Solar Energy Storage Applications Research Articles

Review on phase change materials for solar energy storage applications.

The energy storage application plays a vital role in the utilization of the solar energy technologies. There are various types of the energy storage applications are available in the todays world. Phase change materials (PCMs) are suitable for various solar energy systems for prolonged heat energy retaining, as solar radiation is sporadic.This literature review presents the application of the PCM in solar thermal power plants, solar desalination, solar cooker, solar air heater, and solar water heater. Even though the availability and cost of PCMs are complex and high, the PCMs are used in most solar energy methods due to their significant technical parameters improvisation. This review's detailed findings paved the way for future recommendations and methods for the investigators to carry work for further system developments.

Optical constants, dispersion parameters and energy loss functions of crystal violet as a potential absorber thin film for solar energy conversion and storage applications

Highly homogenous crystal violet (CV) thin films are grown by spin coating technique. X-ray diffraction (XRD) measurements have been carried out to identify the dominant orientation of the films. The XRD pattern of as-deposited film showed an amorphous structure which turns into nanocrystalline by thermal annealing at 150 °C for 1 h. The spectroscopic characterization of as-deposited and annealed CV films was estimated via spectrophotometric measurements of transmission and reflection in the spectral range 190–2000 nm. Optical constants of CV films were determined. Wemple-DiDomenico model was applied to the normal dispersion region of refractive index spectrum and from which, many dispersion parameters were calculated. The type of most probable transitions and values of optical energy gaps for CV films were estimated by Tauc plot. The dissipation energy and volume & surface loss functions were estimated. The influence of annealing temperature on the spectroscopic properties, dispersion parameters and energy loss functions were investigated which revealed an improvement in the optical properties and decreased values of energy loss functions for the annealed CV films. The obtained results of optical features for CV films reveals that CV films are an excellent potential absorbing material in solar energy conversion and storage devices.

Prepared Pd/MgO/BiVO4 composite for photoreduction of CO2 to CH4

AbstractIn this study, several Pd/MgO/BiVO4 nanocomposites were prepared using the hydrothermal method and their effective photocatalyst activity for the photoreduction of CO2 to CH4 was investigated. The microstructure and photocatalytic behavior of the prepared photocatalysts were studied through X‐ray diffraction, scanning electron microscopy, tunneling electron microscopy, X‐ray photoelectron spectroscopy, ultraviolet–visible spectrophotometry, Fourier‐transform infrared spectroscopy, Brunauer–Emmett–Teller specific surface area, and photoluminescence spectroscopy. CH4 yields of 5.9 and 9.4 μmol g−1 hr−1 were obtained using BiVO4 and 25% MgO/BiVO4 nanocomposites, respectively. The highest production rate of CH4 was measured as 12.8 μmol g−1 hr−1 on overloading 0.3% Pd on 25% MgO/BiVO4. Pd/MgO/BiVO4 exhibited excellent CO2 photoreduction stability with negligible loss after five consecutive cycles. Finally, a possible mechanism of CO2 photoreduction using Pd/MgO/BiVO4 was proposed for understanding the synergistic effects. The results of the experiment revealed that Pd/MgO/BiVO4 can be a promising photocatalyst in solar energy conversion and storage application and can achieve excellent CO2 photoreduction performance.

Nano-Enhanced Phase Change Materials in Latent Heat Thermal Energy Storage Systems: A Review

Latent heat thermal energy storage systems (LHTES) are useful for solar energy storage and many other applications, but there is an issue with phase change materials (PCMs) having low thermal conductivity. This can be enhanced with fins, metal foam, heat pipes, multiple PCMs, and nanoparticles (NPs). This paper reviews nano-enhanced PCM (NePCM) alone and with additional enhancements. Low, middle, and high temperature PCM are classified, and the achievements and limitations of works are assessed. The review is categorized based upon enhancements: solely NPs, NPs and fins, NPs and heat pipes, NPs with highly conductive porous materials, NPs and multiple PCMs, and nano-encapsulated PCMs. Both experimental and numerical methods are considered, focusing on how well NPs enhanced the system. Generally, NPs have been proven to enhance PCM, with some types more effective than others. Middle and high temperatures are lacking compared to low temperature, as well as combined enhancement studies. Al2O3, copper, and carbon are some of the most studied NP materials, and paraffin PCM is the most common by far. Some studies found NPs to be insignificant in comparison to other enhancements, but many others found them to be beneficial. This article also suggests future work for NePCM and LHTES systems.

