Portion Of Energy Research Articles

Study on overvoltage suppression method of phase modulation of hydroelectric generating units and its cooperative optimization in new energy grid

When a significant portion of renewable energy is transmitted to the power grid through high voltage direct current, when the monopolar blocking occurs, as a result of the converter station’s filter and reactive power compensation equipment’s influence, overvoltage will be generated, which will cause harm to the new energy station, and even lead to large-scale new energy grid disconnection. This paper initially examines the mechanism behind overvoltage in a new energy power grid and then puts forward a method to restrain overvoltage by using phase modulation operation of hydroelectric generating units. To improve the phase modulation capability of hydroelectric generating units and optimize the utilization of new energy sources, this paper proposes a particle swarm optimization to determine the optimal phase modulation capacity. Finally, this paper builds an example of the PSASP platform to verify the correctness and effectiveness of collaborative optimization.

Development of composite cereal flour noodles and their technological, antioxidant and sensory characterization during storage

Cereals and their products form an intrinsic part of the human diet, besides contributing to the major portion of dietary energy and nutrients of people worldwide. In this study, composite noodles were prepared by combining different cereal flours (rice, corn and wheat) in order to develop a nutritional and quality product. Five formulations used for the noodle formation were wheat 100 % (W) as control, rice:wheat 50:50 (RW), wheat:corn 50:50 (WC) rice:corn 50:50 (RC) and rice:wheat:corn 34:33:33 (RWC). The samples were evaluated for the different physicochemical, antioxidant, textural, structural, color and rheological parameters during the 40-day storage period. Among the composite flours, the highest protein 9.98%, was found in wheat:corn 50:50 (WC), while the lowest protein content, 7.97 %, was found in rice:corn 50:50 (RC). The visco-elastic behavior of wheat:corn 50:50 (WC) was slightly greater than that of rice:wheat 50:50 (RW) composite flour. The highest DPPH scavenging activity (24.66 %) was found in wheat:corn 50:50 (WC) noodles, while wheat 100 % (W) noodles showed the lowest DPPH scavenging activity (15.23 %). The visco-elastic behavior of wheat:corn 50:50 (WC) was slightly greater than that of rice:wheat 50:50 (RW) composite flour. Also, wheat:corn 50:50 (WC) showed the highest acceptance and rice:corn 50:50 (RC) noodles showed the lowest level of acceptance. The wheat:corn 50:50 (WC), maintained better overall quality attributes as compared to other noodles throughout the storage.

Impact resisting mechanism of tension–torsion coupling metamaterials

Tension–torsion coupling (TTC) metamaterials are man-made architectures that exhibit unexpected rotational deformation when subjected to unidirectional loads. Since their discovery, numerous studies have been conducted to investigate the static properties of TTC metamaterials resulting from this twisting effect. However, research on their dynamic properties, particularly in terms of impact resistance, has been limited with little understanding of the underlying mechanisms. In this study, we performed simulations at different length scales to quantitatively analyze the energy flow during impact and gained insights into the mechanisms of energy damping and impact resistance. Our simulations demonstrate that the twisting effect of cellular materials generally leads to reduced stiffness, which is advantageous for improving impact mitigation. Furthermore, we discovered that the unique chiral characteristics of TTC metamaterials enable a greater amount of strain energy to be stored during impact, and this portion of energy will be ultimately dissipated through after-impact vibrations. Additionally, we found that energy dissipation via friction between lateral struts or ligaments, although less significant, is enhanced by the TTC effect. The current study provides a preliminary analysis of energy flow and sheds light on the mechanisms underlying the energy damping and impact resistance of TTC metamaterials. These findings not only contribute to a better understanding of the dynamic properties of TTC metamaterials but also have practical implications for the advanced design of impact resistance structures.

