Option For Thermal Energy Storage Research Articles

Manufacturing and performance of eco-efficient cementitious blocks for thermal cycling in thermal energy storage

Solar energy is a promising renewable option to provide energy demands in combination with conventional energy sources. However, to enhance the integration of renewable energies into the industrial section, it is necessary to employ thermal energy storage media. Among different thermal energy storage options, concrete has proven to be a very effective sensible thermal energy storage solution. However, its main raw material (i.e., the Portland cement), is the cause of huge CO2 emissions to the environment. This study focuses on the design, manufacture, assembly and experimentation of thermal energy storage blocks made of alternative binders in substitution of Portland cement: i.e., hybrid materials and alkaline activated materials. The thermal energy storage blocks have been thermally cycled, with a charging temperature of 228 °C and a discharging temperature of 30 °C, in order to analyze the operational times and temperatures. The results obtained are very promising and comparable to those of the Portland cement system. Charging times have improved, with the alternative materials achieving temperature increases of up to 4%, while greater stabilization has been achieved during discharge, with the fluid reaching temperatures up to 6% higher than the reference system. These advancements support efficient, sustainable thermal energy storage technologies.

Quick charging adsorption-based thermal energy storage system

This work presents the computational modeling of a fast-charging battery-like thermal energy storage system using a heat exchanger with adsorbent-coated microchannels and a condenser. The utilization of microchannels leads to an extreme asymmetry in the operation of the energy storage system, where the charging time becomes <10 % of the total cycle time. When the system is charged with a 90 °C heat source, it can recover heat at the same temperature for ten times longer. Using silica gel as the adsorbent and water as the medium, this system can store up to 70 kWh m−3 of heat, which is >3.5 times energy over the conventional thermal energy storage options, including latent and sensible heat techniques. Additional advantages of this system include a perfectly scalable operation, flexibility to use diverse adsorbents and refrigerants and location independence, warranting a detailed experimental validation.

A novel trigeneration energy system with two modes of operation for thermal energy storage and hydrogen production

This article introduces a new trigeneration system designed to meet the escalating energy demands by harnessing solar energy. Notably, the system features dual-mode operation and integrates ultrasound technology for hydrogen production, enabling it to adapt to varying levels of energy production by seamlessly transitioning between two modes. Through comprehensive energy, exergy, and environmental analyses, this study evaluates the system's performance and its environmental advantages. The results demonstrate that the system achieves the energy and exergy efficiencies of 58.28 % and 76.75 %, respectively. Moreover, it demonstrates that, under sunlight conditions, the system can produce hydrogen at a rate of 1 kg/h and deliver a power output of 1957 kW. During the periods utilizing a thermal energy storage option, the system is capable of generating hydrogen at 0.8 kg/h and an electrical power output of 1481.2 kW. The environmental analysis indicates that the system is eco-friendly, with the potential to reduce carbon dioxide emissions by 4.54 kg/kWh. These results underscore the system's efficiency and its contribution toward a more sustainable and environmentally friendly energy future.

Performance and environmental impact evaluations of a novel multigeneration system with sonic hydrogen production and energy storage options

This article designs and develops a unique system integrated with hydrogen production and energy storage effectively to meet the variable energy demands of residential communities by harnessing both solar and geothermal energies. The system features a synergy of technologies, including a steam Rankine cycle, an ammonia-water-based double-effect absorption system, two organic Rankine cycles, a thermal energy storage, battery and hydrogen storage options, and a sonohydrogen production device. In order to develop a new system for producing cooling, electricity, heat and hydrogen, the present study dives deep into an analysis based on energy and exergy approaches using balance equations. The present system has the ability to generate 0.0016 kg/s of hydrogen, creates a net output of 2177 kW, supplies 4337 kW for heating purposes, and offers 903.8 kW of cooling capacity. In addition, the system's performance was rigorously evaluated, revealing an energy efficiency of 83.28 % and an exergy efficiency of 58.71 %, with energetic and exergetic coefficients of performance (COP) of 1.646 and 0.6215, respectively. Additionally, an environmental impact assessment was conducted, focusing on CO2 emissions to gauge the system's sustainability. This assessment further indicates that the system could potentially avoid the release of 3.351 kg of carbon dioxide per kilowatt-hour into the atmosphere which might have come from conventional systems.