Fatty amines/oxidized multi-walled carbon nanotubes phase change composites with enhanced thermal properties

The development of phase change composites with both high latent heat and better thermal conductivity is of great importance for thermal energy or solar energy storage applications. Here, three kinds of oxidized multi-walled carbon nanotubes (p-MWCNTs, a-MWCNTs and c-MWCNTs) prepared though multiple oxidations with different oxygen contents were used as porous support materials for construction of phase change composites, in which two kinds of fatty amines (FAs), e.g. tetradecylamine (TDA) and octadecylamine (ODA), were employed as organic phase change materials (PCMs). The thermal conductivity of FAs/oxidized-MWCNTs phase change composites increased with the increase of the oxygen content of oxidized-MWCNTs. As a kind of novel phase change composites, FAs/c-MWCNTs have excellent thermal stability and energy storage density (latent heat up to 273.8 kJ kg−1 for ODA/3%c-MWCNTs), which can compete or superior to those conventional organic PCMs-based (paraffin, PEG, etc.) composites. Benefiting from the merits mentioned above, the FAs/c-MWCNTs phase change composites may have great potentials for real energy-saving applications.

Ionic Liquids–Cobalt(II) Thermochromic Complexes: How the Structure Tunability Affects “Self-Contained” Systems

With the aim of obtaining thermochromic systems with potential applications in solar energy storage, we evaluated the behavior of some sugar-based ionic liquids (ILs)–Co(NTf2)2 complexes, in IL solution, as a function of temperature. Different structural changes on the cation, the nature of the anion, and the nature of the IL used as the solvent were considered. The analysis of the above factors was carried out through a combined approach of different techniques, that is, variable temperature UV–vis and NMR spectroscopies, conductivity, and thermal gravimetric analysis. The thermochromic systems were analyzed both as solutions and as thin films, and the data collected highlight the defining role played by both the cation structure and the solvent nature in determining their performance. Most of the investigated systems show a chromogenic transition from pink to blue, occurring in a temperature range suitable for practical applications (40–60 °C). Interestingly, when embedded in a polymeric matrix, thin films with high recyclability and long life are also described.

Novel composite phase change materials based on hollow carbon nanospheres supporting fatty amines with high light-to-thermal transition efficiency

The construction of high-performance materials with superior light-to-thermal conversion efficiency is of great importance for harvesting and utilization of solar energy. Hence, we report the creation of novel composite phase change materials (CPCMs) CPCMs by incorporating three kinds of organic phase change materials (PCMs), i.e. 1-Tetradecylamine (TDA), 1-hexadecanamine (HDA) and Octadecylamine (ODA), into hollow carbon nanospheres (HCNS) via a simple impregnation treatment for efficient light-to-thermal transition. Owing to their carbon in nature, the HCNS show better light absorption of higher than 90%. After incorporation of organic PCMs, their light absorption could still attain 62–70%, which can compete with the existing CPCMs. Beneficial from their abundant porosity and high specific surface areas, organic PCMs can be spontaneously diffused and immersed into the porous architecture of HCNS. In this way, the as-resulted CPCMs containing with TDA, HDA and ODA show high phase change enthalpy of 61.23J/g, 119.5J/g and 101.8J/g, respectively. The CPCMs also exhibit better thermal conductivity and excellent thermal stability, e.g., the enthalpy of HAD based CPCMs remains nearly unchanged even after 100 times of melting/freezing cycles. Under 1 sun irradiation, the light-to-thermal conversion efficiency of CPCMs containing with TDA, HDA and ODA were measured to be 73.04%, 74.46% and 71.74%, respectively, Thus showing great potential as a kind of promising photothermal conversion devices for solar or thermal energy storage applications.

