A power plant for integrated waste energy recovery from liquid air energy storage and liquefied natural gas

Liquefied natural gas(LNG)is regarded as one of the cleanest fossil fuel and has experienced significant developments in recent years.The liquefaction process of natural gas is energy-intensive,while the regasification of LNG gives out a huge amount of waste energy since plenty of high grade cold energy(-160℃)from LNG is released to sea water directly in most cases,and also sometimes LNG is burned for regasification.On the other hand,liquid air energy storage(LAES)is an emerging energy storage technology for applications such as peak load shifting of power grids,which generates 30%-40%of compression heat(-200℃).Such heat could lead to energy waste if not recovered and used.The recovery of the compression heat is technically feasible but requires additional capital investment,which may not always be economically attractive.Therefore,we propose a power plant for recovering the waste cryogenic energy from LNG regasification and compression heat from the LAES.The challenge for such a power plant is the wide working temperature range between the low-temperature exergy source(-160℃)and heat source(-200℃).Nitrogen and argon are proposed as the working fluids to address the challenge.Thermodynamic analyses are carried out and the results show that the power plant could achieve a thermal efficiency of 27%and 19%and an exergy efficiency of 40%and 28%for nitrogen and argon,respectively.Here,with the nitrogen as working fluid undergoes a complete Brayton Cycle,while the argon based power plant goes through a combined Brayton and Rankine Cycle.Besides,the economic analysis shows that the payback period of this proposed system is only 2.2 years,utilizing the excess heat from a 5 MW/40 MWh LAES system.The findings suggest that the waste energy based power plant could be co-located with the LNG terminal and LAES plant,providing additional power output and reducing energy waste.

Comparative Analysis of Diagonal and Centrifugal Compressors with Synergy Theory in Compressed Air Energy Storage System

Energy storage technology is an essential part of the efficient energy system.Compressed air energy storage(CAES)is considered to be one of the most promising large-scale physical energy storage technologies.It is favored because of its low-cost,long-life,environmentally friendly and low-carbon characteristics.The compressor is the core component of CAES,and the performance is critical to the overall system efficiency.That importance is not only reflected in the design point,but also in the continuous efficient operation under variable working conditions.The diagonal compressor is currently the focus of the developing large-scale CAES because of its stronger flow capacity compared with traditional centrifugal compressors.And the diagonal compressor has the higher single stage pressure ratio compared with axial compressors.In this paper,the full three dimensional numerical simulation technologies with synergy theory are used to compare and analyze the internal flow characteristics.The performance of the centrifugal and diagonal impellers that are optimized under the same requirements for large-scale CAES has been analyzed.The relationship between the internal flow characteristics and performance of the centrifugal and diagonal impellers with the change of mass flow rates and total inlet temperature is given qualitatively and quantitatively.Where the cosine value of the synergy angle is high,the local flow loss is large.The smaller proportion of the positive area is the pursuit of design.Through comparative analysis,it is concluded that the internal flow and performance changes of centrifugal and diagonal impellers are different.The results confirm the superiority and feasibility of the off-design performance of the diagonal compressor applied to the developing large-scale CAES.

Efficiency Analysis of an Arrayed Liquid Piston Isothermal Air Compression System for Compressed Air Energy Storage

Compressed air energy storage(CAES)is an important technology in the development of renewable energy.The main advantages of CAES are its high energy capacity and environmental friendliness.One of the main challenges is its low energy density,meaning a natural cavern is required for air storage.High-pressure air compression can effectively solve the problem.A liquid piston gas compressor facilitates high-pressure compression,and efficient convective heat transfer can significantly reduce the compression energy consumption during air compression.In this paper,a near isothermal compression method is proposed to increase the surface area and heat exchange by using multiple tube bundles in parallel in the compression chamber in order to obtain high-pressure air using liquid-driven compression.Air compression with a compression ratio of 6.25:1 is achieved by reducing the tube diameter and increasing the parallel tube number while keeping the compression chamber cross-sectional area constant in order to obtain a high-pressure air of 5 MPa.The performances of this system are analyzed when different numbers of tubes are applied.A system compression efficiency of 93.0%and an expansion efficiency of 92.9%can be achieved when 1000 tubes are applied at a 1 minute period.A new approach is provided in this study to achieve high efficiency and high pressure compressed air energy storage.