Energetic/exergetic study of Kalina and refrigeration bottoming cycles on different solar‐driven organic Rankine cycles

AbstractCombination of different power cycle scenarios is of prime importance in achieving maximum energy utilization from solar‐driven multigeneration systems. To fulfill such objective, the present article proposes a novel energy distribution system, leveraging a combination of direct‐fed organic Rankine cycle (ORC) and a bottom‐cycled arrangement of Kalina cycle system (KCS) and double‐effect absorption refrigeration cycle (DEARC) within a parabolic trough solar collector powered trigeneration system. The study explores three different ORC configurations: simple ORC; ORC equipped with internal heat exchanger (ORC‐IHE) and regenerative ORC (RORC). It is shown that although higher efficiencies are achievable from a larger portion of PTSC energy absorbed by the ORC, the ORC energy absorption is limited by ORC evaporator temperature differences, and there is unused energy that can be recovered by the KCS, based on the proposed energy system. The results indicate that the addition of bottoming KCS leads to a considerable increase in the exergy efficiency of ORC, ORC‐IHE and RORC‐based systems by 11.7%, 30.7% and 32.6%, respectively. The impact of different ORC configurations, key ORC parameters and various organic working fluids on the energetic/exergetic efficiencies is also examined to find the optimal configuration. In terms of overall energetic/exergetic efficiencies, the highest performance belongs to ORC (78.4%/30.4%) while the lowest energetic and exergetic efficiencies belong to ORC‐IHE and RORC, respectively (56.3% and 25.65%). On the basis of a comparative study with the available literature, these values are higher than what is already reported for similar solar‐driven multigeneration systems. Appropriate thermal match and lower exergy destruction in the KCS, and bottoming cycle arrangement of the DEARC are the main reasons for such enhanced performance. This research not only contributes valuable insights into efficient solar‐driven systems but also sets a new benchmark for performance metrics in the existing literature.

Biaxial fatigue failure of short glass fiber reinforced polyamide 6,6: An in-depth investigation of stiffness drop and microstructural evolution

In the automotive industry, short glass fiber-reinforced thermoplastics are widely used under the hood and subjected to dynamic vibrations of the engine in multiple directions resulting in fatigue failure. Under fatigue loading, a significant portion of the strain energy is stored within the material, while the remaining portion is lost due to internal frictions and the damage occurrence. Internal friction results in heat generation, which in turn causes an increase in external temperature. This increase in temperature leads to thermal degradation of the polymer. Investigations on the cause of the stiffness drop are not widely available in the literature. Therefore, this study explores the source of the stiffness drop under biaxial fatigue loading of a polyamide 6,6 reinforced with 30 wt. % short glass fibers (PA66GF30) and distinguishes the contributions of thermal degradation and damage accumulation. The thermal evolution of the specimens was captured by means of thermography. In addition, the digital image correlation (DIC) technique was used to measure the in situ strain field during the fatigue. Despite the temperature stabilization being observed around the 10,000th cycle, the reduction in the stiffness continued until failure which was attributed to the mechanical damage accumulation and cyclic creep during the fatigue tests. Dynamic mechanical analyses (DMA) were carried out to quantify the stiffness drop with the varying temperature. From the results, it is seen that the damage accumulation and cyclic creep during the fatigue tests were responsible for the major part of the stiffness drop. Finally, scanning electron microscopy (SEM) inspection of the fracture surface was performed to identify fatigue damage mechanisms. Four unique features associated with the fatigue damage were identified: (1) debonding of fibers from the matrix, (2) polymer matrix crazing, and (3) cavitation and porosities, (4) pull out fiber ends and break on the fiber.

Using the Degree-Day Method to Analyze Central Heating Energy Consumption in Cities of Northern China

In the context of global population growth and energy scarcity, building energy consumption has become a critical issue with implications for the sustainable development of human society. Winter heating consumption constitutes a large portion of total energy used in buildings, especially in regions with cold climates. This paper employs the degree-day method to analyze the energy consumption of central heating in northern Chinese cities. The study sample consists of 60 target cities, including 30 located in severe cold regions and the remaining 30 in cold regions. By utilizing heating energy consumption and climate data from 2019, the relationships between heating intensity (kWh/m2) and heating degree days (HDDs) are established for the selected cities. Additionally, statistical analysis and model comparisons are conducted. The results show strong positive correlations between heating intensity and HDDs in both severe cold regions and cold regions, with the actual heating base temperatures for the two regions being 21 °C and 22.3 °C, respectively. Moreover, the deviation index of heating intensity is introduced to analyze the energy consumption characteristics of central heating in northern cities from three perspectives: city size, level of heating development, and geographical regions. The analysis suggests that cities with large population, strong economies, and high levels of development exhibit better energy-saving performance. Lastly, several improvement suggestions are proposed to address the potential problems related to energy conservation of central heating systems in cities of northern China.

