Levelized Cost Of 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.

Powering the circular future: Climate change and economic perspectives on second‐life batteries in the Belgian context

AbstractThis paper calculates the future levelized cost of storage (LCOS) and conducts a prospective life cycle assessment (PLCA) for second‐life batteries (SLB) in Flanders, Belgium. A cradle‐to‐grave approach is chosen for climate change (CC) and economic impacts of SLB. Impacts of processes related to the first and the second life are allocated according to the delivered electricity. Furthermore, impacts are determined according to their temporal occurrence. For LCOS, activities are time adjusted by discounting. For PLCA, new background databases are generated and changed based on the activities occurrence in time. Additionally, future CC impact of three Belgian energy paths is modeled, introducing user‐defined scenarios of PLCA. To conceptualize impacts, three use cases are defined: (a) residential, (b) industrial and (c) utility use case (UTI). The residential and industrial use cases (INDs) represent photovoltaic (PV) installations with battery storage, the UTI is a large‐scale battery participating in the Belgian secondary reserve market. Lowest LCOS of the SLB in 2050 are found in the IND, namely 39.66 €/MWh, and are below the benchmark batteries. CC impact of SLB in the residential is 58.7 /kWh and below the benchmark batteries. The CC impact of SLB is 75.2 and 78.5 /kWh in the industrial and UTI and thus higher than the benchmark batteries. Crucial for both assessments are increased dismantling and repurposing facility throughput, fair charging tariffs, the manufacturing, the charging electricity generated by PV installations, and power electronics. On the contrary, changing the background does not lead to major changes in CC.

An Evaluation of the Levelised Cost of Storage of Buoyancy Energy Storage Technology at Smaller Scales

Buoyancy Energy Storage Technology (BEST) offers a promising solution to the intermittency of renewable energy sources like wind and solar. This paper aims to evaluate the feasibility of using BEST for small- scale energy storage applications. The methodology involves calculating the levelized cost of storage (LCOS) and energy capacity of two BEST variants: Fabric BEST and Reeling BEST. Results indicate that Fabric BEST can store 96 kWh per cycle with an LCOS of $356.73/MWh, while Reeling BEST stores less energy at a significantly higher cost of $683/MWh.

Multi-objective optimization and influence degree analysis of the thermally integrated HP-ORC carnot battery based on the orthogonal design method and grey relational analysis

Thermally integrated heat pump (HP)-organic Rankine cycle (ORC) Carnot battery is a promising solution for efficient energy storage and waste heat utilization. Firstly, in order to research the influence degree of the operating parameters on the system performance, single-objective optimization is conducted by the orthogonal design method. Then, multi-objective optimization is conducted by combining the grey relational analysis (GRA) and orthogonal design method to assess the comprehensive performance of the system. The importance order and contribution rates of the operating parameters and the optimal operating combinations are determined. Finally, in order to explore the influence mechanism of the parameters on the system performance, the influence of the parameters on the subsystems and the subsystems on the whole system is quantitatively analyzed. The results show that thermal storage temperature difference, waste heat temperature difference and cold source temperature are the most important parameters affecting the comprehensive performance of the whole system. Under the optimal operating conditions, round-trip efficiency, exergy efficiency, energy storage capacity (ESC), energy storage density (ESD) and levelized cost of storage (LCOS) are 47.05 %, 22.66 %, 1943 kW, 2.90 kWh/m3 and 0.38$/kWh, respectively. Compared to the ORC subsystem, the HP subsystem is more important to round-trip efficiency and exergy efficiency.

