Power Generation Performance Research Articles

Preliminary monitoring and performance evaluation of photovoltaic system in rural buildings in severe cold area

ABSTRACT In recent years, the photovoltaic (PV) systems of rural buildings have been demonstratively applied in severe cold areas of China. However, the lack of power generation performance and economic evaluation results is not conducive to the PV promotion. This study innovatively presented the performance and economic evaluation of the grid-connected rural building applied PV (BAPV) system in Hailar, China from the predicted and measured data. The measured monthly PV outputs were counted and analyzed from the year 2020 to 2021. The ambient temperature, solar radiation and predicted output were obtained by the software of PVSYST. The performance ratio (PR), efficiency and loss were investigated, and their relationship with temperature and sunshine was analyzed. According to the measured data and theoretical calculation, the payback periods and profits were calculated. The results indicate that the measured output yields are 14,123.70 kWh in 2020 and 13,265.10 kWh in 2021, which are 6.05%~11.76% lower than the predicted value due to snow cover in the cold months. The monthly predicted array output is about 3.4% higher than the energy output. The array capture loss (L C ) is 14.99–34.80 kWh and the system loss (L S ) is 29.6–5.81 kWh. The PR is 83.30%-99.80%. The average system efficiency and array efficiency are 16.15% and 15.62%. The lower PR and efficiency are caused by the high temperature. The measured and theoretical payback periods are 6.7 and 5.6 years, respectively. The theoretical annual rate of income is 4828.15 Chinese yuan (CNY). These results provide an important reference for the promotion of rural residential BAPV in severe cold areas.

Hybrid solar photovoltaic and salinity-gradient based osmotic energy conversion system with synergistic performance enhancement

Solar photovoltaic has become essential for generating renewable electricity to overcome global crisis of fossil energy. However, solar photovoltaic suffers from a dramatic decrement on its output power when panel surface temperature is extremely high. In addition, osmotic energy conversion is a fascinating route for utilizing energy existed between ionic aqueous solutions with salinity-gradient. Nevertheless, osmotic energy conversion also confronts a drawback of insufficient power density. When the ionic aqueous solution temperature increases, the osmotic power generation under salinity-gradient is improved owing to the strengthened ion selective diffusion. Under these circumstances, we present a hybrid solar photovoltaic and osmotic energy conversion system, and their power generation performance can be synergistically improved via heat transfer from solar photovoltaic panel to ionic aqueous solution using high thermal conductive copper heat pipes. The theoretical modelling indicates that output power of solar photovoltaic is increased by 22.8 % with a decreased panel surface temperature of 35.6 °C by using 10 copper heat pipes, while the corresponding osmotic power with a salt concentration ratio of 50-fold is simultaneously increased by 36.8 %. Then, a hybrid solar photovoltaic and osmotic energy conversion system is experimentally constructed. Due to heat transfer from photovoltaic panel to ionic aqueous solution through 10 copper heat pipes, the maximum surface temperature of photovoltaic panel is dropped from 67.3 °C to 43.4 °C, and its output power is consolidated by 35.2 %. Besides, the osmotic power density under 50-time salinity-gradient ratio is synergistically ameliorated from 1.39 W/m2 to 2.72 W/m2 by 95.7 %. The current research designs a hybrid solar photovoltaic and osmotic energy conversion system, paving a fetching way for synergistic utilization of solar energy and salinity-gradient energy.

Rational design of oriented glass fibers within nano-porous SiO2 films to improve evaporation-induced hydroelectric generation

Harvesting energy from the ubiquitous water evaporation process on earth has recently proved to be an effective solution for obtaining renewable energy. However, the electricity generated in this process is still difficult to meet practical use, and the energy conversion mechanism is controversial. Here, an enhanced output was generated by the rational design of oriented glass fibers within nano-porous SiO2 film. The ordered glass fibers could effectively improve the power generation performance by promoting the movement of water flow and carriers, achieving an induced open-circuit voltage of 1.4 V and an induced short-circuit current of 400 nA, and providing a performance improvement strategy for such evaporation-induced generators. And it is revealed that the generated voltage driven by evaporation is related to the humidity difference and water flow. The availability of raw materials and the simplicity of the fabrication process also enable the generators easy to scale up.

