Improve Generation Efficiency Research Articles

Enhancing concentrated photovoltaic power generation efficiency and stability through liquid air energy storage and cooling utilization

Amid escalating climate concerns, particularly global warming, there is a significant shift towards renewable energy sources. Concentrated Photovoltaics (CPV) are at the forefront of this transition due to their high efficiency and clean energy generation capabilities. However, CPV cell stability and reliability are compromised by high operating temperatures, necessitating effective cooling solutions. This study proposes a novel coupled Concentrated Photovoltaic System (CPVS) and Liquid Air Energy Storage (LAES) to enhance CPV power generation efficiency and mitigate the challenges of high cell temperatures and grid integration. The research introduces an innovative process employing the cell liquefaction cycle for LAES, utilizing surplus cooling capacity to maintain CPV cells at optimal temperatures. A comprehensive thermodynamic analysis optimizes the coupled system’s operation and evaluates its economic benefits. The integrated system improves generation efficiency and economic viability of CPVS, resulting in a 24.41 % increase in photovoltaic module efficiency and a 2.03 % increase in overall rated power output. This leads to a 56.59 % increase in annual revenue for a 50 MW CPVS. Importantly, the findings demonstrate that integrating LAES with CPVS not only enhances solar energy utilization and economic benefits but also significantly contributes to the sustainability of clean, low-carbon energy systems, inspiring a greener future.

A novel higher rotational speed maintaining control for wind power generation systems under unstable wind conditions

This study proposes the Higher Rotational Speed Maintaining (HRSM) control algorithm that is suitable for large wind speed fluctuations. One of the challenges faced by wind generators is operating with significant wind speed oscillations. A wind generator with a large moment of inertia increases the time constant in rotational speed control and delays the tracking of the optimal operating point. This delay could reduce generated power by up to 40% or more. There are numerous regions in Japan’s inland areas where average wind speeds exceed 6.5 m/s. However, frequent fluctuations in wind speeds make wind power generation challenging. Therefore, this paper proposes a control algorithm suitable for wind turbines operating under unstable wind conditions. Higher rotational speeds are required to convert sudden high wind speeds into higher power output, especially when wind speed oscillations are large. Hence, the proposed algorithm focuses on maintaining the rotational speed during periods of unstable wind conditions to improve generation efficiency. The effectiveness of the proposed control method for wind turbines is verified through numerical simulation results. The novel control algorithm aims to promote the spread of wind turbines in areas with unstable wind conditions by overcoming these disadvantages.

Application of Fuzzy Control and Neural Network Control in the Commercial Development of Sustainable Energy System

Sustainable energy systems (SESs) occupy a prominent position in the modern global energy landscape. The purpose of this study is to explore the application of fuzzy control and neural network control in photovoltaic systems to improve the power generation efficiency and stability of the system. By establishing the mathematical model of a photovoltaic system, the nonlinear and uncertain characteristics of photovoltaic system are considered. Fuzzy control and neural network control are used to control the system, and their performance is verified by experiments. The experimental results show that under the conditions of low light and moderate temperature, the fuzzy neural network control achieves a 3.33% improvement in power generation efficiency compared with the single control strategy. Meanwhile, the system can still maintain relatively stable operation under different environmental conditions under this comprehensive control. This shows that fuzzy neural network control has significant advantages in improving power generation efficiency and provides beneficial technical support and guidance for the commercial development of SESs.

Root cause localization for wind turbines using physics guided multivariate graphical modeling and fault propagation analysis

Under the background of widespread utilization of wind energy, the improvement of power generation efficiency and the reduction of operation and maintenance costs have increased the demand for anomaly detection and localization of wind turbines through fault propagation analysis, while the large-scale data collected by SCADA systems provide sufficient data support and promising assistance for this purpose. It is an effective and cost-saving solution to this demand to construct a high-precision wind turbine digital twin model under normal operating conditions based on multivariate monitoring data, and to realize root cause localization based on prediction deviation and backtracking analysis. This paper proposes a root cause localization framework for wind turbines based on explicit-implicit knowledge fusion and multivariate time-series graph neural networks, fully utilizing the inter-variable dependencies mining capability of graph structure learning and the temporal prediction advantage of time-series graph neural networks. Five types of explicit knowledge based on explicit rules are constructed to describe the explicit relationships between monitoring variables. The fused knowledge (i.e., graph adjacency matrix) is obtained by fusing the explicit knowledge with the implicit knowledge hidden in the data through a quasi-hard-attention mechanism based on the idea of graph structure learning. A high-precision digital twin model for wind turbines based on fused knowledge is constructed using the multivariate time-series graph neural network. The anomaly degree of monitoring variables’ state is defined based on the prediction deviation, with which the propagation of fault's state over time can be accurately described, and the root cause localization through backtracking analysis can be achieved. Case studies are conducted using field fault data from a wind farm, a sugar factory and a thermal power plant. The results show that the proposed framework can provide a solution for studying the fault propagation process and root cause localization, also demonstrating certain robustness and generalizability.

