Liquid Air Energy Storage Research Articles

Thermodynamic, exergoeconomic, and economic analyses with multi-objective optimization of a novel liquid air energy storage coupled with an off-shore wind farm

The liquid air energy storage is a cutting-edge technology that covers the geographical drawbacks of other utility-scale energy storage alternatives. The coupling the liquid air storage system with renewable energies and heat recovery units can compensate the grid unstability and lack of their round trip efficiency, respectively. In the present paper, an off-shore wind farm including different wind turbines is assessed from technical, availability, and economic viewpoints to be combined with a liquid air energy storage unit, expolits a Kalina cycle for waste heat recovery. First, a comprehensive energy, exergy, and economic analyses are conducted for the integrated system; then, a coupling of artificial neural network and multi-objective genetic algorithm optimization method are carried out to find the optimum design condition. The findings show that around 93 MWh of the generated power in the wind site during off-peak period can be utilized to charge the system. Then, in addition to power generation in the wind farm, the reference system generates 76.4 MWh of extra power and 585 tons of domestic hot water during peak hours for peak shaving. Based on the optimization results, the round trip efficiency and total cost rate are 44.7% and 476 $/hr, repectively. The result of economic analysis demonstrated that the Enercon E-126 EP4 is the most cost-effective wind turbine for the proposed system, resulting in a period of 5.5 years. It has been also resulted that the existence of the LAES-KC system can half the paybacks.

A day-ahead planning for multi-energy system in building community

A novel integrated energy system is proposed to provide stable electricity and cold energy for a multi-building community, which comprises wind turbines, solar photovoltaic panels and a liquid natural gas station as energy sources, and liquid air energy storage and packed bed for energy storage. A predictive algorithm based on long short-term memory is adopted to forecast the electricity and cooling load, wind speed and available cold energy for day-ahead scheduling. Furthermore, a comparative study of energy allocation schemes including electricity and cooling are carried out. The thermal inertia of room temperature is considered in the cooling allocation scheme. The pivotal results are presented as follows. The forecast errors are no more than 5%, proving the reliable accuracy of the following analysis. The robust schemes based on forecast method and uncertainty analysis have lower energy mismatch rates compared to the conservative schemes and radical schemes, which are 4.6% for electricity scheduling and 5.0% for cooling scheduling, respectively.

Thermo-economic analysis of the integrated system of thermal power plant and liquid air energy storage

In the context of the rapid development of renewable energy, load regulation of the power grid has become a vital issue, and many researches on load regulation by thermal power plants (TPP) have been conducted. As a promising large-scale energy storage technology, the liquid air energy storage (LAES) system has significant advantages such as clean, low investment cost, and no geographical restrictions. In this paper, a coupled system combined by TPP and LAES system (TPP-LAES) is proposed, and technical and economic analysis are carried out to obtain the best configuration of the integrated system and verify its economic benefits. Technical analysis results demonstrate that the maximum round trip efficiency (RTE) of the LAES subsystem can reach 93.74 % when the extraction pressure is 242.00 bar. The RTE of the LAES subsystem of the optimal configuration is 58.31 %, at which the extraction pressure is 8.55 bar. The comprehensive efficiency of the optimal TPP-LAES integrated system is 40.86 %, which is about 1 % higher than the standalone LAES system. The energy storage density is 95.80 kWh/m3, and the net output power is 79.30 MW, exhibiting excellent system performance. The economic analysis results reveal that the initial investment cost of the TPP-LAES integrated system is 67.17 % of that of the standalone LAES system, and the levelized cost of storage (LCOS) is 154.30 USD/MWh, 24.63 % lower than that of the standalone LAES system, with outstanding economic benefits.

Optimization and analysis of different liquid air energy storage configurations

Energy storage technologies are required to ensure stability of energy systems when the share of renewable energy forms (wind and solar) is increasing. Liquid air energy storage (LAES) is a promising technology for storing electricity with certain advantages, such as high energy density and being geographically unconstrained. However, one drawback of a standalone LAES is the relatively low round-trip efficiency (RTE). In this work, the performance of a standalone LAES system with different number of compression and expansion stages is studied. All cases are optimized by using a particle swarm optimization (PSO) algorithm. The optimal results show that the highest RTE of 66.7% is obtained when there is a 2-stage compressor and a 3-stage expander in the LAES system. When the number of compression stages is fixed, the highest RTE is obtained when hot and cold streams have close to parallel temperature profiles in the preheaters of the expansion section.