Techno-Economic Assessment of Industrial Vanadium Flow Batteries Based on Experimental Data

This work presents a techno-economic model based on experimental and market data to provide forecasts of the profitability of vanadium flow batteries (VFBs), which are emerging as a promising technology for specific stationary energy services [1‒2]. Each component affecting the capital and operative costs was analyzed and the impact of side phenomena on capacity losses was considered. Relevant economic parameters were taken from real market data: discount rate was calculated based on the Capital Asset Pricing Model (CAPM) to account for real market conditions; the electricity price follows an arbitrage strategy to profit of the daily price fluctuations taken from the historical data of the Italian energy market [3‒4]. Technical parameters are taken from large-area multi-cell stack, rather than from small single cell experiments, thus allow to characterize the behavior of real industrial reactors [5‒6]. The economic performance indicators obtained are the capital cost, the operative cost, the Levelized Cost of Storage (LCOS) and the Net Present Value (NPV). The resulting values are: a discount rate of 9.12% and electricity prices of 200 € MWh–1 in selling and of 100 € MWh–1 in buying. Capital costs and LCOS were calculated for different system power and energy (E/P) ratings. At E/P = 2 h, the values of capital costs and LCOS were in the range of 800 – 900 € kWh–1 and 0.50 – 0.55 € kWh–1, respectively, whereas at E/P = 10 h they reduced to 350 – 380 € kWh–1 and 0.29 – 0.32 € kWh–1, respectively. In addition, a NPV analysis was carried out in order to evaluate whether these capital costs could provide a profit. The analysis suggests that only at capital cost < 105 € kWh–1 the break-even point (NPV = 0) was reached. The result is that the assumed techno-economic scenario VFBs were not profitable for every considered E/P. A perspective analysis was developed to reveal when VFBs can become profitable. Different screenings were made on both technical and economic parameters. At a technical level, a power density of 0.25 W cm–2, a RTE = 85%, a SOC = 90%, and a reduced number of regenerating processes in the lifespan (Nreg = 4) were considered. Regarding the economic parameters, a discount rate of 7 % was assumed, an electricity selling price of 250 € MWh–1 and a purchasing price of 75 € MWh–1 were used, compatible with a more pronounced Duck Curve of the daily electricity price, induced by the expansion of renewable energy sources expected in the near future. Under this scenario, the system costs decreased considerably: at E/P = 2 h, the Capital Costs and LCOS ranged as 530 – 570 € kWh–1 and 0.25 – 0.27 € kWh–1, respectively, whereas at E/P = 10 h, the Capital Costs and LCOS ranges as 260 – 270 € kWh–1 and around 0.17 € kWh–1, respectively. The latter figures made VFBs profitable for E/P in the range of 4 – 10 hours, as shown in the figure below.

Harvesting energy horizons: Bifacial PV and reversible fuel cells unite for sustainable building solutions

This study explores the integration of bifacial photovoltaic (PV) panels with proton exchange membrane (PEM) reversible fuel cells (RFC) to enhance renewable energy storage across various U.S. climates. It assesses the impact of environmental variables like sunlight exposure, climate fluctuations, and energy demands on system efficiency and resilience. The cities considered in the study were Tucson, Los Angeles, Denver, Dallas, and Minneapolis. Each city was chosen for its unique climatic characteristics, ranging from the arid heat of Tucson to the cold temperatures of Minneapolis. This diverse selection helps to evaluate the system's performance and economic viability across a broad spectrum of environmental conditions. Economic analysis focuses on metrics such as the Levelized Cost of Electricity (LCOE), Levelized Cost of Hydrogen (LCOH), and Levelized Cost of Storage (LCOS). Findings indicate significant economic benefits through varying bifacial PV gains from 0 to 20% yield with reductions in LCOE by 16%, LCOH by 14%, LCOS by 13%, and overall system LCOE by 18%. The results highlight the potential of bifacial PV and PEM-RFC systems to boost energy yield and economic efficiency amid dynamic environmental conditions. This analytical framework offers detailed insights into the economic viability and advantages of these systems in different climatic zones in the United States.

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.

