Thermal Energy Storage Capability Research Articles

Performance evaluation of nano-enhanced phase change materials for thermal energy storage: An experimental study

In rapidly developing economies, the increasing energy demand and fossil fuel consumption have made the need for renewable energy sources and efficient thermal energy storage (TES) solutions more urgent than ever. This study focuses on enhancing the thermal energy storage capabilities of paraffin-based phase change materials (PCMs) by incorporating Al2O3, MgO, and CuO nanoparticles. The evaluation of nano-enhanced PCMs focused on their melting temperatures, thermal storage capacities, thermal conductivities, and charge/discharge times. The experimental results revealed significant changes in the thermal properties of the nano-enhanced PCMs compared to pure paraffin. The melting temperature was raised by 2 °C due to Al2O3 nanoparticles, whereas CuO and MgO nanoparticles decreased it by 1.7 °C and 1.8 °C, respectively. Compared to pure paraffin, Al2O3-PW, MgO-PW, and CuO-PW exhibited improvements of 13 %, 39 %, and 48 % in thermal conductivities, respectively. CuO-doped paraffin showed an 11.8 % decrease in discharge time, suggesting its suitability for rapid heat transfer applications like defrosting systems or thermal management in electronics. On the other hand, paraffin doped with MgO showed a minimal 2.24 % reduction in discharge time, indicating its effectiveness in applications requiring heat retention, particularly for improved thermal insulation in building materials. The results highlighted the potential of nano-enhanced PCMs in energy storage and construction is underlined, offering a sustainable approach to improving energy efficiency in various sectors.

Multifunctional 3D-Printed Thermoplastic Polyurethane (TPU)/Multiwalled Carbon Nanotube (MWCNT) Nanocomposites for Thermal Management Applications

In this work, multiwalled carbon nanotubes (MWCNTs) were melt-compounded into a novel thermal energy storage system consisting of a microencapsulated paraffin, with a melting temperature of 6 °C (M6D), dispersed within a flexible thermoplastic polyurethane (TPU) matrix. The resulting materials were then processed via Fused Filament Fabrication (FFF), and their thermo-mechanical properties were comprehensively evaluated. After an optimization of the processing parameters, good adhesion between the polymeric layers was obtained. Field-Emission Scanning Electron Microscopy (FESEM) images of the 3D-printed samples highlighted a uniform distribution of the microcapsules within the polymer matrix, without an evident MWCNT agglomeration. The thermal energy storage/release capability provided by the paraffin microcapsules, evaluated through Differential Scanning Calorimetry (DSC), was slightly lowered by the FFF process but remained at an acceptable level (i.e., >80% with respect to the neat M6D capsules). The novelty of this work lies in the successful integration of MWCNTs and PCMs into a TPU matrix, followed by 3D printing via FFF technology. This approach combines the high thermal conductivity of MWCNTs with the thermal energy storage capabilities of PCMs, creating a multifunctional nanocomposite material with unique thermal management properties.

CURRENT TRENDS IN PHOTOVOLTAIC THERMAL (PVT) SYSTEMS: A REVIEW OF TECHNOLOGIES AND SUSTAINABLE ENERGY SOLUTIONS

This systematic review explores advancements and challenges in photovoltaic thermal (PVT) systems, focusing on efficiency improvements, cooling mechanisms, material innovations, Internet of Things (IoT) integration, and cost and environmental considerations. Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, 45 articles were analyzed to provide a comprehensive understanding of current trends and future directions in PVT technology. Findings reveal that cooling mechanisms, particularly liquid-based and nanofluid-based systems, are essential for maintaining high PVT efficiency under diverse environmental conditions. Material advancements, including phase change materials (PCMs) and nanotechnology, have enhanced thermal management and energy storage capabilities, yet their high costs and environmental impacts remain significant barriers to broader adoption. IoT and smart grid integration have transformed PVT system functionality by enabling real-time monitoring, predictive maintenance, and energy flow adjustments within connected energy networks. However, persistent challenges—including high initial investment costs, environmental concerns related to materials, and the need for adaptable designs—highlight areas for future research. Advancements in adaptive materials, sustainable cooling solutions, and digital automation are essential for developing cost-effective, resilient PVT systems that contribute to global renewable energy goals. This review provides a foundation for future research to address the identified challenges and maximize the potential of PVT systems in sustainable energy production.

