Liquid Air Energy Storage Research Articles

Dynamic characteristics of pumped thermal-liquid air energy storage system: Modeling, analysis, and optimization

Pumped thermal-liquid air energy storage (PTLAES) is a novel energy storage technology that combines pumped thermal- and liquid air energy storage and eliminates the need for cold storage. However, existing studies on this system are all based on steady-state assumption, lacking dynamic analysis and optimization to better understand the system’s performance under cyclic operation. To fill this gap, the mainbody-linearized cyclic dynamic model of the PTLAES system with packed bed thermal energy storage (TES) was first developed. Then, the dynamic characteristics of the baseline system were investigated. Sensitivity analyses were carried out on TES parameters. Minimal values of levelized cost of storage (LCOS) were observed for all parameters in the range of interest. Subsequently, the TES circuit was optimized, and a triple improvement of efficiency and energy density enhancement, discharge stabilization, and cost reduction was achieved. The optimized system's round-trip efficiency and energy density increased from 61.7% to 63.1% and from 141.9 kWh/m³ to 159.2 kWh/m³, and the LCOS decreased from 163.2 $/MWh to 159.4 $/MWh. A power offset ratio lower than 3% was reached, which is the lowest value ever reported in the literature. This study provides reference for future design and operation of the PTLAES system.

Environmental performance of a multi-energy liquid air energy storage (LAES) system in cogeneration asset – A life cycle assessment-based comparison with lithium ion (Li-ion) battery

Increase in energy demand is shaping both developed and developing countries globally. As a result, the endeavour to reduce carbon emissions also encompasses electrical energy storage systems to ensure environmentally friendly power production and distribution. Currently, the scientific community is actively exploring and developing new storage technologies for this purpose. The focus of this work is to compare the eco-friendliness of a relatively novel technology such as liquid air energy storage (LAES) with an established storage solution such as Li-Ion battery (Li-ion). The comparison is carried out through Life Cycle Assessment (LCA) methodology which aims to assess the environmental impacts from each life stage, according to different impact categories. In particular, the study refers to the unitary storage and the delivery of electricity as well as cooling energy, considering all the inefficiencies and limits of each technology. The results show that in the full electric case study Li-ion battery environmentally outperform LAES due to (1) the higher round trip efficiency and (2) the significantly high environmental impact of the diathermic oil utilized by LAES, accounting for 92 % of the manufacture and disposal phase. Conversely, the cogeneration case study highlights that the “flexibility” and “dualism” of LAES, capable to efficiently deliver both electricity and cooling, offset the impact related to the higher electricity consumption during the use phase. Notably in energy mix frameworks with high share of primary energy source from fossil fuels, cogenerative LAES demonstrates superior environmental performance compared to Li-ion battery (i.e. 1302 kgCO2eq/MWhe vs 1140 kgCO2eq/MWhe for Singapore energy mix), attributable to its reduced electricity consumption.

Diffusive solubility of nitrogen in Propane: Measurement from 96 K to 227 K at 0.1 MPa

The burgeoning demand for large-scale energy storage has catalyzed the advancement of Liquid Air Energy Storage (LAES) technology. However, the liquid-phase propane cold storage process in LAES systems encounters a significant challenge: the dissolution of nitrogen protection gas in propane poses a substantial risk to both operational safety and performance. Given the dearth of data on the diffusive solubility of nitrogen in propane under constant atmospheric pressure and low-temperature conditions, this study constructed a testbench and conducted experiments within a temperature range of 96–227 K at a pressure of 0.1 MPa. The molar diffusive solubilities at 227 K, 176 K, 139 K, and 96 K are 0.030 %, 0.177 %, 0.297 %, and 0.962 %, respectively. Besides, this study also fits a calculation equation for the diffusive solubility of nitrogen in propane, which applies to the propane cold storage process in LAES systems.