Performance assessment of compressed air energy storage systems with and without phase change materials

In this study, two integrated hybrid solar energy-based systems with thermal energy storage options for power production are proposed, thermodynamically analyzed and comparatively evaluated. The first system uses an underground cavern to store compressed air energy. When electricity production is high during the day, a compressor set pressurizes the air and directs it to the storage unit. A heat transfer model is developed to determine temperature variations and heat losses through the cavern walls. During the insufficient solar radiation period, the compressed air inside the cavern is discharged to meet the energy needs. The second energy storage system employs a cascade latent heat storage approach to reduce heat dissipation within the cavern. The temperature of the compressed hot air gradually decreases as it passes through three-stage phase change material (PCM) units. The cascaded PCMs help reduce the temperature differences between the storage media and minimize the exergy destruction rates. Similar to the first energy storage option, the pressurized air is stored in an underground cavern. The compressed air is then discharged and passes through the latent heat storage medium in the energy recovery mode, eventually reaching the turbine inlet temperature. Finally, the high-pressure and high-temperature air drives the gas turbine and hence generator to generate electricity. The thermodynamic quantities, including energy and exergy efficiencies and exergy destruction rates, are determined for all system elements and comparatively assessed. Furthermore, a comprehensive evaluation of the thermodynamic performance criteria of these energy storage options is carried out.

Enhancing solar absorption and reversibility in calcium looping-based energy storage via salt-promoted CaO

Calcium looping (CaL)-based solar to thermochemical energy storage is a promising option for long-term thermal energy storage in concentrated solar power generation. CaL is a chemical looping process involving reversible carbonation-calcination reactions among CaO, CO2, and CaCO3, which has distinct advantages, such as high energy storage density at high operating temperatures. However, the low optical absorption of CaO limits its application as a direct solar absorbing material, and the continuous reduction of reactivity through CaL reactions degrades the energy storage ability. In this work, we investigated the multi-doping of transition metals Fe, Co, Ni, and CaCl2 to improve optical absorption and promote the carbonation reactivity of synthetic CaO-based materials. The synthetic CaO materials were synthesized by acetic acid-based wet mixing and sol–gel method. Proposed materials exhibited significantly enhanced optical absorption up to 88%, preserved within 78 – 85% throughout 45 cycles of CaL reactions. The production and regeneration of Ca2FeO3Cl are expected to enhance optical absorption. The CaL reaction analysis revealed better carbonation conversion performance holding with cyclic stability, achieving 1.94 MJ/kg for 50 cycles or 1.17 MJ/kg for 100 cycles. The reaction mechanism was investigated using in-situ high-temperature XRD, and a salt-promoted carbonation mechanism is proposed, which consists of Ca2FeO3Cl carbonation and carbonation in a molten salt phase, improving the mass transfer of Ca2+O2– to adsorbed CO2. Based on the findings, we suggest the synergistic use of the CaCl2 multi-doping method for synthetic CaO designs.

A solar driven hybrid sulfur cycle based integrated hydrogen production system for useful outputs

Renewable energy resources play a critical role in taking the place of fossil fuels to slow global warming. To make better use of these sources, multigenerational integrated systems that generate multiple beneficial outputs from the same inputs are required. This study describes a multigeneration system that utilizes a hybrid sulfur (HyS) cycle to produce hydrogen. The HyS cycle is a thermochemical-electrochemical cycle that relies on high-grade heat to function effectively. Concentrated solar power (CSP) technology, specifically solar power towers, can provide the high-grade heat required for the cycle. A thermochemical heat pump is also integrated into the current system to achieve the 800 °C temperature required for SO3 decomposition. In this regard, a multigeneration solar tower-based system with a thermal energy storage option is proposed to generate useful outputs of hydrogen and freshwater. The energy and exergy efficiencies for the overall system are determined to be 8.15% and 3.73%, respectively. Furthermore, this integrated system represents a promising solution for renewable hydrogen production and freshwater generation.