Development and evaluation of alkali-activated concrete with thermal energy storage capability for energy geostructures

Energy geostructures, such as energy piles, tunnels, and continuous underground walls, offer an innovative solution for harnessing shallow geothermal energy while serving structural functions. However, their limited energy density often leads to inefficient heat exchange and fluctuations in structural stability, along with significant challenges related to ion erosion in practical applications. This study introduces Alkali-Activated Concrete with Thermal Energy Storage Capability (AAC-TESC), which incorporates Phase Change Material (PCM) with high thermal storage density into Alkali-Activated Concrete (AAC), for energy geostructures. For the first time, the mechanical properties, volume stability, and durability of AAC-TESC under the operational conditions of energy geostructures were systematically investigated. The results reveal that the inclusion of Thermal Energy Storage Aggregate (TESA) containing PCM significantly reduces temperature-induced deformations by 44.8–76.9 % while maintaining compressive strength within the range of 30–60 MPa, making AAC-TESC highly suitable for energy geostructure applications. Additionally, AAC-TESC shows enhanced resistance to chloride diffusion, attributed to increased thermal cycling and lower operating temperature, potentially reducing its activation energy. This study offers valuable insights into the potential of AAC-TESC to improve the volume stability and durability of energy geostructures, presenting a sustainable solution to contemporary construction challenges.

Investigating swastika fins to enhance heat transfer and melting process of nano-enhanced phase change materials units

The ability of nano-enhanced phase change materials (NePCM) to store thermal energy has garnered the interest of scientists. An approach to enhancing thermal conductivity involves the implementation of novel fins that facilitate a more rapid PCM melting process. The present investigation assessed the efficacy of eight distinct fin configurations in augmenting the thermal properties of NePCM. Four occurrences featured swastika fins, whereas the remaining instances exhibited a 45-degree tilt angle. The enthalpy-porosity method was implemented to simulate heat transfer and melting process. The present research investigates the effects of fin tilt angles and swastika fins on the NePCM-thermal energy storage (TES) unit's mean temperature, liquid percentage, and thermal energy storage. Compared to the straight fins (Case 1), the long-arm swastika fins (Case 4) decreased the melting time by a factor of 2.3. In addition, Case 4 demonstrated exceptional thermal energy storage capabilities. Case 7 demonstrated that the tilting angle significantly affected the melting time, with a reduction of 34.9 %, compared to the non-tilted swastika fins utilized in Case 2. However, the increase in the fins' length was more substantial. According to the findings of this study, Case 4 is the optimal fin configuration for NePCM-TES.

Exploring key factors of radiative cooling performance of n-octadecane@SiO2 MEPCMs

With the development of passive daytime radiative cooling, various dielectric scatterers have been utilized. Among these, n-octadecane@SiO2 microencapsulated phase change materials (MEPCMs) have garnered significant attention for their effective radiative cooling, as well as unique temperature control and thermal energy storage capabilities. However, due to incomplete optical data for phase change materials (PCMs), past simulations used simplified parameters, leading to simulation-experiment mismatches. This study used simulation and experimentation to explore how particle size and shell thickness affect the radiative cooling of n-octadecane@SiO2 MEPCMs, leading to the production of n-octadecane@SiO2 MEPCMs with superior cooling capacity. To enhance simulation accuracy, we used a two-thickness inversion method to determine the complex refractive index of n-octadecane across 0.25–2.5 μm wavelengths. The simulation showed that particles of 0.25–0.4 μm radius scatter better with <50 nm shell, while those of 0.4–0.75 μm radius benefit from <100 nm shell for improved scattering. Finally, we designed n-octadecane@SiO2 MEPCMs with an average particle size of 0.66 μm and a shell thickness of 30 nm. This particle size can cause strong Mie scattering effect to reflect sunlight and SiO2 itself has a high mid-infrared emissivity. Thus n-octadecane@SiO2 MEPCMs show a high solar reflectivity of 94.93 % and a high mid-infrared emissivity of 94.62 %. In addition, it not only exhibited a satisfactory temperature control capacity under a latent heat capacity of over 154.4 J/g, but also achieved an excellent thermal cycling performance. This work expands the potential applications of MEPCMs and radiative cooling in energy conservation and environmental protection.