High-energy and light-actuated phase change composite for solar energy storage and heat release

Phase change materials (PCMs) show great potential for solar thermal energy application due to the large latent heat and high efficiency. However, it is difficult to implement long-term storage because of the sensitive phase-transition to environment temperature. Here, we report a high-energy organic phase change composite (PCC) by introducing long-chain azobenzene molecule (AZO) into low-cost tetradecyl alcohol (TA) for light-regulated solar energy storage and release. The photo-switch azobenzene can install a new energy barrier and form a supercooling in liquid-phase charged PCC via molecular photo-isomerization and enhanced intermolecular interactions. Moreover, the charged PCC reveals a large latent heat of 239 J g−1 and a high power density of 594 W kg−1 with a suitable degree of supercooling (3.33–7.67 °C) for energy storage near room temperature. It is noted that the optically-controlled energy release by blue light and excellent cycling stability can be obtained. This kind of PCC is a promising candidate for smart and convenient solar energy storage application.

Flexible textiles with polypyrrole deposited phase change microcapsules for efficient photothermal energy conversion and storage

The design of flexible phase change textiles with photothermal conversion/storage performance provides a new direction for their potential applications in advanced solar energy storage. Herein, photothermal phase change microcapsules (microPCMs) were facilely prepared via surface modification of microPCMs with photothermal converter polypyrrole (PPy). A flexible photothermal phase change textile was further fabricated together with polyurethane (PU). The microPCMs coated with merely 1.91 wt% PPy exhibited high photothermal storage efficiency (up to 94.03%) under 1 solar irradiation and high melting enthalpy (231.6 J/g). Meanwhile, the microPCMs/PU composite fiber remained highly elastic (365% elongation) at a loading of 79.45 wt% microPCMs. Additionally, the photothermal phase change textile showed high cycling durability with essentially unchanged performance after 100 heating-cooling cycles. These favorable features of the composite textile grant it great potential for solar energy-related applications.

A new optimized control system architecture for solar photovoltaic energy storage application

A new optimized control system architecture for solar photovoltaic energy storage application

Theoretical study of the influence of doped niobium on the electronic properties of CsPbBr3.

In the family of inorganic perovskite solar cells (PSCs), CsPbBr3 has attracted widespread attention due to its excellent stability under high humidity and high temperature conditions. However, power conversion efficiency (PCE) improvement of CsPbBr3-based PSCs is markedly limited by the large optical absorption loss coming from the wide band gap and serious charge recombination at interfaces and/or within the perovskite film. In this work, using density functional theory calculations, we systemically studied the electronic properties of niobium (Nb)-doped CsPbBr3 with different concentration ratios. As a result, it is found that doped CsPbBr3 compounds are metallic at high Nb doping concentration but semiconducting at low Nb doping concentration. The calculated electronic density of states shows that the conduction band is predominantly constructed of doped Nb. These characteristics make them very suitable for solar cell and energy storage applications.

Modeling PCM Phase Change Temperature and Hysteresis in Ventilation Cooling and Heating Applications

Applying phase change material (PCM) for latent heat storage in sustainable building systems has gained increasing attention. However, the nonlinear thermal properties of the material and the hysteresis between the two-phase change processes make the modelling of PCM challenging. Moreover, the influences of the PCM phase transition and hysteresis on the building thermal and energy performance have not been fully understood. This paper reviews the most commonly used modelling methods for PCM from the literature and discusses their advantages and disadvantages. A case study is carried out to examine the accuracy of those models in building simulation tools, including four methods to model the melting and freezing process of a PCM heat exchanger. These results are compared to experimental data of the heat transfer process in a PCM heat exchanger. That showed that the four modelling methods are all accurate for representing the thermal behavior of the PCM heat exchanger. The model with the DSC Cp method with hysteresis performs the best at predicting the heat transfer process in PCM in this case. The impacts of PCM phase change temperature and hysteresis on the building energy-saving potential and thermal comfort are analyzed in another case study, based on one modelling method from the first case study. The building in question is a three-room apartment with PCM-enhanced ventilated windows in Denmark. The study showed that the PCM hysteresis has a larger influence on the building energy consumption than the phase change temperature for both summer night cooling applications and for winter energy storage. However, it does not have a strong impact on the yearly total energy usage. For both summer and winter transition seasons, the PCM hysteresis has a larger influence on the predicted percentage of dissatisfied (PPD) than the phase change temperature, but not a strong impact on the transition season average PPD. It is therefore advised to choose the PCM hysteresis according to whether it is for a summer night cooling or a winter solar energy storage application, as this has a significant impact on the system’s overall efficiency.