A real options-based framework for multi-generation liquid air energy storage investment decision under multiple uncertainties and policy incentives

Liquid Air Energy Storage (LAES) is a promising energy storage technology renowned for its advantages such as geographical flexibility and high energy density. Comprehensively assessing LAES investment value and timing remains challenging due to uncertainties in technology costs and market conditions. This study introduces a real options-based framework to evaluate investments in multi-generation LAES systems in China's power market by considering uncertain factors, such as investment cost and electricity price. Additionally, the impact of various incentives, including subsidies and preferential taxation policies, on LAES investment is investigated. The proposed investment decision framework is applied in a case study of a 10 MW-class multi-generation LAES system. Results show that the current economic environment is insufficient to trigger immediate LAES investment. The recommended optimal investment times are 2029 for Guangdong, 2031 for Jiangsu, and 2036 for Beijing and Qinghai without incentives. The levelized cost of storage at the optimal investment time is 0.105-0.174$/kWhe, and the optimal investment value is 882-9269k$. It is also found that preferential taxation policies can increase the LAES investment value. Increasing investment subsidies and technology learning effects have limited impacts on stimulating investments. In contrast, discharge subsidies are more favorable for promoting the deployment of LAES systems.

Techno-economic analysis on a hybrid system with carbon capture and energy storage for liquefied natural gas cold energy utilization

For cold energy utilization in the liquefied natural gas (LNG) regasification process, integrated cryogenic CO2 capture using high-grade cold energy is a mainstream method. However, high-grade cold energy for carbon capture may lead to a decrease in cold energy utilization efficiency. This paper aims to propose a hybrid system in which high-grade cold energy is used for liquid air energy storage (LAES) and post-combustion amine scrubbing technology is considered to replace cryogenic carbon capture for improved working efficiency. The medium and low-grade cold energy is utilized for similar working processes, e.g., organic Rankine cycle (ORC), carbon dioxide liquefaction, and data center cooling for comparison. Results show that the proposed hybrid system can produce 437.7 MW of power, 28.8 t·h−1 of CO2 capture capacity, and 23.0 MW of cooling capacity, respectively. The levelized cost of electricity and the annual revenue are 112.3 $·MWh−1 and 2.17 million $, respectively. LNG cold energy utilization efficiency, system energy efficiency, and cold exergy efficiency are 53.4 %, 24.0 %, and 51.5 %, higher than similar processes using cryogenic CO2 capture. It is demonstrated that the proposed system could be a promising method for cold energy utilization and post-combustion capture.

Enhancing concentrated photovoltaic power generation efficiency and stability through liquid air energy storage and cooling utilization

Amid escalating climate concerns, particularly global warming, there is a significant shift towards renewable energy sources. Concentrated Photovoltaics (CPV) are at the forefront of this transition due to their high efficiency and clean energy generation capabilities. However, CPV cell stability and reliability are compromised by high operating temperatures, necessitating effective cooling solutions. This study proposes a novel coupled Concentrated Photovoltaic System (CPVS) and Liquid Air Energy Storage (LAES) to enhance CPV power generation efficiency and mitigate the challenges of high cell temperatures and grid integration. The research introduces an innovative process employing the cell liquefaction cycle for LAES, utilizing surplus cooling capacity to maintain CPV cells at optimal temperatures. A comprehensive thermodynamic analysis optimizes the coupled system’s operation and evaluates its economic benefits. The integrated system improves generation efficiency and economic viability of CPVS, resulting in a 24.41 % increase in photovoltaic module efficiency and a 2.03 % increase in overall rated power output. This leads to a 56.59 % increase in annual revenue for a 50 MW CPVS. Importantly, the findings demonstrate that integrating LAES with CPVS not only enhances solar energy utilization and economic benefits but also significantly contributes to the sustainability of clean, low-carbon energy systems, inspiring a greener future.

Discussion On Three Optimization Plans for Photovoltaic Systems

In the context of the global energy structure, photovoltaic (PV) generation plays a critical role in reducing greenhouse gas emissions and improving energy sustainability. However, PV systems differ significantly from conventional power generation like coal and nuclear power due to their dependence on environmental factors such as weather and seasons, resulting in significant load fluctuations. To mitigate this issue, the optimization of PV systems is widely accepted, involving techniques such as energy storage and performance enhancement. Three methods are proposed to address the issue of power instability in photovoltaic systems: changing the tilt angle between photovoltaic panels and sunlight, changing the electrical parameters of photovoltaic cells, and compensation using liquid air energy storage technology. Based on these three methods, corresponding implementation directions and applicable ranges are provided for different needs. The advantages and disadvantages are also discussed.