Experimental and numerical study on the thermocline behavior of packed-bed storage tank with sensible fillers

Packed-bed thermocline tank with sensible fillers is a cost-effective option for thermal energy storage (TES). In real charging and discharging, the thermocline stability is disturbed and thermocline expansion occurs due to various factors, leading to the decreased global performances of storage tank. The purpose of this work is to experimentally and numerically study the impact of inlet configuration and insulation on the thermocline expansion in a lab-scale tank under various operating parameters. Firstly, a DC-3P model considering the wall effect and heat loss is developed and validated by experimental results, capable of precisely predicting the performance of storage tank under the tested conditions. Especially, the temperature difference between the fluid and solid filler center is detected both in experiments and in modeling, indicating the existence of temperature gradient inside large solid particles. Results also show that the injecting flow causes the radial temperature non-uniformity and thermocline expansion at the near-entrance region of the tank, but its effect on the global performance of the storage tank is rather limited. Good insulation of the tank could reduce the thermocline thickness by about 20%, and increase the energy efficiency and the capacity ratio by 5–7% and 3–5%, respectively.

Thermal Energy Storage Options: Comparisons between Molten Salt, Liquid Air, and Liquid Nitrogen Technologies

Thermal energy storage is crucial for the transition to a low-carbon, renewable energy future. This literature review critically compares and contrasts three sustainable thermal energy storage technologies: molten salt, liquid air energy storage (LAES), and the liquid nitrogen engine (LNE). Molten salt systems have a high energy density and long thermal stability, but are restricted by their high cost and maintenance needs. LAES has a high energy density and low environmental impact, yet suffers from low efficiency. LNE is highly efficient but limited to low-power applications and needs a high-pressure storage tank. Each technology has its benefits and drawbacks, and the most appropriate technology will depend on the specific application. Molten salt may be suitable for large-scale projects, LAES for urban environments and LNE for low-power applications. Therefore, research and development in thermal energy storage should focus on improving efficiency, and cost-effectiveness and exploring new technologies to aid in the transition to a low-carbon, renewable energy future.

Experimental analysis of hydrogen storage performance of a LaNi5–H2 reactor with phase change materials

Energy storage, especially thermal energy storage, has an important place in terms of efficient use of energy. Systems in which phase change materials (PCMs) are used are among the thermal energy storage (TES) options, thanks to their advantages such as energy storage at almost constant temperature. The use of PCM as a TES material in the metal hydride (MH) reactor is an influential method to store the heat released by the exothermic reaction occurring in the hydrogen charging process and to recover this heat with the endothermic reaction occurring in the hydrogen discharge process. In the present study, hydrogen charge and discharge processes in a LaNi5–H2 reactor were experimentally investigated and compared with and without PCM. Therefore, a hybrid system was designed by integrating PCM around the cylindrical MH reactor filled with LaNi5 alloy. The hydration process was carried out at both constant pressure and variable pressure. The temperature changes on the reactor surface and inside the PCM were measured over time. In experiments to determine the change in the amount of hydrogen stored in MH reactors over time, it was determined that the hydrogen storage pressure and reactor design significantly affect the hydrogen charge-discharge rate. Considering the use of MH reactors in transportation vehicles such as automobiles and submarines, designing a hybrid MH-PCM storage system is promising for the development of hydrogen storage technologies and transportation technologies.