Exploiting green energy potential via FinTech: The role of DLT-based crowdfunding in PV and ESS investments

This article explores the interplay of green energy potential and innovative financial technology (FinTech). To achieve this, an in-depth study on the technological, economic, and environmental aspects of residential-scale solar energy and storage investments was performed. As the first part of the study, residential-scale solar energy and associated energy storage investments were modeled in the assessed countries. As the next step, the effects of Distributed Ledger Technology (DLT) enabled crowdfunding on the modeled investments were highlighted with a Proof-of-Concept (PoC) DLT-enabled investment tool. As the last step, the Life Cycle Assessments (LCAs) of the investments were carried out for each of the assessed countries in order to provide better investment decisions to various investors. The results of this research indicate that with the integration of novel Fintech tools, the Levelized Cost of Storage (LCOS) values of the assessed investments may be reduced by up to 58%. Meanwhile, the LCA results highlighted that solar silicon production and battery cell manufacturing have the highest LCA results, accounting for 19.1 and 63.8 kgCO2eq/kWh respectively. Meanwhile, the transportation sector had an emission of 9 kgCO2eq/kWh. Thus, with cleaner manufacturing and transportation, the emissions from PV and ESS investments may be reduced drastically.

Integrating Life Cycle Principles in Home Energy Management Systems: Optimal Load PV–Battery–Electric Vehicle Scheduling

Energy management in the residential sector contributes to energy system dispatching and security with the optimal use of renewable energy systems (RES) and energy storage systems (ESSs) and by utilizing the main grid based on its state. This work focuses on optimal energy flow, ESS parameters, and energy consumption scheduling based on demand response (DR) programs. The primary goals of the work consist of minimizing electricity costs while simultaneously extending the lifetime of ESSs in conjunction with extracting maximum benefits throughout their operational lifespan and reducing CO2 emissions. Effective ESS and photovoltaic (PV) energy usage prices are modeled and an efficient energy flow management algorithm is presented, which considers the life cycle of the ESSs including batteries, electrical vehicles (EVs) and the efficient use of the PV system while reducing the cost of energy consumption. In addition, an optimization technique is employed to obtain the optimal ESS parameters including the size and depth of discharge (DOD), considering the installation cost, levelized cost of storage (LCOS), winter and summer conditions, energy consumption profile, and energy prices. Finally, an optimization technique is applied to obtain the optimal energy consumption scheduling. The proposed system provides all of the possibilities of exchanging energy between EV, battery, PV system, grid, and home. The optimization problem is solved using the particle swarm optimization algorithm (PSO) in MATLAB with an interval time of one minute. The results show the effectiveness of the proposed system, presenting an actual cost reduction of 28.9% and 17.7% in summer and winter, respectively, compared to a base scenario. Similarly, the energy losses were reduced by 26.7% in winter and 22.3% in summer, and the EV battery lifetime was extended from 9.2 to 19.1 years in the winter scenario and from 10.4 to 17.7 years in the summer scenario. The integrated system provided a financial contribution during the operational lifetime of EUR 11,600 and 7900 in winter and summer scenarios, respectively. The CO2 was reduced by 59.7% and 46.2% in summer and winter scenarios, respectively.

Renewable green oil as a low-cost option for large-scale, long duration energy storage to produce on-demand electricity

