Cryogenic Energy Storage System Research Articles

Thermodynamic and economic analyses of the integrated cryogenic energy storage and gas power plant system

Thermodynamic and economic analyses of the integrated cryogenic energy storage and gas power plant system

Thermodynamic performance of a cryogenic energy storage system based on natural gas liquefaction

Cryogenic energy storage (CES) is a viable method for grid-scale electrical energy storage. Considering the high energy density and mature application of liquefied natural gas (LNG), we proposed an LNG cryogenic energy storage (LNGES) system. A steady-state process model of the LNGES system was established using Aspen HYSYS. The effects of the natural gas composition and key operating parameters such as the charging pressure, discharging pressure, throttling temperature, and liquid storage pressure on the system performance were investigated. A multi-parameter genetic algorithm model built using the MATLAB software was used to optimize the LNGES system to optimize the round-trip efficiency (RTE). Then, an exergy analysis of the optimal configuration was conducted. The results suggested that the LNGES system could achieve optimal RTE and exergy efficiency values of 60.14% and 71.64%, respectively. Exergy destruction mainly occurred during the compression, throttling, expansion, and heat exchange. The proposed LNGES system could be a promising candidate for the large-scale application of CES technology in power grids and gas networks.

Comparative study on the globally optimal performance of cryogenic energy storage systems with different working media

Cryogenic energy storage (CES) has garnered attention as a large-scale electric energy storage technology for the storage and regulation of intermittent renewable electric energy in power networks. Nitrogen and argon can be found in the air, whereas methane is the primary component of natural gas, an important clean energy resource. Most research on CES focuses on liquid air energy storage (LAES), with its typical round-trip efficiency (RTE) being approximately 50% (theoretical). This study aims to explore the feasibility of using different gases as working media in CES systems, and consequently, to achieve a high system efficiency by constructing four steady-state process models for the CES systems with air, nitrogen, argon, and methane as working media using Aspen HYSYS. A combined single-parameter analysis and multi-parameter global optimization method was used for system optimization. Further, a group of key independent variables were analysed carefully to determine their reasonable ranges to achieve the ideal system performance, that is, RTE and liquefaction ratio through a single-parameter analysis. Consequently, a multi-parameter genetic algorithm was adopted to globally optimize the CES systems with different working media, and the energy and exergy analyses were conducted for the CES systems under their optimal conditions. The results indicated the high cycle efficiency of methane and a low irreversible loss in the liquefaction cycle. Moreover, the Joule-Thomson valve inlet temperature and charging and discharging pressures considerably affected the system performance. However, exergy loss in the CES system occurred primarily in the compressor, turbine, and liquefaction processes. The maximum optimal RTE of 55.84% was achieved in the liquid methane energy storage (LMES) system. Therefore, the LMES system is expected to exhibit potential for application in the CES technology to realize the integration of natural gas pipelines with renewable power grids on a large scale. Moreover, the results of study have important theoretical significance for the innovation of the CES technology.

Numerical study on the thermodynamic performance of a packed bed cryogenic energy storage system

• Developed a 3-D porous media model for cryogenic energy storage in a packed bed. • Studied the influence of key factors on cold charging performance of the packed bed. • Operating conditions of cryogenic gas charged packed bed were analyzed. Cold energy storage devices improve the round-trip efficiency of cryogenic energy storage systems, where a solid packed bed for cold energy storage (PBCES) is widely utilized. In this study, a three-dimensional transient porous media packed bed model was developed using computational fluid dynamics software ANSYS Fluent 2020 to study the thermodynamic characteristics of a solid PBCES system with cryogenic nitrogen as the working medium during the cold charging process. The effects of the superficial mass flow rate ( G in ), inlet temperature of nitrogen, packing materials, porosity on the packed bed temperature distribution, pressure drop, cold storage efficiency ( η s ), and cold exergy efficiency ( η Ex ) were investigated carefully. The results showed that the axial temperature distribution is a typical thermocline. The system performance is predominantly affected by the criterion of the complete charging (the minimum temperature difference between Face-2 and Face-1, Δ T F2-F1,min ) and the G in . The thermocline thickness decreased with a decrease in the G in . The η s and η Ex increased significantly with an increase in the Δ T F2-F1,min . The maximum η s and η Ex were 77.69% and 75.21% at the G in was 0.1 kg/(m 2 ·s) when the Δ T F2-F1,min was 100 K. The change in porosity had a limited influence on the cryogenic storage performance but considerably influenced the pressure drop; Basalt was recommended as the optimal packing material in the present study. The superficial mass flow rate of working medium and the complete charging indicator (Δ T F2-F1,min ) should be carefully determined to achieve high performance in a practical CES system. The developed simulation model would be promising and useful for the design and optimization of a practical packed bed for CES systems.

