Liquid Air Energy Storage Research Articles

Dynamic characteristics of a novel liquid air energy storage system coupled with solar heat and waste heat recovery

Liquid air energy storage (LAES) is a promising energy storage technology for its high energy storage density, free from geographical conditions and small impacts on the environment. In this paper, a novel LAES system coupled with solar heat and absorption chillers (LAES-S-A) is proposed and dynamically modeled. A power-speed control system is established for this system. Two operating control strategies are developed for the solar heat collection process. The transient characteristics of the novel system during the start-up, load-up process and encountering different disturbances are investigated. Besides, the dynamic responses when the waste heat is used for producing heating energy are also studied. The results indicate that the power-speed control system can guarantee a very short equilibrium time and a very small overshoot. The energy efficiency of the LAES-S-A system is 65.84 %, while that is 75.32 % when the waste heat is used for producing heating supply. When a disturbance occurs, the equilibrium times of the absorption chiller, air turbines and heating device are 1500 s, 40 s and 38 s, respectively. Compared with the absorption chiller, the heating device can better cooperate with the air turbines. The results can provide a reference for future studies.

Performance analysis of a hybrid system combining cryogenic separation carbon capture and liquid air energy storage (CS-LAES)

Cryogenic separation carbon capture is a promising green carbon emission reduction approach, which is rarely applied due to its high cold energy requirement. This work proposes a hybrid system combining cryogenic separation carbon capture and liquid air energy storage (CS-LAES), comprehensively utilizing low-temperature and high-pressure conditions of LAES to reduce the energy consumption of cryogenic CO2 separation. Flue gas with higher carbon dioxide (CO2) concentrations from coal-fired power plants is compressed in the charging process of CS-LAES instead of air. The CO2 is captured, and the CO2-free air is liquefied and stored for later use. The results demonstrate that the carbon capture energy consumption of the CS-LAES system is 1.12 GJ/ton, which is 0.68 GJ/ton lower than that of conventional cryogenic capture technology (1.80 GJ/ton). The CO2 capture rate of 99.97 % is higher than that of most existing cryogenic CO2 capture technologies. Moreover, the standalone total exergy efficiency (S_TEE) for energy storage of the CS-LAES system was 63.40 %, which is 5.22 % higher than the baseline LAES. Meanwhile, the dynamic payback period of the CS-LAES system is 5.82 years, which is more economical than that of baseline LAES (12.89 years) due to avoiding expensive carbon tax.

Techno-economic analysis of an advanced polygeneration liquid air energy storage system coupled with LNG cold energy, solar energy, and hydrate based desalination

Techno-economic analysis of an advanced polygeneration liquid air energy storage system coupled with LNG cold energy, solar energy, and hydrate based desalination

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

Novel ASU–LAES system with flexible energy release: Analysis of cycle performance, economics, and peak shaving advantages

This study uses a cryogenic distillation method air separation unit (ASU) coupled with liquid air energy storage (LAES) to improve the round-trip efficiency and reduce the initial investment of LAES. We propose an integrated system (ASU–LAES–DER) with different ways of energy release. In the novel system, the liquid air can be reheated and expanded to produce additional power, or the liquid air energy stream and part of the material stream can be used for ASU distillation to produce power saving effects. This novel integration allows the ASU to have load regulation capability and facilitates the implementation of demand-side power management. Furthermore, the flexible and efficient energy release methods improve the energy efficiency and economic value of LAES. The comprehensive round-trip efficiency of the system can reach 52.1%–69.2 % with a payback period of 3.25–6.72 years. The peaking index is used to analyze the peak-to-valley load transfer capability of the novel system. Results show that the peaking index ranges from 25.5 MW to 50.1 MW at different scales, indicating that the system can be used as an important grid peaking unit when applied on a large scale.

Thermodynamic performance analysis of a novel integrated energy cascade system of liquid air energy storage and two-stage organic Rankine cycles

Liquid air energy storage can enhance the absorptive capacity for renewable energy due to its high energy storage density and extensive application scenarios. This paper proposes an integrated cascade energy system including liquid air energy storage, two-stage organic Rankine cycle, organic Rankine cycle, liquid natural gas regasification and absorption heat pump/chiller to use waste heat and liquid natural gas's cold energy fully and improve the round-trip efficiency. The waste heat of liquid air energy storage and the cold energy of liquid natural gas could increase the temperature and condense the working fluid of organic Rankine cycles. The system's thermodynamic model in design and off-design conditions are established. The charge and discharge minimum loads of liquid air energy storage are 82.5 % and 33.5 %, respectively. The round-trip efficiency of liquid air energy storage obtains a maximum of 49.6 % and a minimum of 29 % in the load ranges. Based on the load changes, the effects on the organic Rankine cycle are discussed, and four control strategies are proposed to absorb the waste heat and cold energy efficiently under off-design conditions. Besides, the organic Rankine cycles are affected by the mass flow of liquid natural gas and split ratio, which are discussed, and its underlying causes are analyzed. The results show that the integrated cascade energy system's round-trip efficiency reaches a maximum of 80.3 % in design conditions and a minimum of 62.7 % in off-design conditions, increasing by 61.9 % and 116.2 %, respectively.