&lt;p class="MsoNormal" style="text-align: justify;"&gt;&lt;span style="font-size: 14pt; font-family: 'times new roman', times, serif;"&gt;The rapid growth of renewable solar and wind energy necessitates extensive, long-term energy storage solutions to stabilize the electric grid and address the intermittent nature of these sources. In the absence of cost-effective long-duration, large-scale (LDLS) energy storage, there is a risk of increased disruptive blackouts and brownouts as intermittent energy sources approach 50% of electricity generation. Our analysis underscores volumetric energy density as a pivotal determinant in LDLS energy storage solutions, which is particularly crucial during periods of diminished renewable resource availability, such as the rainy season. Despite emphasis on conventional electric batteries and mechanical storage technologies such as compressed air and pumped hydro for LDLS, their costs pose a significant obstacle to widespread adoption, especially in emerging economies. In this study, we present a groundbreaking approach to LDLS: on-demand electricity generation from carbon-neutral renewable oil, known as "green oil," leveraging Reliance&amp;rsquo;s innovative catalytic hydrothermal liquefaction (R-CAT-HTL) technology. Our investigation evaluated two distinct sources of green oil production: organic waste streams (e.g., municipal solid waste, agricultural-waste, etc.) and on purpose production of algal biomass. We demonstrate that burning renewable green oil to produce electricity offers a cost-effective solution for large-scale (GWh) long-duration (many days) energy storage, ensuring the stability, reliability, and resiliency of the electric grid. We also demonstrate that minimum 14 days, ideally 30 days energy storage is needed for continuous uninterrupted service, especially critical for manufacturing facilities. Through a meticulous levelized cost of storage (LCOS) analysis comparing green oil with other LDLS technologies reported in literature, we demonstrate the cost effectiveness of green oil. In this model, green oil serves as stored energy, functions akin to a battery and is efficiently converted into electricity through conventional reciprocating engines or next-generation more efficient turbines. Our findings suggest that green oil derived from diverse organic sources is the most economically viable option for GWh-scale storage, particularly when storage requirements extend beyond a single day. This research thus presents a transformative cost-effective solution to the pressing challenge of LDLS energy storage, accelerating a sustainable and resilient energy future.&lt;/span&gt;&lt;/p&gt;

Multivariate multi-objective collaborative optimization of pumped thermal-liquid air energy storage

Pumped thermal-liquid air energy storage (PTLAES) is a novel energy storage system with high efficiency and energy density that eliminates large volumes of cold storage. In this study, three different configurations of PTLAES systems with direct and indirect thermal energy storage were proposed. The “adaptive segmentation-based temperature transfer matrix” method was developed to capture the heat transfer characteristics of multi-stream plate-fin heat exchangers (MPFHEs), which is the key component of the system. To determine the upper limit of the techno-economic performance of the system, single/multi-objective optimization was performed with up to 35 decision variables. Additionally, the “Pareto efficiency” concept was defined to quantify the goodness of a point compared to the Pareto front. The results showed that the irreversible heat transfer and pressure drop in MPFHEs contribute 20.6 %–44.3 % of the total exergy destruction. Therefore, the design of MPFHEs significantly impacts the system performance. Multivariate multi-objective collaborative optimization can significantly improve the optimization results. PTLAES with closed loop indirect thermal energy storage was determined to have the best overall performance, achieving round-trip efficiency of 63.3–70.1 %, levelized cost of storage (LCOS) of 0.162–0.181 $/kWh, and energy density of 122–161 kWh/m3. The optimized PTLAES system can achieve lower LCOS than lithium-ion batteries when the discharge duration exceeds 3.5 h. Furthermore, it was shown that key criteria including round-trip efficiency, LCOS, and energy density can be traded off over a broad design space of different system configurations, parameter combinations, and material choices. This research demonstrated that PTLAES is a promising choice for long-duration energy storage and provided guidance for the design and techno-economic optimization of PTLAES systems.

