Symposium FF
Thermal Energy Storage: State-of-the-art Materials and Technologies Towards a Low-carbon Society
ABSTRACTS
Session FF-1 Development in TES media
FF-1:IL01 Plastic Crystals and Ionic Liquid-based Solid-solid PCMs
E. PALOMO DEL BARRIO1,2, A. SERRANO-CASERO2, E.J. GARCÍA-SUÁREZ1,2, 1Ikerbasque, Basque Foundation for Science, Bilbao, Spain; 2Centre for Cooperative Research on Alternative Energies (CIC energiGUNE), Basque Research and Technology Alliance (BRTA), Alava Technology Park, Vitoria-Gasteiz, Spain
Today, there is growing interest in solid-solid phase change materials (ss-PCMs) due to the advantages they offer over solid-liquid phase change materials, such as no leakage, easy handling and integration into systems, moderate volume changes, and no corrosion. This presentation focuses on CIC energiGUNE's research work on different families of ss-PCMs for next generation of compact thermal and electrothermal storage systems, as well as future thermal management solutions. We present our latest findings on phase transition mechanisms in plastic crystals, which unlock their use as PCMs by solving the problems of hysteresis and plastic deformation. How to make these materials flexible and how to transform them into materials that respond to alternating magnetic fields will also be part of the presentation. The exploration of new chemistries for solid-state latent heat storage is part of our research activity too. Establishing molecular design principles that link structure with performance, we have extended the portfolio of ss-PCMs to new classes of hybrid organic-inorganic materials, with key advantages of high latent heat, low vapor pressure, compatibility with water and corrosiveness.
FF-1:IL02 Phase Change Material Modeling for Thermal Storage Applications: the role of convective motions
F. FORNARELLI, Dept. of Agricultural Sciences, Food, Natural Resources and Engineering, University of Foggia, Foggia, Italy; Italian National Group of Mathematical Physics (GNFM) of the Italian National Institute of High Mathematics (INdAM), Rome, Italy
The Latent Heat Thermal Energy Storage (LHTES) represents a promising technology to increase the scale up of Concentrated Solar Power Plant (CSP) from proof of concept to an industrial product. The solid liquid Phase Change Materials (PCMs) increases the heat capacity density of the material reducing its impact in terms of mass and space required especially in real scale application. The main challenge in its implementation and managing in a power plant depends on the prediction of its thermal response during the phase change. Indeed, the coexistence of liquid and solid phase implies complex interaction between heat exchange and buoyancy driven flow. This behaviour is also influenced by the temperature distribution and geometry characteristic of the storage that could vary during the charging and the discharging of the storage. Here, the shell-and-tube geometry Is presented, being one of the most promising and reliable configurations, in vertical orientation. It is shown how the liquid is distributed along the LHTES during the phase change. The solid/liquid interface assumes a conical shape during the melting influenced by the buoyant warmer liquid with respect to the solid fraction. Finally, the physical understanding of the problem is used to develop reduced order models.
FF-1:L03 Solid Hybrid Phase Change Materials with Extended Long Alkylammonium Chains for Medium-temperature Thermal Energy Storage
G. CARRASCO, C. PÉREZ-JUNYENT, J.L. TAMARIT, S. LANZALACO, E. ARMELIN, P. LLOVERAS, Universitat Politècnica de Catalunya, Barcelona, Spain; L. RIBAS, R. MATHEU, Universitat de Barcelona, Barcelona, Spain
Thermal energy storage at medium temperatures well above ambient are of increasing interest due to the environmental need of improving efficiency and sustainability of low-grade industrial processes, as those in textile, pulp and paper or food and beverages, among others. Solid phase change materials operating at these medium temperatures are scarce but they could offer advantages over molten phases. Here we present a series of newly synthesized hybrid compounds belonging to two different families, both containing long alkylammonium chains, that can operate in temperature ranges beyond 100 ˚C and with enhanced latent heat. This improvement is achieved via chemical modifications, by extending the alkyl chains with an increased number of carbons, n = 16-22, and also by tuning the inorganic part. We characterize the structure and thermodynamics of the obtained compounds using single-crystal and powder X-ray diffraction, conventional and high-pressure calorimetry, thermogravimetry and spectroscopy techniques. We also demonstrate that free-solvent synthesis is feasible for these compounds. Our results indicate that these materials are interesting for thermal energy storage applications at medium temperatures and that this strategy could be extended further to longer chains.
