Pumped Hydro Energy Storage Research Articles

Integrated Policies to Reduce Australia’s Electricity Sector Greenhouse Gas Emissions to Net Zero by 2050

Recent events within the Australian National Electricity Market have demonstrated that the system of an energy-only market (a market that only compensates power that has been produced) is no longer fit for purpose. The rate of change in installed capacity and generation requires better planning to ensure reliability is maintained at the lowest total system cost during the transition to net zero. Australian National Electricity Market participants will need sufficient incentives and confidence to invest in new capacity. This paper assesses a “no constraints” scenario and recommends a range of policy and market mechanisms that could be utilized to achieve a net zero National Electricity Market in Australia by 2050. This paper adopts the perspective of total system cost, which allows multiple factors relating to decision-making to be incorporated. In the absence of a carbon price, this paper seeks to put forward technology-based policy and market mechanisms to incentivise the changes required. The “Modelling Energy and Grid Services” model used in this study has shown that this “no constraints” future grid will need to contain approximately 100 GW of variable renewable energy, almost 20 GW of firm, low-emissions generation, such as carbon capture, utilisation and storage, bioenergy with carbon capture and storage, hydroelectric power, or nuclear power. It will also require more than 10 GW of storage, including pumped hydro energy storage and other energy storage technologies, and over 30 GW of firm, dispatchable peaking plants, including thermal power generation.

Two-stage robust unit commitment with the cascade hydropower stations retrofitted with pump stations

Cascade hydropower stations are excellent flexible resources to regulate the drastic fluctuations of wind and photovoltaic power generation in the hybrid energy system. By constructing pump stations between two adjacent upstream and downstream reservoirs, the conventional cascade hydropower stations can be transformed into a cascade pumped hydro energy storage (CPHES) system, which further can promote the integration of clean energy resources. In this paper, a two-stage robust unit commitment model for the cascade hydropower stations retrofitted with pump stations is established to address the renewable energy uncertainties. A short-term scheduling framework is proposed for the hybrid energy system including CPHES, which coordinates the operating cost and clean energy curtailment. Besides, a modified nested column-and-constraint algorithm is employed to solve the two-stage robust optimization problem with integer resources. Numerical tests performed on a modified IEEE 24-bus system and a large-scale practical power system verify the effectiveness of the proposed scheduling model and algorithm.

Spatial-temporal evolution of pumped hydro energy storage potential on the Qinghai-Tibet Plateau and its future trend under global warming.

Global warming has brought extensive and far-reaching impacts on human life and production. A pumped hydro energy storage contributes to the large-scale development of renewable energy and serves as an important measure to mitigate climate change. Despite considerable efforts in estimating the potential of the pumped hydro energy storage, research gaps in response to global warming remain. In this regard, this study conducts a novel assessment of the pumped hydro energy storage's potential from a dynamic perspective, taking the Qinghai-Tibet Plateau as the study area. The spatiotemporal evolution of the pumped hydro energy storage's potential over the past few decades (the 1970s-2017) is analyzed, and its response to precipitation is identified innovatively. On this basis, the trend in the future period is further predicted for the first time, which is divided into near, short, medium, and long terms. Results show that the pumped hydro energy storage potential has a generally upward but not monotonic trend, decreasing from the 1970s to 1995 and then rising more dramatically, with slopes of 5548.5 ± 69.2 GWhyr-1 and -238.1 ± 90.4 GWhyr-1. In the majority (68.6 %) of lake basins (68.6 %), changes in precipitation positively contribute to the pumped hydro energy storage potential, resulting in a noticeable growth in the future. Under the representative concentration pathway of 8.5, the mean potential density is projected to rise by 23.4 %, 25.2 %, 28.3 %, and 30.6 % in the near, short, medium, and long terms, respectively. This result indicates that high-intensity greenhouse gas emissions under this scenario will lead to a greater potential for the pumped hydro energy storage in the future.