Preparation of AuNP-CQD/PDA/GO anode for MFC and its treatment of oily sewage from ships.

Oily sewage discharged from ships has brought many harms to the marine environment, even endangered marine life and human life. As a new type of water treatment technology, microbial fuel cell (MFC) can efficiently treat pollutants and recover energy, which can be converted into electric energy. However, its large internal resistance restricts its development. In order to solve the problems of low power generation performance and poor biocompatibility of microbial fuel cell, a gold nanoparticle-carbon quantum dot/polydopamine/graphene oxide/bacterial cellulose (AuNP-CQD/PDA/GO/BC) electrode was prepared, and it was applied to the treatment of oily sewage from ships. Fourier transforms infrared spectroscopy, X-ray diffraction, scanning electron microscopy, gas chromatography-mass spectrometry, and contact angle measuring instrument were used to characterize the electrode. The results show that PDA bridges GO and AuNP-CQD particles through the electrostatic interaction/π-π bond/hydrogen bonding, respectively. This attracts a large number of microorganisms to attach to the surface of the porous anode material, which greatly improves the activity and quantity of microorganisms. Moreover, the maximum power density of AuNP-CQD/PDA/GO/BC electrode is 2624.91 mW/m2, which obviously improves the electrochemical performance of MFC. The oil content of the treated water is ≤ 15mg/L, reaching the discharge of MARPOL 73/78 convention. Therefore, the proposed approach has paved new dimensions in not only the preparation of a new composite electrode materials but also its applications as effective degradation of ship oily sewage in MFC.

Research on integrated electrical and mechanical response of piezoelectric asphalt pavement material under bidirectional cyclic loads

In recent years, road vibration capture technology based on the piezoelectric effect has been a research hotspot in the field of road engineering. In tests, although some researchers often use vertical vibration to simulate vehicle load, they ignore the influence of the tangential force of vehicle load on the field road on the power generation performance of the road piezoelectric energy harvester (RPEH). Therefore, this study used a static and dynamic large-scale direct shear instrument to conduct a bidirectional cyclic load test on a piezoelectric-asphalt pavement specimen, and the effects of different vertical vibration and horizontal shear values on the RPEH open-circuit voltage and output power were analysed. Simultaneously, a 3D simulation model of the piezoelectric-asphalt pavement specimen and piezoelectric ceramic sheet were established, and the test results were verified. The experimental and simulation results showed that when vertical vibration or horizontal shear acted alone, the output power of the RPEH increased in proportion to the vertical (load magnitude and frequency) and horizontal (shear frequency and displacement) conditions. The output power remained at an energy level of 10−5 W under vertical vibration, which is three orders of magnitude greater than that of horizontal shear action. However, under the combined action of vertical vibration and horizontal shear, the specimen displayed “dilatancy behaviour”. During vertical vibration (200 kPa, 4 Hz) and horizontal shear (1 Hz, 0.1 mm), the maximum output power of the RPEH was 5.05 × 10−5 W. Thus, this research provides an important reference for the power generation performance prediction of an RPEH under bidirectional cyclic dynamic loads.

High Efficiency Transparent and Semi‐Transparent Photovoltaics Based on a Layer‐By‐Layer Deposition

Transparent and semitransparent photovoltaics offer an exciting opportunity to integrate existing infrastructure with renewable energy. Organic photovoltaics (OPVs) are key enablers for wavelength‐selective transparent photovoltaics (TPVs) because of their selective absorption in the near‐infrared (NIR) that enables simultaneously high power conversion efficiency (PCE) and average visible transmittance (AVT). The recent rise of OPVs and TPVs has been accelerated in large part by the development of nonfullerene acceptors (NFAs) as highly adaptable deep NIR harvesting materials. Herein, sequential layer‐by‐layer (LBL) deposition of a selectively NIR absorbing nontraditional acceptor polymer is paired with a NIR absorbing donor IEICO‐4F that is typically considered an NFA via solvent orthogonality. With detailed optimization of the active layers and top electrode, semi‐transparent photovoltaics with a PCE of 8.8%, AVT of 40.9%, and a light utilization efficiency of 3.6% are demonstrated. The LBL approach enables explicit optical modeling of the device structure to extract exciton diffusion lengths >100 nm for both the polymer and IEICO‐4F with a transition in charge collection length regimes dependent on the acceptor thickness. Furthermore, the LBL deposition technique enables an investigation of the full range of polymer thickness and its impact on power generation and optical performance.

