic (PV) power plant is intermittence and inability to provide continuous energy supply, this paper proposes its hybridization with hydro energy, or with pump storage hydroelectric (PSH) as a possible solution. This creates a new type of sustainable hybrid power plant which can work continuously, using solar energy as primary energy source and water for energy storage. The characteristics of the solution as an open thermodynamic system are presented, as well as the basic theoretical settings for its application, i.e. key relationships between power and collector field area of PV power plant and working volume of upper storage. The paper introduces hydrological and hydro-energetic indicators for the hybrid plant description, “artificial rainfall”, as the relationship between the water pumped into the upper water storage of the PSH (artificial water inflow) and collector field area of the PV power plant, as well as hydroenergy potential. The proposed hybrid electric power plant does not emit greenhouse gases, produce waste or significantly exploit water resources while the risks to humans and the environment are far smaller than when using conventional technology. This solution is flexible for implementation and can be applied in various climates, hydrological and physical conditions. It is especially productive in cases of joint use of solar and hydro energy where they naturally complement each other as natural energy sources in the annual working cycle.
Renewable power (photovoltaic, solar thermal or wind) is inherently intermittent and fluctuating. If renewable power has to become a major source of base-load dispatchable power, electricity storage systems of multi-MW capacity and multi-hours duration are indispensable. An overview of the advanced energy storage systems to store electrical energy generated by renewable energy sources is presented along with climatic conditions and supply demand situation of power in Saudi Arabia. Based on the review, battery features needed for the storage of electricity generated from renewable energy sources are: low cost, high efficiency, long cycle life, mature technology, withstand high ambient temperatures, large power and energy capacities and environmentally benign. Although there are various commercially available electrical energy storage systems (EESS), no single storage system meets all the requirements for an ideal EESS. Each EESS has a suitable application range.
This paper investigates how large-scale energy storage can assist the integration of fluctuating renewable energy by using the Irish energy system, pumped hydroelectric energy storage (PHES), and wind power as a case study. In total three key aspects were investigated in relation to PHES: its operation, size, and cost. From the results it was evident that PHES can increase the wind penetration feasible on the Irish energy system and also reduce its operating costs. However, under predicted 2020 fuel prices and a conventional 6% interest rate, these savings may not be sufficient since the savings are sensitive to changes in the PHES capacities used, fuel prices, interest rates, and the total annual wind energy produced. Finally, the optimum capacities of PHES identified for Ireland in 2020 were compared to two other alternatives which required the same investment: domestic heat pumps and district heating with CHP. These alternatives offer similar savings to PHES, but are not as sensitive to changes in fuel prices, interest rates, and wind power production. This outlines the importance of considering all sectors of an energy system when assessing future alternatives, as significant savings are feasible using existing technologies, especially by integrating the electricity and heat sectors.
The increasing demand for peaking power has resulted in a greater need for pumped storage power stations. This is particularly so where storage lakes already exist, as pre-construction planning can be avoided and less building is required. In response to this need, Voith Siemens Hydro supplied equipment for the extension of two stations in Austria. However, with each project differing drastically from the other, Voith Siemens Hydro had to access each station individually to determine its independent needs.
A simulation model is presented to evaluate the operational benefits of Tianhuangping Pumped Storage Hydro-Plant (TPSHP) in the Shanghai electrical network. The benefits from the hydro-plant include the electricity from the pumped water, the efficiency improvement of the overall units and the increase of peak load capacity. More specifically, Tianhuangping provides an average coal consumption of 5.1 g/kW · h decrease and an additional 600 MW peak capacity for the Shanghai electrical network.
The possibility to create a combined wind–hydro energy station in a medium size island of the Aegean Archipelago is investigated on a techno-economic basis. The proposed solution may be used to face the extremely high electricity production cost in these regions, taking also advantage of the excellent local wind potential. Additionally, a parametrical analysis is performed on a techno-economic basis in order to select the appropriate number of wind turbines and the optimum size of water reservoirs. The calculation results obtained, based on real measurements and on experimental data, validate the proposed solution. More precisely, the electricity demand of the remote system is covered in any case, the imported fuel is minimized, the renewable energy sources penetration exceeds 90%, and the negative environmental effects are remarkably reduced.