Simulation and analysis of a peak regulation gas power plant with advanced energy storage and cryogenic CO_(2) capture

Flexible gas power plants are subject to energy storage,peak regulations,and greenhouse gas emissions.This study proposes an integrated power generation system that combines liquid air energy storage(LAES),liquefied natural gas(LNG)cold energy utilization,gas power systems,and CO_(2) capture and storage(CCS)technologies,named the LAES-LNG-CCS system.The off-peak electricity can be stored in liquid air.During the peak period,air and gas turbines generate supplementary electricity.Both LNG chemical energy and cold energy were considered:the former was used for gas power plants,and the latter was used for LAES regasification and CCS processes.Based on the thermodynamic analysis,we evaluated the effects of the recovery pressure,CCS pressure,and combustion temperature on the system power consumption and efficiency.The results demonstrated that the system recovery pressure,CCS pressure,and combustion temperature had the greatest effects on system power generation.Round-trip efficiency(RTE)was significantly affected by combustion temperature.The largest exergy loss occurred in the gas power plant.The optimal system operating ranges of the system recovery pressure,CCS pressure,and combustion temperature were 6−10 MPa,0.53−0.8 MPa,and 1,503−1,773 K,where the RTEs and𝜂Ex,RS reached 55%−58.98%and 74.6%−76%,respectively.The proposed system can simultaneously achieve the synergistic functions of large-scale energy storage,multilevel energy utilization,peak regulation,and carbon emission reduction.It can also be widely used in advanced distributed energy storage applications in the future.

Development and technology status of energy storage in depleted gas reservoirs

Utilizing energy storage in depleted oil and gas reservoirs can improve productivity while reducing power costs and is one of the best ways to achieve synergistic development of"Carbon Peak–Carbon Neutral"and"Underground Resource Utiliza-tion".Starting from the development of Compressed Air Energy Storage(CAES)technology,the site selection of CAES in depleted gas and oil reservoirs,the evolution mechanism of reservoir dynamic sealing,and the high-flow CAES and injection technology are summarized.It focuses on analyzing the characteristics,key equipment,reservoir construction,application scenarios and cost analysis of CAES projects,and sorting out the technical key points and existing difficulties.The devel-opment trend of CAES technology is proposed,and the future development path is scrutinized to provide reference for the research of CAES projects in depleted oil and gas reservoirs.

The carbon dioxide removal potential of Liquid Air Energy Storage: A high-level technical and economic appraisal

Liquid Air Energy Storage(LAES)is at pilot scale.Air cooling and liquefaction stores energy;reheating revaporises the air at pressure,powering a turbine or engine(Ameel et al.,2013).Liquefaction requires water&CO2 removal,preventing ice fouling.This paper proposes subsequent geological storage of this CO2–offering a novel Carbon Dioxide Removal(CDR)by-product,for the energy storage industry.It additionally assesses the scale constraint and economic opportunity offered by implementing this CDR approach.Similarly,established Compressed Air Energy Storage(CAES)uses air compression and subsequent expansion.CAES could also add CO2 scrubbing and subsequent storage,at extra cost.CAES stores fewer joules per kilogram of air than LAES–potentially scrubbing more CO2 per joule stored.Operational LAES/CAES technologies cannot offer full-scale CDR this century(Stocker et al.,2014),yet they could offer around 4%of projected CO2 disposals for LAES and<25%for current-technology CAES.LAES CDR could reach trillion-dollar scale this century(20 billion USD/year,to first order).A larger,less certain commercial CDR opportunity exists for modified conventional CAES,due to additional equipment requirements.CDR may be commercially critical for LAES/CAES usage growth,and the necessary infrastructure may influence plant scaling and placement.A suggested design for low-pressure CAES theoretically offers global-scale CDR potential within a century(ignoring siting constraints)–but this must be costed against competing CDR and energy storage technologies.

