Solar Energy Storage Materials Research Articles

Analysis of the Variable Influence and Energy Storage Performance in Preparation of Solar Energy Storage Materials via Modification of Carbide Slag Using MnO2 through Wet Doping

Analysis of the Variable Influence and Energy Storage Performance in Preparation of Solar Energy Storage Materials via Modification of Carbide Slag Using MnO₂ through Wet Doping

A Dual Modification Method to Prepare Carbide Slag into Highly Active CaO-Based Solar Energy Storage Materials

A Dual Modification Method to Prepare Carbide Slag into Highly Active CaO-Based Solar Energy Storage Materials

Oriented High Thermal Conductivity Solid-Solid Phase Change Materials for Mid-Temperature Solar-Thermal Energy Storage.

As the global energy crisis intensifies, the development of solar energy has become a vital area of focus for many nations. The utilization of phase change materials (PCMs) for photothermal energy storage in the medium temperature range holds great potential for various applications, but their conventional forms face several challenges. For instance, the longitudinal thermal conductivity of photothermal PCMs is inadequate for effective heat storage on the photothermal conversion surface, and there is a risk of leakage due to repeated solid-liquid phase transitions. Here, we report a solid-solid phase change material, tris(hydroxymethyl)aminomethane (TRIS), which has a phase change temperature of 132 °C in the medium temperature range, enabling high-grade and stable solar energy storage. To overcome the low thermal conductivity problem, we propose a large-scale production of oriented high thermal conductivity composites by compressing a mixture of TRIS and expanded graphite (EG) using the pressure induction method to create in-plane highly thermally conductive channels. Remarkably, the resulting phase change composites (PCCs) exhibit a directional thermal conductivity of 21.3 W/(m·K). Furthermore, the high phase change temperature (132 °C) and large phase change entropy (213.47 J/g) enable a large-capacity high-grade thermal energy to be used. The developed PCCs, when combined with selected photo-absorbers, exhibit efficient integration of solar-thermal conversion and storage. Additionally, we also demonstrated a solar-thermoelectric generator device with an energy output of 93.1 W/m2, which is close to the power of photovoltaic systems. Overall, this work provides a technological route to the large-scale fabrication of mid-temperature solar energy storage materials with high thermal conductivity, high phase change enthalpy, and no risk of leakage, and also offers a potential alternative to photovoltaic technology.

Reversible thermochromic transparent bamboo for dynamically adaptive smart windows

The development of energy-saving functional materials plays a crucial role in the field of smart windows. Transparent bamboo is an emerging sustainable alternative to glass. However, the use of transparent bamboo in combination with organic thermochromic materials has not yet been thoroughly studied. In this study, reversible thermochromic transparent bamboo with dynamically temperature-adaptive functions was developed by incorporating thermochromic microcapsule powder. Reversible thermochromic transparent bamboo is colorless and has high transmittance at low temperatures, whereas it is purple with low transmittance at high temperatures providing a visually cool emotional impression. With the increase in thermochromic powder addition, the transmittance of thermochromic transparent bamboo decreased and the haze increased. When the amount of thermochromic powder was 1 wt % of the resin mass, the highest transmittance in thermochromic bamboo was 79.27 % for colorless and 63.67 % for colored. The highest tensile strength (77.79 MPa) and lowest thermal conductivity (0.225 W m−1 K−1) were obtained when the amount of powder was 3 wt %. Thermochromic transparent bamboo has excellent potential for smart window applications and its impressive haze and light absorption properties may also allow it to be used as a solar energy storage material.

Extraction of natural piperine crystals from black pepper with expanded graphite for thermal energy storage

Substantial research was done on the synthesis of piperine crystals (PC) from black pepper using expanding graphite (EG) as a promising organic phase change material (O-PCM). Researchers examined the chemical structure and thermal properties of the substance. Using the diffusion–exudation circle method, the PC/EG-blended PCM had the highest PC mass content, at 93.4 %. According to (DSC) study, the melting and crystallization temperatures are 135.6 °C and 117.4 °C, and their related latent energies are 283.14 KJ/kg and 192.45 KJ/kg. This finding implies that the material retains a respectable capacity for heat storage after being exposed to multiple heat patterns. Thermal storage/discharge studies revealed that the EG/PC material had much better heat storage/discharge ratios than the PC sample. At ambient circumstances, our findings indicated that the Herbal Piperine crystals/expandable graphite PCM was a superior thermal energy storage medium. The results demonstrated that the proposed hybrid composite can be considered as a potential solar energy storage material for a variety of applications, including thermal cooling of photovoltaic panels, automobiles, digital units, solar residential heating systems, and passive solar heating systems.