Life Cycle Environmental Impact of Pumped Hydro Energy Storage

Pumped hydro energy storage (PHES) is one of the energy storage systems to solve intermittent renewable energy and support stable power generation of the grid. About 95% of installed capacity of the global energy storage system is contributed by PHES. Life cycle assessment (LCA) is used to analyse the environmental impact of PHES construction and operation phase in this study, and 1 MWh of electricity delivered from PHES to the power grid is set as the functional unit. The results show that the electricity power structure and electricity loss caused by the charging-discharging of PHES are the main environmental burden contributors, contributing 80 to 99% of the total environmental emissions. And environmental impacts during the construction phase is mainly due to the use of concrete, steel, and cement. In the future, as the proportion of renewable energy in the grid structure increases, the environmental impacts caused by PHES will decrease accordingly.

Micro Pumped Hydro Energy Storage: Sketching a Sustainable Hybrid Solution for Colombian Off-Grid Communities

Currently, electricity generation in off-grid communities is done through polluting and often inefficient diesel generators. When renewable energies are implemented, they are often coupled with chemical batteries, whose specificities do not fit well with remote and harsh environments. As a more sustainable alternative, this paper looks at micro pumped hydro energy storage coupled with solar photovoltaic production. Rural electrification in Colombia is selected as the best potential context for such a solution. Several electrical machines are considered for energy conversion (associated with one pump also utilized as turbine for robustness and cost reasons) and rated over-dedicated criteria: reactive power, efficiency, price, flexibility of power intake, complexity, and robustness. This sketching phase highlights two machines, induction and permanent magnet synchronous machines, both coupled with a variable frequency drive. Two microgrid configurations are also selected that best suit this storage technology to the needs of Colombian non-interconnected zones. A pursuit of low-tech, robust solutions is carried in this paper for reasons of costs, maintenance, and local appropriation.

Greenhouse gas emissions from hybrid energy storage systems in future 100% renewable power systems – A Swedish case based on consequential life cycle assessment

To promote the development of renewables, this article evaluates the life cycle greenhouse gas (GHG) emissions from hybrid energy storage systems (HESSs) in 100% renewable power systems. The consequential life cycle assessment (CLCA) approach is applied to evaluate and forecast the environmental implications of HESSs. Based on the power system of Sweden, different HESS combinations, which include energy storage (ES) technologies: pumped hydro ES, hydrogen ES, lithium-ion (Li-ion) batteries, lead-acid (PbA) batteries, vanadium redox (VR) batteries, supercapacitors (SCs), and flywheels, are discussed. The results show that for Sweden and similar large-scale utility applications, the cradle-to-gate GHG emissions from the HESS contribute to a major share of the life cycle GHG emissions due to the under-utilization of the cycle life. Among the HESSs compared in this study, the Pumped hydro+Li-ion+Flywheel combination exhibits the least life cycle GHG emissions. Moreover, the phasing out of nuclear power brings a severe challenge to the carbon reduction target. However, the introduced HESS manages to reduce GHG emissions from a 100% renewable power system.

Selection of energy storage technologies under neutrosophic decision environment

The variability of renewable energy can be addressed by incorporating energy storage technologies (ESTs). Multiple energy storage technologies are available for renewable energy with wide disparity in attributes. Reports regarding the attributes are conflicting and complex, which makes it a multi-attribute decision analysis problem. To address this issue, new decision support tools are needed to aid in selecting ESTs based on their technical, environmental, and economic characteristics. In this study, a neutrosophic data envelopment analysis (NDEA) technique is developed and applied to selection of ESTs considering neutrosophic uncertainty inherent in new technologies. The decision tool systematically evaluates EST options by considering the expert's degree of satisfaction for higher technical performance, degree of dissatisfaction for lower technical performance and degree of indeterminacy for attaining better technical performance. Two case studies adapted from literature are used to illustrate the decision support tool. The first case study, which is used to demonstrate the tool for EST selection, involves the selection of thermal energy storage options. The second case study involves eight ESTs with different mechanisms: supercapacitor, flywheel, compressed air energy storage, pumped hydro energy storage, Li-ion battery, NiCd battery, NaS battery, and Pb-acid battery. The results reveal certain ESTs that are preferred over wide range of expert's perception to uncertainty in terms of dissatisfaction and indeterminacy. For example, Li-ion battery is DEA efficient if the risk tolerance for indeterminacy is greater than 40% and Pb-acid battery is DEA efficient at falsity tolerance greater than 80% and indeterminacy tolerance of less than 5%. These alternatives can be regarded as robust choices. Insights gained from the application of the decision tool can be used for guiding investment decisions in planning of renewable energy systems with energy storage.