Disentangling the "tip-effects" enhanced antibacterial mechanism of Ag nanoparticles.

Silver nanoparticles (Ag NPs) exhibit strong antibacterial activity and are widely used in industries such as medical, food and cosmetics. In this study, Ag nanospheres and Ag nanotriangles are selected as antibacterial agents to reveal the distinct mechanism of tip effects towards their antibacterial performance. A series of antibacterial experiments were implemented, including in situ monitoring as well as studying and determining the evolution of the inhibition zone, minimum inhibitory concentration (MIC)/minimum bactericidal concentration (MBC) values, growth kinetics, bactericidal curve, bacterial morphologies and intracellular reactive oxygen species (ROS). Ag nanotriangles can eradicate E. coli and S. aureus at extremely low concentrations in comparison to Ag nanospheres, in particular under sunlight irradiation. The destroyed bacterial cell walls were examined by scanning electron microscopy. Through the investigation of ROS production, the generation efficiency of ROS is improved by the merit of sunlight irradiation thanks to the localized surface plasmon resonance (LSPR) properties of Ag NPs. However, a more significant improvement in ROS generation efficiency occurred in the presence of Ag nanotriangles contributed by the pronounced "tip effects". This study sheds light on the structure-performance relationship for the rational design of antibacterial agents.

Surface generation mechanism and efficiency improvement in ultrasonic vibration assisted belt flapwheel flexible polishing GH4169

Surface generation mechanism and efficiency improvement in ultrasonic vibration assisted belt flapwheel flexible polishing GH4169

Parallel Multi-Layer Monte Carlo Optimization Algorithm for Doubly Fed Induction Generator Controller Parameters Optimization

This work proposes a parallel multi-layer Monte Carlo optimization algorithm (PMMCOA) that optimizes proportional–integral parameters for a doubly fed induction generator-based wind turbine controller. The PMMCOA, an improved form of the Monte Carlo algorithm, realizes the optimization process via a parallel multi-layer structure. The PMMCOA includes rough search layers, precise search layers, and re-precise search layers. Each layer of the PMMCOA adopts a multi-region and multi-granularity approach to increase the diversity and randomness of the search samples. The PMMCOA is employed to tune the controller parameters for achieving maximum power point tracking and improving generation efficiency. The controller fitness function reflects the sum of the rotor angular velocity error and the reactive power error. Compared with the five metaheuristic algorithms, the PMMCOA has a higher global convergence and more accurate power tracking ability.

Durability and Interfacial Elemental Diffusion about BZYb based Protonic Ceramic Fuel Cell

Protonic ceramic fuel cells (PCFCs) are expected to be a highly efficient next-generation fuel cell because the fuel is not diluted by the generated water vapor during power generation. In the past research, we have found that Yb-doped BaZrO3 (BZYb) is promising in terms of the durability against CO2, proton conductivity, and less reactivity with NiO used for the fuel electrode. We are currently developing improvement of power generation efficiency and durability of PCFCs using BZYb electrolyte. In terms of the durability of PCFCs, there is concern about degradation due to diffusion of transition metals such as Co and Ni used in the air and fuel electrodes. In this study, we evaluated the durability of PCFCs using BZYb electrolyte focusing on the diffusion of transition metals derived from electrodes. We also examined the effect of a buffer layer on the air electrode side. In this study, fuel electrode supported cells with BaZr0.8Yb0.2O3-δ(BZYb20) electrolyte and NiO-BZYb20 fuel electrode was used. The fuel electrode half cells were fabricated by integrally firing process of the laminated green sheets of the electrolyte and fuel electrode to densify the electrolyte. For air electrode, BaZr0.375Yb0.125Co0.50O3-δ was screen printed on the fuel electrode half cell and fired at 900°C. For the cell with buffer layer between the air electrode and the electrolyte, BaCe0.7Zr0.1Y0.1Yb0.1O3- δ was spin-coated on the half-cell and then fired at 1300°C. The air electrode was then prepared in the same way. Durability tests were conducted at constant-current mode at 600°C, and the elemental diffusion state of the cells before/after the test was observed by cross-sectional EPMA. During 1000h power generation, the increase of ohmic resistance and polarization resistance was observed, and the increase in resistance was found to be smaller in cells with buffer layer. The results of cross-sectional EPMA analysis after the power generation test showed differences in the segregation state of Co and Ni in the electrolyte, with a tendency for segregation to be suppressed in the presence of a buffer layer.Acknowledgement: This work is partially based on results obtained from a project (JPNP20003), commissioned by the New Energy and Industrial Technology Development Organization (NEDO) of Japan.