Cryogenic energy storage: Standalone design, rigorous optimization and techno-economic analysis

Energy storage allows flexible use and management of excess electricity and intermittently available renewable energy. Cryogenic energy storage (CES) is a promising storage alternative with a high technology readiness level and maturity, but the round-trip efficiency is often moderate and the Levelized Cost of Storage (LCOS) remains high. The complex flowsheets with intricate thermodynamics at cryogenic temperatures as well as the presence of multiple loops and refrigeration cycles pose considerable challenges for rigorous model-based design and optimization of CES systems. We present an optimization strategy that couples rigorous process simulation and Bayesian optimization with flowsheet decomposition and identification of hidden coupling constraints to optimally design standalone CES systems. Further refinement is done via a local search using the limited-memory Broyden–Fletcher–Goldfarb–Shanno algorithm. Our results indicate that it is possible to achieve more than 52% round-trip efficiency and an LCOS of $153/MWh for a standalone 100 MW/400 MWh CES system limited to short-term storage with daily charging–discharging. However, a detailed techno-economic assessment reveals that the LCOS considering total capital investment may exceed $267/MWh when all direct and indirect costs of installation and operation are considered.

Optimization of a cryogenic liquid air energy storage system and its optimal thermodynamic performance

For grid-scale intermittent electricity storage, liquid air energy storage (LAES) is considered to be one of the most promising technologies for storing renewable energy. In this study, a steady-state process model was developed for an LAES, by combining a Linde liquefaction process and an open Rankine power cycle. To investigate the system performance and achieve global optimization, a single-factor analysis approach and multifactor genetic algorithm (GA) optimization model were built using MATLAB software. The effects of the charging pressure, storage pressure, discharging pressure, and isentropic efficiency of the compressor/turbine on the LAES performance parameters, such as the inlet temperature of the Joule–Thomson valve, round-trip efficiency (RTE), liquefaction ratio (LR), and power consumptions in the compressor, cryo-pump, and turbine, were investigated. Subsequently, the optimal conditions were obtained using the GA optimization method to achieve the optimal performance of the LAES. The results showed that the charging pressure, discharging pressure, and isentropic efficiencies of the compressor and turbine had significant effects on the RTE; an increase in the discharging pressure resulted in an improved expansion power output; the GA optimization could achieve RTE, LR, the system energy storage and recovery exergy efficiencies of 53.33%, 86.96%, 81.00%, and 78.16%; the power consumption in the compressor of GA optimization was 10.02% maximum saving. The proposed optimization method can be used to further explore the global optimization of cryogenic energy storage systems, such as different-layout LAES systems and different cryogenic liquefaction media energy storage systems.

Cryogenic-Energy-Storage-Based Optimized Green Growth of an Integrated and Sustainable Energy System

The advancement of using the cryogenic energy storage (CES) system has enabled efficient utilization of abandoned wind and solar energy, and the system can be dispatched in the peak hours of regional power load demand to release energy. It can fill the demand gap, which is conducive to the peak regulation of the power system and can further promote the rapid development of new energy. This study optimizes the various types of energy complementary to the CES system using hybrid gravitational search algorithm-local search optimization (hGSA-LS). First, the mathematical model of the energy storage system (ESS) including the CES system is briefly described. Second, an economic scheduling optimization model of the IES is constructed by minimizing the operating cost of the system. Third, the hGSA-LS methods to solve the optimization problem are proposed. Simulations show that the hGSA-LS methodology is more efficient. The simulation results verify the feasibility of CES compared with traditional systems in terms of economic benefits, new energy consumption rate, primary energy saving rate, and carbon emissions under different fluctuations in energy prices. Optimization of the system operation using the proposed hGSA-LS algorithm takes 5.87 s; however, the GA, PSO, and GSA require 12.56, 10.33, and 7.95 s, respectively. Thus, the hGSA-LS algorithm shows a comparatively better performance than GA, PSO, and GSA in terms of time.