Experimental and numerical study on the heat transfer deterioration of supercritical nitrogen in a vertical tube

Supercritical cryogenic fluids exhibit significant potential for diverse applications across various industries, including liquid air energy storage, high-temperature superconducting cables, and hypersonic vehicle engine cooling. Heat transfer deterioration (HTD) poses a substantial risk to the system safety. In this study, we constructed an experimental system and performed numerical simulations to illustrate buoyancy (Bu) and thermal acceleration (Ac) effects on HTD of supercritical nitrogen (SCN2). The newly established thresholds for buoyancy and thermal acceleration (Buth=1.8×10−4 and Acth=4.4×10−5), considering pseudo two-phase characteristics, can effectively capture buoyancy and thermal acceleration in the first and second HTD regions. The first region is influenced by the combined effect of buoyancy and thermal acceleration, while the second region is mainly influenced by thermal acceleration. The new correlations and thresholds accurately predict the occurrence of HTD and the peak position. The experimental and simulation results contribute to understanding the impact of buoyancy and thermal acceleration on SCN2 HTD.

Integration of the single-effect mixed refrigerant cycle with liquified air energy storage and cold energy of LNG regasification: Energy, exergy, and efficiency prospectives

The escalating global energy demand has prompted increased focus on the industry of liquefied natural gas (LNG), emphasizing the need for optimizing liquefaction processes to minimize capital costs. Thus, the integration between liquified natural gas LNG regasification and liquid air energy storage (LAES) to produce electricity and utilize the cold energy of LNG regasification has several interests to maximize the benefits of the process to generate power and face the challenges such as energy saving and reducing the total operations costs … etc. Fortunately, this study introduces a novel approach that combines a single-effect mixed refrigerant (SMR) cycle with air liquefaction, incorporating regenerative Rankine cycles for enhanced efficiency. The effectiveness of the LNG-SMR-LAES process was evaluated using comprehensive energy, exergy, and economic analyses to ascertain its viability. The results showed a notable improvement in the overall net power energy by 6 % and an increase in exergy efficiency by 11.7 % compared to the base case. Energy savings of 31.6 % (470.10 kW) contributed to the process's environmental and economic feasibility. The net present value was estimated at 11,230.4 US dollars, affirming the industrial-feasible design and economic viability of the LNG-SMR-LAES process.

Thermodynamic and economic analysis of multi-generation system based on LNG-LAES integrating with air separation unit

LNG consumption is rising globally, releasing significant cold energy during regasification. Coupling LNG vaporization with liquid air energy storage (LAES) maximizes this cold energy recovery, enhancing LAES efficiency. However, current LNG-LAES systems face issues like insufficient high-grade cold energy use and high liquid air temperatures. LAES's inability to recover LNG cold energy during energy release necessitates cold storage fluid, increasing costs. Safety concerns also arise from LNG and air coexisting in the same heat exchanger, and LNG vaporization fluctuations can destabilize LAES operations. This study proposes a multi-generation system (LNG-LAES-ASU) incorporating an air separation unit (ASU) to address these challenges. The ASU recovers LNG cold energy during energy release, adapts to LNG vaporization fluctuations, and reduces ASU energy consumption. Energy, economic, and peak-shaving performance analyses show the system achieves a 91.07 % round-trip efficiency (RTE). The ASU's average energy consumption is 0.1356–0.1506 kWh/Nm³ O₂, much lower than a standalone ASU's 0.4 kWh/Nm³ O₂. Over 30 years, the system yields a net present value (NPV) of $56,111,291 and a dynamic payback period of 3.23 years. Its peak-shaving capacity is 2.47–2.57 times greater than LNG-LAES alone. This research offers valuable insights into efficient LNG cold energy utilization.

Power generation system utilizing cold energy from liquid hydrogen: Integration with a liquid air storage system for peak load shaving

Liquid hydrogen (LH2) can serve as a carrier for hydrogen and renewable energy by recovering the cold energy during LH2 regasification to generate electricity. However, the fluctuating nature of power demand throughout the day often does not align with hydrogen demand. To address this challenge, this study focuses on integrating liquid air energy storage with a power generation system based on LH2 regasification. Three configurations are proposed and compared: no-storage, partial-storage, and full-storage. In the no-storage system, power is generated using recuperated Brayton cycle and two organic Rankine cycles without energy storage. In contrast, the partial-storage system offers flexible operational modes. During peak times, cold energy is utilized for power generation, while it is diverted to store liquid air during off-peak times. In the full-storage system, produced energy is partially reserved throughout the day. Thus, compared to the partial-storage system, the full-storage system boasts a simplified configuration, eliminating the need for operational mode transitions. Furthermore, its larger liquid air storage capacity maximizes the difference in power production up to 4.53 MW between on- and off-peak times. Consequently, despite its higher capital costs, the full-storage system demonstrates greater economic viability, especially when considering government subsidies.