Life Cycle Analysis of Energy Storage Technologies: A Comparative Study

This study offers a thorough comparative analysis of the life cycle assessment of three significant energy storage technologies—Lithium-Ion Batteries, Flow Batteries, and Pumped Hydro—evaluating their environmental, economic, and social aspects in a complete manner. When considering the environmental effect, it is evident that Lithium-Ion Batteries surpass Flow Batteries and Pumped Hydro in terms of carbon footprint, water use, and land utilization. Flow Batteries and Pumped Hydro exhibit significant decreases, ranging from 40% to 60%, showcasing their potential as ecologically sound alternatives with heightened sustainability advantages. From an economic standpoint, it can be confidently said that Flow Batteries and Pumped Hydro surpass Lithium-Ion Batteries in terms of both capital and operational expenses, resulting in a decreased Levelized Cost of Storage (LCOS). The examination of percentage change showcases significant decreases, ranging from 20% to 50%, underscoring the economic competitiveness of Flow Batteries and Pumped Hydro. Regarding societal consequences, Flow Batteries and Pumped Hydro exhibit a propensity for heightened job production, augmented community acceptability, and enhanced health and safety records in contrast to Lithium-Ion Batteries. The assessments of percentage change further underscore the societal benefits of Flow Batteries and Pumped Hydro, demonstrating a substantial increase of 40% to 100% in job creation, a notable rise of 6.25% to 12.5% in community acceptability, and a significant decrease of 50% to 75% in health and safety problems. These results jointly emphasize the comprehensive benefits of Flow Batteries and Pumped Hydro, indicating their potential as sustainable, cost-effective, and socially responsible energy storage options. Given the ongoing evolution of the energy landscape, the findings obtained from this research greatly enhance the ability of stakeholders and policymakers to make well-informed decisions in their efforts to design a more environmentally friendly and robust energy future. The study emphasizes the significance of taking into account not only the technological efficacy, but also the wider environmental, economic, and social circumstances when implementing energy storage technology.

Off-design performance evaluation of thermally integrated pumped thermal electricity storage systems with solar energy

Pumped thermal electricity storage that integrates with low-grade heat source (thermally integrated PTES, TI-PTES) have gained widespread attention due to the superior performance compared to traditional PTES systems. In this work, a TI-PTES system integrated with solar energy is constructed. R1233zd(E) is employed as the working fluid in the system. Select solar data from four typical days (Vernal Equinox, Summer Solstice, Autumn Equinox, Winter Solstice) throughout the year in Chuxiong City, Yunnan Province, which has abundant solar resources. Design conditions for the system are determined by a multi-objective optimization approach, and based on this, the off-design performance of both the charge and discharge processes are studied. The off-design models for the main components of the system are established. In the charge process, the weather conditions from 10:00 to 15:00 on a typical day are selected for a 6-hour charge period, and a parameter analysis of the system is conducted under different weather conditions. In the discharge process, the off-design performance of the system under different load levels is analyzed for two operating modes: constant pressure mode and variable pressure mode. The results indicate that in the charge process, the values of the compressor power under off-design conditions (Wcomp,off), the mass flow rates of the heat pump system (mRHP), and thermal energy storage system (mts) of Winter Solstice are the highest from 11:00 to 15:00 compared to the other 3 days. In the discharge process, the power-to-power efficiency (ηPTP) and Levelized Cost of Storage (LCOS) of the Vernal Equinox and Autumn Equinox reach their maximum (74.47 %) and minimum (0.247 $·kWh−1) values at an 80 % load level under variable pressure mode. Under constant pressure mode, the power-to-power efficiency and LCOS of the Vernal Equinox and Autumn Equinox reach their maximum (74.34 %) and minimum (0.232 $·kWh−1) values at 70 % and 40 % load levels. Comparing the off-design performance between the variable pressure mode and constant pressure mode in the discharge process, the variable pressure operation mode is recommended for load levels between 78 % and 85 %, while the constant pressure operation mode is recommended for load levels between 40 % and 78 %, as well as between 85 % and 120 %. The obtained results can serve as a reference for the off-design performance analysis of TI-PTES.

Non-Saturated 3E (Energy, Exergy, and Economic) Analysis of Carnot Battery Systems Based on Organic Rankine Cycle