A Capacitor‐type Faradaic Junction for Direct Solar Energy Conversion and Storage

AbstractTwo‐electrode solar rechargeable devices trigger intense attention due to their potential applications in solar energy conversion and storage. However, interface energy barriers lead to severe loss of output voltage and negligible dark discharge current. Therefore, external biases are required for dark discharge in these devices, limiting their practical applications. Herein, we report a new two‐electrode device of Si/WO3/H2SO4(aq)/C that can work without bias. The device has the highest dark output power among all of the two‐electrode solar rechargeable devices. The device based on a Si/WO3 junction indicates photoinduced adjustable interface barrier height during charge transfer, which can overcome the energy barrier and realize dark discharge without bias. Owing to the interface characteristics, the Si/WO3 is designated as a capacitor‐type Faradaic junction.

A Capacitor-type Faradaic Junction for Direct Solar Energy Conversion and Storage.

Two-electrode solar rechargeable devices trigger intense attention due to their potential applications in solar energy conversion and storage. However, interface energy barriers lead to severe loss of output voltage and negligible dark discharge current. Therefore, external biases are required for dark discharge in these devices, limiting their practical applications. Herein, we report a new two-electrode device of Si/WO3 /H2 SO4(aq) /C that can work without bias. The device has the highest dark output power among all of the two-electrode solar rechargeable devices. The device based on a Si/WO3 junction indicates photoinduced adjustable interface barrier height during charge transfer, which can overcome the energy barrier and realize dark discharge without bias. Owing to the interface characteristics, the Si/WO3 is designated as a capacitor-type Faradaic junction.

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.

Significance of Nanomaterials in solar energy storage applications

In the present decade, energy demand is one of the most challenging issues being faced throughout the world. To overcome the problems in the high energy production, the recent advances in nanotechnology, with a huge range of nanostructured materials have become all the rage for energy storage applications. A great number of devices have been developed in recent decades with the advancement of nanoscience. In the concept of renewable energy resources, Solar Energy can be referred to as the “elixir of power production” throughout the world. Extensive research is being carried out for distinguished Nanomaterials on energy storage applications by researchers and scientists to produce an efficient power absorption and storage material with high thermal conductivity and high corrosion resistance. In this paper, reviewing the concepts of nanotechnology in solar energy applications is made excessively focussing on PCM, Nano fluids, and Nanocomposites. Also by considering several other important factors in energy storage applications a statistical/graphical approach is presented for a better understanding by taking different research and review articles. This paper extensively would give researchers ease in the selection of material for energy storage applications.

Analysis of high-flux solar irradiation distribution characteristic for solar thermochemical energy storage application

Designing equipment that meets the needs of efficient solar energy conversion and utilization is of great significance. In this paper, the design method of a solar simulator with Fresnel lens is studied from the perspective of concentrating solar energy research, high-temperature material testing, and optimal design method of reactor receiving surface. The Monte Carlo ray-tracing technique is applied to analyze the concentrating performance of a single xenon lamp-lens unit and hexagonal arrays of seven xenon lamp-lens units. For the single-disc concentrating unit, the Fresnel lens is analyzed and optimized for the reduction of the irradiance unevenness of the central spot, improvement in the peak irradiance, and the light convergence into different shapes to meet various needs. The numerical calculations are performed on the multi-disc simulator to obtain suitable installation conditions and reactor temperature distribution. A 42 kWel seven-disc Fresnel lens-based high-flux solar simulator is simulated. The solar simulator can provide a peak energy flow of 2.32 MW/m2 with a spot diameter of 46 mm. The temperature of the cavity receiver reached 964 K and 1024 K when using a parabolic mirror and ellipsoidal mirror, respectively under the illumination of 6 kW xenon lamp. The concentrating unit coupled with the solar reactor exhibited reasonable thermal energy storage efficiency, as well as electro-thermal efficiency. The designed concentrating system could be considered suitable for high-temperature solar thermal and thermochemical applications, especially where there is a strict requirement for the shape or uniformity of the spot.