Experimental Assessment of a Novel Dual Opening Dewar for Use on a Liquid Air Energy Storage System Installed on Remote, Islanded, Renewable Microgrids

Islanded, renewable energy microgrids for use at remote operating facilities reduce logistical burdens associated with fossil fuel based electrical power sources and provide greater operational flexibility; however, energy generation can be intrinsically intermittent on renewable microgrids. This intermittent electrical generation can be mitigated with electrical energy storage. Liquid air energy storage (LAES) is one promising technology proposed to meet this energy storage issue due to its high energy density and lack of geographical constraints. Small-scale microgrids may not have enough excess capacity to store pressurized liquid air (LA), and instead may rely on unpressurized LA storage and their associated unpressurized power recovery systems. Using commercial off-the-shelf components, this article conducts a performance-based tradespace study for several dual opening, unpressurized Dewar designs for use with Stirling- or Peltier-based power recovery cycles. The dual opening Dewar design is found to be ineffective for the short-term LA storage times necessary for small-scale microgrid use, primarily due to excessive conductive thermal losses; however, the design may be useful as a LA receiver and immediate use energy storage medium for a connected Stirling generator. A proposed alternative solution using a self-pressurized Dewar for LA storage and transport for microgrid applications is presented for future work.

Modelling and optimization of liquid air energy storage systems with different liquefaction cycles

Liquid air energy storage (LAES) is one of the large-scale mechanical energy storage technologies which are expected to solve the issue of renewable energy power storage and peak shaving. As the main energy loss of a standalone LAES occurs in the liquefaction process, this paper focused on the thermodynamic analysis of LAES systems with different liquefaction cycles. Six liquefaction cycles were considered. To obtain a higher system efficiency and fair comparative analysis of the performance of different LAES systems, authors used a combined genetic algorithm (GA) and HYSYS process simulation method to perform the multi-parameters global optimization. Subsequently, energy and exergy analyses were conducted on the optimized LAES systems. The results show that the system efficiency of the LAES based on turbo-expander refrigeration (i.e., the Claude cycle, Kapitza cycle, and Heylandt cycle) increases with an increase in the split ratio. The LAES with Kapitza liquefaction cycle shows the most competitive system performance compared with the other liquefaction cycles based-LAES systems. The LAES with Kapitza liquefaction cycle exhibits the lowest optimal charging pressure of 10.73 MPa and achieves the highest round-trip efficiency, system storage exergy efficiency, and system recovery exergy efficiency of 60.02 %, 86.41 %, and 84.98 %, respectively. The obtained GA optimization and thermodynamic analysis results of LAES systems with different liquefaction configurations can provide significant theoretical guidance for further industrial applications of LAES.

New regulation strategies study of solar aided liquid air energy storage system under off-design conditions

Liquid air energy storage (LAES) is a large-scale physical energy storage system with high energy storage density. At present, the coupling matching regulation mechanism of the cold and thermal cycles is unclear under off-design conditions, which makes the stable and efficient operation of the LAES system difficult. New multivariable control strategies for cold and thermal cycles are proposed based on the solar aided liquid air energy storage (SA-LAES) system. The study results show the “equal proportion cold recovery” strategy is superior to other strategies, improving the system performance and meeting the demand of the maximum capacity of the charging process. When the liquid air mass flow ratios are 0.7 and 0.4, the air liquefaction ratios increase by 20.20% and 86.43%, and the round-trip efficiency (RTE) values increase by 19.44% and 84.86%, respectively. The new thermal cycle control strategy achieves a good heat coupling matching and maximizes the discharging time and RTE in the zero-carbon environment. Under 70% load and 40% load, the discharging time increase by 16.26% and 53.83%. RTE values increase by 16.28% and 53.84%, respectively. Finally, the operation domains of SA-LAES at different molten salt temperatures are obtained with the optimal cold and thermal cycle strategies. The achievements in this paper will provide valuable reference for the stable operation of SA-LAES under off-design conditions.