Passive and Active Techniques for Cooling Photovoltaic Cell using PCM: An Investigation of Recent Advances

Photovoltaic (PV) technology is one of many renewable energy sources, which converts solar energy directly received into electricity. In recent years, PV has advanced quickly as researchers try to make it more effective. 80% of the solar radiation that hits PV cells is absorbed, but only 12–18% of that energy is converted into electricity, with a maximum conversion rate of 24%. This indicates that a significant amount of sunlight is lost irretrievably. when a significant portion of the solar energy that is absorbed but not used by the photovoltaic process is converted to heat, which causes PV cells' operating temperature to increase above their design temperature, Consequently, the cell's effectiveness declines as a result of this increase. The crystalline silicon-based PV cells’ efficiency drops by 0.5% for each Celsius increase in temperature of operating. When operating temperature of cell exceeds design temperature, open-circuit voltage decreases significantly while the closed-circuit current slightly increases. Research has shown that PCMs can be applied in a variety of ways to enhance performance of PV cells, including as a coating applied directly onto the surface of the modules, as a heat exchanger in contact with module's back, or as an integrated component within the module itself. One recent advancement in the area of PCM-based cooling of PV modules is the development of hybrid cooling systems that combine PCMs with other cooling methods, such as air or water cooling. These hybrid systems have been shown to significantly improve the temperature stability and efficiency of PV modules compared to single PCM-based systems. PCMs have unique thermal properties that make them suitable for use in cooling systems because they can store and release thermal energy when phase transitions occur due to their high latent heat capacities. Recommendations for the use of phase change materials in Photovoltaic cooling, continue to research and develop new phase change material-based cooling systems that are more stable, have higher thermal conductivity and are effective in a wider range of temperatures.

Three-dimensional numerical simulations of oblique internal solitary wave-wave interactions in the South China Sea

Satellite images show that the oblique internal solitary wave-wave interactions frequently occur in the South China Sea, especially in the periphery of Dongsha Island. Depending on the amplitudes and angles of initial oblique waves, theoretical works illustrated that the evolution pattern falls into different regimes characterised by the respective four-fold augmentation of wave amplitudes (relative to the initial waves) and occurrence of Mach stem waves in the interaction region. Nevertheless, these results were based on the reduced theories rooted from the primitive Navier-Stokes equations and the disparities induced by these simplifications with the scenarios in realistic ocean are still unclear. To fill this research gap, three-dimensional numerical simulations in the South China Sea are used to evaluate the oblique internal solitary wave-wave interactions. It is found that transformations between mode-1 and mode-2 waves occur near the Dongsha Island when two waves obliquely collide, together with a small portion of energy is converted into higher modes, most of which is dissipated locally due to their unstable vertical structures. This conclusion has been seldom reported in previous studies (if any). These oblique interactions are essentially nonlinear and impacted by the dynamical factors, such as varying depth, background current, etc., exhibiting complicated variations of waveforms and energy, which, further, enhance the mixing at local sites in the mechanism of both shear and convective instabilities indicated by the Richardson number.

On the Required Energy to Break Down the Thickener Structure of Lubricating Greases

The rheology of a conventional lithium-12 hydroxystearate bearing grease changes significantly when it is subjected to mechanical shear. Often this shear energy–along with the consequent entropy–is measured and used in engineering and thermodynamic models, leading to grease life models for predicting bearing seizure due to insufficiently thick film or loss of lubricity of the base oil/grease. In this degradation process, the bonds between the individual molecules, consisting mainly of the fairly weak van der Waals bonds and/or hydrogen bonds, are broken during this shearing process. In this article, we show that only a very small portion of the shear energy is needed to break these bonds and that the vast majority is dissipated as heat due to the lubricant viscosity, also known as viscous dissipation. We model the thickener as rod-shaped fibers, wherein the grease viscosity is reduced by a factor of 5 when the length of a fiber is reduced by a factor of 2.5. The energy needed to break the bonds between the molecules to shorten these fibers is 6 to 7 orders of magnitude smaller than the energy applied by shear. Hence, it is very difficult to measure this fiber structure breakage energy from grease shear aging experiments directly.