Development and characterization a novel leakage-proof form stable composite of graphitic carbon nitride and fatty alcohol for thermal energy storage

The form-stabilization ability of the produced graphitic carbon nitride (g-C3N4) for preventing the leakage of stearyl alcohol (SAOH) as promising organic phase change material (O-PCM) was investigated comprehensively. The SEM analysis showed that the g-C3N4 had well defined pores which is capable to confine the molten SAOH in them. The FTIR and XRD confirm the chemical compatibility of g-C3N4 and SAOH. The differential scanning calorimetry thermogram showed that the melting and freezing temperature of the FS-OPCMs including 70 wt% SAOH were 54.57 °C and 55.25 °C with respective high latent heats as 191 kJ/kg and 187 kJ/kg respectively. The thermal aging test for 1000 melt/freeze cycles confirmed that structure and thermal degradation durability are excellent. The thermal conductivity of developed FS-OPCM is enhanced by 122 %, which were resulted in about 50–54 % reduction in the charging/discharging time of FS-OPCM relative to the SAOH. The results exposed that the developed g-C3N4/SAOH (70 wt%) composite can be considered as potential solar energy storage material in different implementations such thermal cooling of photovoltaic panels, automotive and electronic units as well as solar residential water heating and passive solar space heating.

Phase change materials based thermal energy storage for solar energy systems

This manuscript discusses one of the proposed methods for storing solar energy. Applications of PCMs, mono and binary nanofluids and molten salts as storage materials in solar energy are the major important techniques explained. A summary of various other solar energy storage materials that are currently under application is also presented. This paper overlooks the most current research in this specific field through the main focus of measuring absorption efficiency and effects of different particles on it with changed concentration and assessing thermophysical and storage properties of discussed materials. Presented studies expressed extraordinary efficiency enhancement and other outcomes of these materials. However, there are many problems associated with these materials that hindered their commercialization. These major problems include high costs, corrosion and erosion, pressure drop and friction factor appreciation and instability are also discussed.

Improving thermal energy storage and transfer performance in solar energy storage: Nanocomposite synthesized by dispersing nano boron nitride in solar salt

Solar salt (SS) is an energy storage material widely used in concentrating solar power (CSP) stations at industrial thermal energy storage (TES) systems in the current. Hence, a conventional high-temperature static melting method was used to prepare nano hexagonal boron nitride-SS (h-BN-SS, BS system) composite materials with different content of nano BN to improve the heat storage and transfer performance of SS. The specific heat (cp) of 1.81 J·g−1·K−1 was obtained at nano BN content of 0.8 wt% (sample BS6), which had increase of 16.03% compared with pure SS (sample BS0). The crystal planes (104) and (221) of nitrate appeared on the surface of nano BN (100), promoted the enhancement of surface energy of whole system. The using temperature zone was widened and thermal conductivity (λ) had been increased by 18.52%. The existence forms of nano BN hadn't changed at high temperature, and the cation environment around NO3− of BS0 and BS6 were changed after adding nano BN demonstrated by high temperature Raman spectroscopy. Moreover, BS6 had excellent thermal stability at long-term thermal stability measurement within 7200 min. The observations suggested that nano BN may serve as promising additive for solar energy storage material toward TES system applications.

Fabrication and performance of shape‐stable phase change materials based on epoxy group crosslinking