The aim of this work is to investigate in detail the optimum design and operation strategy of a stand-alone hybrid desalination scheme, capable to fulfill the fresh water demand of an island or other remote coastal regions. The scheme consists of a reverse-osmosis desalination unit powered by wind and solar electricity production systems and by a pumped storage unit.A specific computer algorithm is developed to simulate in detail the entire plant operation and also to perform economic evaluation of the investment. A stochastic optimization software based on evolutionary algorithms is implemented to accomplish design optimization studies of the plant for various objectives, like the minimization of fresh water production cost or the maximization of water needs satisfaction. Miscellaneous parametric studies are also conducted in order to analyze the effects of various critical parameters, as population, water pricing, water demand satisfaction rate and photovoltaics cost are.The results demonstrate not only the performance, the role and the contribution of each subsystem but also the production and economic results of the whole plant. An optimally designed scheme is found to be economically viable investment, although energy rejections are significant and there is a clear need for better exploitation of renewable energy production surplus.
Promoting renewable energy has been a key ingredient in energy policy seeking to de-carbonize the energy mix and will continue to do so in the future given the European Union's high ambitions to further curb carbon emissions. A wide range of instruments has been suggested and implemented in various countries of the EU. A prominent policy promoting investment in renewable technologies is the use of feed-in tariffs, which has worked well at large scale in, e.g. Germany, but which has only been implemented in a very limited way in countries such as the UK.Being subject to environmental uncertainties, however, renewables cannot be seen in isolation: while renewables-based technologies such as wind and solar energy, for example, suffer from uncertain loads depending on environmental conditions, hydropower allows for the storage of water for release at peak prices, which can be treated as a premium (partially) offsetting higher upfront investment costs. In addition, electricity prices will respond to changes in electric capacity in the market, which is often neglected in standard investment models of the electricity sector.This paper contributes to the existing literature in two ways: it provides a review of a renewables-based technology in a specific policy context and provides additional insight by employing a real options approach to investigate the specific characteristics of renewables and their associated uncertainties in a stylized setting taking explicitly into account market effects of investment decisions. The prices of the model are determined endogenously by the supply of electricity in the market and by exogenous electricity price uncertainty. The inclusion of market effects allows us to capture the full impact of public incentives for companies to invest into wind power and hydro pumped storage installations.
Acquiring a pumped-storage power generation site utilizing river water recently faces several restrictions due to environmental assessment. On the other hand, there are many sites favorable for constructing a pumped-storage power plant utilizing seawater in Japan, which is surrounded by the sea. Seawater pumped-storage power plants have several advantages such as lower civil construction cost and lower power distribution cost due to their proximity to nuclear or steam turbine power plants. Seawater pump turbines are used under the condition where the corrosion environment is noticeably severe, rather than conventional river water pump turbines. In addition, pump turbines have many narrow spaces between parts and their major parts are embedded, so that it would be very difficult to apply proper corrosion prevention measures. This problem cannot be solved only by conventional corrosion-preventive engineering. The Agency of Natural Resources and Energy of the Ministry of International Trade and Industry entrusted Electric Power Development Co., Ltd. with the construction of the world's first seawater pumped-storage pilot plant in Kunigami Village in Okinawa Prefecture, Japan, to execute verification tests for five years after the completion of construction in March, 1999. This paper will deal with materials, structure, and corrosion-preventive engineering of the pump turbine for the seawater pumped-storage power plant.
This work presents the main features of the new power plant that comprises the modified reversible hydroelectric (HE) power plant operating together with the photovoltaic (PV) power plant. Such Solar Hydroelectric Power Plant (SHE) uses solar energy as the only input for production of solar and hydro energy. Thereat, water reservoir serves for daily and seasonal energy storage, thus basically solving the problem of energy storage, which is the biggest problem of wider use of solar energy. The most expensive part of SHE is the PV generator, whose optimal sizing is essential for providing energetic independence of a settlement or isolated consumer. A systematic approach that includes all relevant elements of this system has been implemented for optimal sizing of the PV power plant. The developed model was used in analysis of certain parameters of the SHE system. The results of the analysis show the system characteristics and that the proposed model describes the operation of the power plant very well. The feasibility and characteristics of the power plant were tested on electric energy supply of the island of Vis in Croatia. It has been established that the system is real, feasible and can be very successfully applied on different locations, for different consumers and can vary in size. The prerequisite for realization of such system is the construction of a modified reversible HE power plant. The presented SHE represents a permanently sustainable energy source that can continuously provide power supply to a consumer, using exclusively natural and renewable energy sources, without causing harmful effects on the environment.
This article presents a survey of different possible technical solutions for the grid integration of wind farms. These solutions concern the main problems encountered today and, whenever possible, examples of actual implementation in wind farm projects are given. More specifically the following types of solutions are discussed: choice of an appropriate wind turbine generator technology; solutions based on co-ordinated wind farms and power system operation; reactive compensation and voltage control systems; fault ride-through systems; energy storage systems; current limitation devices; directional protections; etc. Copyright © 2005 John Wiley & Sons, Ltd.