Comparative study on the performance of the application of clean alternative fuels in SOFC/ICE hybrid power systems on electric aircraft

Solid oxide fuel cells (SOFC) have gradually become possible to be used in the aviation field because of their high efficiency and fuel flexibility. The number of internal combustion engines (ICE) that are already in use is large, which makes it difficult to completely abandon them in a short period. Hence, finding low-carbon alternative fuels is significant for the development of cleaner internal combustion engines. In this paper, different hybrid power systems configured with different fuels, i.e., hydrogen, methanol, liquid ammonia, isooctane, natural gas and gasoline, which consist of a solid oxide fuel cell and an internal combustion engine, are constructed to help find the optimal set of fuel and system structure by analyzing the power generation performance and weight of different systems. The results show that the hybrid power system with ammonia or methanol (except gasoline) as fuel presents the lowest actual fuel consumption rate (around 310 g/kWh). The hybrid power system with ammonia as fuel performs the highest power generation efficiency of 61.58%, and the corresponding power density is estimated at 0.556 kW/kg. In conclusion, the proposed system with ammonia as fuel has obvious advantages in fuel consumption rate, power generation efficiency, carbon emission reduction and fuel storage.

In-pipe hydropower vertical axis parallel turbines prototype: performance and workability testing

ABSTRACT An improvised version of a vertical axis twin turbine in-pipe hydropower prototype, with bigger power generation (PG) channels and turbines as compared to the previous one was developed and designated as P40. The P40 was fabricated mainly using mild steel. This study aims to evaluate the flow properties, power generation performance, and workability of the P40. At the maximum flow rate of 0.076 m3/s, each of the PG channels at both sides of the P40 allowed about 13% of the water to flow through them and the P40 absorbed 34.4% of the 1.25 bar stagnation pressure of the flow. Both turbines showed almost identical performance, generating a total mechanical power up to 0.608 kW at the maximum flow rate. Overall, a turbine efficiency of more than 70% was obtained at respective flow rate conditions and the highest was 84.7%. All the valves at the inlets and outlets of the PG channels functioned perfectly not to let water flow through them to allow for maintenance work of the turbines’ system when necessary. Overall, the P40 performed effectively as a device that allowed most water to flow uninterruptedly, while simultaneously generating power. Based on the water splash effect in the turbine casing, further study is recommended to increase turbine efficiency by improvising the prototype design.

Industrial experiment and numerical analysis of the effect of pulsing water flow in thermoelectric generators

Thermoelectric conversion technology can effectively recover industrial waste heat and improve industrial energy utilization efficiency. Most of the industrial waste heat is released irregularly, making it difficult for the thermoelectric generator (TEG) to achieve optimal power generation performance. In order to improve the power generation performance of the TEG in the industrial environment, it is a simple and efficient method to control the internal temperature gradient of the TEG by pulsing water flow. In this study, the numerical calculation method is used to analyze the effect of cooling water conditions on the performance of the TEG in an industrial environment. The numerical calculation process is divided into two parts: steady calculation and transient calculation. Steady calculations are used to analyze the effect of cooling water's initial temperature and flow rate. The cooling water reduces the temperature of the hot end of the thermoelectric module (TEM), which prevents the TEM from reaching the maximum temperature gradient. The flow condition of cooling water is changed to pulse flow, which is used to adjust the temperature gradient of the TEM. The transient calculation is used to analyze the effect of different pulse conditions in TEG's performance. According to the numerical calculation results, industrial experiments are designed, and the experimental results verify the accuracy of the numerical calculation results. The results show that when the cooling water temperature is 20 °C and the flow rate is 3 ms−1, the power generation performance of the TEG reaches the best state. The maximum output power is 281.2 W. Pulsing water flow improves TEG power generation performance. The output power of the TEG is increased by 8.43% when the pulse condition is 0.3 s, and the output power is 304.64 W.