Thermodynamic assessment of cryogenic energy storage (CES) systems in cogeneration regime

This article demonstrates that Cryogenic Energy Storage (CES) systems benefit from a high round-trip efficiency, applying cogeneration concepts to the charging and discharging operating regimes. CES systems are an emerging technology that can mitigate the power grid instabilities in an adverse scenario of high penetration of intermittent sources. We evaluate this novel concept using mass, energy, and exergy balances. We perform numerical simulations and find that the specific liquid yield is 21.4% higher than that reported for other CES systems. The optimization analysis shows that the exergy efficiency is as high as 85.2% whereas the base CES, with no cogeneration, is 50.3%. For the integrated charging and discharging processes, the round-trip efficiency is 41.9%, for the cryogenic tank capacity of 200 t, which is higher than that reported in the previous studies. The optimum values of electrical efficiency and exergy density of the proposed cycle operating in the discharging regime are 81.0% and 123.7 kWh/m3, respectively. In general, the simultaneous operation of the charging and discharging phases in the proposed CES cogeneration system improves the main indexes and indicators. Readers can also benefit from a novel exergy methodology to estimate the efficiency of CES systems.

Liquid air might transform the way we store and use energy

In order to achieve the net-zero carbon system that is the vision of many worldwide, we need to make big changes - and fast. Not only do we need to transform the way we produce energy, but we need advances in storage so that it is readily available. A British company has the answer: a liquid storage system that will help us realise the full value of our renewables. Highview Power has developed a proprietary cryogenic energy storage system called the CRYOBattery that can cool solar or wind energy into a liquid state.

Pinch and exergy evaluation of a liquid nitrogen cryogenic energy storage structure using air separation unit, liquefaction hybrid process, and Kalina power cycle

Starting up thermal power plants for peak shaving is very time-consuming and expensive. Therefore, when the consumption demand is less than the baseload, the surplus energy that can be produced can be stored in a cryogenic energy manner, and in the hours of increasing demand, the stored energy can be injected into the consumption network as electrical energy. The main problems of liquid air energy storage systems are the high cost of development and low energy efficiency. In the present study, an integrated power generation system with liquid nitrogen recovery as a cryogenic energy storage system is developed. For this purpose, by producing pure nitrogen through air separation unit and liquefaction it during off-peak time and recovery it at the on-peak time, the required power of the grid is supplied. By using the excess heat of the integrated system in the Kalina power cycle and producing more power during the on-peak time, an attempt has been made to increase the system round-trip efficiency. Important parameters of the proposed system are the liquid yield (59.17%), multifunctional round-trip efficiency (40.67%), and baseline round-trip efficiency (54.69%). Pinch analysis is applied to the multi-stream exchangers of the system and the corresponding heat exchanger networks being extracted. The results of exergy analysis show that the exergy efficiencies of the nitrogen liquefaction unit and power generation unit are calculated as 79.75% and 85.11%, respectively. The exergy efficiency of the whole integrated system is 43.85%. The most exergy destruction belongs to the heat exchangers, which accounts for 48.56% of the total destruction. One of the important results of the parametric study is the increase of baseline round-trip efficiency to 57.24% by increasing the Kalina cycle pressure up to 1100 kPa.

Improvement potential of Cryogenic Energy Storage systems by process modifications and heat integration

Cryogenic Energy Storage (CES) system is currently gaining significant attention in the field of large-scale energy storage systems. This is because this system can provide high energy-density during storage and uses air or nitrogen that are available at no or a low cost. Moreover, the technology has matured and can be used on-site in a decoupled manner. The CES system has three sub-processes, namely, charging or liquefaction, storage, discharging or power cycle. To investigate the improvement potential of such systems, state-of-the-art configurations for each sub-processes have been analyzed in this paper. A configuration consisting of a multi-stage turbine expansion, a turbine and a JT-valve connected in series at the liquefaction stage, Organic Rankine cycle for utilization of heat of compression, and a four-stage reheat Rankine cycle with thermal energy storage at cryogenic temperature has been proposed. The study suggests that a high turnaround efficiency (about 90%) of the process may be achieved by an appropriate external source of thermal energy.

Introducing a novel liquid air cryogenic energy storage system using phase change material, solar parabolic trough collectors, and Kalina power cycle (process integration, pinch, and exergy analyses)

Today, using new energy storage systems for peak shaving and load leveling with the approach of maximizing the efficiency of energy systems is inevitable. In the present study, a cogeneration integrated structure of power and cooling using liquefied natural gas regasification and solar collectors is developed and analyzed. In this regard, the purposes can be achieved by producing liquid air at an off-peak time and storing it as a cryogenic energy storage system and recovering it on-peak time. This new integrated structure generates 11.66 MW power and 4.502 MW cooling at the on-peak time. A Kalina-based combined cooling and power cycle and a gas turbine power generation unit are used to generate power from liquid air. Phase change material is used to store the heat from the compressed air entering the liquefaction stage (at the off-peak time) and recovering it at the on-peak time as the heat source of the Kalina cycle. Also, the solar parabolic trough collector provided with Zahedan climatic conditions the heat required for the direct expansion section. The electrical storage, round-trip, energy storage, and exergy efficiencies of the proposed energy storage system are 57.62%, 45.44%, 79.87%, and 40.17%, respectively. The most exergy destruction belongs to the heat exchangers section, which accounts for 50.85% of the total exergy destruction. One of the important results of the parametric study is the increase of round-trip and electrical storage efficiencies up to 47.59% and 61.60%, respectively, by minimizing the pressure of the inlet air to the liquefaction stage while maximizing the pressure of the liquid air inlet to the power generation stage.