Analyzing the Impact of In Situ Workpiece Temperature on Thermally Induced Part Distortion during Turning

In the metal cutting process, a substantial portion of the mechanical energy in the cutting zone is transformed into heat, causing a rapid rise in temperature. The uneven distribution of temperature results in workpiece distortion, leading to reduced machining accuracy. As the demand for higher product quality increases, the prediction of cutting temperature and compensation for thermally induced deformations has become a crucial area of research. This paper introduces a novel experimental setup that enables in situ monitoring of process temperature using infrared thermography. Through the analysis of experimental data, a numerical model is proposed and calibrated to quantitatively predict the temperature evolution in the workpiece. The derived model facilitated the prediction of workpiece distortion, and the results can enhance machining accuracy by integrating contour correction. The developed approach offers valuable insights into mitigating the adverse effects of temperature-induced distortions in turning operations.

Carbon Capture Performance Enhancement of Solid State Synthesized Li4SiO4 Powders by Using Different Kind Steel Slags as SiO2 Source

The potential of lithium orthosilicate (Li4SiO4) as a material to capture carbon dioxide (CO2) is being explored due to its excellent capture capability and thermal stability. Currently, a significant portion of the world's energy needs are met through the burning of fossil fuels, which leads to an increase in atmospheric CO2 and contributes to global warming. While fossil fuels will remain the primary source of energy for several more years, it is crucial to develop cost-effective and environmentally friendly technology for large-scale CO2 capture and storage before its release into the atmosphere in order to mitigate the associated greenhouse effect. This study focuses on optimizing the synthesis of lithium orthosilicate using a solid-state method to enhance CO2 capture. The research involves assessing the key characteristics of the synthesized material that improve CO2 capture efficiency. The starting materials used for comparison include lithium carbonate (Li2CO3), BF (blast furnace), BOF (blast oxygen furnace) and EAF (electric arc furnace) slags, and pure reagents of silicon dioxide (SiO2). The effect of process conditions, such as synthesis temperatures ranging from 850 to 950°C and varying holding times of 4, 6, 8, and 10 hours in a muffle furnace, were studied and compared. X-ray diffraction (XRD) analysis was performed to characterize the samples and slags. CO2 capture performance of the samples were evaluated in thermobalance test under 92 vol% CO2 (N2 balance) gas concentration at 600°C. As to conclude, carbon dioxide capturing sorbent material was produced by utilizing the slags generated as a by-product in steel production. Thus, considering the principles of circular economy, a material defined as waste was used as raw material for the production of another product used for lowering atmospheric CO2 levels.

Higher hydrogen fractions in dielectric polymers boost self-healing in electrical capacitors.

Electrical capacitors are omnipresent in modern electronic devices, in which they swiftly release large portions of energy on demand. The capacitors may suffer from arc discharges due to local structural heterogeneities in their components and inappropriate exploitation practices. High energies of the arc discharge are transferred as phonons to the electrode and dielectric film, which burn out locally. The dielectric breakdown takes place. The complete burnout leads to the isolation of the failed region and the capacitor's self-healing. The emerging soot can form a semiconducting channel and damage the capacitor. The efficiency of self-healing depends on the dielectric properties of the soot and its amount. We employ reactive molecular dynamics simulations to reveal the regularities of the high-temperature polymer destruction and record by-products emerging during this process. We found the formation of multiple volatile low-molecular compounds and contaminated quantum carbon dots (CQD) designated as soot. The percentage of carbon in soot is higher compared to the polymer. Furthermore, the CQD contains numerous unsaturated C-C bonds and aromatic C6-rings suggesting an enhanced electrical conductivity. The size of the CQD depends on the available volume, i.e., on the spatial scale of the dielectric breakdown. The elemental composition of the soot is unique for each polymer. Polypropylene undergoes the most efficient self-healing thanks to containing a large molar fraction of hydrogen atoms. The results are addressed to the experts in electrical engineering and polymer fine-tuning.