Liquid Air Energy Storage for Decentralized Micro Energy Networks with Combined Cooling,Heating,Hot Water and Power Supply

Liquid air energy storage(LAES)has been regarded as a large-scale electrical storage technology.In this paper,we first investigate the performance of the current LAES(termed as a baseline LAES)over a far wider range of charging pressure(1 to 21 MPa).Our analyses show that the baseline LAES could achieve an electrical round trip efficiency(e RTE)above 60%at a high charging pressure of 19 MPa.The baseline LAES,however,produces a large amount of excess heat particularly at low charging pressures with the maximum occurred at~1 MPa.Hence,the performance of the baseline LAES,especially at low charging pressures,is underestimated by only considering electrical energy in all the previous research.The performance of the baseline LAES with excess heat is then evaluated which gives a high e RTE even at lower charging pressures;the local maximum of 62%is achieved at~4 MPa.As a result of the above,a hybrid LAES system is proposed to provide cooling,heating,hot water and power.To evaluate the performance of the hybrid LAES system,three performance indicators are considered:nominal-electrical round trip efficiency(ne RTE),primary energy savings and avoided carbon dioxide emissions.Our results show that the hybrid LAES can achieve a high ne RTE between 52%and 76%,with the maximum at~5 MPa.For a given size of hybrid LAES(1 MW×8 h),the primary energy savings and avoided carbon dioxide emissions are up to 12.1 MWh and 2.3 ton,respectively.These new findings suggest,for the first time,that small-scale LAES systems could be best operated at lower charging pressures and the technologies have a great potential for applications in local decentralized micro energy networks.

Response Characteristics of Flexible Risers in Offshore Compressed Air Energy Storage Systems

With the rapid development of marine renewable energy technologies, the demand to mitigate the fluctuation of variable generators with energy storage technologies continues to increase. Offshore compressed air energy storage (OCAES) is a novel flexible-scale energy storage technology that is suitable for marine renewable energy storage in coastal cities, islands, offshore platforms, and offshore renewable energy farms. For deep-water applications, a marine riser is necessary for connecting floating platforms and subsea systems. Thus, the response characteristics of marine risers are of great importance for the stability and safety of the entire OCAES system. In this study, numerical models of two kinds of flexible risers, namely, catenary riser and lazy wave riser, are established in OrcaFlex software. The static and dynamic characteristics of the catenary and the lazy wave risers are analyzed under different environment conditions and internal pressure levels. A sensitivity analysis of the main parameters affecting the lazy wave riser is also conducted. Results show that the structure of the lazy wave riser is more complex than the catenary riser;nevertheless, the former presents better response performance.

新能源用钢管的应用现状、需求分析及思考

“双碳”战略下新能源及相关产业发展给钢管带来新的应用场景,对钢管的功能和性能提出新的需求。聚焦于碳捕获、利用与封存技术领域中的CO_(2)输送用管、氢能领域中的氢气输送用管和储能领域中的盐穴压缩空气储能用注采管,总结了新能源用钢管的应用现状和研究进展,分析了各领域用管需求,并就“双碳”背景下新能源用钢管的基础理论研究、关键技术开发和标准体系建设等方面进行了思考,提出了建议。

等温压缩空气储能技术研究综述

压缩空气储能是一种新型的大型物理储能技术,具有很好的发展前景。介绍了等温压缩空气储能的基本原理,以及关键设备与相关技术的原理及发展现状;对液体活塞、水泵和水轮机进行分析和总结;对等温压缩空气储能的基本原理进行了归纳和说明;分析了现有等温压缩空气储能技术研究进展情况,对系统中液体活塞技术以及水泵和水轮机技术进行分析和总结;对已有的压缩空气储能电站数据进行汇总分析。在此基础上,对等温压缩空气储能技术未来发展方向进行了展望,可为等温压缩空气储能系统中动力设备的选用以及示范项目的推进提供一定的数据参考。

二氧化碳电热储能与液态储能系统热力性能对比分析

二氧化碳电热储能与液态二氧化碳储能技术具有适用范围广、储能密度大等特点,是目前压缩气体储能技术的研究热点,然而,上述系统在储能形式及流程上的差异造成了系统在储能效率、储能密度等方面的不同,目前尚无系统性研究。基于此,本工作阐述了上述系统的能量存储原理及流程构型特点,建立了热力学分析模型,在设定工况下比较了两者性能指标以及不可逆损失分布特性,并进一步探讨了关键参数变化对两种储能系统的性能影响。结果表明,二氧化碳电热储能系统通过将工质的压力势能进一步转化为冷能储存,从而获得了更高的储能密度(7.36 kWh/m^(3)),而液态二氧化碳储能系统通过高压罐将压力势能直接储存,避免了额外的叶轮机械损失,具有更高的循环效率(63.60%);此外,通过参数研究发现,提高压缩机等熵效率和出口压力对液态二氧化碳储能系统的性能提升更加明显,提高透平等熵效率对二氧化碳电热储能系统的提升更加明显。研究成果将为二氧化碳储能技术路径选择和技术进步提供支撑。