Thermodynamics Investigation of S-CO2 Power System Combined with Composition Adjustment ORC

Supercritical carbon dioxide power cycle (S-CO2) is a promising technology in comparison to the conventional Rankine cycle for power conversion. However, the waste heat from the turbine outlet is not well utilized. Zeotropic Organic Rankine cycle (ORC) recovering waste heat is an advanced heat-to-power conversion method. Novel composition adjustment zeotropic ORC has advantages over ORC using fixed mixture components in the power generation performance. The present study proposed a novel S-CO2 power cycle combined with composition adjustment zeotropic ORC. Thermodynamic performance investigation and a mathematical model of the novel cycle are developed. Finally, an example is given to verify the method. The results show that this method can improve the thermal performance. Novel system thermal efficiency can be improved by 1.83% compared with the basic S-CO2.

Synergistically enhanced thermoelectric and mechanical performance of Bi2Te3 via industrial scalable hot extrusion method for cooling and power generation applications

To meet the fast-expanding needs of thermoelectric cooling for high heat flux systems, high-performance thermoelectric devices must be constructed with materials possessing both high thermoelectric properties and mechanical strength. However, the synergistic improvement of thermoelectric and mechanical properties is challenging because of the anisotropic thermal and electrical transports in the layered Van der Waals structure of Bi2Te3, particularly for n-type Bi2(TexSe1-x)3 material. The hot extrusion (HE) technique was believed as the most efficient approach to decoupling the thermoelectric and mechanical properties of Bi2Te3. However, the mechanism and performance of Bi2Te3 materials prepared by the HE method have been elusive. In this work, we developed an industrial-scalable HE technique to manipulate the texture ordering in Bi2Te3 material, achieving simultaneous improvement of thermoelectric and mechanical properties. Compared to SPS samples, our HE samples not only show 19% enhancement of the peak ZT, but also exhibit record high compressive strength of 205 MPa and flexural strength of 79 MPa, respectively. Furthermore, 7-pairs thermoelectric modules were fabricated to verify the cooling and power generation performance. A maximum temperature difference of 72 K (Th = 300 K) compared to 68 K for commercial devices and a maximum conversion efficiency of 5% at Th ≤ 500 K were realized.

The Development of 10 kW Class Tidal Power Generator System - Focusing on Field Experiments with Pipelines

Along with the growing interest in renewable energy development, Korea’s west coast is one of the favorable regions for tidal power. Tidal power using tidal barrages that work like hydroelectric dams is a representative method of tidal power through long-term operation, but the promotion of tidal power projects is being delayed or stopped due to impacts on ecological changes, reproduction, water column processes and hydrology. In order to reduce the high construction cost and environmental cost problems caused by tidal power using tidal barrages, in this study, field experiments were conducted to develop and verify the performance of tidal power generation devices applicable to sea areas where dykes are already installed. As a result of conducting five cases of experiments using two water tanks, pipe lines, open channels, and water turbine and generator, the possibility of developing a power generation system capable of generating more than 10 kW output and more than 60% efficiency were confirmed. The results of this study can be used for small-scale tidal power by utilizing the existing dykes of the west coast.

Dynamics of an oscillating wave surge converter: an analysis on the influence of the bottom slope

The Oscillating Wave Surge Converter represents a technology with great potential for generating electricity from ocean waves, promoting energy continuously throughout a day. Its development is on a pre-commercial scale and has been encouraging several companies and institutions to invest in the improvement and study of this conversion system. Simulations in Computational Fluid Dynamics are very important tools for the development of these converters, since they provide essential details for the analysis of the variables that influence the system. In this context, the present work uses the Large Eddy Simulation modeling to study the influence of the bottom slope on the device dynamics, which is performed using the OpenFOAM v.4.1 computational code and its extension OlaFlow. The model used in the analysis is two-dimensional and based on the Wall-Adapting Local Eddy-Viscosity methodology, while a structured mesh is applied. Through a detailed analysis, it was observed that the converter hydrodynamics is strongly influenced by the bottom slope, which is responsible for the intensification of the captured power in regions with slopes lower than 5º, and for the power decrease in cases where the slope exceeds 15º. Significant increases in slope can cause a decrease up to 28% in the converter excitation torque, significantly affecting its performance in electric power generation.