Analysis of Liquid Air Energy Storage System with Organic Rankine Cycle and Heat Regeneration System

Liquid air energy storage (LAES) is one of the most promising technologies for power generation and storage, enabling power generation during peak hours. This article presents the results of a study of a new type of LAES, taking into account thermal and electrical loads. The following three variants of the scheme are being considered: with single-stage air compression and the use of compression heat for regasification (Case 1); with single-stage compression and the organic Rankine cycle (Case 2); and with three-stage air compression/expansion and the organic Rankine cycle (Case 3). To analyze the proposed schemes, the Aspen HYSYS v.12 software package was used to compile models of the studied cycles. The analysis shows that round-trip efficiency (RTE) can be as high as 54%. The cost of 1 kg of liquid air is USD 7–8. Moreover, it is shown that the generation of electrical energy largely depends on the operation of the expander plant, followed by the organic Rankine cycle (ORC).

Investigation of an integrated liquid air energy storage system with closed Brayton cycle and solar power: A multi-objective optimization and comprehensive analysis

Energy storage has garnered global attention as a promising solution to the intermittent nature of renewable energy sources. For large-scale (>100 MW) energy storage technology, there are only three types: Pumped Hydroelectric energy storage (PHES), Compressed air energy storage (CAES) and Liquid air energy storage (LAES). The limitation of PHES is that several natural geological features are needed. The traditional CAES needs a combustion chamber, which will result in environmental problems. LAES offers several advantages over traditional CAES systems, including higher energy density, scalability, flexibility in site selection, lower environmental impact, cost-effectiveness, and compatibility with renewable energy sources. Under these conditions, LAES is more suitable than other systems. This investigation examined a novel zero-carbon system integrating LAES with CBC and solar power. The primary objective is to maximize the round-trip efficiency (RTE) of the system while simultaneously minimizing the total investment cost per unit of output power (ICPP). By systematically exploring the trade-offs between RTE and ICPP, the study seeks to identify the proposed system’s most efficient and economically viable configurations. Each subsystem was simulated using Aspen Plus® V12 and validated against actual plant data. The analysis indicates that the proposed optimal LAES-CBC system could achieve a remarkable increase in RTE up to 67.81 %, representing an increase of 11.18 % compared to the baseline. Additionally, the total ICPP could be reduced to 0.2739 $/kWh, marking a decrease of 5.96 %. The charging process of the LAES system emerges as a critical focal point due to its significant contributions to exergy destruction and equipment costs. This study provides valuable insights into enhancing and achieving maximum efficiency and cost-effectiveness. These insights are essential for accelerating the transition towards a carbon–neutral energy system, highlighting the importance of research in advancing sustainable energy technologies.

A novel liquid air energy storage system with efficient thermal storage: Comprehensive evaluation of optimal configuration

Liquid air energy storage (LAES) stands out as a highly promising solution for large-scale energy storage, offering advantages such as geographical flexibility and high energy density. However, the technology faces challenges inherent in the cold and heat storage processes. While systems with liquid-phase medium can offer high efficiency, it comes with drawbacks including environmental pollution, safety concerns, and high costs. Alternatively, systems with solid-phase media in packed beds can address these issues, yet it profoundly weakens system performance. Compounding these issues, many current economic evaluations of LAES rely on inaccurate or outdated data, resulting in skewed assessments. In response to these challenges and to drive scientific evaluation and engineering advancements in LAES, this study introduces an innovative LAES system with efficient thermal storage (ETS-LAES). An original thermal storage method is introduced for the first time, based on gravity-driven solid-phase particle flow and gas-solid direct contact heat transfer. The study establishes thermodynamic and heat transfer models, along with a universally applicable economic evaluation model. The ETS-LAES system is comprehensively assessed utilizing different operational modes introduced in the study. Research findings showcase a round-trip efficiency (RTE) of 58.76%, currently standing as the highest RTE record for cold and heat storage based on solid-phase media. The economic evaluation reveals substantial advantages for the ETS-LAES system during the transition from demonstration projects to commercial projects and guides the selection of the scale for the LAES system. The levelized cost of storage (LCOS) for the ETS-LAES system can decrease to 0.0982 USD/kWh as the capacity increases to 1000MW, due to the use of inexpensive solid-phase thermal storage media throughout. The investment payback period (IPP) is halved compared to conventional LAES systems, indicating a strengthening of the profitability. The proposed solution in this study holds great potential, particularly in offering valuable insights into the practical implementation and commercialization of LAES.

