Effect of Viscosity Variations on Charge and Discharge Time of a Sulfur-Based Thermal Energy Storage System

2016 ◽  
Author(s):  
Reza Baghaei Lakeh ◽  
Karthik Nithyanandam ◽  
Amey Barde ◽  
Louis Tse ◽  
Richard E. Wirz
Keyword(s):  
Heat Transfer ◽  
Energy Storage ◽  
Computational Model ◽  
Power Grid ◽  
Renewable Energy Sources ◽  
Energy Sources ◽  
Viscous Layer ◽  
Discharge Time ◽  
Molten Sulfur ◽  
The Stability

Most of the renewable energy sources, including solar and wind suffer from significant intermittency due to day/night cycles and unpredictable weather patterns. On the other hand increasing share of renewable sources imposes additional stability risks on the power grid. Increased share of solar energy in power generation during noon along with increased power demand during afternoon peak hours generates a significant risk on the stability of power grid. Energy Storage systems are required to enable the renewable energy sources to continuously generate energy for the power grid and enhance the stability of future grid that benefits from more renewable sources. Thermal Energy Storage (TES) is one of the most promising forms of energy storage. Although round trip efficiency is relatively high in thermal storage systems, heat transfer is a well-known problem of most TES systems that use solid state or phase change. Insufficient heat transfer may significantly impact the performance of the TES system. The TES system of this study utilizes molten sulfur as the storage medium. Although thermal conductivity of molten sulfur is relatively low, the sulfur-based TES system benefits from enhanced heat transfer due to the presence of buoyancy-driven flows. In this study, the effect of natural convection on the heat transfer characteristics of a sulfur-based isochoric TES system is studied computationally and theoretically. It turns out that the viscosity of sulfur in the temperature range of this study (250–400 °C) varies by two orders of magnitude. A computational model was developed to investigate the effect of viscosity variations on the buoyancy-driven flow and corresponding charge and discharge times. The computational model is developed using an unsteady Finite Volume Method by a commercially available CFD package. The results of this study show that the heat transfer process in the isochoric TES element is highly impacted by natural convection. The viscous flow of molten sulfur near the boundaries of the isochoric TES element leads to different charge and discharge times. The discharge time is almost two times longer than the charge time due to formation of a viscous layer of elemental sulfur near the heat transfer surface. The viscous layer of sulfur decreases the activity of the buoyancy-driven flow and decreases the heat transfer rate during discharge cycle. The computational model was validated by comparing the results of a representative case with experimental data.

scholarly journals Grid Modernization - Integration of Storage

2016 ◽  
Vol 9 (2) ◽  
Author(s):  
Z. Islifo
Keyword(s):  
Energy Storage ◽  
Large Scale ◽  
Power Grid ◽  
Renewable Energy Sources ◽  
Customer Participation ◽  
Energy Sources ◽  
Electric Power Grid ◽  
Time Flow ◽  
Storage Technologies ◽  
Vanadium Redox

The existing electric power grid is reliable enough to meet everyday needs of U.S. electricity users. However, the grid needs major infrastructure upgrades to meet the rising demands for a reliable, resilient, and secure electricity delivery. Drivers to modernize the grid include increased demand for clean sources of energy, growing number of renewable energy sources on the grid and customer participation in power generation. Smart grid technologies are critical for monitoring, managing and controlling the power grid. Energy storage introduces an important new dimension on the grid, the ability to store electricity at one time and release the stored electricity for use at another time. Flow batteries are one type of energy storage technologies that are well suited for large-scale utility application on the grid. Currently, vanadium redox ow batteries are the most common used utility-scaled ow batteries.

Design of a Modular Solid-Based Thermal Energy Storage for a Hybrid Compressed Air Energy Storage System

2016 ◽  
Author(s):  
Reza Baghaei Lakeh ◽  
Ian C. Villazana ◽  
Sammy Houssainy ◽  
Kevin R. Anderson ◽  
H. Pirouz Kavehpour
Keyword(s):  
Renewable Energy ◽  
Energy Storage ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Computational Study ◽  
Power Grid ◽  
Renewable Energy Sources ◽  
Compressed Air ◽  
Energy Sources ◽  
Compressed Air Energy Storage

The share of renewable energy sources in the power grid is showing an increasing trend world-wide. Most of the renewable energy sources are intermittent and have generation peaks that do not correlate with peak demand. The stability of the power grid is highly dependent on the balance between power generation and demand. Compressed Air Energy Storage (CAES) systems have been utilized to receive and store the electrical energy from the grid during off-peak hours and play the role of an auxiliary power plant during peak hours. Using Thermal Energy Storage (TES) systems with CAES technology is shown to increase the efficiency and reduce the cost of generated power. In this study, a modular solid-based TES system is designed to store thermal energy converted from grid power. The TES system stores the energy in the form of internal energy of the storage medium up to 900 K. A three-dimensional computational study using commercial software (ANSYS Fluent) was completed to test the performance of the modular design of the TES. It was shown that solid-state TES, using conventional concrete and an array of circular fins with embedded heaters, can be used for storing heat for a high temperature hybrid CAES (HTH-CAES) system.

scholarly journals Empirical Analysis and Geomechanical Modelling of an Underground Water Reservoir for Hydroelectric Power Plants