The Cleaning Effect of Photovoltaic Modules According to Precipitation in the Operation Stage of a Large-Scale Solar Power Plant

A large-scale solar power plant costs a lot of money in the early stage of development and is greatly affected by the natural environment. Therefore, efficient operation is very important. The purpose of this study is to analyze the cleaning effect of photovoltaic modules according to precipitation during the operation stage of a large-scale solar power plant. The first analysis compared ‘average power generation on sunny days under standard cloudiness from after precipitation to the next precipitation’ and ‘average daily power generation per quarter’ and confirmed that precipitation had an effect on increasing power generation by 26%. The second analysis compared ‘average power generation on sunny days under the standard cloudiness from after precipitation to the next precipitation’ and ‘average daily power generation on a clear day just before precipitation’. It was confirmed that the average power generation efficiency of the entire sample increased by 4.8% on average after precipitation than before precipitation. This study quantitatively analyzed the cleaning effect of photovoltaic modules by precipitation through actual power generation data of large-scale solar power plants. This study has sufficient value in establishing an operation manual for decision-making on the appropriate input cost for cleaning photovoltaic modules and improvement of power generation efficiency.

Assessing the roles of efficient market versus regulatory capture in China’s power market reform

China began implementing market-based economic dispatch through power sector reform in 2015, but the reform has encountered some political and economic challenges. Here we identify the reform’s efficiency changes and explore the influences of market-driven and politically driven mechanisms behind them. We do this through a cost-minimizing dispatch model integrating high-frequency data in southern China. We find that the dispatch transition improves the overall efficiency, but regulatory capture in provincial markets limits its full potential. The preference for local enterprises over central state-owned enterprises (SOEs) by local governments, in the form of allocated generation quotas, demonstrates the political challenge for market reform. The allocated generation quota protects small coal-fired and natural gas generators owned by local SOEs, lessening their motivation to improve generation efficiency, even after the reform. As a result, nearly half of the potential carbon dioxide emissions reduction and social welfare gains through market reform is not realized.

Techno-economic assessment of solar technologies to meet hospitals energy needs

<span lang="EN-US">Hospitals present one of the highest energy consumptions per surface unit, meaning that on-site renewable energy generation and energy efficiency improvements are key to lower hospitals energy demand, external energy dependence and greenhouse gases (GHG) emissions. In this work, the feasibility from the techno-economical point of view of the installation of three solar-based energy generating technologies in hospitals in different climate locations in Europe is addressed. The potential of solar energy technologies to cover the energy needs of the hospitals under study is conducted proposing a novel design and sizing optimization methodology for on-roof installations. The profitability of the different solar-based installations will vary depending on the solar technology output (electrical, thermal or both) and on the type of energy needs of the hospital; but in all cases, profitability is mostly influenced by the price of the current energy source supplying the hospital energy needs. Levelized cost of energy (LCOE) values for on-roof photovoltaic (PV), solar thermal (ST), and photovoltaic-thermal (PV-T) installations obtained are in the range of <br /> 0.028-0.056, 0.051-0.096, and 0.053-0.128 €/kWh, respectively; for locations in latitudes from 37 N (Seville) to 60 N (Oslo) in Europe. Results from this work aim to serve as reference for similar studies in a wide range <br /> of climates.</span>

Advancements in solar technology, markets, and investments – A summary of the 2022 ISA World Solar Reports

This paper provides a summary of the Annual World Solar Reports on Technology, Markets, and Investments published by the International Solar Alliance (ISA) in October 2022. Solar has emerged as the technology of choice to drive the renewable energy transition. This preference for solar has been driven by technology maturity and improvements, cost reductions, and improved methods for grid integration of solar generation. Globally, solar has grown nearly 20 fold in the last decade to reach 920 GW of installed capacity in 2021. As solar approaches and crosses into Terawatt scale of deployment, a number of technological innovations are emerging to continue improving generation efficiency, power output, and material consumption. Additionally, manufacturing capacity is growing rapidly to meet demand for installations. The market for solar installations continues to grow around the world but will need to scale rapidly to meet net zero requirements. The growth in solar markets will also require a significant scale up in solar investments across the world through a wide range of instruments. The deployment of the correct solar related interventions can ensure that the world can achieve multi terawatt scale of solar deployment in the coming decades, thus supporting the global energy transition.