An integrated system based on liquid air energy storage, closed Brayton cycle and solar power: Energy, exergy and economic (3E) analysis

In pursuing net zero emissions amid increasing energy consumption, renewable energy sources offer a path towards environmental sustainability. However, they are plagued by instability and intermittency. Energy storage systems have emerged as a solution to address these challenges, ensuring a stable power supply despite the fluctuations of renewables. Liquid air energy storage (LAES) has advantages over compressed air energy storage (CAES) and Pumped Hydro Storage (PHS) in geographical flexibility and lower environmental impact for large-scale energy storage, making it a versatile and sustainable large-scale energy storage option. However, research on integrated closed Brayton cycle (CBC) systems with LAES is still in infancy. A novel integrated system is proposed, incorporating LAES, CBC and solar power. Steady-state models for LAES and CBC were developed and validated in Aspen Plus® V12. A comprehensive and systematic evaluation of the proposed LAES-CBC system was performed. The optimal round-trip efficiency (RTE) reaches up to 68.82 %, improving 11.70 % compared to the base LAES-CBC system. Parametric analysis reveals that higher compressor outlet pressures enhance both exergy efficiency and RTE. Compressors contribute significantly to exergy destruction, particularly in the charging process. The optimal outlet pressure for PUMP1 is found to be 80 bar. Economic analysis shows a reasonable payback period of 8.60 years and 0.307 $/kWh of LCOS, confirming the system's financial viability.

Exergy and pinch assessment of an innovative liquid air energy storage configuration based on wind renewable energy with net-zero carbon emissions

Given the rising global energy demands and the fluctuating nature of load demand, advancing various energy storage systems to enhance their efficiency is essential. Moreover, the increase in greenhouse gas emissions from various industries has prompted governments to implement carbon dioxide (CO2) capture systems and invest in renewable energy sources. In this research, a cryogenic energy storage configuration is developed according to the air liquefaction process, liquefied natural gas (LNG) regasification operation, CO2 capture cycle, and organic Rankine plant. During off-peak times, the air entering the energy storage system is compressed and liquefied using wind energy and the cold energy from LNG vaporization, producing 83.12 kg/s of liquid air. During on-peak times, the liquid air and LNG after recovering the cold energy enter the power generation cycle, generating 119 MW of electrical power. This power generation cycle includes a combustion chamber, gas turbine power plant, and organic Rankine cycles. Flue gases from the power generation cycles enter the amine-based CO2 capture and then the output CO2 is stored in liquid form. The storage and round-trip efficiencies of the present energy storage configuration are 67.97 % and 62.50 %, respectively. The results of exergy analysis show that the exergy efficiency of the whole system, off-peak, and on-peak sections are calculated as 64.88 %, 82.40 %, and 74.03 %, respectively. The pinch method for multi-stream exchangers (HX6, HX7, and HX8) is accomplished and the exchanger network related to each one is determined. Three-dimensional sensitivity analysis indicates that storage and round-trip efficiencies increase up to 80.45 % and 66.20 %, respectively when the power generation section pressure increases up to 110 bar and compressed air pressure decreases to 135 bar.