Effect of geometric parameters on the heat transfer performance of a submerged coil condenser for heat-pump water heating

Water heating with heat pumps can contribute to reduce carbon dioxide emissions and meet sustainability goals due to its high thermal efficiency, versatility in terms of alternative energy sources and thermal energy storage capability. In this study, the heat transfer of the condenser subsystem of an accumulation heat-pump water heater is analyzed by means of 2D CFD simulations. After validating the simulation methodology with benchmark natural convection problems, the influence of different geometric parameters of the condenser coil on the heat transfer is studied, which include the distance between turns and the distance from the tank wall. For each case, Nusselt number correlations in terms of Rayleigh number are found via power-law fitting. According to the CFD results, a greater coil pitch improves the average heat transfer. Moreover, a shorter distance from the tank wall generates a velocity field that laterally diverts the plume that forms around each turn. Hence, the heat transfer is enhanced because the preheating effect from downstream turns is mitigated, while the velocity gradients are strengthened. Additionally, a condenser design is proposed with geometric parameters that promote effective heat transfer, and the performance is compared against a reference design with geometric parameters that limit the heat transfer but are common in commercial solutions. The proposed geometry has a 43% increase in the Nusselt number, with respect to the reference geometry. Also, based on a dynamic simulation model of heat pump performance, it is determined that, for the same operating conditions, the proposed geometry improves the overall coefficient of performance (COP) of the system by up to 7%. These results highlight the importance of the geometric design of the condenser in heat-pump water heating systems, since they can contribute to a better overall performance and a more efficient thermal storage.

Polymer‐based supporting materials and polymer‐encapsulated phase change materials for thermal energy storage: A review on the recent advances of materials, synthesis, and characterization techniques

AbstractPhase change materials (PCMs) can be classified as smart materials having its applications in varied fields like domestic and commercial refrigerators, solar absorption chillers, air conditioning, free and radiative cooling, solar air heaters, solar stills, solar absorption cooling, electric and electronic devices for cooling purposes and in textiles. Here, in this review, the various polymer‐based and encapsulated PCMs used for fulfilling the above applications are discussed along with their varied synthesis/fabrication methods. Furthermore, chemical characterization is discussed by FTIR for understanding the chemical structure along with functional groups present in the materials. The thermogravimetric analysis (TGA) is also critically discussed for understanding the thermal stability of the Polymer PCM or the phase change composites and the latent heat of PCM melting was also explored by differential scanning calorimetry (DSC) for various PCM which gives insight into the thermal energy storage capability and property. The inbuilt surface structure of the polymer PCM was also tried to be investigated by scanning electron microscopy (SEM) which when understood gives a clear picture about the structure–property relationship.Highlights Polymeric supporting materials and polymer encapsulation on PCM were reviewed. The materials used and the synthesis of polymeric PCM were studied in depth. Chemical characterization was reviewed for chemical structure. Thermal stability checks by TGA and latent heat prediction was done by DSC. Morphology was reviewed using SEM for the structure–property relationship.