Artificial activities, environmental factors, and industrial production lead to periodic fluctuations in electricity consumption, necessitating peak-shaving measures to ensure efficient and stable operation of the power grid. The Carnot battery system represents an effective solution due to its high efficiency and convenience. In this paper, we propose a novel Carnot battery system based on a dual-function unit and establish thermodynamic and economic models. This paper proposed a simple reversible heat pump-organic Rankine cycle Carnot battery system, where a compression and expansion dual-function unit was developed to simplify the system and reduce investment costs. Subsequently, considering the unsaturated operating conditions that occur during practical operation, a comprehensive performance analysis of the system is conducted by varying pressure and temperature parameters. Afterward, an exergy analysis is performed on the proposed system to determine the exergy losses of its components for subsequent optimization. The results indicate that pressure drop has a detrimental effect on the system. When the pressure drop is 15 kPa, the system achieves a power-to-power ratio (P2P), levelized cost of storage (LCOS), and exergy efficiency of 27.57%, 0.66 $/kW∙h, and 62.8%. However, this also leads to increased exergy losses in the evaporator, resulting in decreased exergy efficiency. The evaporator exhibits the highest exergy loss, with a maximum loss of 21.16 kW among all components. Undercharging mode, the condenser shows the lowest exergy efficiency of 64.43%.

Real-time modeling and optimization of molten salt storage with supercritical steam cycle for sustainable power generation and grid support

This research article presents an innovative approach to enhance sustainable power generation and grid support by integrating real-time modeling and optimization with Molten Salt Energy Storage (MSES) and a Supercritical Steam Cycle (s-SC). As renewable energy usage grows, intermittent resource availability challenges grid stability and reliable power supply. To address this, we develop a system that merges real-time modeling and optimization for precise control of MSES and s-SC components. This integration ensures uninterrupted energy generation, storage, and distribution, optimizing renewable energy use during high-demand periods. Mathematical models and simulations assess the system's dynamic behavior, performance, and economic viability. Rigorous techno-economic analysis highlights cost-effectiveness and environmental benefits. Findings reveal exceptional energy efficiency and grid support, making it a promising solution for sustainable power generation and grid stability amid renewable energy growth. Real-time modeling and optimization emerge as crucial components in modern energy systems. The Combined Heat and Power (CHP) system achieves 56% energy efficiency with off-design impacts considered and 63.61% without. Also, the overall system exergy efficiency decreased from 73.36% at design to approximately 63.55% under off-design scenarios. Regarding the economic aspect, the levelized cost of storage (LCOS) for the CHP system is estimated at 114.4 €/MWh with off-design conditions and 106.8 €/MWh without.

Challenging Prevalent Solid Electrolyte Interphase (SEI) Models: An Atom Probe Tomography Study on a Commercial Graphite Electrode.

Lithium-ion batteries (LIBs) are the dominating energy storage technology for electric vehicles and portable electronic devices. Since the resources of raw materials for LIBs are limited and recycling technologies for LIBs are still under development, improvements in the long-term stability of LIBs are of paramount importance and, in addition, would lead to a reduction in the levelized cost of storage (LCOS). A crucial limiting factor is the aging of the solid electrolyte interphase (SEI) on the active material particles in the anode. Here, we demonstrate the potential of atom probe tomography for elucidating the complex mosaic-type structure of the SEI in a graphite composite anode. Our 3D reconstruction shows unseen details and reveals the existence of an apolar organic microphase pervading the SEI over its entire thickness. This finding is in stark contrast to the prevalent two-layer SEI model, in which organic compounds are the dominating species only in the outer SEI layer being in contact with the liquid electrolyte. The observed spatial arrangement of the apolar organic microphase promises a better understanding of the passivation capability of the SEI, which is necessary to expand the battery lifetime.

Cogeneration systems of solar energy integrated with compressed air energy storage systems: A comparative study of various energy recovery strategies