Selection of energy storage technologies under neutrosophic decision environment

The variability of renewable energy can be addressed by incorporating energy storage technologies (ESTs). Multiple energy storage technologies are available for renewable energy with wide disparity in attributes. Reports regarding the attributes are conflicting and complex, which makes it a multi-attribute decision analysis problem. To address this issue, new decision support tools are needed to aid in selecting ESTs based on their technical, environmental, and economic characteristics. In this study, a neutrosophic data envelopment analysis (NDEA) technique is developed and applied to selection of ESTs considering neutrosophic uncertainty inherent in new technologies. The decision tool systematically evaluates EST options by considering the expert's degree of satisfaction for higher technical performance, degree of dissatisfaction for lower technical performance and degree of indeterminacy for attaining better technical performance. Two case studies adapted from literature are used to illustrate the decision support tool. The first case study, which is used to demonstrate the tool for EST selection, involves the selection of thermal energy storage options. The second case study involves eight ESTs with different mechanisms: supercapacitor, flywheel, compressed air energy storage, pumped hydro energy storage, Li-ion battery, NiCd battery, NaS battery, and Pb-acid battery. The results reveal certain ESTs that are preferred over wide range of expert's perception to uncertainty in terms of dissatisfaction and indeterminacy. For example, Li-ion battery is DEA efficient if the risk tolerance for indeterminacy is greater than 40% and Pb-acid battery is DEA efficient at falsity tolerance greater than 80% and indeterminacy tolerance of less than 5%. These alternatives can be regarded as robust choices. Insights gained from the application of the decision tool can be used for guiding investment decisions in planning of renewable energy systems with energy storage.

Thermo-economic analysis of steam accumulation and solid thermal energy storage in direct steam generation concentrated solar power plants

In direct steam generation (DSG) concentrated solar power (CSP) plants, a common thermal energy storage (TES) option relies on steam accumulation. This conventional option is constrained by temperature and pressure limits, and delivers saturated or slightly superheated steam at reduced pressure during discharge, which is undesirable for part-load turbine operation. However, steam accumulation can be integrated with sensible-heat storage in concrete to provide higher-temperature superheated steam at higher pressure. In this paper, this conventional steam accumulation option (existing) and an integrated concrete-steam TES option (extended) are described and analysed, and their thermo-economic performance are compared taking the 50-MW Khi Solar One DSG CSP plant in South Africa as a case study. The results show that the extended option with five 10-m long, square cross-section concrete blocks, each with 3600 equally spaced tubes, provides an additional TES capacity of 177 MWh compared to the existing configuration as a result of utilising most of the available thermal power in the solar receivers. Moreover, the extended option delivers 58 % more electricity with a 13 % enhancement in thermal efficiency during TES discharging mode. With an estimated additional investment of $4.2M, the levelised costs of storage and electricity for Khi Solar One with the extended TES option are, respectively, 29 % and 6 % lower than those obtained with the existing TES option. With the extended TES option, the projected net present value of Khi Solar One increases by 73 %, from $41M to $71M, at an average electricity price of 280 $/MWh.

A Numerical Parametric Study of a Double-Pipe LHTES Unit with PCM Encapsulated in the Annular Space

Latent heat thermal energy storage (LHTES) with Phase Change Materials (PCM) represents an interesting option for Thermal Energy Storage (TES) applications in a wide temperature range. A tubular encapsulation model of an LHTES with PCM was developed, and the calculated data were analyzed. In addition, a parametric analysis for the preferable system geometry is presented. Organic paraffin RT18 with a melting point of 18 °C was utilized as PCM for different geometries of LHTES, and the addition of internal and external fins and their influence on LHTES thermal conductivity was investigated. One-step heat exchange from outdoor air to PCM and from PCM to water characterizes the LHTES system in solidification and melting processes, respectively. A 2D axisymmetric model was developed using Comsol Multiphysics 6.0. The LHTES unit performance with PCM organic paraffin RT18 encapsulated in electrospun fiber matrices was analyzed. The study results show that longer internal fins shorten the melting and solidification time. Direct contact of PCM electrospun fiber matrix with 23 °C water showed instant melting, and the phase change process was accelerated by 99.97% in the discharging cycle.