Enhancing reliability and efficiency of solar chimney by phase change material Integration: An Experimental study

The Solar Chimney Power Plant (SCPP) presents an eco-friendly and straightforward technique for converting solar radiation into electricity. However, the performance limitations and reliability challenges of SCPPs are inherently linked to the variability and intermittency of solar radiation. To tackle this issue, using phase change materials (PCMs) can enhance the thermal energy storage and release capabilities of SCPPs. This study aims to explore the impact of PCM on the exergy efficiency and performance of a solar chimney. Two pilot solar chimneys with identical dimensions were constructed, each featuring a 4 m height chimney and a 5 m diameter collector. One solar chimney was equipped with hydrated salt PCM as an energy storage layer, while the other operated without PCM. Both systems' power production and ventilation potential were evaluated using theoretical turbines, and subsequent exergy analysis discerned the operational behavior and efficiency of the systems. Results indicate that PCM increased the average air mass flow rate through the solar system during the day. The average daily air mass flow rate was 0.045 kg/s with PCM and 0.033 kg/s without PCM. Notably, mean pressure drops resulting from the airflow through the turbine were 2.44 and 1.83 Pa in the presence and absence of PCM, respectively, over a complete day. Additionally, PCM improved exergy efficiency by about 19 % due to enhanced thermal energy storage.

Phase Engineered Composite Phase Change Materials for Thermal Energy Manipulation.

Phase change materials (PCMs) present a dual thermal management functionality through intrinsic thermal energy storage (TES) capabilities while maintaining a constant temperature. However, the practical application of PCMs encounters challenges, primarily stemming from their low thermal conductivity and shape-stability issues. Despite significant progress in the development of solid-solid PCMs, which offer superior shape-stability compared to their solid-liquid counterparts, they compromise TES capacity. Herein, a universal phase engineering strategy is introduced to address these challenges. The approach involves compositing solid-liquid PCM with a particulate-based conductive matrix followed by surface reaction to form a solid-solid PCM shell, resulting in a core-shell composite with enhanced thermal conductivity, high thermal storage capacity, and optimal shape-stability. The core-shell structure designed in this manner not only encapsulates the energy-rich solid-liquid PCM core but also significantly enhances TES capacity by up to 52% compared to solid-solid PCM counterparts. The phase-engineered high-performance PCMs exhibit excellent thermal management capabilities by reducing battery cell temperature by 15°C and demonstrating durable solar-thermal-electric power generation under cloudy or no sunshine conditions. This proposed strategy holds promise for extending to other functional PCMs, offering a compelling avenue for the development of high-performance PCMs for thermal energy applications.

Experimental study and numerical simulation of a structural concrete column for building heating integration and energy storage

A steel pipe assemblage is integrated into a structurally reinforced precast concrete column to demonstrate thermal energy storage (TES) and space heating capabilities. This thermal energy column is heated via hot water at varying flow conditions. The system is used as a thermal storage medium, as a means of reducing the demands on the building heat pump, and for regulating the thermal comfort of the building interior environment. The thermal performance of the energy column is examined experimentally and numerically in both charging and discharging phases. Two examples are used to demonstrate the improvements in the operation of building thermal equipment and in the building thermal environment offered by either passive or active discharging of the energy column. Following the conclusion of thermal evaluation, the structural performance of the column under axial compression was evaluated by loading the system to failure. The experiment was paused for visual observation at both the service level and nominal capacity milestones. The longitudinally embedded steel pipes developed comparable strains to the column longitudinal steel reinforcing bars. The structural capacity of the energy column can be accurately predicted using standard concrete design approaches that account for the mechanical influence of the embedded steel pipe assemblage. It is demonstrated that the developed concrete energy column provides a viable option for improving the building thermal energy efficiency and maintaining structural performance.

Scattered Co-anchored MoS2 synergistically boosting photothermal capture and storage of phase change materials