Introducing a novel integrated cogeneration system of power and cooling using stored liquefied natural gas as a cryogenic energy storage system

Nowadays, it is inevitable to use energy storage systems for peak shaving and load leveling purposes. In the present study, a new integrated structure of power generation and refrigeration is developed for the use and recovery of the stored liquid natural gas energy as a cryogenic energy storage system. Kalina power cycle, molten carbonate fuel cell, carbon dioxide power cycle, and absorption-compression refrigeration system using solar energy are employed to achieve this goal. This new integrated structure generates 161,287 kW power, 1964 kW refrigeration at 266 K through LNG recovery with 4.066 kg/s mass flow rate and 8464 kW refrigeration at 218.5 K. Electrical, thermal and exergy efficiencies of the whole system are 57.92%, 61.66%, and 68.21%, respectively. In the present study, considering the efficiency of the LNG production and storage sector at the off-peak time as well as its cryogenic energy recovery sector at the on-peak time, round-trip efficiency of the proposed cryogenic storage system is calculated as 66.29%. Via the parametric study on major system parameters such as Tu101 and Tu102 turbines inlet pressures, Tu201 turbine outlet temperature, etc., the performance of the system in various conditions is evaluated. Important results of the parametric study include an increase in the system total thermal efficiency up to 70.03% by reducing the outlet temperature of the Tu201 turbine to 880 K.

Experimental Investigations on Cold Recovery Efficiency of Packed-bed in Cryogenic Energy Storage System

Cryogenic Energy Storage (CES) system has large power generation capability, and comparable cost with respect to the non-cryogenic technologies (pumped-hydro, compressed air energy storage systems). This is not location specific unlike the non-cryogenic energy storage systems and also is environment friendly. High-energy requirement for liquefaction process in the CES system, however, leads to low turnaround efficiency of the system. Efforts have been made to reduce the specific work-requirement in the liquefaction process by thermal energy storage at temperature around 150 K as available during power generation stage of the system. One of the methods of storing the thermal energy at such low temperature is using packed-bed of pebbles. A few studies have been reported in the available literature indicating a reduction in storage efficiency during continuous operation of such packed-beds leading to reduction in turnaround efficiency of the CES system. In this paper, experimental findings for better insight into the packed-bed behavior are reported. An experimental setup of packed-bed thermal energy storage using rock pebbles as bed material was used for this purpose. Temperatures along the axial direction inside the bed were measured and the results were analyzed and the storage efficiencies during full-load and part-load of operations were determined.

Novel massive thermal energy storage system for liquefied natural gas cold energy recovery

The concept of heat integration with cryogenic energy storage (CES) is a possible option for the recovery of wasted cold energy from liquefied natural gas (LNG). For maximizing energy storage capacity, we propose a conceptual design for a massive cryogenic energy storage system integrated with the LNG regasification process (MCES). The novel aspect of this study is the transmission of LNG cold energy via two different methods at different times: (1) MCES stores cold energy in liquid propane during on-peak times, enabling increase in the energy storage capacity; and (2) MCES directly transfers cold energy with help of liquid propane during off-peak times to liquefy air using surplus electricity from the grid. Thus, the surplus energy is stored in liquefied air and released to generate electricity on demand. Based on the process simulation, exergy analysis and economic evaluations are conducted. MCES exhibits a round trip efficiency of 85.1%, whereas existing bulk power management systems exhibit a maximum efficiency of 75%. Moreover, using a three-million-ton-per-annum LNG regasification plant, MCES enables the supply of 138 MW of electrical power which is up to 96% more power than that achieved by other recently proposed process designs, and has potential for bulk power management.