液氢制-储-运-加关键技术发展现状及展望

【目的】液态储运是实现氢气大规模、远距离储运,保证氢能规模化应用的有效途径之一。目前,我国针对液氢制备、储运及加注领域的研究相对较少,为此,对该领域关键技术发展现状进行了分析。【方法】对比了高压气态、液态及固态储氢技术的优缺点;综述了液氢制备过程中的主要液化方法、液氢储存绝热技术与关键材料;分析了不同液氢运输方式与装备的特点;梳理了液氢加氢站建设情况,并对比了液氢加注技术;阐述了液氢主要应用领域和产业化模式,并对近年来我国液氢储运专利技术进行了统计分析。【结论】提出了我国液氢储运发展面临的“卡脖子”难点及亟需技术攻关的方向。研究结果可为液氢关键技术的研究与装备的研制提供参考。

新型储能技术进展及应用分析

对新型储能技术进展与应用情况进行了综述。通过分析现阶段国内外储能技术发展情况,梳理了机械储能、电化学储能、电磁储能、储热技术、氢储能科研方面的进展情况,对比了不同储能技术的效率、优缺点与应用场景,总结了2023年我国储能行业的发展情况,为新能源行业的工作者提供参考。

多管阵列近等温压缩空气储能方法研究

针对压缩空气储能系统传热性能和压缩/膨胀效率低的问题,提出了一种多管阵列近等温压缩空气储能方法,设计了液体活塞结构与管式换热结构耦合的多管阵列压缩/膨胀机,液体活塞结构实现高压密封,管式换热结构增加换热面积以提高换热量,采用隔膜式结构实现气-液隔离避免空气的溶解,采用水箱储存压缩热并在空气膨胀时释放。建立了系统热力学模型和传热学模型,分析了多管束参数对空气压力、温度和压缩功的影响,使空气从0.8 MPa增压至5 MPa,采用1000根管、压缩时间60 s时,可实现空气压缩效率达到70%。为高压和高效的近等温压缩空气储能提供了一种新的方式。

非补燃液态压缩空气储能系统性能模拟研究

【目的】压缩空气储能是大容量、长周期、低成本、高效率的一种储能技术,由于气态压缩空气储能受制于储气室的苛刻要求,无法多场景、规模化推广应用,因此提出一种非补燃液态压缩空气储能系统。【方法】构建了系统理论计算模型,对系统内压缩机级间温度、压缩机级数、透平入口温度等关键参数进行了敏感性分析,同时与非补燃气态压缩空气储能系统进行了对比。【结果】压缩机级间温度过低或过高都会制约系统电-电转化效率的提升;压缩机级数与压缩机耗功呈现正相关趋势,与透平发电功率呈现负相关趋势;在入口压力相同的条件下,透平入口温度越高,发电功率越大,电-电转化效率越高;与非补燃气态储能系统相比,非补燃液态储能密度增加了3.7倍,储气室容积缩小了9/10。【结论】非补燃液态压缩空气储能系统有效解决了储气室的难题,使压缩空气储能技术能够在多场景、规模化推广应用,对火电机组深度调峰及电网大容量储能具有重要意义。

