Renewable Energy Conversion Systems Research Articles

Application of activated carbon in renewable energy conversion and storage systems: a review

Application of activated carbon in renewable energy conversion and storage systems: a review

A New Smart Grid Hybrid DC–DC Converter with Improved Voltage Gain and Synchronized Multiple Outputs

This paper introduces a new hybrid DC–DC converter with enhanced voltage gain and synchronized multiple output capabilities, specifically tailored for smart grid applications. The proposed converter is based on the integration of non-isolated Zeta and Mahafzah converters, comprising a single controlled switch, two diodes, three inductors, and two coupling capacitors. The primary objective of this novel hybrid converter is to improve voltage gain as compared to conventional Zeta and Mahafzah topologies. By achieving higher voltage gain at lower duty cycles, the converter effectively reduces voltage stress on semiconductor switches and output diodes, thereby enhancing overall performance and reliability. A comprehensive examination of the hybrid converter’s operating principle is presented, along with detailed calculations of duty cycle and switching losses. The paper also explores the converter’s application in smart grids, specifically in the context of renewable energy systems and electric vehicles. Two distinct scenarios are analyzed to evaluate the converter’s efficacy. Firstly, the converter is assessed as a DC–DC converter for renewable energy systems, highlighting its relevance in sustainable energy applications. Secondly, the converter is evaluated as an electric vehicle adapter, showcasing its potential in the transportation sector. To validate the converter’s performance, extensive simulations are carried out using MATLAB/SIMULINK with parameters set at 25 kW, 200 V, and 130 A. The simulation results demonstrate the converter’s ability to efficiently supply multiple loads with opposing energy flows, making it a promising technology for optimized grid management and energy distribution. Moreover, the paper investigates the total harmonic distortion (THD) of the grid current, focusing on its impact in smart grid environments. Notably, the new hybrid converter topology achieves a THD of 21.11% for the grid current, indicating its ability to effectively mitigate harmonics and improve power quality. Overall, this research introduces a cutting-edge hybrid DC–DC converter that enhances voltage gain and synchronizes multiple outputs, specifically catering to the requirements of smart grid applications. The findings underscore the converter’s potential to significantly contribute to the advancement of efficient and resilient power conversion technologies for smart grids, enabling seamless integration of renewable energy systems and electric vehicles into the grid.

Recent Progress in the Application of Ion Beam Technology in the Modification and Fabrication of Nanostructured Energy Materials.

The development of green, renewable energy conversion and storage systems is an urgent task to address the energy crisis and environmental issues in the future. To achieve high performance, stable, and safe operation of energy conversion and storage systems, energy materials need to be modified and fabricated through rationalization. Among various modification and fabrication strategies, ion beam technology has been widely used to introduce various defects/dopants into energy materials and fabricate various nanostructures, where the structure, composition, and property of prefabricated materials can be further accurately tailored to achieve better performance. In this paper, we review the recent progress in the application of ion beam technology in material modification and fabrication, focusing on nanostructured energy materials for energy conversion and storage including photo- (electro-) water splitting, batteries (solar cells, fuel cells, and metal-ion batteries), supercapacitors, thermoelectrics, and hydrogen storage. This review first provides a brief basic overview of ion beam technology and describes the classification and technological advantages of ion beam technology in the modification and fabrication of materials. Then, modification of energy materials by ion beams is reviewed mainly concerning doping and defect introduction. Fabrication of energy materials is also discussed mainly in terms of heterojunctions, nanoparticles, nanocavities, and other nanostructures. In particular, we emphasize the advantages of ion beam technology in improving the performance of energy materials. Finally, we point out our understanding of challenges and future perspectives in applying ion beam technology for the modification and fabrication of energy materials.

Design and Analysis of Novel High-Gain Boost Converter for Renewable Energy Systems (RES)

Design and Analysis of Novel High-Gain Boost Converter for Renewable Energy Systems (RES)