CFD-subset-FVM-based MATLAB-simulation of Heat Transfer in High Grade Cold Storage Augmenting Cryogenic Energy Storage System by Circulating Natural Gas as Working Fluid

Cryogenic Energy Storage (CES) improves power grid application with renewable intermittent power sources. In CES, off-peak excess electricity liquefies air or natural gas. Cryogenic fluid so obtained is stored in large Dewar tanks for long periods of time. Whenever electricity need is in peak, work available in cryogen is recovered by thermodynamic cycle using hot storage waste heat (HSWH) that has been generated by liquefier’s compressor. Many researchers focus on liquid air energy storage (LAES). But, natural gas (NG) is good working substance for CES liquefaction process. This paper reviews NG-CES containing high grade cold storage (HGCS). Cold stored HGCS is utilized to raise CES efficiency and hike liquefier yield. This paper models HGCS unit and compares output with experimental data. Impact of cold recycling is analyzed for liquefier yield and storage efficiency.

CFD-subset-FVM-based MATLAB-simulation of Heat Transfer in High Grade Cold Storage Augmenting Cryogenic Energy Storage System by Circulating Natural Gas as Working Fluid

CFD-subset-FVM-based MATLAB-simulation of Heat Transfer in High Grade Cold Storage Augmenting Cryogenic Energy Storage System by Circulating Natural Gas as Working Fluid

Simulation of Thermodynamic Efficiency and Plant Equipment Finance for Cryogenic Energy Storage Systems as Applied to Medium to Large Scale Liquid-Air Electricity-Storage

Simulation of Thermodynamic Efficiency and Plant Equipment Finance for Cryogenic Energy Storage Systems as Applied to Medium to Large Scale Liquid-Air Electricity-Storage

Experimental study and thermodynamic modeling of solid-liquid equilibrium of binary systems: Dodecane-tetradedcane and tridecane-pentadecane for cryogenic thermal energy storage

In the present work, the equilibrium phase behaviors and thermal characteristics (phase diagrams, enthalpies, melting/freezing temperatures) of the binary systems dodecane-tetradedcane (C12H26-C14H30) and tridecane-pentadecane (C13H28-C15H32) were experimentally investigated to employ the potential PCMs for cryogenic applications. In addition, the phase diagrams were theoretically obtained by using both the ideal and non-ideal thermodynamic models. Results show that the compositions of eutectic points appear at 18 wt% C14 for the C12-C14 system and 10 wt% C15 for the C13-C15 system. The specific eutectic compositions of these two systems have satisfied enthalpies (158.0 J/g for C12-C14 and 143.1 J/g for C13-C15 in the melting process), slight supercooling (0.3 °C for C12-C14 and 0.4 °C for C13-C15), minor hysteresis (3.9 °C for C12-C14 and 2.2 °C for C13-C15) and superior thermal stability. Therefore, they are very attractive as the candidate PCMs in cryogenic energy storage systems. Moreover, the melting temperatures calculated by the theoretical models agree well with the experimental data. Especially for the non-ideal solubility model, the mean relative deviations are only 4% for the C12-C14 system and 8% for the C13-C15 system, respectively.

Exergetic and economic assessment of integrated cryogenic energy storage systems

Cryogenics-based Energy Storage (CES) is a thermo-electric bulk energy storage technology that received much attention lately both in academia and industrial applications. CES charges surplus electricity in an energy-intense gas liquefaction process, stores electricity in form of liquid air and discharges electricity in a liquid-air Rankine cycle.CES is associated with a number of advantages towards competing bulk-energy storage technologies. CES is based on mature technologies, having a low environmental impact, no geographical constraints, long cycle life, low standby losses and a remarkable exergy density. At present, CES is at a pre-commercial state, which makes its claimed competitive specific costs and reported stand-alone efficiency of 40–60% crucial to its further development and application. This paper aims to identify the efficiencies and specific costs of a number of CES system configurations and to investigate the sensitivity of estimating CES costs to the wide range of reported characteristics. The exergetic and economic analyses are based on results from simulation of seven system configurations in ASPEN Plus®. Economic sensitivity analysis is conducted independently and relies solely on data from literature. Among others, the effects of the following parameters on the CES levelized cost of discharged electricity are evaluated: price of electricity, specific investment cost, annual operation hours and economic life.The exergetic analysis revealed the favourable integration of regasifying LNG, in which the CES exergetic efficiency reaches 55%. Integration of waste heat was shown to reduce the specific costs of 300 MW CES systems from 1400 €/kWh to 1100 €/kWh. Lowest levelized cost of electricity was reached by diabatic CES systems with combustion of natural gas (161 €/MWh) closely followed by waste heat integration (171 €/MWh). In the sensitivity analysis the effects of the specific costs and the cost of charged electricity were found to be of greater importance than efficiency. Moreover, CES was evaluated to be economically feasible in comparison to other bulk energy storage technologies.