Advancing liquid air energy storage with moving packed bed: Development and analysis from components to system level

Liquid air energy storage (LAES) technology is a promising large-scale energy storage solution due to its high capacity, scalability, and lack of geographical constraints, making it effective for integrating renewable energy sources. The core unit of the LAES system is the cold energy storage (CES) unit, which significantly influences its overall efficiency. However, the current mainstream liquid-phase and solid-phase CES methods have inherent drawbacks, including safety, environmental issues, and the dynamic effect of the thermocline. Moreover, previous research has often over-idealized the CES unit and neglected the actual heat transfer processes during the CES and cold energy release (CER) processes. In the innovative study, a gravity-driven moving packed bed (MPB) based LAES system (MPB-LAES) adopting quartz sand as the CES medium is proposed. A thermodynamic model for the LAES system is constructed, and the gas-solid counterflow coupling heat transfer model for the MPB is developed based on the continuous solid-phase model and finite difference method. The accuracy of the model is validated through experimentation using the constructed test apparatus. The research findings reveal the gas-solid coupling heat transfer characteristics in the low-temperature region of −180 °C to 30 °C, particularly the asymmetry during the CES and CER processes. The cold energy transfer mechanism within the CES unit is also uncovered, and the analysis of exergy destruction within various components is carried on. Through design parameter analysis and optimization of the MPB-LAES system, an impressive round-trip efficiency of 57.0% is achieved. This marks a significant breakthrough as it is the first report that a LAES system based on solid-phase CES has attained a round-trip efficiency (RTE) of over 55.0% while considering the actual heat transfer processes.

Thermodynamic and economic analysis of new coupling processes with large-scale hydrogen liquefaction process and liquid air energy storage

Liquid hydrogen serves as an environmentally friendly energy carrier, playing a crucial role in alleviating greenhouse effects. In order to tackle the challenges concerning energy consumption and economic costs, it becomes imperative to develop an efficient and cost-effective large-scale hydrogen liquefaction process (LHLS). This study integrates of LHLS with liquefied air energy storage (LAES) and introduces three liquefaction processes to reduce the economic cost associated with hydrogen liquefaction. By coupling LAES, electricity generated during off-peak hours can be stored and subsequently utilized in LHLS operations during peak hours, leading to a reduction in electricity costs. Furthermore, utilizing the surplus cooling capacity of LAES can enhance the efficiency of LHLS. A genetic algorithm is used to optimize the coupling processes. The calculated total annual cost (TAC) of the most economically viable coupling process amounts to 12271.8 k$/year, representing in a 20.91 % reduction compared to the independent LHLS. This indicate a clear economic advantage with the coupling process. The levelized cost of hydrogen (LCOH) and the payback period (PBP) for this particular coupling process are 2.523 $/kg and 4.56 years, respectively. A sensitivity analysis reveals that the economic benefits of the coupling processes escalate with higher electricity prices and greater liquefaction capacity.

Towards mega-scale decarbonized industrial park (Mega-DIP): Generative AI-driven techno-economic and environmental assessment of renewable and sustainable energy utilization in petrochemical industry

In alignment with climate change mitigation plans, renewable and sustainable energy integration into the industrial sector should be investigated for decarbonization purposes by 2050. This study aims to examine the feasibility of decarbonization of mega-scale industrial parks with two emerging technologies; first, an integrated energy system involving an air separation unit (ASU) and a liquid air energy storage (LAES)-based power generation system (ALPG) with the assistance of a large-scale liquified natural gas (LNG) plant and second, the green electricity predicted by various renewable energy (VRE) scenarios using an AI-driven generative model concerning techno-economic and environmental analyses. Firstly, the electricity demand of mega-scale petrochemical industrial complexes was allocated, and remote sensing data of VRE (wind and solar) were collected in South Korea. Then, the ALPG was modeled to consider the actual operation of an LNG plant near target complexes. Subsequently, the CC-informed VRE scenario generation model (CC-VRES) based on an adversarial autoencoder (AAE) algorithm was developed to generate VRE scenarios considering the CC effects. Finally, techno-economic and environmental assessments were conducted to target the mega-DIP by 2050. The results showed that the levelized cost of electricity of the proposed ALPG was 150 $/MWh, which is enough to supply the required sustainable electricity, considering the Korean energy plan and CC effects in the CC-VRES model. Therefore, the excess VRE can be used to decarbonize the target industrial parks; it is anticipated that 26,084 GW h/yr of renewable and sustainable electricity will be generated and cover the total electricity demand of Yeosu and Ulsan target complexes while reducing 13,943-kilo t CO2 eq./yr through 2050.