Pristine phase change materials (PCMs) suffer from inherent deficiencies of poor solar absorption and photothermal conversion. Herein, we proposed a strategy of co-incorporation of zero-dimensional (0D) metal nanoparticles and two-dimensional (2D) photothermal materials in PCMs for efficient capture and conversion of solar energy into thermal energy. Highly scattered Co-anchored MoS2 nanoflower cluster serving as photon and phonon triggers was prepared by in-situ hydrothermal growth of ZIF67 polyhedron on 2D MoS2 and subsequent high-temperature carbonization. After encapsulating thermal storage unit (paraffin wax), the obtained composite PCMs integrated high-performance photothermal conversion and thermal energy storage capability. Benefiting from the synergistic enhancement of 0D Co nanoparticles with localized surface plasmon resonance effect, carbon layer with the conjugation effect and 2D MoS2 with strong solar absorption, composite PCMs exhibited a high photothermal conversion efficiency of 95.19%. Additionally, the resulting composite PCMs also demonstrated long-term thermal storage stability and durable structural stability after 300 thermal cycles. The proposed collaborative co-incorporation strategy provides some innovative references for developing next-generation photothermal PCMs in solar energy utilization.

Evaluation of the thermal capacity of cement-based thermal energy storage components. A case study

In this paper, we evaluate the heat capacity performance of cement-based heat exchangers for thermal energy storage and analyze their structural integrity under elevated temperatures. Fluid flow is modeled using the Navier-Stokes equations, conservation of mass, and energy. The response of the cement-based material is modeled considering thermomechanical coupling, obtaining the temperature profile within the thermal energy storage. This study allows us to observe the thermal energy storage capabilities for different thermal energy storage designs: plain concrete and concrete with nanoparticles of SiO2. Finally, we use our model for the evaluation of the concrete thermal energy storage component, which has been previously functionalized for use in low to medium temperature ranges (i.e., 100 °C to 400 °C).

A Eutectic Mixture of Calcium Chloride Hexahydrate and Bischofite with Promising Performance for Thermochemical Energy Storage

Thermochemical energy storage using salt hydrates is a promising method for the efficient use of energy. In this study, three host matrices, expanded vermiculite, expanded clay, and expanded natural graphite were impregnated with a eutectic mixture of CaCl2·6H2O and bischofite (MgCl2·6H2O). These composites were subjected to various humidity conditions (30–70% relative humidity) at 20 °C over an extended hydration period to investigate their cyclability. It was shown that only expanded natural graphite could contain the deliquescent salt at high humidity over 50 cycles. Hence, the expanded natural graphite composites containing either CaCl2·6H2O or CaCl2·6H2O/bischofite eutectic mixture were placed in a lab-scale open packed bed reactor, providing energy densities of 150 and 120 kWh/m3 over 20 h, respectively. The eutectic composite showed slightly lower temperature lift, water uptake rate, and power output but at reduced cost. Using the eutectic mixture also decreased the composite’s dehydration temperature at which the maximum mass loss rate occurred around 16.2 °C to 62.3 °C, allowing recharge using less energy-intensive heating methods. The cost of storing 1 kWh of energy with expanded natural graphite composites is only USD 0.08 due to its stability. This research leveraging cost-effective composites with enhanced stability, reaction kinetics, and high thermal energy storage capabilities benefits renewable energy, power generation, and the building construction research communities and industries by providing a competitive alternative to sensible heat storage technologies.

A numerical study on the effects of inclination angle and container material on thermal energy storage by phase change material in a thick-walled disc

PurposeThe purpose of this study is to examine the effects of inclination angle on the thermal energy storage capability of a phase change material (PCM) within a disc-shaped container. Different container materials are also tested such as plexiglass and aluminium. This study aims to assess the energy storage capacity, melting behaviour and temperature distributions of PCM with a specific melting range (22°C–26°C) for various governing parameters such as inclination angles, aspect ratios (AR) and temperature differences (ΔT) and compare the melting behaviour and energy storage performance of PCM in aluminium containers to those in plexiglass containers.Design/methodology/approachA finite volume approach was adopted to evaluate the thermal energy storage capability of PCMs. Five inclination angles ranging from 0° to 180° were considered and the energy storage capacity. Also, the melting behaviour of the PCM and temperature distributions of the container with different materials were tested. Two different AR and ΔT values were chosen as parameters to analyse for their effects on the melting performance of the PCM. Conjugate heat transfer problem is solved to see the effects of conduction mode of heat transfer.FindingsThe results of the study indicate that as AR decreases, the effect of the inclination angles on the energy storage capacity of the PCM decreases. For lower ΔT, the difference between the maximum and minimum stored energies was 20.88% for AR = 0.20, whereas it was 6.85% for AR = 0.15. Furthermore, under the same conditions, the PCM stored 8.02% more energy in plexiglass containers than in aluminium containers.Originality/valueThis study contributes to the understanding of the influence of inclination angle, container material, AR and ΔT on the thermal energy storage capabilities of PCM in a novel designed container. The findings highlight the importance of AR in mitigating the effect of the inclination angle on energy storage capacity. Additionally, comparing aluminium and plexiglass containers provides insights into the effect of container material on the melting behaviour and energy storage properties of PCM.