AbstractShape‐stable phase change materials (SSPCMs) have attracted increased attention as they can be used in applications such as solar energy storage materials and smart textiles. Hexadecyl acrylate (HDA) was free‐radical copolymerized with allyl glycidyl ether (AGE) to form a copolymer with epoxy groups. It was further solidified with diethylenetriamine to form a series of novel SSPCMs. HDA could be limited to a stable 3D cross‐linking network constructed from epoxy groups, giving PCM excellent shape stability. Infrared spectroscopy and hydrogen nuclear magnetic spectroscopy showed the successful fabrication of poly(hexadecyl acrylate) (PHDA) with epoxy group. The maximum enthalpies of the SSPCMs with 5 wt% AGE during heating and cooling were 86 and 86 J/g, respectively, which indicated that they have good thermal energy storage densities. The initial melting and freezing temperatures were 32 and 29°C, respectively, which were within the comfortable temperature range of human body. In addition, the thermal decomposition temperature of SSPCMs was higher than 270°C. After 50 thermal cycles, the materials still showed excellent phase change performances. Moreover, the specimen with low degree of cross‐linking had similar temperature control and thermal response capabilities to PHDA. These SSPCMs exhibited excellent thermal performance, thermal reliabilities, and stabilities. Therefore, they were expected to be applied in various applications, including solar energy storage, energy‐saving buildings, and wearable temperature control textiles.

Phase-Changing Microcapsules Incorporated with Black Phosphorus for Efficient Solar Energy Storage.

A new solar energy storage system is designed and synthesized based on phase‐changing microcapsules incorporated with black phosphorus sheets (BPs). BPs are 2D materials with broad light absorption and high photothermal performance, which are synthesized and covalently modified with poly(methyl methacrylate) (PMMA) to produce the PMMA‐modified BPs (mBPs). With the aid of PMMA, the mBPs and phase‐changing materials (PCM, eicosane) are encapsulated together to form microcapsules. The microencapsulated eicosane and mBPs (mBPs‐MPCM) composites exhibit a high latent heat of over 180 kJ kg−1, good thermal reliability, as well as excellent photothermal characteristics inherited from BPs. Owing to the direct contact in the integrated mBPs‐MPCM composites, the thermal energy generated by mBPs is transferred to eicosane immediately giving rise to three times higher efficiency in solar energy storage compared to microcapsules with mBPs on the surface. The mBPs‐MPCM composites have great potential in solar energy storage applications and the concept of integrating photothermal materials and PCMs as the core provides insights into the design of high‐efficiency solar energy storage materials.

From biomass residue to solar thermal energy: the potential of bagasse as a heat storage material

Solar energy is an ecofriendly potential alternative to nonrenewable sources of energy, which are becoming increasingly scarce. Issues with the use of solar energy, such as temporal variations in the intensity of sunlight, could be solved by storing solar energy. This work introduces the concept of using waste as a sustainable material for energy storage. Sugarcane crop is a potential feedstock for the agro-industry in Egypt. However, while sugarcane is a source of both ethanol and sugar, extracting these substances from sugarcane results in a significant amount of solid biomass waste, known as “bagasse”. This investigation demonstrates that sugarcane bagasse, which is produced in increasingly large quantities each year, could be employed in a cost-efficient method of storing solar energy. In this study, the bagasse was modified using facile chemical and thermal treatments and then examined using XRD (X-ray diffractometry) and SEM (scanning electron microscopy), which revealed the presence of quartz. An inexpensive solar energy storage material was then created by impregnating paraffin wax with the treated bagasse using an ultrasonic technique. This composite material showed excellent form-stable phase-change behaviour that allowed it to absorb large amounts of solar energy, especially around solar noon, and store that energy in the form of heat. The composite was found to store 72 kJ/min of heat, as compared to only 7 kJ/min for pure paraffin. Thus, this study suggests that a composite material capable of enhanced solar energy storage can be created from industrial waste, permitting an environmentally integrated approach to storing green energy.

Characterization and thermal performance of microencapsulated sodium thiosulfate pentahydrate as phase change material for thermal energy storage

In this work, a novel microencapsulated phase change material based on sodium thiosulfate pentahydrate as core and poly(ethyl-2-cyanoacrylate) as shell was successfully synthesized by interfacial polymerization in a water-in-oil emulsion system. The morphology, microstructure, surface elemental distribution, chemical composition and crystalline structure of the resultant microcapsules were determined by scanning and transmission electron microscopies, energy dispersive spectroscopy, Fourier-transform infrared spectroscopy and X-ray diffraction. Besides, their thermal properties were also investigated systematically by differential scanning calorimetry and thermogravimetry analysis. The results showed that the microcapsules presented almost spherical profiles with a diameter of about 1.0 µm and a well-defined core-shell structure. Meanwhile, the microcapsules possessed phase change temperature of 46.44 °C and latent heat of 107.0 kJ·kg−1 at the core material/monomer mass ratio of 4/2. Due to the protective effect of shell material, the thermal stability of the microcapsules was improved. In addition, the thermal cycling test revealed that the microcapsules had good thermal reliability. Considering the above results, this synthetic technique can be considered as a feasible way to prepare microencapsulated salt hydrates and is expected to extend to the encapsulation of other hydrophilic substances. And the obtained microcapsules have great potential as a solar energy storage material.