2020 ◽  
Vol 10 (17) ◽  
pp. 5853
Author(s):  
Javier Menéndez ◽  
Falko Schmidt ◽  
Heinz Konietzky ◽  
Antonio Bernardo Sánchez ◽  
Jorge Loredo
Keyword(s):  
Renewable Energy ◽  
Rock Mass ◽  
Energy Storage ◽  
Support System ◽  
Storage Systems ◽  
Renewable Energy Sources ◽  
Water Reservoir ◽  
Energy Sources ◽  
Pumped Storage ◽  
The Stability

The European Union policy of encouraging renewable energy sources and a sustainable and safe low-carbon economy requires flexible energy storage systems (FESSs), such as pumped-storage hydropower (PSH) systems. Energy storage systems are the key to facilitate a high penetration of the renewable energy sources in the electrical grids. Disused mining structures in closed underground coal mines in NW Spain have been selected as a case study to analyze the construction of underground pumped-storage hydropower (UPSH) plants. Mine water, depth and subsurface space in closured coal mines may be used for the construction of FESSs with reduced environmental impacts. This paper analyzes the stability of a network of tunnels used as a lower water reservoir at 450 m depth in sandstone and shale formations. Empirical methods based on rock mass classification systems are employed to preliminarily design the support systems and to determinate the rock mass properties. In addition, 3D numerical modelling has been conducted in order to verify the stability of the underground excavations. The deformations and thickness of the excavation damage zones (EDZs) around the excavations have been evaluated in the simulations without considering a support system and considering systematic grouted rock bolts and a layer of reinforced shotcrete as support system. The results obtained show that the excavation of the network of tunnels is technically feasible with the support system that has been designed.

scholarly journals The Application of Molten Salt Energy Storage to Advance the Transition from Coal to Green Energy Power Systems

Energies ◽  
2020 ◽  
Vol 13 (9) ◽  
pp. 2222 ◽  
Author(s):  
Wojciech Kosman ◽  
Andrzej Rusin
Keyword(s):  
Energy Storage ◽  
Power Systems ◽  
Molten Salt ◽  
Power Grid ◽  
Renewable Energy Sources ◽  
Green Energy ◽  
Operating Conditions ◽  
Energy Sources ◽  
Steam Turbines ◽  
Technical Solutions

The paper presents technical solutions for a power grid that undergoes the elimination of a significant number of coal-based power generating units. The purpose of the solutions is to adapt the existing machines with sufficient lifespans to the new operating conditions. In particular these include steam turbines. The steam turbines’ cycles may be extended with energy storage systems based on a molten salt. This allows to increase the flexibility of the power generating units while maintaining the largest possible efficiency of the power generation. The solutions presented here allow to connect the steam turbines cycles to renewable energy sources and reduce the overall number of the units that create the fundamental layer of the power grid. The analysis of the solutions involves numerical modeling. The paper describes the assumptions and the results of the modeling for chosen cases of the modernization. The researched considered a number of options that differed in the investment costs and the resulting performance.

Modeling an Energy Storage System Based on a Hybrid Renewable Energy System in Stand-alone Applications

2017 ◽  
Vol 68 (11) ◽  
pp. 2641-2645
Author(s):  
Alexandru Ciocan ◽  
Ovidiu Mihai Balan ◽  
Mihaela Ramona Buga ◽  
Tudor Prisecaru ◽  
Mohand Tazerout
Keyword(s):  
Renewable Energy ◽  
Energy Storage ◽  
Storage Systems ◽  
Renewable Energy Sources ◽  
Storage System ◽  
Energy Storage System ◽  
Compressed Air ◽  
Energy Sources ◽  
Energy Storage Systems ◽  
Hybrid Renewable Energy System

The current paper presents an energy storage system that stores the excessive energy, provided by a hybrid system of renewable energy sources, in the form of compressed air and thermal heat. Using energy storage systems together with renewable energy sources represents a major challenge that could ensure the transition to a viable economic future and a decarbonized economy. Thermodynamic calculations are conducted to investigate the performance of such systems by using Matlab simulation tools. The results indicate the values of primary and global efficiencies for various operating scenarios for the energy storage systems which use compressed air as medium storage, and shows that these could be very effective systems, proving the possibility to supply to the final user three types of energy: electricity, heat and cold function of his needs.

scholarly journals Sizing and Management of Energy Storage Systems in Large-Scale Power Plants Using Price Control and Artificial Intelligence

Energies ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3296
Author(s):  
Carlos García-Santacruz ◽  
Luis Galván ◽  
Juan M. Carrasco ◽  
Eduardo Galván
Keyword(s):  
Energy Storage ◽  
Power Plants ◽  
Large Scale ◽  
Storage Systems ◽  
Renewable Energy Sources ◽  
Ancillary Services ◽  
Energy Sources ◽  
Energy Storage Systems ◽  
Electric System ◽  
Fundamental Part

Energy storage systems are expected to play a fundamental part in the integration of increasing renewable energy sources into the electric system. They are already used in power plants for different purposes, such as absorbing the effect of intermittent energy sources or providing ancillary services. For this reason, it is imperative to research managing and sizing methods that make power plants with storage viable and profitable projects. In this paper, a managing method is presented, where particle swarm optimisation is used to reach maximum profits. This method is compared to expert systems, proving that the former achieves better results, while respecting similar rules. The paper further presents a sizing method which uses the previous one to make the power plant as profitable as possible. Finally, both methods are tested through simulations to show their potential.

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