Thermal characteristics enhancement of Paraffin Wax Phase Change Material (PCM) for thermal storage applications

This study investigates the integration of graphene nanoplatelets and nano SiO2 into paraffin wax to enhance its thermal energy storage capabilities. Dispersing graphene nanoplatelets and nano SiO2 nanoparticles at weight percentages of 0.5 and 1.0 respectively, in paraffin wax yielded mono and hybrid phase change materials (HYB). Transmission electron microscopy, Field Emission Scanning Electron Microscopy and X-ray diffraction were used to determine the size and phases of secondary particles of graphene nanoplatelets and nano SiO2. Differential Scanning Calorimetry, Thermogravimetric Analysis and Thermal Conductivity Measurement were employed to investigate the impact of hybrid nanoparticles on thermo physical characteristics of paraffin wax. The weight fraction of nano particles distributed in the PCMs is directly related to the enhancement of thermal conductivity of hybrid PCM. The highest enhancement in thermal conductivity was observed when hybrid nanoparticles were present at a weight fraction of 1 %. The analysis shows that mixing graphene nanoplatelets and nano SiO2 with paraffin wax was uniform and the hybrid nanoparticles boosted its thermal conductivity by 38 %, 42 %, and 50 %, respectively. Experimental evidence indicate that the addition of nanoparticles can decrease the melting temperature and increase the solidification temperature of hybrid phase change materials (PCMs). When dispersed in large quantities, nanoparticles can alter properties like latent heat, specific heat, and viscosity. These promising findings suggest that graphene nanoplatelets and nano SiO2 can enhance paraffin wax's thermal properties for thermal storage application.

Using Carbonized Cotton Fabric Waste to Prepare Poly(ethylene glycol) Composite Phase Change Materials with Improved Thermal Conductivity and Solar-to-Thermal Conversion.

Poly(ethylene glycol) (PEG) boasts excellent thermal energy storage capabilities but lacks efficiency in thermal conductivity and solar absorption. Simultaneously, the escalating concern surrounding the substantial volume of discarded cotton fabric underscores environmental issues. In this study, we devised composite phase change materials (PCMs) by embedding PEG into a carbon cotton material (CCM), varying PEG content from 50 to 80%, and conducted a comprehensive analysis of their thermal properties and solar-to-thermal conversion. The CCM, crafted from a waste 100% cotton towel through carbonization, provided an optimal porous structure that accommodated a significant 70% PEG content without any leakage, thanks to interactions such as surface tension, capillary forces, and interfacial hydrogen bonds. These PEG/CCM composites exhibited impressive crystallization fractions (>92%), resulting in notable thermal energy storage capacities ranging from 85.3 to 143.2 J/g as the PEG content increased from 50 to 80%. Moreover, these composites showed high thermal stability and exceptional cycling durability even after 500 melting/crystallization cycles. Notably, their thermal conductivities markedly increased to a range of 0.46-0.85 W/m·K compared to pure PEG's modest 0.24 W/m·K. Furthermore, the PEG/CCM composites substantially augmented visible and near-infrared (VIS-NIR) light absorption. Evaluation of solar-to-thermal conversion illustrated the composite's ability to efficiently convert solar energy into thermal energy, storing and subsequently releasing it through melting and crystallization processes. This study introduces a novel class of composite PCMs characterized by cost-effectiveness, outstanding thermal performance, and impressive solar-to-thermal conversion capabilities. These composite PCMs hold significant promise for large-scale solar-to-thermal energy storage applications while contributing to the sustainability of cotton waste management.