A Record Chromophore Density in High-Entropy Liquids of Two Low-Melting Perylenes: A New Strategy for Liquid Chromophores.

Liquid chromophores constitute a rare but intriguing class of molecules that are in high demand for the design of luminescent inks, liquid semiconductors, and solar energy storage materials. The most common way to achieve liquid chromophores involves the introduction of long alkyl chains, which, however, significantly reduces the chromophore density. Here, strategy is presented that allows for the preparation of liquid chromophores with a minimal increase in molecular weight, using the important class of perylenes as an example. Two synergistic effects are harnessed: (1) the judicious positioning of short alkyl substituents, and (2) equimolar mixing, which in unison results in a liquid material. A series of 1‐alkyl perylene derivatives is synthesized and it is found that short ethyl or butyl chains reduce the melting temperature from 278 °C to as little as 70 °C. Then, two low‐melting derivatives are mixed, which results in materials that do not crystallize due to the increased configurational entropy of the system. As a result, liquid chromophores with the lowest reported molecular weight increase compared to the neat chromophore are obtained. The mixing strategy is readily applicable to other π‐conjugated systems and, hence, promises to yield a wide range of low molecular weight liquid chromophores.

Study on Modification of Phase Change Energy Storage Materials Suitable for Biogas Fermentation

In this study, the problems of supercooling and phase separation of inorganic hydrated salts as phase change energy storage materials when applied to biogas generating devices were investigated. In the experiment, two common hydrated salts of zinc nitrate hexahydrate and disodium hydrogen phosphate dodecahydrate were selected as phase change materials, and tested at room temperature. Recording temperature and drawing the step cooling curve method, by adding different proportions of nucleating agent and dye to improve the supercooling and phase separation of the phase change materials, so that the reaction temperature of the biogas plant was always maintained at a suitable temperature (20-30 °C) to ensure the activity of microorganisms. The experimental results showed that sodium tetraborate decahydrate can effectively reduce the subcooling degree of zinc nitrate hexahydrate, and the azo (-N = N-) dye not only improved the solar absorption rate but also weakened the phase separation of phase change materials to some extent. This study proposed a possible reaction mechanism and provided reference for the development and application of other solar energy storage materials for bioreactors.

Phase Change Energy Storage Material Suitable for Solar Heating System

Differential scanning calorimetry (DSC) was used to investigate the thermal properties of palmitic acid, myristic acid, laurel acid and the binary composite of palmitic/laurel acid and palmitic/myristic acid. The results showed that the phase transition temperatures of the three monomers were between 46.9-65.9°C, and the latent heats were above 190 J/g, which could be used as solar energy storage material. When the mass ratio of Palmitic acid and myristic was 1:1, the eutectic mixture could be formed. The latent heat of the eutectic mixture was 186.6 J/g, the melting temperature and the solidification temperature was 50.6°C and 43.8°C respectively. The latent heat of phase change and the melting temperature had not obvious variations after 400 thermal cycles, which proved that the binary composite had good thermal stability and was suitable for solar floor radiant heating system.

Thermal Gravimetric Analysis Study of Silicoaluminophosphate Synthesized from Non-Aqueous Media for Solar Energy Storage Material

Solar cell is not new technology but suffering from some limitation of material efficiency. The efficiency of solar cell affected by two factors: stability of material (degradation of material) and long diffusion length of material during solar energy absorbent. Silicoaluminophosphate have lower mass degradation at high temperature and have short diffusion length, so this material may have possibilities for better combination of solar thin film material. In this paper we worked on synthesis of nano-crystalline SAPO -11 from non-aqueous material for. Some characterization e.g. SEM, TGA and XRD have verified the successful synthesis of nano-crystaline material. TGA of material shows the higher resistance and low degradation on higher temperature.