FLNG船舶能量管理系统设计与性能优化

浮式液化天然气生产储卸装置(floating liquefied natural gas system,FLNG)特种液货船作为开发海上天然气田的新式装置,极大的方便了对处于深海的气田的开发利用,该文以“Prelude”号FLNG作为母船,提出一种新型FLNG低温能量管理系统。该系统主要利用液态空气作为媒介储存和释放能量,通过液态空气冷能与混合制冷循环相结合实现天然气液化过程,在提高LNG生产性能的同时集成了CO_(2)液化循环和电力的生产,通过CO_(2)液化和剩余冷能发电提高系统的输出性能,实现了FLNG船舶冷能的多级利用,也为FLNG船舶冷能利用提供新方法,新途径。所提系统相较于基准模型具有更好的性能,在7.04年可实现成本回收。最后采用多目标性能优化,进一步提高系统㶲效率达60.67%,同时降低约2.3%的成本。该FLNG低温能量管理系统有高效、低耗、稳收益、低碳化等特点,可更好优化海上LNG供应链,促进航运业“双碳”发展。

油黏度对单螺杆膨胀机压力损失的对比实验分析

膨胀机性能对压缩空气储能系统的影响已被广泛研究。然而,仅有少数研究是集中于不可逆损失的影响,尤其是压力损失对膨胀机性能的影响往往被忽略。润滑油的加入可以达到改善压力损失的目的,为了阐明润滑油对压力损失的影响关系,以压缩空气为工作介质,采用6种不同运动黏度的润滑油对3台不同结构参数的单螺杆膨胀机在不同运行条件下进行了对比实验研究。结果表明,提高润滑油的运动黏度可以大幅减小压力损失及占比以及有效降低压力能量损失对轴效率的影响率。相反,虽然提高润滑油的运动黏度可以在一定程度上有效提高轴效率,但两者之间并不存在正比关系。

面向工程应用的先进绝热压缩空气储能模型及先进㶲分析

先进绝热压缩空气储能(advanced adiabatic compressed air energy storage system,AA-CAES)仿真建模及分析是其工程实践的基础。然而,目前模型一般基于理想工况建立,分析结果与实际工况相偏差较大,无法指导工程应用。为此,在传统热力学模型基础上,考虑了空气流动阻力损失和能量转换设备损耗等因素,建立了面向工程应用的AA-CAES模型并以200MW盐穴AA-CAES系统为例进行了分析。同时,对系统效率分析方法进行改进并对其进行了先进㶲分析。结果表明,空气管道㶲损失占总㶲损失比例接近7%,能量转换设备损耗导致电-电效率比轴功效率低5%,二者对系统性能影响较大,在进行工程设计时不可以忽略。系统各部件可避免㶲损失占比均较大,表明系统具有较大的性能提升潜力。各部件㶲损失为其内部㶲损失,与其他部件是否工作在最佳状态关系不大。

耦合液态乙烯冷能的液态空气储能系统热力学及经济性分析

液态空气储能(LAES)技术因其高储能密度和与外部能源的灵活耦合特性,成为了一种重要的大规模储能技术。构建了一种回收液态乙烯再气化废冷、引入外部低温热源的LAES系统。从热力学和经济性两方面对压缩机等熵效率、膨胀机等熵效率以及热源温度等系统关键参数进行分析,结果表明:当乙烯流量为34 t/h,储能容量可达5 MW/40 (MW·h);在90%的压缩和膨胀等熵效率下,仅依赖25℃的环境热源加热空气,往返效率为77.45%;当热源温度提升至125℃时,系统的最优往返效率、净现值及动态回收期分别达到了106.99%、14 473万元和3.56年。该研究结果能为LAES系统与外部冷能的耦合研究提供参考。

基于液态天然气冷能利用的液态空气储能系统优化与性能评估

液态空气储能(LAES)具有不受地理限制和储能密度高的特点,是有潜力的大规模储能技术。为了进一步提升LAES的系统往返效率和经济效益,提出了联合液态天然气(LNG)冷能利用和有机朗肯循环(ORC)与LAES的新型集成系统。建立了集成系统的热力学和经济性评价方法,基于仿真计算探究了关键参数对系统热力性能的影响并对系统进行了经济性分析。结果表明:随着系统膨胀压力的增大,系统效率和功率输出也增加,但是增加的幅度在减小;系统往返效率随着膨胀级数先增大再减小;采用四级膨胀时,系统的效率达到了62.26%,相较于常规的LAES系统效率提升了7%~12%;当峰谷电价差为0.848元/(k W·h)时,系统的净现值、动态回收期以及平准化度电成本分别为11905.85万元、4.48年和0.893元/(k W·h)。该研究结果可为LAES系统的工程应用和效率提升提供参考和依据。