FF-1:L05 Investigation of the Influence of Additional Elements on the Microstructure of Al Commercial Alloys with Sn Additions
F. VILLA1, H. ARSHAD1, N. BENNATO1, E. BASSANI1, E. GARIBOLDI2, P. BASSANI1, 1CNR ICMATE, Lecco, Italy; 2Politecnico di Milano DMEC, Milano, Italy
Metallic Phage Change Materials represent a valuable and effective alternative to salt-based or organic PCMs, when higher thermal conductivity is required. Among metallic PCMs, Al-Sn based alloys have gained increasing attention and several method of production have been proposed to obtain the desired microstructure. Additional elements could be in any case considered. In the present work, small ingots of Al and Al alloys with addition of pure Sn were produced by induction melting. The obtained microstructures of the as-cast alloy were investigated through optical microscopy, scanning electron microscopy and energy dispersive X-ray analysis. The microstructural features have been analyzed and discussed on the basis of CALPHAD-based predictions, providing a guideline for the development of efficient systems for thermal energy storage or management based on advanced metallic PCMs. Acknowl. - Authors greatly acknowledge M-TES Project ( g.a.101115307), funded by EU within HORIZON-EIC Pathfinder action. Views and opinions expressed are however those of the author(s) only and do not necessarily reflect those of the European Union or EISMEA – European Innovation Council and SMEs Executive Agency. Neither the European Union nor the granting authority can be held responsible for them.
FF-1:L05b EERA JP-CSP Thermal Storage: Five Years of High-Temperature Solar Energy Innovation for Industrial Deployment
W. GAGGIOLI, ENEA, Rome, Italy
The EERA Joint Programme on Concentrating Solar Power (JP-CSP), launched in 2011, brings together Europe’s leading research institutions to advance Concentrating Solar Power (CSP) and Concentrating Solar Thermal (CST) technologies in line with STE-EII and SET-Plan objectives. Thermal Energy Storage (TES) is central to this effort, enabling flexible, low-carbon electricity generation and industrial heat while facilitating the integration of variable renewable energy sources into the grid. Over the past five years, the Thermal Storage subprogram has focused on improving efficiency, reducing costs, and simplifying operations across CSP plants of various scales. TES technologies have evolved from basic solar-field stabilizers to high-temperature, long-duration storage systems, with double-molten salt tanks as the current reference technology. Emerging TES concepts are increasingly seen as versatile “energy hubs,” capable of interfacing with multiple energy carriers and directly coupling with high-temperature solar fields. The subprogram is organized into four main tasks. Task (i) developed TES solutions for large-scale CSP plants, testing configurations including single-tank thermocline, packed-bed, particle-based, and dual-media systems, integrated with advanced power cycles such as Rankine and supercritical CO₂. Task (ii) addressed TES integration into hybrid renewable systems, including Carnot Batteries, to improve dispatchability and reduce photovoltaic curtailment. Task (iii) focused on application-specific TES solutions for industrial processes, combined heat and power, green buildings, and the agro-food sector, demonstrating operational flexibility and scalability. Task (iv) characterized TES materials and heat transfer fluids, evaluating compatibility, degradation, and reliability under realistic conditions, advancing multiple technologies to TRL 4–6. Collectively, these efforts have produced a validated portfolio of TES solutions capable of high-temperature operation, long-duration storage, and integration with advanced power cycles. This portfolio provides a clear pathway for industrial-scale deployment, enhances renewable energy integration, and supports Europe’s transition to a low-carbon energy system, establishing TES as a cornerstone of sustainable energy.
FF-1:IL06 Rethinking the Future of Clean Cooling through an Innovative Bio-based Thermochemical Material
E. MASTRONARDO, I. ACQUARO, M.A. AVILA-GUTIERREZ, L. CALABRESE, C. MILONE, Engineering Department, University of Messina, Messina, Italy
The Horizon Europe Pathfinder CharCool project (Grant Agreement No. 101162196) is developing a clean, efficient cooling system to aid Europe in reducing its carbon footprint and ensuring energy security. This system utilises a modular thermochemical energy storage (TCS) system to store excess clean renewable energy or waste heat, enabling seasonal storage. The core innovation is a bio-based sorption composite material that integrates sustainability, energy efficiency, and circular economy principles. This composite features biochar, derived from agricultural residues via gasification, which acts as a porous matrix for a hydrated salt. The biochar significantly improves thermal exchange due to its mesoporous structure, enhancing vapour adsorption and diffusion. The chosen salt hydrates belong to the organic salts family. These salts offer low water solubility, increasing resistance to deliquescence, alongside the ability to coordinate with a high number of water molecules and stability under operating conditions. Here, we experimentally assessed the thermochemical behaviour of these composite materials for thermochemical energy storage applications.