Turning weakness into strength - A feasibility analysis and comparison of datacenter deployment in hot and cold climates

Datacenters are major components of the Information and Communication Technologies (ICT) responsible for storing, processing and transmitting enormous amounts of data every second. The significance and importance of datacenters in the world economy can be identified from studies which report that in 2023, datacenter infrastructures consumed a total of 4 % of global electricity and contributed 3–5% of global carbon emissions, whereas between the years of 2017–2021, datacenters added $2.1 trillion to the U.S. Gross Domestic Product (GDP). A big portion of energy supplied in datacenters is consumed by the required cooling systems hence companies do not favor developments in hot climate countries. However, due to environmental and climate change concerns along with the steep increase of energy production costs in recent years made the industry look for alternatives. This work includes an in-depth feasibility and comparative study of datacenter construction and operation in hot and cold European countries and addresses the environmental impact of photovoltaics integration in the electrical supply system. The study considers cost parameters (land, operating expenses, photovoltaic system, etc.), the net present cost and levelized cost of energy which are different for each European country under investigation. Furthermore, for every country under consideration, the PV generation was simulated using the PVsyst software which includes multiple meteorological databases, whereas the feasibility analysis was simulated using the HOMER Pro software which integrates components, resources and economic calculations. An elaborate analysis of the results knocks down the common belief that datacenters have lower operational and running expenses in cold climates because of lower cooling requirements. On the contrary, this study shows that hot climates with high solar radiation levels may favor the operation of datacenters by providing 45 % higher green energy and 35 % lower CO2 emissions, whereas the cooling cost is only 5 % higher. In addition, the break-even period for the photovoltaic system in Southern European countries with hot climates is 3–4 times faster.

THE CULTURE OF THE CO-EXISTENCE OF A PLANNED WIND FARM IN THE CONTEXT OF ENVIRONMENTAL CHANGES

Offshore wind power (OWP) as a renewable energy source (RES) is expected to have a significant share in the green energy market in the upcoming decades. Onshore energy generation is already a mature and proven technology, while its younger sibling is still in its infancy in the realities of our country. The development of OWP is a quantum leap towards using the natural energy potential of the Baltic Sea. It is supported by the government and is part of the country's energy transition plan. Experts make optimistic claims whereby the first energy from the Baltic Sea will flow into the national power grid in the middle of the next decade at the earliest. Economists and environmentalists agree that the development of energy technology in the Baltic Sea is an opportunity for the economy. It will be powered by another portion of clean energy. All parties claim that their primary task is to support environment protection from the point of view of sozology and avoid making a negative impact on the environment, including destructive events caused by natural forces and human activity, with considerations for socio-economic needs. The article contains the results of research conducted by the students of the University of Rzeszów as potential future consumers of electricity. They assessed the impact of OWP on Poland's energy security and ecological security through the lens of culture, manifested as the lack of excessive consumerism.

Enhancing Sustainability in Smart Cities: IoT-Enabled with Fog and Haze Mitigation Using EDN-GTM Technology

the growing reliance on Information and Communication Technologies (ICT) has prompted a shift towards smart city concepts, especially as over 70 per cent of the global population is expected to reside in urban areas by 2050. The smart city paradigm addresses the challenges of managing critical infrastructure by integrating intelligent ICT solutions across various sectors such as the economy, mobility, environment, people, living spaces, and governance. Central to this vision is the Internet of Things (IoT) role, acting as a pivotal network connecting devices and enabling seamless interactions in urban settings. Efficient energy usage is a key aspect of IoT-enabled smart cities, given the increasing demand for power with population growth. Lighting, a fundamental need, consumes a significant portion of energy, and an SLS becomes crucial for effective energy management in a smart city leveraging IoT technologies. The proposed system aims to enhance image quality and address fog-related challenges in Smart City applications by integrating IoT-based technology. In urban environments, foggy conditions can significantly impact visibility, affecting surveillance and monitoring systems. The system employs a comprehensive approach, utilising sensor data, image processing techniques, and deep learning models for efficient fog detection and removal. Key objectives include fog removal and image quality enhancement, focusing on adaptability to varying environmental conditions. The system dynamically adjusts fog removal processes based on real-time fog density information collected from cloud-based sensors. The dataset for training and evaluation is obtained from Kaggle, comprising fully foggy images. Pre-processing involves grey conversion and wavelet transform filters, simplifying image representation and extracting relevant features for subsequent stages. Segmentation with a region of interest (ROI) approach optimises processing efficiency by focusing on information-rich areas. Enhanced Dehazing Network (EDN) and Guided Transmission Map (GTM) models are separately implemented for haze removal and transmission map refinement. A hybrid approach combines the strengths of both models, aiming for superior fog removal and image quality improvement. Performance is assessed using metrics like PSNR, SSIM, TMQI, and FSIMc, providing a comprehensive evaluation. The proposed system, leveraging deep learning, adaptive processing, and IoT integration, offers an effective solution for mitigating the impact of foggy conditions in Smart City scenarios.