Performance assessment and productivity of a simple-type solar still integrated with nanocomposite energy storage system

Paraffin wax (PW) is one of promising solar energy storage materials in solar distillers because of its relatively large latent heat with a stable phase change process. However, paraffin’s low thermal conductivity is a negative aspect for its efficient practice. In this study, adding nanomaterial to enhance paraffin’s low thermal conductivity and its performance parameters is examined. Three cases have been investigated and compared to each others, case 1 without PW, case 2 with PW, and case 3 with copper-PW nanocomposite (NCPW). The results showed apparent advantage of nanocomposite on thermal conductivity of PW and that enhanced the heat energy storage and water productivity. The productivity increased by about 125% and 119% for cases 3 and 2, respectively, compared to case 1. The system working time extended during night by 5h and 6h at applying PW and NCPW, respectively. It was also shown that adding nanomaterials to PW can not only increase its thermal conductivity but also the system efficiency and thermal storage capacity.

Characterization of thermal performance of a solid–solid phase change material, di-n-hexylammonium bromide, for potential integration in building materials

Di-n-hexylammonium bromide ((n-C6H13)2NH2Br) undergoes a solid–solid phase transition at about 20°C. The fact that it remains as a solid phase, yet the transition has a rather large enthalpy change (85Jg−1) suggests possible advantages as a phase change material (PCM) for integration into building materials. We investigated the phase change of (n-C6H13)2NH2Br in its pure form, and as a 30mass% composite in gypsum. In the latter, we show that after 1000 cycles, which would correspond to about 3 years of use as a solar energy storage material, the temperature of the transition changes by less than 1K and the enthalpy of transition is reduced by less than 3%. We also report the heat capacity and thermal conductivity of (n-C6H13)2NH2Br in the temperature range below and above the phase transition, and the volume change associated with the transition.

Fabrication and characterization of microencapsulated n-octadecane with different crosslinked methylmethacrylate-based polymer shells

Microencapsulations of n-octadecane with different crosslinked methylmethacrylate-based polymer as shells were carried out by suspension-like polymerizations. 1,4-butylene glycol diacrylate (BDDA), divinylbenzene (DVB), trimethylolpropanetriacrylate (TMPTA) and pentaerythritol tetraacrylate (PETRA) were employed as crosslinking agents. The influences of the type and amount of crosslinking agent, the type of initiator and polymerization temperature on the properties of as-prepared microencapsulated phase change materials (MicroPCMs) have been studied. The MicroPCMs were characterized using Fourier transformed infrared (FTIR) spectroscopy and scanning electron microscopy (SEM). Thermal properties and thermal stability of MicroPCMs were investigated by differential scanning calorimetry (DSC) and thermalgravimetric analysis (TGA). Shell mechanical strength was measured by micro/nano-hardness tester. Thermal properties, thermal resistant temperatures as well as shell mechanical strength of MicroPCMs enhanced as the number of crosslinkable functional moieties of the crosslinking agents increased. The MicroPCMs containing 75.3wt% n-octadecane obtained using PETRA as crosslinking agent has the highest latent heats of melting (156.4J/g) and crystallization (182.8J/g) and displays the highest thermal stability and shell mechanical strength. The MicroPCMs prepared with DVB shows a relatively higher shell mechanical strength and heat capacity compared with those prepared with BDDA. Both heat capacity and thermal stability of MicroPCMs prepared by combining 2,2′-azobisisobutyronitrile (AIBN) and redox initiators at 45°C were lower than that of MicroPCMs prepared with AIBN or benzoyl peroxide (BPO) at 85°C. Hence, MicroPCMs with crosslinked methylmethacrylate-based polymer as shells, especially crosslinked polymer shells of higher crosslinking density, show a good potential as a solar-energy storage material.

Concentrating Solar Power Development in China

Research on concentrating solar power (CSP) technologies began in 1979 in China. With pressure on environmental and energy resources, the CSP technology development has been accelerating since 2003. After 30 years of development, China has made significant progress on solar absorbing materials, solar thermal-electrical conversion materials, solar energy storage materials, solar concentrator equipments, evacuated tube solar trough collectors, solar thermal receivers, solar dish-Stirling systems, solar high-temperature air power generations, and solar power tower system designs. A 1 MW solar tower plant demonstration project landmark is currently being built in Beijing, to be completed by 2010 with a maximum temperature of 390°C and pressure of 2.35 MPa.