Thermo-economic optimization of the thermal energy storage system extracting heat from the reheat steam for coal-fired power plants

• Thermal energy storage options with reheat steam as a heat source are introduced. • A energy-exergy-economic comparison of three heat storage options is investigated. • Minimum power load ratio of thermal power system can be reduced by 12%-points. • The largest round-trip efficiency is achieved at 67.54% by two-stage heat storage. • Sensible and latent hybrid heat storage has economic advantages than other options. The load cycling range enlargement of thermal power plants is essential to ensure the power grid stability, which can facilitate the penetration of large-scale renewable power. If a part of reheat steam is extracted from the intermediate pressure turbine inlet to the thermal energy storage system, the minimum power load of the coal-fired power plant can be decreased. Moreover, constructing a thermal energy storage system extracting heat from the reheat steam is relatively easy because no modification on the boiler system is required. The reheat steam carries some sensible heat and much latent heat, and how to store the heat efficiently and cost-effectively is investigated in this study. Three thermal energy storage configurations are introduced: configuration A, as a basic configuration, one-stage sensible heat storage; configuration B applied two-stage sensible heat storage; and configuration C applied sensible and latent hybrid heat storage. Thermodynamic and economic performance of three thermal energy storage systems is evaluated and compared. The results show that integrating the thermal energy storage allows the minimum power load to be reduced from 30% to 17.64% of the rated load. Configuration B achieves the largest equivalent round-trip efficiency (67.54%), which is higher 2.56% than that of configuration A, and configuration C exhibits the lowest total cost of the equipment and storage materials (14.75 million USD) and levelized cost of delivery (143.98 USD/MWh), which is 5.94 million USD and 12.69 USD/MWh lower than those of configuration A.

A structured procedure for the selection of thermal energy storage options for utilization and conversion of industrial waste heat

Thermal energy storage is a key enabling technology for the recovery and valorisation of industrial waste heat. Nevertheless, there is a wide gap between the variety of heat storage options investigated and the recurrent few types virtually implemented in the industries. To take advantage of a wider spectrum of solutions, a structured procedure is proposed in this work for the selection of storage material and layout. The algorithm developed consists of a preliminary storage design followed by a performance estimation of the overall system where the heat storage is integrated. The preliminary design allows a first screening and ranking of sensible, latent or thermochemical materials using a quasi-stationary approach. The performance estimation leads to the final selection of the heat storage system, which is based on the analysis of the dynamic thermal response of the heat storage along with physically based or input-output models for the load. The algorithm is applied to improve the heat recovery of a discontinuous and fluctuating flue gas at medium temperature from a steel industry, targeting the production of process steam or electricity. The results show that the integration of a packed bed heat storage, either of the sensible or latent type, allows the highest amount of steam to be generated in the discharging. Moreover, the combination of the same heat storage with an organic Rankine cycle or the Kalina cycle results in the highest amount of generated electricity. The investment in a packed bed rock storage was found to result in payback times of about seven years, whereas tank-based storage units appear not profitable due to the high cost of the silicone oil.

PCM products and their fields of application - An overview of the state in 2020/2021

Phase Change Materials, or briefly PCM, are a promising option for thermal energy storage, depending on the application also called heat and cold storage. Systematic investigations of PCM already started after the oil crises, and then in the late 1990s R&D on PCM intensified significantly. While there is still a large demand for R&D from basics to applications in many areas, this is not the case in general. This overview shows that PCM are already applied in a wide variety of commercial products, in many fields of application, in some at an early stage, but in others already as the standard. Some commercial products even exist already for many years, and not just in some niche application. Examples are applications in buildings, for logistics, specifically the cold chain, the human body etc. This overview shows that PCM are used in many commercial applications already, and in many fields. It thereby demonstrates their enormous potential, also in applications still needing significant R&D.

Phenomenon Identification and Ranking Table Development for Future Application Figure-of-Merit Studies on Thermal Energy Storage Integrations with Light Water Reactors

There are no standard prioritization criteria for evaluating thermal energy storage (TES) options for use in integrated energy systems. A framework for proposing, analyzing, and presenting energy storage integration with power producers and users is presented along with a specific figure-of-merit (FOM) study based in this framework. This basis for evaluating storage technologies can provide a structure for the energy industry to analyze and prioritize energy storage in different applications and environments. The phenomena identification and ranking table (PIRT) presents a series of design questions specific to energy storage applications. The FOM study, built in this PIRT framework based on a nuclear-renewable hybrid energy system using TES to produce power and provide process energy for a secondary user, successfully identified specific technologies to use based on the project requirements. Expanding the library of projects using this framework will expand the deployable options for energy storage and increase its potential for energy security.