FF-1:IL07 Design of Nanoporous Materials for Adsorption Heat Storage
A. RISTIĆ1, S. MAL1, C. BYRNE1,2, M. MAZAJ1, N. ZABUKOVEC LOGAR1,2, 1Laboratory for Adsorbents, Department of Inorganic Chemistry and Technology, National Institute of Chemistry Slovenia, Ljubljana, Slovenia; 2School of Science, University of Nova Gorica, Nova Gorica, Slovenia
Adsorption heat storage can offer the possibility to store heat with the highest energy density in comparison to sensible and latent heat storage. The efficiency of this kind of thermal energy storage technology is determined by the performance of the adsorbent used, which should, in addition to high thermal stability and good cycling performance, enables high adsorption capacity of working fluid at low relative humidity and medium regeneration temperature, if waste heat is to be exploited. In the scope of the MUSPELL project (Pathfinder Challenge, Grant Agreement No. 101114987) various thermochemical materials (TCMs) have been prepared and evaluated for the new hybrid thermal energy storage system that is optimized for medium temperatures with integrated heat pump capabilities. The appropriate selection of the solid TCMs and the system design in the early stages of design can allow quick identification of the most promising solutions. A reliable methodology for TCM screening has been applied to evaluate developed TCM candidates for the target application through water adsorption capacity determined between 100 and 150 °C. In addition to the green synthesis, our work focused on the study of the structure-property relationship, using XRD, TG and calorimetric approaches.
FF-1:L08 A Smart Hydrogel-Encapsulated Thermochemical Adsorbent (SHETA) for Thermal Management
JIEHAO CHEN, YUHANG HU, George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, USA; School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, GA, USA
The Smart Hydrogel-Encapsulated Thermochemical Adsorbent, or SHETA, introduces a new class of high–energy density materials that merge the superior sorption capacity of hygroscopic salts with the tunable and resilient architecture of hydrogels. SHETA demonstrates exceptional water uptake, ultrahigh salt loading exceeding 75 weight percent, and a gravimetric energy density above 2300 kilojoules per kilogram in the dehydrated state, nearly three times higher than advanced lithium-ion batteries and far beyond the latent heat storage capacity of conventional phase-change materials, which typically range from 150 to 250 kilojoules per kilogram. This high performance arises from reversible hydration and dehydration reactions within the hydrogel matrix, where thermochemical energy is stored through chemical bonding rather than physical phase transitions, eliminating the leakage, poor cycling stability, and limited energy density that constrain conventional latent heat storage systems. The material is fabricated through a dual-initiator photopolymerization process in a density-gradient suspension, forming porous hydrogel beads approximately one to three millimeters in diameter with adjustable hydrophilicity and excellent mechanical integrity. The resulting porous network promotes rapid vapor diffusion and efficient water capture, achieving more than 200 percent weight gain under moderate humidity. In additional to the improved discharging performance, unlike zeolite or silica-based adsorbents that require regeneration temperatures exceeding 200 degrees Celsius, SHETA fully regenerates within one hour at roughly 80 to 85 degrees Celsius which can be achieved through solar-thermal heating. Cyclic differential scanning calorimetry confirms stable discharging profiles and minimal degradation over repeated hydration and dehydration cycles. The polyacrylamide network can effectively enhances fatigue resistance and prevents salt crystallization or delamination during cycling. Together, these characteristics establish SHETA as a fast-regenerating, high-capacity thermochemical energy storage medium that bridges the gap between battery-like energy density and the reversibility of phase-change systems, providing a versatile platform for next-generation sustainable thermal energy materials.