Batch Acquisition for Parallel Bayesian Optimization—Application to Hydro-Energy Storage Systems Scheduling

Bayesian Optimization (BO) with Gaussian process regression is a popular framework for the optimization of time-consuming cost functions. However, the joint exploitation of BO and parallel processing capabilities remains challenging, despite intense research efforts over the last decade. In particular, the choice of a suitable batch-acquisition process, responsible for selecting promising candidate solutions for batch-parallel evaluation, is crucial. Even though some general recommendations can be found in the literature, many of its hyperparameters remain problem-specific. Moreover, the limitations of existing approaches in terms of scalability, especially for moderately expensive objective functions, are barely discussed. This work investigates five parallel BO algorithms based on different batch-acquisition processes, applied to the optimal scheduling of Underground Pumped Hydro-Energy Storage stations and classical benchmark functions. Efficient management of such energy-storage units requires parallel BO algorithms able to find solutions in a very restricted time to comply with the responsive energy markets. Our experimental results show that for the considered methods, a batch of four candidates is a good trade-off between execution speed and relevance of the candidates. Analysis of each method’s strengths and weaknesses indicates possible future research directions.

Short-term assessment of pumped hydro energy storage configurations: Up, down, or closed?

We study the energy generation and storage problem for various types of two-reservoir pumped hydro energy storage facilities: open-loop facilities with the upper or lower reservoir fed by a natural inflow and closed-loop facilities. We formulate this problem as a stochastic dynamic program under uncertainty in the streamflow rate and electricity price. We include the streamflow rate and electricity price as exogenous state variables in our formulation. We compare the short-term total cash flows obtained by running different pumped hydro energy storage configurations in a market setting where the electricity price can be negative. We first derive theoretical bounds on the revenue gains and losses from switching from one configuration to another. We then conduct numerical experiments by employing time-series models to formulate the evolution of our exogenous state variables. We consider three distinct seasons with different streamflow rates, different negative price occurrence frequencies, and different reservoir capacities. Our results show that: (1) The open-loop facility with the upstream flow can yield cash flows that are up to four times as large as those of the closed-loop facility; (2) The cash flow from operating a large closed-loop facility can be achieved by operating an open-loop facility with 10 times smaller reservoirs; and (3) The open-loop facility with the downstream flow can be more advantageous than the open-loop facility with the upstream flow (with an improvement of more than 10% in the cash flow) if the negative electricity price occurs more than 30% of the time.

Solid gravity energy storage technology: Classification and comparison

Large-scale energy storage technology plays an essential role in a high proportion of renewable energy power systems. Solid gravity energy storage technology has the potential advantages of wide geographical adaptability, high cycle efficiency, good economy, and high reliability, and it is prospected to have a broad application in vast new energy-rich areas. As a novel and needs to be further studied technology, solid gravity energy storage technology has become one of the important development directions of large-scale energy storage technology. This paper firstly briefly introduces various types of SGES technologies and their characteristics. Secondly, to address the problem that there is no detailed quantitative analysis of multiple kinds of SGES, this paper presents a detailed analysis and discussion of various types of SGES technologies based on the evaluation indexes of large-scale energy storage technologies. Again, by assigning reasonable weights to each evaluation index and performing normalized analysis, the quantitative analysis of the performance levels of different SGES technologies is conducted. The results will provide valuable references for selecting specific SGES technologies in engineering practice. Finally, based on the results of this paper, we provide some suggestions for the following research on SGES technologies. Considering the lack of construction conditions for pumped hydro energy storage in many areas rich in new energy resources, solid gravity energy storage will gain huge development space with low cost and excellent performance.