Compressed Air Energy Storage (CAES) and Liquid Air Energy Storage (LAES) Technologies—A Comparison Review of Technology Possibilities

This paper introduces, describes, and compares the energy storage technologies of Compressed Air Energy Storage (CAES) and Liquid Air Energy Storage (LAES). Given the significant transformation the power industry has witnessed in the past decade, a noticeable lack of novel energy storage technologies spanning various power levels has emerged. To bridge this gap, CAES and LAES emerge as promising alternatives for diverse applications. The paper offers a succinct overview and synthesis of these two energy storage methods, outlining their core operational principles, practical implementations, crucial parameters, and potential system configurations. The article also highlights approaches to enhance the efficiency of these technologies and underscores the roles of thermal energy storage within their processes. Furthermore, it delves into the discussion of the significance of hybrid systems and polygeneration in the contexts of CAES and LAES technologies. Moreover, we briefly explore the potential integration of these technologies into other power systems.

Novel heat transfer fluid for maximum recovery of heat of compression: A steady state analysis on improving the performance of liquid air energy storage

BackgroundEnergy storage is a key technology required to manage the limitation of the variability of renewable energy resources. In this study, a concept of energy storage based on Liquid Air Energy Storage (LAES) is presented, with proposed designs to improve the performance based on the heat transfer fluid. The heat generated from the compression of ambient air during the charging stage is usually stored in the heat storage tank and later used for power recovery in the discharging process. The challenge with the LAES is their low round-trip efficiency. Studies have proposed different system configurations and materials for improving the efficiency of the LAES technology, by incorporating multigeneration systems (like organic Rankine cycle, refrigeration system etc.), packed beds for the charging and discharging process, and fluids for cold storage. MethodThis study presents a first-of-its-kind nanofluid analysis for heat recovery in the charging process of ambient air. The effect of hybridization and volume fraction of carbon nanotubes was analysed, in comparison with other oils (Therminol-VP1, Therminol-66, and Dowtherm Q). ResultThe results show that nanofluid@0.005 requires 3331 m3 of storage tank, which caused the least investment cost of the high-temperature storage tank, with $ 2.318 Million. The levelized cost of storage for the LAES systems utilizing nanofluid@0.005, nanofluid@0.001, nanofluid@0.0005, Therminol-VP1, Dowtherm-Q, and Therminol-66 are 208.4 $/MWh, 209.1 $/MWh, 209.7 $/MWh, 211.1 $/MWh, 211.7 $/MWh, and 210.2 $/MWh respectively.

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.

Comprehensive performance investigation of a novel solar-assisted liquid air energy storage system with different operating modes in different seasons

Recently, many researchers have put a spotlight on solar-assisted liquid air energy storage (LAES) system for its cleanliness and large storage capacity. However, the energy efficiencies of such systems are relatively low, resulting in poor economic performance. In addition, very few studies are conducted on the performance of such systems with multi-generation output. Thus, a novel solar-assisted LAES system with different operating modes (LAES-S-D) in different seasons is proposed, which fully utilizes the solar heat and air compression heat to supply cooling/heating/power/domestic hot water in different seasons to meet the energy requirements of users in different seasons. The waste heat recovery/utilization potential of the system is analyzed from the perspective of the energy cascade utilization. Energy, exergy, techno-economic and exergoenvironmental performances are deeply investigated. In contrast with the reference system, the energy efficiency is improved from 0.5101 to 0.5561 (transition seasons), 0.7849 (summer) and 0.8674 (winter), respectively. The net present value is improved by 324.63 million $, the levelized cost of energy is reduced by 0.0774 $/kWh and the dynamic payback time is decreased by 4.87 years.