Thermal energy storage unit (TESU) design for high round-trip efficiency of liquid air energy storage (LAES)

A parametric study of a TESU (thermal energy storage unit), an essential component of a LAES (liquid air energy storage) system that stores a large amount of useful energy in an eco-friendly manner, is performed. The geometric conditions of the TESU cover the overall heat conductance, the volume, and the type of thermal energy storage material. The operating conditions of the TESU are defined by the operating time, the working mass, and the power generation pressure of the LAES system. The effectiveness is used as a thermal performance indicator of the TESU considered as a heat exchanger and a thermal battery. The heat capacities of the TESU and high-pressure working fluid, the overall heat conductance, the operating time of the TESU, and the maximum temperature span are selected as critical parameters. We calculate the effectiveness using the parameters in seventy-three different conditions. Based on the calculation results, this paper nondimensionalizes the parameters using the π theorem. This research paper presents a correlation between the obtained π groups and the effectiveness, which satisfies the Pearson correlation coefficient (PCC) of 0.82.

Liquid Air Energy Storage Model for Scheduling Purposes in Island Power Systems

Moving towards clean energy generation seems essential. To do so, renewable energy penetration is growing in the power systems. Although energy sources such as wind and solar are clean, they are not available consistently. Using energy storage will help to tackle variability. Liquid air energy storage is gaining attention among different energy storage technologies, as it is a promising option for grid-scale energy storage. This paper presents a detailed mixed integer linear model of liquid air energy storage to be used in scheduling and planning problems. A comprehensive cycle diagram of different processes of liquid air energy storage is presented, and a model has been developed accordingly. Simulations of the proposed model are carried out for the power system of Tenerife island and compared with the basic models. Basic models overlook specific characteristics of liquid air energy storage systems, such as charging and discharging start energy. Results confirm that the use of simple models will lead to misleading conclusions and overestimate the economic benefits of liquid air energy storage.

Liquid air energy storage for ancillary services in an integrated hybrid renewable system

High shares of intermittent renewable sources cause volatile frequency movements that could jeopardize the continuous operation of the grid. Liquid Air Energy Storage (LAES) is an emerging technology that not only helps with decarbonisation of energy sectors, but also has potentials for reliable ancillary services. In this paper, a hybrid LAES, wind turbine (WT), and battery energy storage system (BESS) is used to investigate their contributions in fast frequency control. The inertial control, droop control and combined inertial and droop terms are applied on each source of the hybrid renewable system and a comprehensive analysis is conducted to study their impacts on the frequency nadir improvement. The analysis shows that LAES with combined inertial and droop control terms along with inertial control of WT and BESS provide reliable frequency control. To further improve the frequency nadir, a Fuzzy control is proposed and applied on the LAES. The proposed control system provides a more adaptive performance against disturbances. Also, experimental tests are conducted to validate the proposed control method using a real-time hardware-in-the-loop test rig. The simulation and experimental results show that LAES in a hybrid renewable system can significantly contribute to the frequency control when variable gain control schemes are implemented.

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.

Integration of cryogenic energy storage with renewables and power plants: Optimal strategies and cost analysis

Energy storage is critical for overcoming challenges associated with the intermittency and the variable availability of renewable sources for decarbonizing the energy sector. Cryogenic energy storage (CES) is of interest due to its high technology readiness level, no geographical limitations, and moderate round-trip efficiency. The time-varying nature of demands and renewable availability needs to be considered at the design and integration stages of energy storage. We develop a mixed-integer nonlinear program (MINLP) model to obtain the energy storage costs on a daily basis for different scenarios that typically arise over an entire year. Using this optimization-based framework, we address key decision-making questions towards energy transition: What is the energy cost when CES is integrated with renewables and power plants? How does each scenario affect the overall energy cost? How much storage is needed for complete transition to renewables? What is the optimal integration towards 100% renewable energy? What are the optimal storage designs for both renewables and fossil-based power generation with current and future energy demands? We discuss different scenarios and solutions to these questions.

Numerical Investigation on Thermal–Hydraulic Performance of a Printed Circuit Heat Exchanger for Liquid Air Energy Storage System

A printed circuit heat exchanger (PCHE) is utilized to cool the compressor inlet air to increase the compression efficiency in a liquid air energy storage and liquid natural gas (LNG) coupled system, which can offer large-scale energy storage with significantly improved exergy efficiency and round-trip efficiency. In this work, the effect of pressure of air, incline angle, and hydraulic diameter on the performance of a compressed air–water PCHE with a semicircle cross-section was studied. The results show that PCHE can realize the intermediate cooling of air compression in the liquid air energy storage system, and the pressure variation of air shows a limited effect on the heat transfer of PCHE; however, the hydraulic diameter and the incline angle both affect the heat transfer and the flow resistance of PCHE, and the best incline angle is 15°.