Modelling and Simulation Study of a Segmented Converging Thermoelectric Heat Exchanger for Power Generation Efficiency Improvement

Modelling and Simulation Study of a Segmented Converging Thermoelectric Heat Exchanger for Power Generation Efficiency Improvement

Efficiency of chemical generation of volatile species of zinc from non-acidic conditions

Chemical vapor generation (CVG) producing volatile species of zinc was carried out in a custom made generator with high-resolution continuum-source atomic absorption detection. The influence of composition of the reaction medium and various reaction modifiers was studied. The optimum conditions included neutral to basic pH of the reaction mixture, i.e., 0.1 M HCl and 0.5% (m/v) NaBH4 prepared in 0.1 M NaOH. Substantial improvement of generation efficiency (approx.18-times) was achieved with 8-hydroxyquinoline and a LOD of 4 ng mL−1 was obtained. The overall CVG efficiency of 2.7% was determined by comparison of sensitivity obtained with CVG and conventional solution nebulization (both coupled to inductively coupled plasma mass spectrometry) and 2.5% was determined by employing a radioactive isotope 65Zn. The described method is reasonably resistant to interferences, the greatest interference effect was observed with Bi(III) and Fe(III), other transition and noble metals interfered at a 100-times surplus over Zn and their effects decreased in the order Co(II) > Ni(II) > Cd(II) > Mn(II) > Ag(I) > Cr(III) > Cu(II). The accuracy of the method was verified by determination of zinc in the certified reference materials NIST 1643f (fresh water) and ERM CA713 (waste water).

Carbon reduction and flexibility enhancement of the CHP-based cascade heating system with integrated electric heat pump

The energy utilization efficiency and the flexibility enhancement of the combined heat and power (CHP) plant can promote both decarbonization and renewable energy integration. In this research, we proposed a novel CHP cascade heating system by integrating it with the electric heat pump (EHP). The integration of EHP can consume power generation load and bear part of the heat load, which improves the flexible peak regulation ability of the novel heating system. Based on the detailed simulation model of a typical 2 × 300 MW subcritical CHP plant, the reference and novel systems are compared in thermodynamic and peak-load regulation performance to present the benefits of the EHP design. The results showed that, under the design condition, the heating capacity in the novel system had an increment of 6.02 % to that in the reference system, bringing out a 4.51 % improvement in electricity generation efficiency. Correspondingly, the average standard coal consumption rate for generating of the novel system reduced by 9.53 g/kWh. Under the same heat load, the peak shaving lower limit of the novel system is 59 MW lower than the reference system on average, and the load rate is reduced by 10 % of the rated power generation capacity on average. In the case study, under the typical day operation of the regional electric-thermal integrated energy system, the wind power curtailment ratio of the novel system is 10.75 % lower than that of the reference system. Meanwhile, with further waste heat recovery, the daily standard coal consumption of the novel system can be saved by 231.81 t, equivalent to a reduction of 607.34 t of CO2 emissions.

Vapor Generation of Rare-Earth Elements via Reaction with Tetrahydroborate: Chemical Identities and Mechanisms of Formation.

This technical note reports for the first time the simultaneous vapor generation of 16 rare-earth elements (REEs) via reaction with sodium tetrahydroborate (THB). Significant improvement in REE vapor generation efficiency was discovered in the presence of arsenazo III (ARS). Subsequent to a critical evaluation on the impacts of various experimental variables, including the concentrations of acids, THB, and ARS, blank-limited (reagent contamination and impurity from ARS) detection limits (LODs) in the range of 0.004-0.15 μg L-1 were achieved based on three times the standard deviation of the method blank by the proposed vapor generation inductively coupled plasma mass spectrometry (ICP-MS). The nature of released REE species was studied by various approaches and identified to be REE nanoparticles and REE-ARS chelates; a dual-route mechanism for the vapor generation of REEs was thereby proposed.