FF-1:L09 Thermo-mechanical Characterization of Sn-bearing Al-based Systems for Thermal Energy Storage
E. GARIBOLDI, S. MAROLA, M. MOLTENIA, P. BASSANI, Politecnico di Milano, DMEC, Milano, Italy; and CNR-ICMATE, Lecco, Italy
Metallic Phase Change Materials, due to their high thermal conductivity and the wide spectrum of solid-liquid transition temperatures, represent an efficient solution for systems characterized by Latent heat storage. Furthermore, fully metallic composite PCM, made by a PCM phase and a high melting one, could provide form-stability and at the same time, combine sensible and latent heat according to specific needs for heat storage. For this reason, the present work takes into account the possibility of dispersing Sn (the actual PCM, activating around 230°C) within a passive Al-based matrix. These two elements form immiscible systems indeed, so that the material can be considered as a composite Phase Change Material (C-PCM) whose properties can be tuned via modifications of alloy composition. Various alloys, produced via induction melting have been investigated. Thermal and thermomechanical properties such as specific heat, latent heat and coefficient of thermal expansion have been measured before and after thermal cycling, to evaluate the PCM behavior in order to assess the reliability of the selected metallic systems. The results have been discussed in the light of the C-PCMs composition and microstructure to properly drive the design of suitable metallic PCMs.
Session FF-2 Encapsulation methods
FF-2:IL10 Magnetic Nanocolloids for Thermoelectric Energy Harvesting
E. SANI1, M.R. MARTINA1, T.J. SALEZ2,3, T. FIUZA2, E. DUBOIS4, V. PEYRE4, S. NAKAMAE2, 1CNR-INO National Institute of Optics, Firenze, Italy; 2SPEC, CEA, CNRS, Université Paris-Saclay, Gif-sur-Yvette, France; 3École des Ponts ParisTech, Champs-s/Marne, Marne-la-Vallée, France; 4PHENIX, CNRS Sorbonne University, Paris, France
In the current pursuit to improve the energy conversion, production and storage efficiency of renewable technologies, hybridization (i.e. combining different energy production technologies in a single system) is considered a promising approach. Nanofluids (i.e. stable colloidal suspensions of nanoparticles) are being studied from a long time for several renewable energy applications, including solar thermal collectors, thermal energy storage and thermal transfer in solar and wind technologies. Large thermoelectric effects have been reported in nanofluids containing magnetic nanoparticles with corresponding Seebeck coefficient values above 1 mV/K, an order of magnitude higher than that of semiconductor counterparts. In this work, we report the first experimental investigation on the thermoelectric and the optical properties of stable aqueous magnetic nanofluids containing maghemite nanoparticles. These nanoparticles are found to be an excellent solar radiation absorber and a thermoelectric power-output enhancer with only a very small volume fraction. Combined together, magnetic nanofluids open a new R&D opportunity in hybrid solar thermal collectors for co-generating heat and power.
FF-2:IL11 Colloidal Stability and Emerging Challenges in Molten-Salt Nanofluids: A Critical Overview
Y. GROSU, Centre for Cooperative Research on Alternative Energies (CIC energiGUNE), Basque Research and Technology Alliance (BRTA), Alava Technology Park, Vitoria-Gasteiz, Spain; and Institute of Chemistry, University of Silesia, Katowice, Poland
Molten-salt nanofluids (MS-NFs) have emerged over two decades as tunable high-temperature media for CSP receivers and TES. Reports that adding ≤1 wt% of oxides or carbons to nitrate/carbonate salts significantly raised specific heat and thermal conductivity, with small viscosity penalties boosted a huge interest of scientific and engineering communities. However, the mechanism behind the reported enhancements, that strongly deviate in literature, still remains elusive with colloidal stability being the greatest challenge to be achieved. This is because organic stabilizers cannot be used at expected high temperatures of CSP while electrostatic stabilization collapses in dense ionic media. Stability relies on non-DLVO solvation layering and inorganic hard-steric shells which are non-trivial to achieve. The field now extends beyond thermophysical metrics to corrosion/compatibility, rheology under flow, and optical tailoring for direct-absorption receivers. In this report, we intend to critically assess the field of MS-NFs addressing aggregation/sedimentation under thermal cycling, measurement scatter, moisture/impurity control, and scale-up.