Dynamic feature extraction and recognition of flow states in vaneless space of a prototype reversible pump turbine in generating mode based on variational mode decomposition and energy index

Dynamic feature extraction of pressure fluctuation signals and recognition of flow states in vaneless space have important engineering significances to guarantee the operational stability of the prototype reversible pump turbine (RPT) in the pumped hydro energy storage power station. In the present paper, in order to carry out accurate dynamic feature extraction of the flow states in the vaneless space, a method based on variational mode decomposition (VMD), energy index (EI) and support vector machine (SVM) is proposed. During the analysis procedure of pressure fluctuation signals, VMD can greatly avoid the mode mixing phenomenon, which often occurs in conventional empirical mode decomposition (EMD). After VMD analysis, several mode components with strong physical significances and separated central frequencies are obtained. Then, the EI of each mode component based on VMD is calculated and screened out. The EIs of the first three mode components are further constructed as the eigenvector that can accurately reflect different flow states in the vaneless space of the RPT. In addition, the intelligent classifier of SVM is employed to identify three types of flow states. The above eigenvectors can be employed as the input vectors of SVM. The average recognition results of 10 times show that the correct recognition rate of the proposed VMD-EI-SVM method (98.67 %) is higher than that of the EMD-EI-SVM method (88.00 %), which is more suitable for engineering applications.

Optimization of a diabatic compressed air energy storage coupled with photovoltaics for buildings: CO2-eq emissions vs payback time

The necessary path towards sustainable development makes increasingly crucial the role of energy storage systems because the most affordable renewable energy sources (RES) are typically intermittent In this perspective compressed air energy storage (CAES) is one of the main alternatives to batteries and pumped hydro energy storage. This study shows how an integrated system coupling RES and CAES may significantly reduce greenhouse gas emissions with acceptable payback times. The electrical load is provided by a representative building sample (RBS) located in Naples (Southern Italy), generated using the simulation-based large-scale uncertainty/sensitivity analysis of building energy performance (SLABE) methodology. A Pareto multi-objective optimization is performed via a brute-force search to minimize CO2-eq emissions and payback time. The design variables refer to a photovoltaic system design and to size and operation of an associated diabatic CAES. Two different application scenarios are envisaged: 1000 buildings and 2000 buildings. The avoided greenhouse gas emissions are about 55% and 51% with simple payback times of 14.3 years and 12.4 years, respectively. The results show that the proposed integrated framework, with the right mix of renewables, may lead to the complete satisfaction of the electrical load at reasonable costs.

Geographic Information System-based Multi-Criteria Decision-Making analysis for assessing prospective locations of Pumped Hydro Energy Storage plants in Morocco: Towards efficient management of variable renewables

The considerable potential offered by wind and Solar Photovoltaic (SPV) energy, at competitive costs, constitutes a real opportunity to reduce CO2 emissions, thus contributing to significant decarbonization. Nevertheless, these sources require energy storage, which remains a key solution to mitigate their intermittency and variability, as they are dispatchable energy production systems. Among these latter, Pumped Hydro Energy Storage (PHES) stands as the most widely adopted technology for utility-scale applications, since it offers numerous advantages. Finding a suitable site for a PHES plant, however, remains a challenge for new project development, as it is highly dependent on topographic and geological site conditions. In this perspective, this paper presents an approach aiming at identifying and classifying appropriate locations for PHES plants based on the Analytic Hierarchy Process (AHP) method along with Geographic Information System (GIS) tools - ArcGIS 10.8. Considering the various PHES topologies, this assessment seeks to explore two: the first uses existing dams and lakes as primary reservoirs (Topology - T2), while the second considers the sea as a lower reservoir (Topology - T4). To our knowledge, this study introduces for the first time two novel decision criteria: evapotranspiration and sea surface salinity. These parameters lead respectively to evaporation losses from the storage reservoirs and corrosion effects on the different components of the installation. The proposed methodology was then applied to the case of Morocco, whereby the results revealed that a total of 1606 potential sites were identified, from which >36 % were deemed highly suitable. Furthermore, a total energy storage capacity of 6862 GWh was estimated from those locations, where about 72 % is represented by T2. This research work, the first of its kind for Morocco, aimed at securing cost-effective sites to help policy- and decision-makers develop strategies tailored to the country's conditions for a wide integration of variable renewables.