국내 인증용 에너지 성능 평가 도구의 태양광발전시스템 생산량 분석 방법 고찰 및 개선방안

Purpose: Using renewables has been considered as one of the reliable solutions for building applications to achieve zero-energy building goals. Photovoltaic (PV) systems are a highly applicated option because of their ease of installation and cost-effectiveness. Effective evaluation methods and tools are needed to determine the building energy efficiency rate and acceptable zero-energy building certifications. This study aims to examine the PV generation analysis method of the evaluation tool for advancing the PV system evaluation method. Method: This study considers different PV calculation methods (e.g., ECO2, simple, one-diode, and PVWatts) and investigates the calculation characteristics of each approach to compare with the evaluation tool. Among the PV calculation methods, the most used one-diode model is adopted to compare the details of PV input variables and thus evaluate power generation performance under various simulation conditions for the improvement potential of the current evaluation tool. Result: Various input parameter conditions need to be reflected to improve the PV system analysis method of the evaluation tool. The evaluation tool should adopt the installation azimuth conditions for analysis and application scalability. In addition, the subdivision of the inclination is suggested as an improvement measure for further analysis options. The expansion of the installation azimuth can affect the utilization of the roof and elevation on the north side. The subdivision of the inclination enables a reliable zero-energy certification grade to improve through the calculation of more precise energy self-sufficiency rate evaluation results in a detailed manner.

Efficient Optimization of Energy Recovery From Geothermal Reservoirs With Recurrent Neural Network Predictive Models

AbstractImproving the long‐term energy production performance of geothermal reservoirs can be accomplished by optimizing field development and management plans. Reliable prediction models, however, are needed to evaluate and optimize the performance of the underlying reservoirs under various operation and development strategies. In traditional frameworks, physics‐based simulation models are used to predict the energy production performance of geothermal reservoirs. However, detailed simulation models are not trivial to construct, require a reliable description of the reservoir conditions and properties, and entail high computational complexity. Data‐driven predictive models can offer an efficient alternative for use in optimization workflows. This paper presents an optimization framework for net power generation in geothermal reservoirs using a variant of the recurrent neural network (RNN) as a data‐driven predictive model. The RNN architecture is developed and trained to replace the simulation model for computationally efficient prediction of the objective function and its gradients with respect to the well control variables. The net power generation performance of the field is optimized by automatically adjusting the mass flow rate of production and injection wells over 12 years, using a gradient‐based local search algorithm. Two field‐scale examples are presented to investigate the performance of the developed data‐driven prediction and optimization framework. The prediction and optimization results from the RNN model are evaluated through comparison with the results obtained by using a numerical simulation model of a real geothermal reservoir.

Crack Detection in Photovoltaic Panel Electroluminescence Image Using Matched Filter for Performance Loss Estimation

The long-term use of renewable energy investments which have gained importance in recent years, can be realized by tracking errors and malfunctions. It is very important to determine the cracks, microcracks and flaws that occur especially during the production and use of solar energy panels. Errors in the panels can seriously affect the energy production performance of the installed system. According to the panel arrangement in the power plant, flaws in any panel not only affect the energy production of a single panel, but also reduce the production of the entire series to which it is connected. Cracks and faults in solar panels cannot be seen with the naked eye, but can be determined by electroluminescence images. However, detecting these errors requires special expertise and a long examination time. In this study, fractures, microcracks and connection errors are detected automatically from electroluminescence images taken from photovoltaic panels. Before analyzing the images taken with the electroluminescence device, some preprocessing is required. Since the images taken from the installed power plants are not standard in terms of layout, background removal, size and perspective correction are required. In the study, the panels are not examined as a whole, but cell-based examination is carried out. For this reason, the panels are divided into cells. By applying the Matched filter to the dividing cell images, the fractures and cracks are highlighted and the features are extracted. The obtained features are evaluated statistically and the cell status is determined. An accuracy of 98.6% is achieved in determining cell damage status. The losses in the power generation performance of the panel are calculated according to the status of all cells on the panel. The calculated values are compared with the measured I-V values. As a result, efficiency loss was calculated with an accuracy rate of 96.2%.