Session FF-3 Selection criteria of TES media and structural materials for CSP plants
FF-3:IL12 Structural Materials and Coatings for the Next Generation of CSP Plants: Opportunities for High Entropy Alloys
A.G. FERNÁNDEZ1, T. GURAYA2, 1Department of Chemical and Environmental Engineering, Faculty of Engineering of Gipuzkoa, University of the Basque Country UPV/EHU, Donostia-San Sebastián, Spain; 2Department of Mining & Metallurgical Engineering and Materials Science, Faculty of Engineering of Bilbao, University of the Basque Country UPV/EHU, Bilbao, Spain
The selection of a high-temperature molten-salt chemistry is needed to improve the turbine block efficiency in new CSP plants, as well as the need to understand its impact on new containment materials, to achieve acceptable strength, durability, and cost targets at these high temperatures. The aim of this work is the proposal of different high entropy alloys (HEA) to evaluate their corrosion resistance with high temperature molten salts. HEAs exhibit an unique combination of properties attributed to four core effects: high mixing entropy, lattice distortion, sluggish diffusion, and cocktail effect. We are proposing different high entropy alloys, produced by additive manufacturing, in contact with the eutectic ternary Li2CO3–K2CO3–Na2CO3 (32.1–34.5–33.4 wt%) salt mixture at 650 °C as well as to ternary chloride salt, 20.4 KCl + 55.1 MgCl2 + 24.5 NaCl at 720ºC under inert atmosphere (N2), using a special setup to integrate electrochemical electrodes in the corrosion reactor. In this invited talk, we will show the main results obtained, during the last years, in this topic, evaluating the corrosion behaviour in HEA as bulk and coating materials, including static and dynamic conditions in high temperature molten salts for the next generation of CSP plants.
FF-3:IL13 Corrosion Mechanisms in Molten Nitrate Salts and Mitigation Strategies
C. OSKAY, C. GRIMME, M. GALETZ, DECHEMA-Forschungsinstitut, Frankfurt, Germany
Thermal energy storage (TES) systems are critical components of energy generation systems such as concentrated solar power (CSP) plants. The state-of-the-art heat transfer fluid and storage medium is a non-eutectic sodium nitrate -potassium nitrate mixture (also known as Solar Salt) which enables maximum temperatures around 565°C. Compared to direct steam generating systems, the utilization of molten nitrates complexifies the prevailing corrosion mechanisms and leads to higher corrosion rates for structural components. Corrosion in molten nitrates is governed by the thermal decomposition reactions of nitrates and the consequential increase in the concentration of corrosive species and the basicity of the melt. Corrosion mechanisms in molten nitrates generally include scale formation, Na incorporation into the scales, dissolution of Cr into the salt melt as toxic chromate species and the nitridation of the alloy sub-surface. This study focuses on the investigation of the corrosion behavior of pure metals, commercial and model alloys, and mitigation strategies based on Ni- and Al-rich coatings on cost-efficient alloys in molten solar salt at application relevant temperatures.
FF-3:IL15 Compatibility Study between MS Mixtures and Materials Feasible to be used for the Construction of Thermal Storage Components
S. SAU, E. VECA, A.C. TIZZONI, N. CORSARO, A. SPADONI, M. D’AURIA, G. GIORGI, M. LANCHI, L. TURCHETTI, ENEA; M. BATTAGLIA, C. D’OTTAVI, Università di Roma TorVergata, Rome, Italy; N. ROSHAN, Università Sapienza di Roma, Rome, Italy
Molten salts can be used for thermal storage purposes in three main ways: as sensible heat accumulation media, as phase change materials (PCM) and as heat exchange fluids for passive-undirect storage systems (typically solid fillers). Molten nitrates and, sometimes, nitrites, are the most commonly materials in this category; ENEA, in the context of several National and European programs, largely investigated their corrosion behaviour with metal alloys, especially stainless steels at medium high temperatures. Mainly alkaline nitrates were investigated, but also lower melting mixtures were considered. The most interesting results are summarized and presented, together with comparisons with the available scientific literature. Molten nitrates and nitrites are characterized by a relatively low thermal stability, which prevents operations above 600°C; for this reason, other molten salts were evaluated. Chlorides mixtures present a significantly higher freezing point than nitrates and can be (depending on their formulation) unstable in presence of air, but they can be used at higher temperatures. The ENEA experience regarding their compatibility with several alloys is as well presented and commented.