Performance improvement of liquid air energy storage: Introducing Stirling engine and solar energy

Liquid air energy storage (LAES) is a promising energy storage system with the main advantage of being geographically unconstrained. The efficiency of LAES could be improved by utilizing compression heat and integration with other systems. As an effective heat recovery process, the Stirling engine (SE) is introduced to the LAES system. The Pseudo Stirling model and Malmo relation are used to obtain practical results. Firstly, the Stirling engine is used to utilize compression heat, in which the Round Trip Efficiency (RTE) could be improved by 3.16% points and 8.96% points in LAES-SE and Liquified Natural Gas (LNG)-LAES-SE systems. Then, with solar energy introduced as heat source for the Stirling engine and air before the expander as heat sink, a more flexible Solar-LAES-SE system with decoupled charging and discharging sections is proposed. The RTE and exergy efficiency of the Solar-LAES-SE system are studied and compared with those in a Solar-LAES-Organic Rankine Cycle (ORC) and an LAES system directly heated by Solar energy. The exergy analysis shows that it is more effective to directly heat the air before expanders by solar energy than to integrate an ORC or a Stirling engine if the solar energy is insufficient. The Solar-LAES-SE systems show the best performance in terms of RTE when the air temperature before expanders is low and the molten salt (solar energy carrier) outlet temperature is high. The cost evaluation of the solar energy storage section shows that when the molten salt outlet temperature is lower than 370 °C, the cost of the molten salt-based storage system for the Solar-LAES-SE will be lower than the cost of the thermal oil-based storage system for Solar-LAES-ORC. The reason is a reduced flowrate of molten salt for decreased outlet temperature, thereby increasing temperature change for the molten salt. With a fixed duty of the heat transfer, this reduces the flowrate of molten salt. As a result, the cost of molten salt and its storage is reduced.

Process design and analysis for combined hydrogen regasification process and liquid air energy storage

In response to the increasing demand for hydrogen as a clean energy source and the need for a cost-effective and efficient regasification process, this paper proposes an energy-efficient process model that incorporates Liquid Air Energy Storage (LAES). The model aims to utilize the cold energy loss during hydrogen regasification to store cold energy for later use. The study analyzes three different cases in terms of energy efficiency, exergy efficiency, and economic feasibility to establish a benchmark for potential commercialisation of the LAES and hydrogen regasification process integration. The exergy efficiencies of the three cases are 56.0%, 57.0%, and 59.7%, respectively. Furthermore, the Net Present Value (NPV) analysis demonstrates positive financial returns for all three cases, indicating values of 13.14, 32.03, and 38.61 million dollars, thereby affirming the viability of the proposed system as a sustainable and economically feasible energy storage option. Overall, the study provides valuable insights into the design of an energy-efficient integrated hydrogen regasification process that could potentially contribute to the efficient utilization of cold energy and power generation.

Cryogenic energy storage characteristics in cascaded packed beds

Energy storage is a key technology required to utilize intermittent or variable renewable energy sources such as wind or solar energy. Liquid air energy storage (LAES) technology has important research value because of its advantages of high energy density and free construction from regional restrictions, and the high efficiency and stable operation of the cold thermal storage subsystem is of great significance for LAES application. Therefore, this paper experimentally studies the operating characteristics of the cryogenic energy storage device in the LAES system. By using a cascaded packed bed to store cryogenic energy in different temperature ranges, different flow rates of fluids with different specific heat capacities can be distributed. Hence, the temperature difference between the heat transfer fluids can be reduced, thereby improving the energy and exergy efficiencies. In this study, the experimental system and operating procedures are detailed herein. The pressure drop correlation of the packed beds under the combined influence of density gradient and frictional losses is obtained. The variations in the temperature fields in the charging and discharging processes are revealed, and the energy and exergy efficiencies are calculated to be 93.13 % and 85.62 % with 0.25-h preservation, and 90.46 % and 76.98 % with 4-h preservation, respectively. The exergy loss mechanism of the packed beds during the holding process is revealed. It is found that axial thermal conduction exergy loss accounts for 21.65 % and 7.04 % of the total loss in the packed beds in the full- and low-temperature regions, respectively.

Optimization of a Solvay cycle-based liquid air energy storage system

Liquid air energy storage systems (LAES) are being built as an alternative to battery storage to address the intermittent nature of renewable energy sources. In this work, optimization of the LAES operating on a Solvay cycle is performed to determine the best possible operating conditions and round-trip efficiency of the process. The simulation model of the process accounts for the non-linear variation of heat capacity of air, propane, methanol, and thermal oil and the occurrence of internal temperature pinches in the heat exchangers. The optimization results in this work show that the ‘sweet spot’ operating regime corresponds to a charging pressure between 130 and 190 bar and a discharging pressure between 70 and 120 bar, resulting in a round trip efficiency (ηRTE) of more than 60%.