Stability and efficiency performance of pumped hydro energy storage system for higher flexibility

The pumped hydro energy storage station flexibility is perceived as a promising way for integrating more intermittent wind and solar energy into the power grid. However, this flexible operation mode challenges the stable and highly-efficient operation of the pump-turbine units. Therefore, this paper focuses on stability and efficiency performance of pumped hydro energy storage system (PHESS) under the various flexibility scenarios. First, a nonlinear model of PHESS coupling the hydraulic loss, mechanical loss and electrical loss of pump-turbine is established to study its stability and efficiency characteristics. Second, six flexibility scenarios including four transient processes and two steady processes are extracted based on the historical power output of a pump-turbine unit. Parameter responses indicate that the stability performance of PHESS got worse when the range of load-variation increased. Parameters response in the first 10s is steeper than that in the later 30s. Rotation speed and water head in part-load fluctuates periodically in a range of from −0.0024 to 0.01. In other words, 10 times more compared to the range response under the rated-load. Efficiency analysis suggests that the friction loss in scroll case is the dominated loss type in the transient processes, except for the FL condition. The responses of friction loss in straight pipe, impact loss in scroll case and volume loss are characterized by the corresponding discharge laws. The response curve of winding loss is similar with the response feature of rotation speed. This paper provides the stability and efficiency perspective when the operator exploits the flexibility potential of pumped hydro energy storage station.

Optimal Bidding Strategy of a Pumped Hydro Energy Storage Integrated Nuclear Power Plant considering Possible Outage

Recently, harmful gases emitted into the atmosphere disrupt the balance of nature and cause climate changes. The tendency towards renewable energy is increasing in order to prevent climate change. The importance of the conventional power plants in the power system is maintained due to the intermittent nature of renewable energy sources. In this regard, nuclear power which is one of the conventional power plants takes attention. In this study, a new approach for optimal scheduling of a Pumped Hydro Energy Storage (PHES) integrated Nuclear Power Plant (NPP) system is proposed. It is expected that PHES provides significant economic contribution to the grid operator especially by ensuring energy supply security of the NPP. Two different market types named Day Ahead Market (DAM) and Balancing Market (BM) in Turkey are implemented in the trades by using real electricity prices obtained from Energy Exchange Istanbul (EXIST), which is Energy Market Operator in Turkey. In order to evaluate the effectiveness of the proposed model, seasonal impacts of four different months are also examined in several case studies. Furthermore, sustainability analyzes are conducted considering probability of interruption of the NPP during 8 hours. According to the results, it is observed that promising solutions can be obtained thanks to the integration of the PHES in the presence of the different market types even if outages are planned.

Trends in renewable energy: an overview

<p>This essay deals with the prospects of supplying humanity with energy in the twenty-first century. The gradual replacement of fossil fuels by green electricity, hydrogen and biofuels is examined in the context of deteriorating climate change and the ongoing depletion of fossil fuels. The production of large amounts of green electricity through the spreading of wind-energy, photovoltaic, concentrated solar power, hydroelectric power and high temperature geothermal plants and its storage through the global interconnection of electricity grids, the spreading of pumped hydro energy storage and melting salts plants and the lithium batteries leads certainly to a future world largely but not exclusively electrical. Hydrogen will be a very important energy carrier. The production of blue and green hydrogen, their transport and usage in cars, industry and trains in the near future as well as in ships and airplanes in the distant future is outlined. Biofuels must be inevitably added to the future energy profile of mankind besides green electricity and hydrogen. The modern trend of producing biofuels from residual fatty raw materials, microalgae and agricultural / forest residual raw materials to overcome the competition with foods production for land and water as well as the residual biomass utility for the production of aircraft fuels and bio-chemicals in the near future is also illustrated. Finally, the increasing contribution of biogas / biomethane to the future energy profile has been presented.</p>

Physical Energy Storage Technologies: Basic Principles, Parameters and Applications

Physical energy storage is a technology that uses physical methods to achieve energy storage with high research value. This paper focuses on three types of physical energy storage systems: pumped hydro energy storage (PHES), compressed air energy storage (CAES), and flywheel energy storage system (FESS), and summarizes the advantages and disadvantages of each technology by collecting and evaluating the principles, components and technical parameters. In addition, this paper presents the practical applications of the technologies and finally provides an outlook on future developments. The results show that PHES technology is the most mature and has the advantages of high efficiency and long lifetime, but the current application is rather single and can be developed in the direction of variable speed/underground/seawater pumped storage in the future; CAES has larger energy capacity and longer service life, outstanding peak regulation capability, and can manage energy as well as provide power for vehicles, but its efficiency and energy density are low and need further optimization in the future; FESS has the advantages of short response time and power density, and minimal environmental effects, but currently it is mostly used for small-scale occasions and military purposes due to its small capacity, and its self-discharge rate is large, and it is being developed in the direction of increasing capacity and improving safety in the future. This paper aims to provide a systematic summary of the progress of physical energy storage technology, so as to provide information to support further research on physical energy storage.