Session FF-4 Scale prototyping, advances in TES applications and trends
FF-4:IL16 Test Facility for Thermal Energy Storage in Molten Salt - TESIS
C. ODENTHAL, T. BAUER, German Aerospace Center (DLR), Cologne, Germany
Since 2018, the German Aerospace Center (DLR) operates the Test Facility for Thermal Energy Storage in Molten Salts (TESIS), a large-scale infrastructure for the experimental validation of high-temperature thermal storage and material systems. The facility comprises 85 t of Solar Salt, providing a thermal capacity of about 4 MWh and a maximum operating temperature of 560 °C. Continuous operation has yielded extensive expertise in molten salt management, system operation, and materials characterization under relevant thermo-chemical conditions. Within several national and European research projects, TESIS has been employed to investigate single-tank thermocline (TC) storage concepts as well as solid-filler configurations (TCF), moving barrier systems (TCMB), and the innovative trickling thermocline concept, also known as crushed rock ultra-large stored heat (CRUSH). This contribution provides an overview of TESIS and presents key experimental results related to material stability, compatibility, and thermal performance in molten salt environments. The findings support the derivation of material selection criteria and requirements for cost-effective filler materials, contributing to the advancement of durable and economically viable thermocline storage systems.
FF-4:IL17 Single-medium Indirect Thermocline Thermal Energy Storage for Hybrid CSP/PV Plants
M. CAGNOLI, M. D'AURIA, ENEA, Rome, Italy
Concentrated solar power (CSP) can integrate a thermal energy storage (TES) that allows producing dispatchable power; however, the electricity cost is still higher than PV. The hybridization of CSP with PV systems is a promising solution to provide dispatchable low-cost electricity. In these hybrid plants, CSP mainly aims at charging the storage to cover non-sun hours, while PV provides cheap electricity to the grid during the sunlight hours. The storage medium is typically a mixture of molten salt, which operating range depends on the salt mixture composition. The thermocline technology has been proposed as a cost-effective TES option. The latter consists of a single tank storage, which contains both the hot and the cold medium, divided by means of a thermal stratification. This work deals with the hybridization of an indirect molten salt thermocline TES prototype. The proposed layout of the prototype includes three serpentines connected to as many oil loops. Two of them allows charging the storage; they connect the TES with (i) the CSP field and (ii) with an electric heater driven by the electricity produced by PV panels. The third serpentine is used to discharge the TES. A numerical model has been developed to assess the performance of such a system.
FF-4:IL18 Innovative Cement-Based Materials for Energy Harvesting & Storage and Radiative Cooling
J.S. DOLADO, Centro de Física de Materiales (CFM) CSIC-UPV/EHU, San Sebastian, Spain
Concrete and cement-based materials are among the most widely used substances on Earth, second only to water. These versatile materials have shaped the modern world, forming the backbone of everything from skyscrapers to highways and bridges. While traditionally valued for their structural properties, recent advancements have revealed their potential in energy conversion and storage. In recent years, innovative construction methods have emerged, leveraging cementitious composites for energy solutions. These include rechargeable concrete batteries, cementitious thermal energy storage devices for concentrated solar power plants, and radiative cooling concretes. Such breakthroughs have the potential to transform how we approach energy storage and efficiency in the built environment.
FF-4:IL19 Innovative Composite Sorbent for Sorption Thermal Energy Storage in Buildings
A. FRAZZICA, A. FOTIA, V. BRANCATO, CNR ITAE, Messina, Italy; L. CALABRESE, E. MASTRONARDO, University of Messina, Messina, Italy; W. MITTELBACH, Sorption Technologies GmbH, Freiburg, Germany
The use of sorption systems for medium- to long-term energy storage is attracting growing interest in many applications (e.g., residential, tertiary, district heating, etc.). At the same time, future energy systems aim to integrate a higher share of renewable sources within both thermal and electrical grids, which calls for effective storage solutions to enable peak shaving and load shifting. Sorption systems represent a promising response to these challenges due to their high operational flexibility—allowing both heating and cooling modes—and their virtually loss-free storage characteristics. Within this framework, the present study details the design, fabrication, and testing of a prototype sorption TES that employs a composite material based on mesoporous silica gel impregnated with calcium chloride. The prototype is based on a double reactor that allows maximizing the energy storage capacity and the specific heating and cooling power achievable. The prototype is under testing at the CNR ITAE lab, under controlled boundary conditions, and, at the same time, a scaled-up version will be installed and demonstrated in the coming months in a building in Spain. The achieved results will be compared to analyze the scaling effect as well as the impact of the real operating condition.