High-performance, Wind-driven Triboelectric-Electromagnetic Hybrid Nanogenerator for Self-powered Wireless Transmission and Wind Speed Sensing in the Internet of Things

Wind energy is becoming more crucial in addressing the scarcity of fossil fuel due to the development of promising technologies like Electromagnetic Generators (EGs), Triboelectric Nanogenerators (TNs), and their hybrid nanogenerators. However, only a portion of wind energy can be efficiently converted into electricity. By integrating 5G technology with the Internet of Things (IoT) and expanding the deployment of wireless sensor networks, vulnerable areas may be effectively monitored for potential disasters. Nevertheless, substituting conventional chemical batteries with new ones in IoT devices poses a substantial difficulty, particularly in distant regions. This article presents a hybrid energy harvester explicitly designed for wind energy harvesting. This work introduces the High Performance, Wind-driven Triboelectric-Electromagnetic Hybrid Nanogenerator (HPW-TEHN) as a solution for self-powered Wireless Transmission (WT) and Wind Speed Sensing (WSS) in the Internet of Things (IoT). Here, we present a High-Performance Wind Turbine with a wide operational range of wind speeds, allowing for efficient harnessing of wind energy across different levels, including gentle breezes and moderate and severe winds. The gadget comprises a spinning body and a sliding body. The power-producing mechanism consists of the EGs in the rotating body and the TNs in the sliding body. All created units are fully enclosed within the device box, effectively insulated from challenging environmental conditions. This research comprehensively analyzes the impact of dielectric material kinds and sizes on the output performance of TNs. Additionally, it investigates the output performance of this device under various wind speeds. The performance of HPW-TEHN improves as the wind speed increases. At a wind speed of 10 m/s, the TN, EG, and HPW-TEHN generate an output power of 0.19 mW, 0.38 mW, and 1.4 mW, respectively.

A database of hourly wind speed and modeled generation for US wind plants based on three meteorological models

In 2022, wind generation accounted for ~10% of total electricity generation in the United States. As wind energy accounts for a greater portion of total energy, understanding geographic and temporal variation in wind generation is key to many planning, operational, and research questions. However, in-situ observations of wind speed are expensive to make and rarely shared publicly. Meteorological models are commonly used to estimate wind speeds, but vary in quality and are often challenging to access and interpret. The Plant-Level US multi-model WIND and generation (PLUSWIND) data repository helps to address these challenges. PLUSWIND provides wind speeds and estimated generation on an hourly basis at almost all wind plants across the contiguous United States from 2018–2021. The repository contains wind speeds and generation based on three different meteorological models: ERA5, MERRA2, and HRRR. Data are publicly accessible in simple csv files. Modeled generation is compared to regional and plant records, which highlights model biases and errors and how they differ by model, across regions, and across time frames.

