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15,332 result(s) for "solar thermal"
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Desert energy : a guide to the technology, impacts, and opportunities
\"This book examines the key technologies being deployed in an effort to tap the potential presented by world's deserts for siting large-scale solar power applications, and surveys the feasibility of such projects given the remoteness and the hostility of these environments Focusing on large scale photovoltaics and concentrating solar thermal power, it explains how the systems work, projects that are being planned, the required scales, and the technical difficulties they need to overcome to function effectively. It then moves on to examine the economics of such projects (including financing) and the social and environmental effects they may have. Illustrated throughout by reference to built or planned projects, and written in a clear, jargon-free style, this is a must-read for anyone interested in the development of large scale solar applications\"-- Provided by publisher.
Concentrating Solar Power Technology
Concentrating solar power (CSP) technology is poised to take its place as one of the major contributors to the future clean energy mix.Using straightforward manufacturing processes, CSP technology capitalises on conventional power generation cycles, whilst cost effectively matching supply and demand though the integration of thermal energy.
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.
High thermal conductivity in amorphous polymer blends by engineered interchain interactions
A high density of strong hydrogen bonds connecting two polymers that are homogeneously mixed in a thin film is shown to enhance the intrachain thermal conductance, boosting thermal transport in fully organic layers. Thermal conductivity is an important property for polymers, as it often affects product reliability (for example, electronics packaging), functionality (for example, thermal interface materials) and/or manufacturing cost 1 . However, polymer thermal conductivities primarily fall within a relatively narrow range (0.1–0.5 W m −1 K −1 ) and are largely unexplored. Here, we show that a blend of two polymers with high miscibility and appropriately chosen linker structure can yield a dense and homogeneously distributed thermal network. A sharp increase in cross-plane thermal conductivity is observed under these conditions, reaching over 1.5 W m −1 K −1 in typical spin-cast polymer blend films of nanoscale thickness, which is approximately an order of magnitude larger than that of other amorphous polymers.
Copper ion liquid-like thermoelectrics
A common route to obtain efficient thermoelectrics is to optimize the ratio between electrical and thermal conductivity. Typically, materials with a complex, glass-like phonon structure and therefore a very low thermal conductivity are studied. Now, a route showing that solid ions in a liquid-like state can have a low enough thermal conductivity to compete with the best existing thermoelectrics is proposed. Advanced thermoelectric technology offers a potential for converting waste industrial heat into useful electricity, and an emission-free method for solid state cooling 1 , 2 . Worldwide efforts to find materials with thermoelectric figure of merit, zT values significantly above unity, are frequently focused on crystalline semiconductors with low thermal conductivity 2 . Here we report on Cu 2− x Se, which reaches a zT of 1.5 at 1,000 K, among the highest values for any bulk materials. Whereas the Se atoms in Cu 2− x Se form a rigid face-centred cubic lattice, providing a crystalline pathway for semiconducting electrons (or more precisely holes), the copper ions are highly disordered around the Se sublattice and are superionic with liquid-like mobility. This extraordinary ‘liquid-like’ behaviour of copper ions around a crystalline sublattice of Se in Cu 2− x Se results in an intrinsically very low lattice thermal conductivity which enables high zT in this otherwise simple semiconductor. This unusual combination of properties leads to an ideal thermoelectric material. The results indicate a new strategy and direction for high-efficiency thermoelectric materials by exploring systems where there exists a crystalline sublattice for electronic conduction surrounded by liquid-like ions.
Engineered doping of organic semiconductors for enhanced thermoelectric efficiency
The conversion efficiency of heat to electricity in thermoelectric materials depends on both their thermopower and electrical conductivity. It is now reported that, unlike their inorganic counterparts, organic thermoelectric materials show an improvement in both these parameters when the volume of dopant elements is minimized; furthermore, a high conversion efficiency is achieved in PEDOT:PSS blends. Significant improvements to the thermoelectric figure of merit ZT have emerged in recent years, primarily due to the engineering of material composition and nanostructure in inorganic semiconductors 1 (ISCs). However, many present high- ZT materials are based on low-abundance elements that pose challenges for scale-up, as they entail high material costs in addition to brittleness and difficulty in large-area deposition. Here we demonstrate a strategy to improve ZT in conductive polymers and other organic semiconductors (OSCs) for which the base elements are earth-abundant. By minimizing total dopant volume, we show that all three parameters constituting ZT vary in a manner so that ZT increases; this stands in sharp contrast to ISCs, for which these parameters have trade-offs. Reducing dopant volume is found to be as important as optimizing carrier concentration when maximizing ZT in OSCs. Implementing this strategy with the dopant poly(styrenesulphonate) in poly(3,4-ethylenedioxythiophene), we achieve Z T = 0.42 at room temperature.