FF-4:IL20 TES by Concrete and PCM in Cascade
R. LIBERATORE, D. NICOLINI, G. NAPOLI, G. GIORGI, A. MILIOZZI, ENEA, Rome, Italy
Thermal Energy Storage (TES) systems are crucial for industry, bridging the gap between heat demand and availability. They boost production efficiency, promote solar energy adoption, and cut greenhouse gas emissions. Among their different categories, including sensible, latent, and thermochemical storage, the Combined Sensible/Latent Heat TES (CSLHTES) configuration is attracting increasing academic and industrial attention. This hybrid approach synthesizes the optimal attributes of both individual sensible and latent heat storage technologies, yielding benefits such as high stored energy density, compactness, elevated efficiency, a stable heat supply temperature, and superior power output. After analyzing various solutions, this work presents an evaluation, based on a proper test campaign, of the thermal performance and potential enhancements of a specific CSLHTES system. It was designed to include two different module technologies connected in series, operating within a medium-to-high temperature range, which satisfies typical industrial application requirements. A further objective is the use of non-toxic, inexpensive, and readily available materials such as concrete or salt. The experimental findings confirm that CSLHTES systems generally exhibit improved overall performance.
FF-4:IL21 Carbon Capture and Heating
M. LINDER, German Aerospace Center (DLR e.V.), Stuttgart, Germany
Thermochemical energy storage systems are generally known for their loss-free storage principle. However, this advantage becomes truly significant only when long storage durations are required. In such cases, the storage material remains inactive most of the time, simply waiting for its next use. Consequently, for these applications, the storage material must be both economically and ecologically affordable. To address this inherent challenge, we have developed a concept that combines three key strategies: 1. the use of natural and abundant materials such as limestone and water, 2. the separation of the storage compartment from the heat exchanger, and 3. the activation of the otherwise passive storage phase. The latter approach introduces an additional benefit: a passive, intrinsic direct air capture process integrated into the storage system. The presentation will give an overview of the current state of the technology, present experimental results from a recently demonstrated thermochemical storage unit, and discuss open questions and remaining challenges.
FF-4:IL22 Role of Thermal Storage for Industrial Heat Decarbonization: Potentials in Agroindustrial Sector
A.M. PANTALEO1,2, C.N. MARKIDES2, 1Dipartimento di scienze del suolo, della pianta e degli alimenti, Università degli studi di Bari Aldo Moro, Bari, Italy; 2Department of Chemical Engineering, Imperial College London, London, UK
Industrial thermal energy storage (TES) offers significant opportunities to enhance energy system flexibility by enabling greater integration of renewable sources, recovering surplus heat, and decoupling energy supply from demand. Despite a broad technology landscape—from mature sensible heat systems to emerging latent, sorption, and thermochemical solutions—industrial uptake remains limited due to high implementation costs, a lack of demonstrated large-scale applications, and the need for substantial adaptations to existing process infrastructures. This contribution outlines the key benefits and persistent barriers associated with industrial TES and identifies coordinated actions required to accelerate its deployment, including integrating TES into long-term energy planning, strengthening targeted R&D programmes, establishing supportive regulatory frameworks, and promoting knowledge-sharing among industry, policymakers, and energy system actors. The contribution also report on the techno-economic feasibility for integration of TES into agro-industrial processes with two representative case studies in diary sector and pasta production. In the first case, the option to integrate low temperature TES into a gas fired steam generator is proposed, to avoid part load operation and thus increase overall efficiency. The further option to shift to a fullly decarbonized system with renewable power to heat option is proposed, identifying the optimal TES size to maximize the investment profitability. In the case study of pasta production, the optimal ntegration of TES and gas fired CHP is explored, to maximize overall energy efficiency and avoid discherged heat in the electric load following mode. 3Long-term progress for TES will additionally depend on innovative business models, stable investment conditions, and the creation of independent testing facilities and communities of practice. Collectively, these measures can position TES as a central enabler of industrial decarbonisation, in particular in the agro-industrial sector where mid to low temperature heat is required and there is an interesting potential for integrating TES and heat electrification, via power to heat or pumped heat.