Dynamic performance analysis of the discharging process of a solar aided liquid air energy storage system

As a clean and high energy density large-scale energy storage technology, liquid air energy storage (LAES) has great development prospects. Among various LAES technologies, solar aided liquid air energy storage (SALAES) is becoming a hotspot for its cleanness and high efficiency, but its dynamic performance characteristics have not yet been revealed. In this paper, the dynamic model and control systems of the discharging process of an SALAES system considering the metal thermal inertia and axial heat conduction are established and two different start-up methods, rated parameter start-up and variable parameter start-up, are proposed and compared. Meanwhile, a parabolic trough collector control strategy with fixed outlet fluid temperature is designed to avoid DNI fluctuations that greatly affect the system's operation. Furthermore, off-design start-ups and predictable molten salt-air heat exchangers trip due to the lack of solar energy caused by continuous bad weather are noted and analyzed. Research results show that the variable parameter start-up is faster and more stable, in which the heat exchange time of two evaporators is about 895 s, the rotor speed stability time is about 12–15 s, and the load stability time is about 75–80 s. The required air quantity for the design condition start-up is 6.84 tons and will rise to 9.02 tons for the off-design start-up. The response times for the unit load to decrease from the rated value to different levels (taking 75 %, 50 %, and 25 % of the rated load as examples) are around 15–20 s, and for the trip of salt-air heat exchangers, the response time is about 20–25 s, resulting in a load fluctuation from 85.5 % to 103.6 %. The research results of this study can guide the dynamic operation of the SALAES system.

Green hydrogen production and liquefaction using offshore wind power, liquid air, and LNG cold energy

Coastal regions have abundant off-shore wind energy resources, and surrounding areas have large-scale liquefied natural gas (LNG) receiving stations. From the engineering perspectives, there are limitations in unstable off-shore wind energy and fluctuating LNG loads. This article offers a new energy scheme to combine these 2 energy units, which uses surplus wind energy to produce hydrogen, and use LNG cold energy to liquefy and store hydrogen. In addition, in order to improve the efficiency of utilizing LNG cold energy, and reduce electricity consumption for liquid hydrogen (LH2) production at coastal regions, this article introduces the liquid air energy storage (LAES) technology as the intermediate stage, which can stably store the cold energy from LNG gasification. A new scheme for LNG-LAES-LH2 hybrid LH2 production is built. The case study is based on a real LNG receiving station at Hainan province, China, and this article presents the design of hydrogen production/liquefaction process, and carries out the optimizations at key nodes, and proves the feasibility using specific energy consumption and exergy analysis. In a 100 MW system, the liquid air storage round-trip efficiency is 71.0% and the specific energy consumption is 0.189 kWh/kg, and the liquid hydrogen specific energy consumption is 7.87 kWh/kg and the exergy efficiency is 46.44%. Meanwhile, the corresponding techno-economic model is built, and for a LNG-LAES-LH2 system with LH2 daily production 140.4 tons, the shortest dynamic payback period is 9.56 years. Overall, this novel hybrid energy scheme can produce green hydrogen using a more efficient and economical method, and also can make full use of surplus off-shore wind energy and coastal LNG cold energy.

Economic feasibility assessment of a solar aided liquid air energy storage system with different operation strategies

In response to severe environmental problems, the proportion of new energy consumption worldwide is on an unprecedented upward trend, bringing energy storage technologies into focus. Among various energy storage systems, the solar aided liquid air energy storage (SALAES) system shows great prospects for development due to its cleanliness and high efficiency. This paper develops a basic operation strategy based on the idea of peak and valley reduction, considering the temporal fluctuation characteristics of solar energy. Further, operation modes for replacing the oil-air heat exchangers are proposed and an optimized strategy is developed accordingly. Real weather data of Beijing are used to estimate the annual power output of each system, and economic analyses are carried out on this basis using the levelized cost of storage (LCOS) method. The results show that the introduction of solar energy can reduce the LCOS of the liquid air energy storage system by 4.1 %–13.67 % and the proposed optimized operation strategy can increase the annual power output, resulting in a 0.2 %–0.4 % reduction in LCOS compared to the basic operation strategy. In addition, the impact of the molten salt tank capacity on the investment and return of the SALAES system is investigated. The optimal molten salt tank capacity obtained in this paper is 5 h, with the lowest LCOS of 0.1477 $/kWh and the shortest dynamic payback period of 10.29 years when operating with the optimized strategy.