Stretchable nanoparticle conductors with self-organized conductive pathways
Stretchable conductors have many applications, from flexible electronics to medical implants; here polyurethane is filled with gold nanoparticles to give a composite with tunable viscoelastic properties arising from the dynamic self-organization of the nanoparticles under stress. Nanoparticle conductors with stretch Flexible electronics, neuroprosthetic and cardiostimulating implants, soft robotics and stretchable displays all require high stretchability and conductivity, properties that are difficult to combine. This paper reports polyurethane–gold nanoparticle composites that combine high conductivity and stretchability. Conventional stretchable conductors generally use nanotubes or nanowires as the conductive component, with high-aspect ratios, but these new materials achieve good performance despite the minimal aspect ratio of the nanoparticles. The properties of the composites derive from dynamic self-organization of the nanoparticles under stress, and they have the added advantage of electronically tunable viscoelastic properties. Research in stretchable conductors is fuelled by diverse technological needs. Flexible electronics, neuroprosthetic and cardiostimulating implants, soft robotics and other curvilinear systems require materials with high conductivity over a tensile strain of 100 per cent (refs 1 , 2 , 3 ). Furthermore, implantable devices or stretchable displays 4 need materials with conductivities a thousand times higher while retaining a strain of 100 per cent. However, the molecular mechanisms that operate during material deformation and stiffening make stretchability and conductivity fundamentally difficult properties to combine. The macroscale stretching of solids elongates chemical bonds, leading to the reduced overlap and delocalization of electronic orbitals 5 . This conductivity–stretchability dilemma can be exemplified by liquid metals, in which conduction pathways are retained on large deformation but weak interatomic bonds lead to compromised strength. The best-known stretchable conductors use polymer matrices containing percolated networks of high-aspect-ratio nanometre-scale tubes or nanowires to address this dilemma to some extent 6 , 7 , 8 , 9 , 10 , 11 . Further improvements have been achieved by using fillers (the conductive component) with increased aspect ratio, of all-metallic composition 12 , or with specific alignment (the way the fillers are arranged in the matrix) 13 , 14 . However, the synthesis and separation of high-aspect-ratio fillers is challenging, stiffness increases with the volume content of metallic filler, and anisotropy increases with alignment 15 . Pre-strained substrates 16 , 17 , buckled microwires 18 and three-dimensional microfluidic polymer networks 19 have also been explored. Here we demonstrate stretchable conductors of polyurethane containing spherical nanoparticles deposited by either layer-by-layer assembly or vacuum-assisted flocculation. High conductivity and stretchability were observed in both composites despite the minimal aspect ratio of the nanoparticles. These materials also demonstrate the electronic tunability of mechanical properties, which arise from the dynamic self-organization of the nanoparticles under stress. A modified percolation theory incorporating the self-assembly behaviour of nanoparticles gave an excellent match with the experimental data.
Vibronic coherence in oxygenic photosynthesis
Photosynthesis powers life on our planet. The basic photosynthetic architecture consists of antenna complexes that harvest solar energy and reaction centres that convert the energy into stable separated charge. In oxygenic photosynthesis, the initial charge separation occurs in the photosystem II reaction centre, the only known natural enzyme that uses solar energy to split water. Both energy transfer and charge separation in photosynthesis are rapid events with high quantum efficiencies. In recent nonlinear spectroscopic experiments, long-lived coherences have been observed in photosynthetic antenna complexes, and theoretical work suggests that they reflect underlying electronic–vibrational resonances, which may play a functional role in enhancing energy transfer. Here, we report the observation of coherent dynamics persisting on a picosecond timescale at 77 K in the photosystem II reaction centre using two-dimensional electronic spectroscopy. Supporting simulations suggest that the coherences are of a mixed electronic–vibrational (vibronic) nature and may enhance the rate of charge separation in oxygenic photosynthesis. Charge separation in oxygenic photosynthesis occurs with high quantum efficiency and is yet to be fully understood. Using two-dimensional electronic spectroscopy, coherent dynamics have now been observed in the photosystem II reaction centre, where charge separation occurs. Supporting simulations suggest that the coherences have mixed electronic–vibrational (vibronic) nature, and may enhance the rate of charge separation. Leaf image: © Michael Wesemann/Alamy.
Attomolar DNA detection with chiral nanorod assemblies
Nanoscale plasmonic assemblies display exceptionally strong chiral optical activity. So far, their structural design was primarily driven by challenges related to metamaterials whose practical applications are remote. Here we demonstrate that gold nanorods assembled by the polymerase chain reaction into DNA-bridged chiral systems have promising analytical applications. The chiroplasmonic activity of side-by-side assembled patterns is attributed to a 7–9 degree twist between the nanorod axes. This results in a strong polarization rotation that matches theoretical expectations. The amplitude of the bisignate ‘wave’ in the circular dichroism spectra of side-by-side assemblies demonstrates excellent linearity with the amount of target DNA. The limit of detection for DNA using side-by-side assemblies is as low as 3.7 aM. This chiroplasmonic method may be particularly useful for biological analytes larger than 2–5 nm which are difficult to detect by methods based on plasmon coupling and ‘hot spots’. Circular polarization increases for inter-nanorod gaps between 2 and 20 nm when plasmonic coupling rapidly decreases. Reaching the attomolar limit of detection for simple and reliable bioanalysis of oligonucleotides may have a crucial role in DNA biomarker detection for early diagnostics of different diseases, forensics and environmental monitoring. Nanoscale plasmonic assemblies are known to display exceptionally strong chiral optical activity. Here, the authors assemble gold nanorods into DNA-bridged chiral systems, and demonstrate their high efficiency for DNA detection at very low concentrations.
Prospects and Challenges of Solar Thermal for Process Heating: A Comprehensive Review
To mitigate the consequences of climate change, there is an increasing need to minimize the usage of fossil fuels, especially in the industrial sector because the majority of the industrial sector primarily rely on fossil fuels to meet their needs for heat energy, and a practical strategy to reduce reliance on fossil fuels is to use energy from the sun. Due to their environmental advantages, energy security, and viability as a potential substitute for fossil fuels, solar thermal collectors are acknowledged as promising technology to harness solar thermal energy fir process heating applications. This review is a thorough compendium and evaluation of contemporary literature on solar thermal collectors and their applications in industry. Apart from applications, this review paper also assesses the challenges and limitations currently hindering the global acceptance of this technology in the industrial sector.