Using the Analytic Hierarchy Process (AHP) method for selection of phase change materials for solar energy storage applications

Selection of a suitable phase change material (PCM) for thermal energy storage systems is important. There are an enormous number of available PCM and hence choosing a particular PCM for a certain application is difficult. Many researchers rely on their expertise or the material available to use PCM for a specific application. The purpose of the selection of a certain PCM is to choose the best material from the commercially available PCM for a given application. An effective evaluation approach is essential to enhance the quality of the decisions. The issue of choosing a material for different applications can be managed as a multi-criteria decision-making issue. In this paper, the Analytic Hierarchy Process (AHP) method is used to select between five PCM for solar heating systems considering both the technical specification and the criteria of the materials. The selected materials have a melting temperature in the required working temperature range. Seven criteria are used in this study and these include the latent heat of fusion, thermal conductivity of the material, specific heat, density, thermal stability, cost, and corrosion. The results show that the paraffin is the best material from the selected PCM using the AHP method for this solar heating system using all known thermo-physical properties and the weights of these criteria to achieve the objective.

Engineering of Norbornadiene/Quadricyclane Photoswitches for Molecular Solar Thermal Energy Storage Applications.

ConspectusRenewable energy resources are mostly intermittent and not evenly distributed geographically; for this reason, the development of new technologies for energy storage is in high demand.Molecules that undergo photoinduced isomerization reactions that are capable of absorbing light, storing it as chemical energy, and releasing it as thermal energy on demand are referred to as molecular solar thermal energy storage (MOST) or solar thermal fuels (STF). Such molecules offer a promising solution for solar energy storage applications. Different molecular systems have been investigated for MOST applications, such as norbornadienes, azobenzenes, stilbenes, ruthenium derivatives, anthracenes, and dihydroazulenes. The polycyclic strained molecule norbornadiene (NBD), which photoconverts to quadricyclane (QC), is of great interest because it has a high energy storage density and the potential to store energy for a very long time. Unsubstituted norbornadiene has some limitations in this regard, such as poor solar spectrum match and low quantum yield. In the past decade, our group has developed and tested new NBD systems with improved characteristics. Moreover, we have demonstrated their function in laboratory-scale test devices for solar energy harnessing, storage, and release.This Account describes the most impactful recent findings on how to engineer key properties of the NBD/QC system (photochemistry, energy storage, heat release, stability, and synthesis) as well as examples of test devices for solar energy capture and heat release. While it was known that introducing donor–acceptor groups allows for a red-shifted absorption that better matches the solar spectrum, we managed to introduce donor and acceptor groups with very low molecular weight, which allowed for an unprecedented solar spectrum match combined with high energy density. Strategic steric hindrance in some of these systems dramatically increases the storage time of the photoisomer QC, and dimeric systems have independent energies barriers that lead to an improved solar spectrum match, prolonged storage times, and higher energy densities. These discoveries offer a toolbox of possible chemical modifications that can be used to tune the properties of NBD/QC systems and make them suitable for the desired applications, which can be useful for anyone wanting to take on the challenge of designing efficient MOST systems.Several test devices have been built, for example, a hybrid MOST device that stores sunlight energy and heat water at the same time. Moreover, we developed a device for monitoring catalyzed QC to NBD conversion resulting in the possibility to quantify a significant macroscopic heat generation. Finally, we tested different formulations of polymeric composites that can absorb light during the day and release the energy as heat during the night for possible use in future window coating applications. These lab-scale realizations are formative and contribute to pushing the field forward toward the real-life application of MOST systems.

Preparation and performances of sunlight-induced phase change PEG/SiO2-dye composite for solar energy conversion and storage

Sunlight-induced phase-change PEG/SiO2-dye composites based on poly(ethylene glycol) (PEG) and dye-grafted silicon dioxide (SiO2) network were prepared by a facile sol-gel process. The structure and thermal properties of PEG/SiO2-dye composites were characterized by FT-IR, XRD, SEM, DSC and TG. The developed PEG/SiO2-dye composites exhibited unique characteristics, such as excellent shape-stabilized properties, thermal stability, a broad sunlight absorption range, and high phase change enthalpy (167.0 J/g). More importantly, the PEG/SiO2-dye composites exhibited a high light-to-thermal energy conversion and storage efficiency (85%–88%). After 300 light-induced phase transition cycles, PEG/SiO2-dye composites maintained thermal reliability and long-term sunlight exposure durability. Thus, PEG/SiO2-dye composites as a novel sunlight-induced phase change material showed great potential for applications in solar energy conversion and storage.