Techno-economic assessment of thermal energy storage technologies for demand-side management in low-temperature individual heating systems

The combined use of thermal energy storage (TES) technologies and heat pumps in building energy systems has been approved to achieve demand-side management. Although there is an increasing number of case studies about the TES applications, crosswise techno-economic evaluations of different technologies are rare, especially for applications in individual heating systems where the storage temperature range is less than 20 K. Hence, in this study, three TES options; water tank (WT), phase change material tank, and building thermal mass (BTM) are simulated and compared. A systematic analysis approach was proposed to assure impartial comparisons of the energy performance and the life-cycle costs (LCC). Special focus was paid on practical issues such as restricted charging power for different TES technologies. It was found that the majority of LCC savings arises from the peak load reduction. The study also shows that BTM is the most cost-effective TES technology while the WT is the least attractive option, due to larger heat loss and lower storage density. Moreover, less discharged energy and cost savings were found in well-insulated buildings due to the restricted discharging power. Still, there could be more incentives for household TES technologies if additional prices or policies are implemented.

A new integrated system with thermal energy storage for five useful outputs: A case study

This paper proposes the design of a novel renewable energy based integrated system with thermal energy storage options which is capable of producing up to five useful outputs consisting of electricity, heating, cooling, freshwater, and hot water. The system is also capable of moderate thermal energy storage through the use of molten salts, NaNO3 and KNO3. Following the design of this integrated multigenerational system, an extensive energetic and exergetic thermodynamic analysis is conducted by studying heating and cooling, power outputs, storage capacities, and exergy destruction rates. The various parametric studies performed will help determine how effective the present system is able to operate under varying conditions such as changes in ambient temperature, and critical system state point values such as different temperatures, pressures, mass flow rates, etc. The proposed system is intended for a high school located within Calgary Alberta, Canada and applied as a case study. The specified system has overall energetic and exergetic efficiencies of 54.42% and 30.24%, respectively. The energetic coefficients of performance during heating and cooling are 0.8169 and 2.265, respectively while the exergetic coefficients of performance during heating and cooling are found 0.2683 and 0.3864, respectively.

Form-stable phase change materials from mesoporous balsa after selective removal of lignin

We produce balsa-based structures by selective removal of lignin. The changes that occur in the main components of balsa upon delignification, including tracheids, closed pits and tylosis vessels, allow the development of mesopores and a substantial increase in fluid permeability. Such system is ideally suited as a support of phase change materials, PCM. Vacuum-assisted impregnation with polyethylene glycol (PEG, a PCM), results in a form-stable PCM system (FPCM). The FPCM displays a high encapsulating capacity (83.5%) at temperatures above the melting PEG transition, with a latent heat of 134 J/g and low supercooling (12 °C). The results are rationalized by the affinity between the unidirectional mesoporous structure and the PCM polymer, involving capillary forces and hydrogen bonding. The leakage-proof FPCM outperforms available systems (based on PEG or other PCMs) supported on minerals or other wood species. Compared to the latter group, the results obtained with balsa relate to its morphology and the effect of residual hemicelluloses in hierarchically-aligned cellulose nano- and microfibrils. The FPCMs resist compressive loads and performs stably for at least 200 cycles of heating and cooling. An insignificant loss in latent heat is observed compared to that of pure PEG. The phase transition temperature fluctuation and non-leaking characteristics under load make the balsa-based FPCM a superior alternative for passive heating/cooling, especially for uses at high ambient temperatures. The reversible thermoregulatory capacity, low cost, high efficiency, renewability, and operability of the balsa-supported FPCM, indicate an excellent option for thermal energy storage and conversion devices.