Influence of tree-shaped fins to enhance thermal storage units

Phase change materials (PCMs) have attracted considerable interest recently due to their remarkable thermal energy storage capabilities for different thermal applications. This would effectively assist in the reduction of CO2 emissions and encourage the transition to sustainable energy on a global scale. The present study investigates the increase in the thermal efficiency of a shell-and-tube heat exchanger using PCM and a novel arrangement of fins in the form of a tree. The enthalpy-porosity method is used to mimic phase changes under the studied conditions. Moreover, copper nanomaterials are incorporated with the PCM to increase thermal conductivity and speed up the charging process. The influences of various parameters, such as the concentration of nano-additive and the distribution of sub-fins, are investigated. The findings derived from the present model demonstrate that the incorporation of elongated sub-fins in the outer part (far from the inner heating tube) of the PCM unit leads to a noteworthy enhancement in the heat transfer distribution, resulting in a 75.7% reduction in melting time. Adding copper nanomaterials to PCM improves thermal performance. For example, a 6% concentration of nanoparticles leads to a reduction in the melting process by >15% compared to pure PCM.

Evaluation of shape-stabilized phase-change materials using calcium carbonate-based starfish microporous materials for thermal energy storage

This study investigates the synergistic potential of shape-stabilized phase-change materials (PCMs) integrated with calcium carbonate-based starfish microporous materials for efficient thermal energy storage. By addressing challenges related to traditional PCMs, such as leakage and stability, this research aims to enhance thermal energy storage capabilities. Starfish and bio-based PCMs prepared from starfish were subjected to porosity, thermophysical, and chemical analyses. The porosity analysis revealed that the surface and skeleton of the starfish had sufficient porosities to contain liquid PCMs inside, and the bio-based PCM formed closed cells in the starfish, effectively blocking leakage to the outside. The maximum latent heat, which indicates the thermal energy storage capacity, was 57.66 J/g. This demonstrated thermal stability below 150 °C, making it suitable as a building material. The chemical analysis revealed that bio-based PCM was composed of carbon, oxygen, and calcium commonly found in sea creatures, and it was confirmed that there was no chemical change during phase stabilization, confirming that it was chemically stable. Therefore, the manufactured bio-based PCM has potential as an eco-friendly heat-storage material.

A real time peer-to-peer energy trading for prosumers utilizing time-varying building virtual energy storage

With the increasing penetration of distributed energy resources (DER) in the electric power system, Peer-to-Peer (P2P) energy trading has become a promising paradigm for future electric power systems. Building thermal load, which is an important demand side resource, should be considered carefully in the design of a P2P trading method. In this paper, we investigate the application of building thermal energy storage capability in P2P energy trading. We aggregate and model building thermal loads as a virtual energy storage and derive a time-varying virtual energy storage system (T-VESS) model to quantify the flexibility of a building. Key parameters of T-VESS, including charging/discharging rate, energy capacity, and state of charge (SOC), are analyzed so that T-VESS can be embedded in the building prosumer model to participate effectively in electricity-oriented P2P energy trading. We propose a real time P2P energy trading method of prosumers based on model predictive control (MPC). This method consists of an energy supply and demand quantification stage and a transaction price optimization stage, which can effectively capture the time-varying nature of T-VESS. To preserve the trading preference for prosumers, we propose a distributed P2P energy trading actions implementation method based on the continuous double auction (CDA) considering multiple trading preference grades. Numerical results demonstrate that the proposed P2P energy trading method considering T-VESS can reduce the operational cost of prosumers by 3.7%, while also promoting the local integration of renewable energy by 3.1%. Furthermore, compared to existing P2P trading methods considering single preference grade, the proposed method greatly enhances the utilities of both individual prosumers and the overall community.