Experimental Study on Mechanical Properties of Reinforcement under Low-Temperature Impact

Abstract Ammonia is an important carrier of hydrogen energy, and the large-scale storage of liquid ammonia is the next trend of cryogenic energy storage. At present, the international mainstream liquid ammonia tank is generally about 50, 000 m3. The outer storage tanks generally adopt a metal structure, and the material applied for larger concrete full-capacity tanks is worth doing further research. Steel reinforcement bars (rebar) are an important construction material for full-capacity cryogenic energy storage tanks. The performance of rebar is an important index in the process of designing the strength of building structures. The factors affecting the properties of rebar are diverse, and reasonable control of each influencing factor can improve the performance of rebar used for liquid ammonia storage tanks. This paper carries out the study on the mechanical properties of the steel reinforcement bars from the concrete of the main container under low temperatures for storing liquid ammonia. Through experimental research on the failure of steel used in external tanks, it has been shown that temperature has a significant impact on the ductile-brittle transition. Further treatment can effectively prevent the brittleness of steel bars, improve the safety and reliability of storage tanks at low temperatures, and is of great significance for the design and construction of subsequent large liquid ammonia storage tanks.

A process flow of an air separation unit with an energy storage function: Utilizing distillation potential to absorb energy storage air and its performance

The integration of liquid air energy storage (LAES) and air separation units (ASUs) can improve the operation economy of ASUs due to their matching at refrigeration temperature. A process flow of an ASU with energy storage utilizing the distillation potential of the ASU to absorb the released air due to storing energy (i.e., the energy storage air) is proposed. Its novelty is thus: the ASU can be used to absorb the energy storage air to maximize the air utilization and improve the energy efficiency of the integrated system. It can be simulated using Aspen Plus software. Based on the simulated data, an optimal process flow is determined by analyzing the effect of a reduction in discharge of energy storage air on the distillation conditions of the ASU, and its energy efficiency analysis and economic evaluation are conducted. When the discharge of energy storage air is reduced by 50 % during energy storage and the stored liquid air is directly recovered into the ASU during energy release, a proposed process flow with largest absorption for energy storage air could be obtained. Its product exergy efficiencies for energy storage and release are 37.80 % and 37.57 %, respectively. The overall exergy efficiency of the LAES and the electrical round-trip efficiency of the proposed system are both 67.48 %, the electricity cost saving ratio is 6.43 %, and the payback period of the LAES is 2.4 years. The investment in an air booster accounts for the largest proportion of the overall cost (being some 49.3 % of the total investment required for such a LAES system). After the proposed system is applied throughout the industry, carbon dioxide emissions can be decreased by 15.12–26.76 Mt/year on the grid side.

Thermodynamic analysis of liquid air energy storage system integrating LNG cold energy

Liquid air energy storage (LAES) presents a promising solution to effectively manage intermittent renewable energy and optimize power grid peaking. This paper introduces a LAES system integrating LNG cold energy to flexibly manage power peaking, including intermediate energy storage, power generation using organic Rankine cycle, multi-stage direct expansion, and solar energy for heating. Aiming to maximize the electrical round-trip efficiency, a genetic algorithm is employed to optimize the operational parameters of the proposed LAES system. The results indicate that the combined design of cold energy utilization, multi-stage direct expansion and solar heating for proposed LAES system significantly improve the power performance, achieving an energy capacity of 0.125 kWh/kgLNG and an electrical round-trip efficiency of 376.7 %. The exergy losses of heat exchange equipment are far larger than mechanical equipment in the LAES system, so the optimization design of heat exchange equipment is preferred to improve the exergy performance. The proposed system achieves both high efficiency and flexibility and hence contributes to the development of liquid air energy storage systems.

Evaluating economic feasibility of liquid air energy storage systems in US and European markets

Liquid air energy storage is a clean and scalable long-duration energy storage technology capable of delivering multiple gigawatt-hours of storage. The inherent locatability of this technology unlocks nearly universal siting opportunities for grid-scale storage, which were previously unavailable with traditional technologies such as pumped hydro energy storage and compressed air energy storage. While the technical viability of liquid air energy storage has been established, its economic viability has not yet been rigorously assessed across diverse electricity markets. In this work, a mixed-integer linear program was used to conduct a high-level economic analysis of this technology in US and European markets. By simultaneously optimizing the design and operation of liquid air energy storage systems to maximize their net present value, a yes/no indication of their economic viability can be obtained. Using this approach, the economic viability of this technology was established for the West load zone of Texas through identification of a system with an optimal net present value of $10.4 million and a levelized cost of storage of $119/MWh. Sensitivity analyses were also performed to elucidate how improved technical performance and economic incentives might affect the economic feasibility and, consequently, the adoption of this technology more broadly in the future.