Multi-factor roadmap for designing wearable micro thermoelectric generators

To further meet the requirement of the Internet of Things (IoT), more and more sensors need to be integrated inside wearable devices. Wearable TEGs directly convert the heat flow generated by the temperature difference between a human body and the environment into electricity, thus acting as a permanent energy supply for sensor systems. In this work, considering the body’s thermoregulation function in the wearing scenario, a three-dimensional numerical model based on the finite element method has been developed to systematically study the power generation performance of micro-TEGs. The multi-factor design involves the packing density (pd), leg width (w), leg height (l) and convective heat transfer coefficient (h) at the cold side of the generator. On this basis, we have proposed a multi-factor roadmap for the design of wearable micro-TEGs with the required power density and open circuit voltage. The theoretical roadmap modeling was verified by fabricating a micro-TEG module of 20 × 20 mm2, with w = 0.5 mm, l = 1.38 mm, and the leg density of pd = 33 legs/cm2. When worn on the wrist (Tcore = 37 ℃, Tair = 22 ℃), a steady voltage output of ∼ 21.0 mV was generated and the corresponding maximum power density reached 1.79 μW/cm2.

The Performance of Magnetostrictive Material for Wind-Induced Vibration Power Generator

This research investigated the effect of span length variation and capless prismatic structure on the performance of the micropower generator from flow-induced vibration. The vibration response type covers galloping and vortex-induced vibration regimes. The mini harvester energy induced by the harmonic oscillation of prismatic structure was implemented based on the magnetostrictive principle to gain electricity using a galfenol alloy (Fe-Ga). The power generation variations are influenced by the amplitude, frequency, structure displacement, span length, and shape of the bluff body. The optimum power generation is 2.87 mW, and the maximum power generation is 10.63 mW at the resonance velocity Vr of 6.45. Reducing the frequency characteristics of circular cylinders by applying a cap end tip affect power generation characteristics and galloping behaviour for the prism with a span length of 200 mm but not for other span lengths. The effect of span length variation on free vibration and power generation performance for all prism models is similar in that both features are decreased by increasing span length. However, it enhances onset valued power generation. Power generation is considered for the independent electricity supply for specific sensor or wireless devices of an IoT system.

Environmental Impact Assessment of PEM Fuel Cell Combined Heat and Power Generation System for Residential Application Considering Cathode Catalyst Layer Degradation

Recently, fuel cell combined heat and power systems (FC-CGSs) for residential applications have received increasing attention. The International Electrotechnical Commission has issued a technical specification (TS 62282-9-101) for environmental impact assessment procedures of FC-CGSs based on the life cycle assessment, which considers global warming during the utilization stage and abiotic depletion during the manufacturing stage. In proton exchange membrane fuel cells (PEMFCs), platinum (Pt) used in the catalyst layer is a major contributor to abiotic depletion, and Pt loading affects power generation performance. In the present study, based on TS 62282-9-101, we evaluated the environmental impact of a 700 W scale PEMFC-CGS considering cathode catalyst degradation. Through Pt dissolution and Ostwald ripening modeling, the electrochemical surface area transition of the Pt catalyst was calculated. As a result of the 10-year evaluation, the daily power generation of the PEMFC-CGS decreased by 11% to 26%, and the annual global warming value increased by 5% due to the increased use of grid electricity. In addition, when Pt loading was varied between 0.2 mg/cm2 and 0.4 mg/cm2, the 10-year global warming values were reduced by 6.5% to 7.8% compared to the case without a FC-CGS.

Slosh-induced piezoelectric energy harvesting in a liquid tank

When a tank containing a liquid is excited externally, the free surface of the liquid becomes violently distorted, generating a large amount of wave energy. We suggest a novel model for harvesting wave energy produced by such sloshing. A deformable energy harvester with an attached piezoelectric patch is mounted vertically in the middle of a liquid tank. By varying the excitation amplitude and frequency of the tank, the level of water, and the thickness of the harvester, the dynamics of the harvester are investigated in terms of tip deflection and phase difference. The excitation frequency corresponding to sloshing resonance is critical for producing large tip deflections. Near resonance, the motions of the tank and the harvester are not necessarily synchronized, and there are large variations in the phase difference. The performance of the energy harvester is evaluated by measuring the open-circuit voltage, short-circuit current, and output power with an electrical load. The model has exceptional power generation performance and would be suitable for supplying power to small electrical devices. Moreover, the harvester is effective in suppressing the peak hydrodynamic pressure exerted on the tank wall, which suggests dual functions of our model as an energy harvester and as a baffle.