Compressed air energy storage (CAES) is considered to be one of the most promising large-scale energy storage technologies to address the challenges of source-grid-load-storage integration. However, the integration strategies of CAES with renewable energy sources (RES), driven by the goal of enhancing system efficiency, have not been fully explored. In this paper, a unique energy allocation strategy is introduced for a CAES system when coupled with solar energy. Intermittent solar energy is transformed into a consistent heat source, jointly preheating the air entering the turbines with compression heat. Besides, three cogeneration systems with different waste heat recovery strategies are designed and compared. Based on the basic integration of CAES and solar collection system (SCS), heat pump (HP) and organic rankine cycle (ORC) are progressively introduced to recover waste heat from compressors and SCS, respectively. Finally, parametric studies and energy, exergy, economic (3E) analysis for the three cogeneration systems are conducted. The results show that the system integrated with HP presents the best system power efficiency (SPE) of 38.9% and system energy efficiency (SENE) of 99.6%. The basic integration system presents the best power-to-power (P2P) efficiency of 57.4%. Additionally, it offers the best economic performance with a levelized cost of storage (LCOS) of 0.520 $/kWh. Besides, the introduction of HP can improve the economic and electricity conversion performance when the air release pressure is in the low-pressure region, but also increases exergy destruction caused by the large temperature difference of heat exchangers. The introduction of ORC raises the overall costs caused by its complex components, but has little effect on system exergy destruction. Finally, by comparing with existing studies, the superiority of the proposed CAES and SCS integration strategy is validated.

Evaluation and optimization of an engine waste heat assisted Carnot battery system for ocean-going vessels during harbor stays

The pollution and environmental damage caused by ship emissions during docking is an urgent issues that needs to be addressed. In this study, a jacket water waste heat Carnot battery (JCB) system is designed as an energy storage device to recover the water waste heat of the ship's main engine cylinder liner and as a power output device when the main engine stops in port. The JCB system is evaluated and optimized from the perspectives of thermodynamics, exergy, and cost, with a focus on the performance under different working fluid combinations. The results show that improving the efficiency of the compressor, turbine, and recuperator can significantly enhance the system's performance, with the compressor and turbine being the most expensive components. The heat exchanger has the highest exergy destruction, accounting for almost half of the total system. In the multi-objective optimization of different working fluid combinations, R365mfc/R365mfc is found to be the best choice, with the power-to-power efficiency of the system reaching 110.15 % and the 5-year levelized cost of storage (LCOS) being 0.139 $/kWh. A case study of the actual route shows that the JCB system designed in this paper can meet the power demand of 100 %, 35.5 %, 61.91 %, and 56.9 % in the four segments during harbor stays. The JCB system proposed in this study provides a new solution for the reduction of emissions and environmental protection during the docking of ships.

Integration of ocean thermal energy conversion and pumped thermal energy storage: system design, off-design and LCOS evaluation

Increasing the penetration of Variable Renewable Energy (VRE) in electric generation systems is a fundamental goal in reducing greenhouse gases emission. To reduce power fluctuations in electricity networks and avoid curtailment, large-scale energy storages represent one of the most promising solutions. Thermally-Integrated Pumped Thermal Energy Storage (TI-PTES) systems are an interesting technology that can be used for this scope if the heat source adopted for thermal integration can provide significant thermal power. The ocean temperature gradient in tropical areas is an attractive heat source to be coupled with the PTES system to realise efficient electric storage when integrated with an Ocean Thermal Energy Conversion (OTEC) system. In this study, a heat pump refrigerated by the warm tropical surface water uses electricity surplus from VRE to heat an amount of water contained in an end-life cargo ship used as water storage. The system discharges the stored energy through an ORC cycle refrigerated by the cold deep seawater when VRE production is low. A preliminary sensitivity analysis of the storage size and temperature is proposed through detailed system modelling to define the optimal design and layout. Therefore, the part-load analysis of the system is assessed to characterise the off-design performances and evaluate the potentialities of this system when applied to a plausible case study that includes VRE generation and an electric demand profile. Finally, the Levelised Cost Of Storage (LCOS) is evaluated and compared to other storage technologies. Results show that the round-trip efficiency may achieve values higher than 60 %, and an equivalent electric battery capacity of 20 MWh is feasible using end-life ships acting as energy storage. In contrast, the obtained LCOS of 388 €/MWh is still not competitive in the energy market. However, since tropical areas have high energy prices, considering this application for remote island electrification could be an interesting solution.

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.