Preface: SolarPACES 2022, 28th International Conference on Concentrating Solar Power and Chemical Energy Systems

The SolarPACES 2022 International Conference was held from September 27 to September 30, 2022 in Albuquerque, New Mexico. As the premier international conference and network for advancing commercial deployment and research and development of concentrating solar-thermal power (CSP) and related technologies, the community was excited to convene in person after two years of virtual collaboration. The conference brought together more than 400 participants from 29 countries. The technical presentations and plenary sessions highlighted exciting advances in state-of-the-art commercial deployment and next-generation research and development. There was much focus on emerging commercial markets, including the value of thermal energy storage for cost-effective long duration energy storage – charged either with electricity or solar heat – and the use of solar thermal energy for industrial and chemical processes, especially to decarbonize the large portion of energy that’s currently used for industrial process heating. By holding the conference in the U.S., we were able to highlight particular technical and strategic objectives being advanced by the U.S. Department of Energy (DOE) and the US Government, including the progress in advancing the Generation 3 (Gen3) CSP test facility [1] at Sandia National Laboratories. This megawatt-scale system will demonstrate a fully integrated thermal transport and storage system that can collect, store, and deliver heat above 700° Celsius, using solid particle heat transfer media. Attendees to the conference were able to tour the globally renowned CSP research center at Sandia National Laboratories and the National Solar Thermal Test Facility (NSTTF). The NSTTF opened in 1978 as the world’s first tower research facility for CSP and has been operating for more than 40 years. The site has been a center of excellence in the development of molten salt technologies for CSP and has played a key role in the demonstration of technologies used in some of the largest solar power plants in the world. We also highlighted the recent announcements from the U.S. Department of Energy of the Energy Earthshot Initiatives to accelerate breakthroughs of abundant, affordable, and reliable clean energy solutions by the end of this decade. Specifically, the Long Duration Storage Shot [2] established a target to reduce the cost of grid-scale energy storage by 90% for systems that deliver 10 or more hours of duration, to $0.05 per kilowatt-hour of electricity delivered from storage. The Industrial Heat Shot [3] aims to develop cost-competitive industrial heat decarbonization technologies with at least 85% lower greenhouse gas emissions by 2035. Hydrogen Shot [4] seeks to reduce the cost of clean hydrogen by 80%, to $1 per 1 kilogram. CSP technologies have promising potential to contribute to all of these important goals. The 2022 conference covered important contributions in all of these areas, and more, across 15 technical tracks, coordinated and chaired by international experts in each field. We had high quality contributions across the board, including 211 oral presentations and 111 posters. Additionally, the plenary sessions brought together leading experts on energy storage, US and global markets for CSP technologies, and a specific focus on industrial decarbonization. On behalf of SolarPACES, I thank all of the conference participants, authors, presenters, track chairs, and the conference organizing committee for an extremely successful meeting! Avi Shultz Chairman of the 28th SolarPACES conference

Numerical and experimental investigation of negative stiffness beams and honeycomb structures

Metamaterial structures that exhibit negative stiffness (MSNS) behavior have shown the potential to be used as energy dissipation systems in different applications. Negative stiffness honeycomb structures consist of multiple pre-buckled beams that snapping through from one pre-buckled mode to another buckled mode, when subjected to transverse loads, displaying negative stiffness, and dissipating a significant portion of the input energy. This paper presents finite element models (FEMs) developed to investigate the performance of negative stiffness pre-buckled beams and honeycombs. The FEMs were validated using experimental results of single pre-buckled beams and honeycomb structures. The experimental testing of the pre-buckled beams was presented in the current study while the results of the honeycomb were available in the literature. The FEMs have the ability to capture the transition of the elements from one mode of buckling to another mode as well as the force thresholds, energy dissipation values, and residual displacements. The FEMs were extended to investigate the effect of different parameters such as boundary condition, apex height-to-beam thickness ratio, and constraining the second mode of buckling on the behavior of negative stiffness honeycombs.

Integrated device for multiscale series vibration reduction and energy harvesting

A multi-degree-of-freedom device is proposed, which can achieve efficient vibration reduction as the main objective and energy harvesting as the secondary purpose. The device comprises a multiscale nonlinear vibration absorber (NVA) and piezoelectric components. Energy conversion and energy measurement methods are used to evaluate the device performance from multiple perspectives. Research has shown that this device can efficiently transfer transient energy from the main structure and convert a portion of transient energy into electrical energy. Main resonance and higher-order resonance are the main reasons for efficient energy transfer. The device can maintain high vibration reduction performance even when the excitation amplitude changes over a large range. Compared with the single structures with and without precompression, the multiscale NVA-piezoelectric device offers significant vibration reduction advantages. In addition, there are significant differences in the parameter settings of the two substructures for vibration reduction and energy harvesting.