Horizontal Bi-Stable Vibration Energy Harvesting Using Electromagnetic Induction and Power Generation Efficiency Improvement via Stochastic Resonance

In this study, a vibration energy-harvesting system is developed by first proposing a horizontal bi-stable vibration model comprising an elastic spring and a mass block and then applying an electromagnetic induction power generation device composed of a magnet and a coil. Subsequently, based on a weight function that considers the mutual positional relationship between the magnet and conducting coil, a set of simultaneous governing equations that consider the elastic force of the elastic spring and the Lorentz force of electromagnetic induction is derived. Additionally, a numerical analysis method employing the Runge–Kutta method is utilized to obtain a numerical solution for the vibration response displacement and vibration power generation voltage simultaneously. Experiments are performed to verify the results yielded by the proposed bi-stable vibration energy-harvesting system. The results shows that the measured vibration response displacement and the vibration power generation voltage are consistent with the analytical results. Moreover, issues including the identification of damping coefficients that consider the mutual effects of normal kinetic friction and electromagnetic induction damping forces, as well as the effects of electromagnetic induction damping on the vibration response displacement, are discussed comprehensively. Simultaneously adding random and periodic signals to the bi-stable vibration model results in stochastic resonance and improves both the vibration amplification effect and vibration power generation.

Conjugated‐Polymer‐Based Photodynamic Therapy

AbstractPhotodynamic therapy (PDT) is a promising method for cancer treatment owing to its high spatiotemporal precision and minimally invasive properties. The efficiency of reactive oxygen species (ROS) production by photosensitizers (PSs) directly affects PDT efficacy. Conjugated polymers (CPs) exhibit excellent light‐harvesting capabilities and effective intra‐ and intermolecular energy transfer between CPs and traditional PSs by the “molecular wire effect,” leading to a significant improvement in ROS generation efficiency when PSs are carefully paired with suitable CPs as energy donors. The recently proposed “polymerization‐enhanced photosensitization effect” further reveals that donor–acceptor type CPs can directly function as high‐performance PSs. Recently, two‐photon excitation and chemiluminescence excitation technologies are employed to enhance the penetration depth, a common challenge in phototherapy of CP‐based PDT systems. Furthermore, if precisely designed, CPs can endow the system with useful functions such as photothermal effects and drug‐delivery capacity, which can lead to a synergistic therapy with PDT. Here, recent advances are summarized in CP‐based PDT, including its underlying phenomena, mechanisms, and applications. Strategies for improving PDT performance are the focus of the discussions. In the conclusion, challenges and opportunities are discussed by considering further perspectives.

Integrated Kalina cycle in a combined polymer membrane fuel cell and evacuated heat pipe collector for a new power generation system

This paper presents the integration of the Kalina cycle process in a combined polymer membrane fuel cell and evacuated heat pipe collector for improvement of power generation efficiency. The proposed system is evaluated from thermodynamic, environmental, and exergoeconomic perspectives, and the effect of key system parameters are investigated. The energy and exergy efficiencies of the proposed system in the given conditions are improved by 13.12% and 10.35%, respectively compared to an independent fuel cell. The system’s product unit cost of the system and output power in this condition are 136.1 $/GJ and 145.1 kW. The system also prevents the production of 116.1 kg/hr of carbon dioxide under these conditions. The analysis of system parameters shows a direct relationship between increased current density, temperature, and operating pressure of the fuel cell and decreased energy and exergy efficiencies. On the other hand, the total product unit cost increases as these parameters increase. The system assessment shows there is a suitable turbine inlet pressure to achieve optimal efficiency, the lowest unit price for the product, and maximum CO2 emission reduction. Although solar collectors reduce the system’s energy efficiency, they increase the exergy efficiency and reduce the cost per unit of the total product.

Economic value and acceptability of advanced solar power systems for multi-unit residential buildings: The case of South Korea

Residential solar power systems offer several advantages to the energy system owing to their proximity to the demand area. To this end, promotion policies have focused on providing financial incentives for installation. However, as residential solar power systems increasingly diffuse, this approach entails considerable costs and thus, is unsustainable in the long term. This study identified the key attributes of advanced residential solar power systems, including not only installation cost but also aesthetics (installation type and panel transparency), flexible power usage (ESS provision), and generation efficiency. This study extends the existing literature by investigating installation types that can be applied to multi-unit residential buildings (balcony and window installations). Using the choice experiment approach to Korean consumers, this study analyzed consumer preferences and the economic value of identified key attributes. The results show that the economic value of an appropriate installation type and transparent solar panel technology was substantial, compared to the economic value of improving generation efficiency. Moreover, according to the results of simulation analyses on consumer acceptance and overall energy potential of residential solar power systems, the trade-off between generation efficiency and other factors must be carefully considered, although aesthetic factors are more important than generation efficiency for improving consumer acceptance.