EXERGY ANALYSIS OF LIQUID AIR ENERGY STORAGE SYSTEM BASED ON LINDE CYCLE

The paper presents a theoretical analysis from an energetic and exergetic point of view for a liquid air energy storage system (LAES). This paper identifies upper bounds on the energy and exergetic efficiency for this system. The system uses the simple Linde-Hampson liquefaction cycle for the liquefaction subsystem and the direct expansion method without heating above ambient temperature, for the power generation subsystem. It is known that as the temperature decreases, the destruction of mechanical work input increases due to the irreversibility of working processes. As a result, any irreversible process is very important to observe in cryogenic processes. The purpose of this paper is to develop an exergetic analysis which is then used in a procedure to optimize the Linde installation within the liquid air energy storage system when some functional parameters are changed. The analysis aims to find the functional parameters for which the exergetic efficiency of the installation is maximum. For each subsystem of the simple Linde installation an exergetic product and a fuel were defined and, based on their definition, the coefficient of performance of each functional area was calculated as well as the exergy destructions. Finally, the analysis of system components is presented in order to identify the components that have the greatest impact on energy and exergetic efficiency in an ideal environment. The analytical approach presented in this paper can be applied to other LAES configurations to identify the optimal operating points in terms of energy and exergetic efficiency.

Design and analysis of flexible integration of solar aided liquid air energy storage system

Liquid air energy storage (LAES) system is a promising technology for large-scale energy storage. It is not restricted by the geographical condition and has a high energy storage density. In this paper, on the base of the baseline LAES (BLAES) system, novel solar aided LAES systems with the poly-generation of cold, heat and power are designed to improve the round-trip efficiency (RTE) of the overall system and minimize the number of additional devices. In the best integration case, the solar energy is stored by using the existing air compression heat recovery system, and the air compression heat is effectively utilized. The organic Rankine cycle (ORC) device can be integrated with both the discharging process side and the charging process side to improve the RTE. The results show that the optimized air liquefaction pressure is 160 bar and the air expansion pressure is 120 bar, and the RTE is 53.26% for the BLAES system. For new system, the RTE of the best integration case is 90.49%, 69.90% higher than that of the BLAES system. The RTE of new system with the dual-side integration of ORC is improved by 15.56% compared to that of new system with the ORC single-side integration.

Parametric analysis and multi-objective optimization of a new combined system of liquid carbon dioxide energy storage and liquid natural gas cold energy power generation

Liquid carbon dioxide energy storage is a potential energy-storage technology. However, it is hindered by the difficulty of condensing CO 2 using high-temperature cooling water because the critical temperature of CO 2 is close to the temperature of the cooling water. Therefore, this study proposes a new combined liquid CO 2 energy storage and two-stage condensation organic Rankine cycle system. Thereby, the condensation of CO 2 is realized, and liquid natural gas (LNG) cold energy is utilized. The impact of key variables on the performance of the system is examined by establishing a mathematical model of the system and analyzing the parameters. In addition, the systems that use pure working fluid and mixed working fluid are optimized and compared using a simultaneous multi-objective optimization method. The results indicate that the system using mixed working fluids is better than that using pure working fluids, with an η R T E of 375.49%, η E X of 81.09%, and LCOS of 0.08 USD/kW·h. The proposed system performs better than the combined liquid air energy storage and LNG cold energy system in the literature from thermodynamic and economic perspectives. • A new combined system of LCES and LNG power generation is proposed. • It improves the difficulty of CO 2 to be condensed by high-temperature cooling water. • The impact of key variables on the performance of the system is explored. • Simultaneous multi-objective optimization method is conducted. • System using pure and mixed working fluid is compared.