GIS-based solar and wind resource assessment and least-cost 100 % renewable electricity modelling for Bolivia

Rapid cost reductions of solar photovoltaics and wind offer a pathway to deep decarbonization of energy at low cost. Off-river pumped hydro energy storage provides mature, cheap and very large-scale storage that helps to balance variable generation and demand while avoiding environmental and social impacts. Many developing countries, especially those in the sunbelt, have the opportunity to adopt this pathway and bypass additional fossil fuel capacities while developing their economies. This study investigates the feasibility of such pathway for Bolivia, a country that relies heavily on fossil gas for both domestic energy consumption and export income. The current reliance on fossil gas, however, is untenable in the long-term due to the worldwide transition to low carbon energy, and the potential growth in per capita energy demand. Instead, a GIS-based resource assessment presented in this study identifies massive low-cost solar photovoltaic, wind and pumped hydro potential that are far more than needed to supply and balance the future electricity demand in Bolivia. A 10-year hourly energy balance model is presented of a future Bolivian electricity system with 100 % renewable electricity supplied by solar, wind and hydroelectricity, and balanced by off-river pumped hydro and high voltage transmission. It is found that the levelized cost of electricity is in the range $44–53/MWh across all scenarios, which is lower than the cost of electricity from new hydroelectricity or gas plants. Importantly, the costs modelled in this study are upper bounds because only technologies that are already deployed in large quantities worldwide are included.

Coupling coordination relationship of pumped storage power station and eco-environment system

Pumped hydro energy storage (PHES) is currently one of the most mature energy storage system technologies. In addition to considering the positive effects of a pumped storage power station (PSPS), its negative ecological effects cannot be ignored. Therefore, it is imperative to study the coupling relationship between the PSPS and the eco-environment. This study systematically analyzed the coupling coordination mechanism of the PSPS and eco-environment. Second, the study established a cloud model fuzzy comprehensive evaluation method and coupling relationship model. Four coupling relationship scenarios were then established. Finally, an econometric model was used to study the internal influencing factors of the coupling coordination degree (CCD). The results showed that the coupling degree (CD) between the eco-environment system and the PSPS increased after construction, and the CCD decreased. From the perspective of influencing factors, the four factors of construction cost, installed capacity, daily pumping volume, and average daily power consumption rate had significant negative effects on coupling coordination. Environmental protection measures for the PSPS must be taken in response to these factors. This study proposes eco-environment restoration suggestions for lowering the eco-environmental impact of the construction and operation of the PSPS.

Load Frequency Control of Microgrid System by Battery and Pumped-Hydro Energy Storage

Energy security is one of the main factors in the development and diffusion of microgrid applications. In networks operating without storage, the operation of their systems is greatly affected by sudden load demand and intermittent generation fluctuations. The main purposes of using energy storage systems in microgrids are stabilizing the intermittent generation of renewable energy sources locally, to ensure that energy production matches energy demands, participating in the frequency regulation process, maintaining the energy balance between generation and demand in renewable energy microgrids, and increasing energy reliability. This study investigates the frequency and power balance of an isolated microgrid system, by including storage systems (battery and pump-hydro). Realistic data for wind and solar sources are used for the optimal tuning of the proportional-integral controller, using the integral of the absolute error criterion multiplied by time, with a Quasi-Newton method. Simulation studies have been carried out, to investigate the performance of the microgrid system, by including the hydroelectric power plant system with pump storage for 24 h, under various operating conditions. The results reveal that by including the storage units in the system, it exhibits a more consistent and smooth dynamic performance, using renewable energy efficiently.