Transcritical carbon dioxide cycle as a way to improve the efficiency of a Liquid Air Energy Storage system

The article deals with the subject of energy storage. This important issue relates to the ongoing transformation toward renewable energy sources. Liquid Air Energy Storage (LAES) is a mechanical energy storage technology that is suitable for large-scale energy storage. The article presents a method to increase the efficiency of LAES by coupling it with the transcritical carbon dioxide cycle. To this end, the paper presents a numerical analysis of two Kapitza LAES systems with the transcritical CO2 cycle: in parallel and subsequent mode. In both cases, maximizing CO2 pressure contributes to greater overall efficiency. It is only profitable to direct residual heat to the CO2 cycle. In contrast, lowering the air temperature prior to expansion in hopes of providing a greater amount of heat to the CO2 cycle actually delivers worse results. Parallel system implementation can add 5–6% to storage efficiency, depending on other factors. In comparison, the subsequent system only adds some 3.5%–5% to storage efficiency.

A Novel Energy Storage System Based on Carbon Dioxide Unique Thermodynamic Properties

Abstract This paper focuses on the thermodynamic performance and techno-economic assessment of a novel electrical energy storage technology using carbon dioxide as a working fluid. This technology, named CO2 battery and recently patented by Energy Dome SpA., addresses an energy market which has a great need for energy storage solutions able to handle the increasing share of nondispatchable renewable energy sources like photovoltaic and wind energy. After a brief introduction, the present study presents the concept of CO2 batteries and their operation. Then the detailed numerical model developed for the accurate calculation of system round trip efficiency is presented with the adopted assumptions and the optimization routine description. Results on the reference case and following sensitivity analysis confirm a round trip efficiency of around 77% (±2%) which makes CO2 batteries a very promising technology with respect to other energy storage systems based on thermodynamic cycles like compressed air and liquid air energy storage thanks to the high performance and the easiness of installation. Finally, calculation of system footprint, capital investment cost and levelized cost of storage are discussed.

RETRACTED: Multi-objective economic environmental energy management microgrid using hybrid energy storage implementing and developed Manta Ray Foraging Optimization Algorithm

Different renewable energy sources, active loads, electric vehicles, and storage devices make an independent microgrid (MG). Energy management of MG is an important issue. In this paper, efficient energy management (EM) of a microgrid using a novel method based on a new meta heuristic algorithm is proposed. Proposed MGs include renewable energy resources (wind turbine, fuel cell, and solar cell), plug-in hybrid electric vehicles (PHEVs), and liquid air energy storage (LAES) combined with high-temperature thermal energy storage (HTES). In order to carefully investigate and improve the management method, uncertainty parameters such as wind speed, solar radiation, load demand, and energy price is modeled using a probabilistic approach based on the point estimate method (2m + 1) and the developed manta ray foraging optimization (DMRFO) algorithm for posture forecasting with an uncertainty-weighted measurement error of feature objective is used to solve the EM algorithm. The multi-objective optimization problem presents an improved energy management method considering cost minimization and pollution as objective functions. Afterward, the function of the proposed algorithm is compared with that of other methods and, then, the superiority of the proposed method is confirmed. Finally, it is proved that by using the proposed model, total cost and emission is reduced about 3.5% and 21.33%, respectively.

Study on Interparticle Interaction Force Model to Correct Saturation Density of Real Cryogenic Fluid for LBM Simulation

Cryogenic liquefaction energy storage is an important form of storage for sustainable energy liquid hydrogen and other gases. The weighting parameter A in the parameter-adjusted two-phase LBM model is important for the deviation of simulation results. The aim of this paper is to discover the appropriate parameter to eliminate the deviation, and to solve the problem of large deviation between the theoretical solution and the simulated value that is caused by using different equations of state in LBM simulation. The modified PT equation of state, which is suitable for cryogenic fluids, is combined with the parameter-adjustable two-phase model to simulate the saturation density at different temperatures. Four typical cryogenic fluids—nitrogen, hydrogen, oxygen, and helium—are exploratively simulated to find the suitable parameters to eliminate errors by analyzing the results with theoretical solutions. This is an efficient solution to the deviation between the simulated value and the theoretical solutions, which is caused by the different equation of state in LBM. The optimal A-value of the model based on the PT equation of state was obtained as −0.21, while droplets and bubbles were set into the calculation region, and an inverse relationship between the interface density gradient and temperature was analyzed. The analysis and comparison of the simulation results under the optimal value and the experimental values have laid an important foundation for the phase change simulation of the real cryogenic fluids at the mesoscopic scale.