2D Metal Covalent Organic Frameworks Towards Electrochemical Catalysis

In the past century, innovative electrochemical reactions with low-consumption and environmental-friend have been a key substance for worldwide chemical industry.[1] Nowadays, the majority of the electrochemical reactions rely on low-cost and high-efficient catalysts, and there is an ever-growing need for the development of advanced catalysts to secure a sustainable future for our society.[2] The pursuit for sustainable energy stimulates the innovative concepts of advanced catalytic materials for electrochemical reactions, such as metal-air battery, nitrogen fixation and carbon neutrality etc.[3] The electrocatalysts play a vital role to promote the renewable energy conversion efficiencies and system performance.[4] However, the electrocatalytic activities of most inorganic catalysts arises from the unsaturated metal sites exposed on the surfaces or edges, and the internal metal atoms in bulk phase are totally inert, resulting in the low utilization and efficiency of metal atoms for electrocatalysis.[5] Exploring novel electrocatalysts with high metal utilization is essential for electrochemical reactions. Recently, single-atom catalysts (SACs) strategy has been proposed to promote the efficiency and utilization of metal atoms in electrocatalysts. In particular, SACs could provide an ideal approach to maximize the efficiency of active metal atom utilization (in principle, up to 100%) and lower the cost of the electrochemical reactions.[6] Inspired by SACs strategy, metal covalent-organic-frameworks (MCOFs) can be emerged as efficient catalysts, due to the numerous single-atom sites, ordered in-plane porous structure and outstanding stable framework. We propose a novel two-dimensional MCOFs, constructed by porphyrin subgroup (Figure 1), for achieving high efficiency of electrochemical reactions. Porphyrinsubgroup is a type of heterocyclic molecules with conjugated structure, which has strong ability to coordinate almost all transition metal ions to form high active single-metal sites. Thus, MCOFs with porphyrin could be a promising next-generation electrocatalyst, and an ideal catalytic model to reveal the mechanism of electrochemical reactions. Acknowledgments: The authors gratefully acknowledge the financial support from H2020 Marie Skłodowska-Curie Actions (101024758) and National Natural Science Foundation of China (22002083).

Deep recurrent neural networks based Bayesian optimization for fault diagnosis of uncertain GCPV systems depending on outdoor condition variation

Energy generated from renewable sources is exposed to extremely dynamic variations in climatic conditions as well as uncertainties (current/voltage variability, noise, measurement errors.). These conditions are relevant issues to be considered when monitoring renewable energy conversion (REC) systems. In fact, these uncertain systems are subjected to many failures leading to performance degradation and long downtime maintenance periods. Therefore, fault detection and diagnosis (FDD) are essential to ensure its high dependability. This paper proposes an FDD under climatic conditions variability of uncertain REC systems using deep recurrent neural networks (DRNNs) techniques. Firstly, a novel modeling strategy for REC systems is built. Secondly, different DRNN-based interval-valued data methods are intended to differentiate between the various REC systems operating states. Finally, the hyperparameters of the proposed techniques are tuned using the Bayesian optimization algorithm. The efficiency and robustness of the novel strategy are demonstrated through REC application, using grid-connected photovoltaic (GCPV) systems. The obtained results show the efficiency of the developed strategy by reaching an accuracy rate of 92.40%.

DEVELOPMENT AND PERFORMANCE EVALUATION OF ROOF TOP SMALL SCALE SOLAR PV SYSTEM

Many renewable energy conversion systems have been built in order to reduce the use of fossil fuel and minimize global warming. Solar power plant, one of many renewable energy systems, has promising potential in green energy sector. However, there are only a few solar PV system installed in roof top of a building. Thus, the present work aims to development small scale roof top solar PV system and to investigate its performance. The 300 WP solar PV system is installed on a roof top of the office building of campus III-IST. AKPRIND. The performance of the system in terms of output current, output voltage, output power, and conversion efficiency. The results shows that maximum output current of 3.91 ampere and maximum output voltage of 58.29 volt were obtained at day 3 and day 5, respectively. The output current give predominant effect on output power of the solar PV system. The trend of output power is similar to that of output current. Maximum output power of 173.25 W was generated at day 3 where maximum output current was measured. Thus, it can be figure out that the solar PV system has an conversion efficiency of almost 58%.

A Novel Isolated High-Step-Up Interleaved Converter for Renewable Energy Systems

In this paper, an isolated high step-up interleaved converter for renewable energy systems is proposed. The input-parallel configuration introduced by two energy storage inductors, which can disperse the input current, reducing conduction losses and also improve the conversion efficiency. In order to improve the voltage gain and recover the energy stored in the leakage inductance, the auxiliary step-up structure is utilized in the proposed converter, that including an auxiliary inductor, an auxiliary capacitor, a voltage multiplier capacitor and two switches which serve to exchange the energy stored in auxiliary capacitors and inductors. On the secondary side, a voltage-doubler circuit is used to extend the voltage gain. Finally, a 48V-input, 400V-output and the rated power of 500 W prototype is implemented to verified the effectiveness of the proposed converter. The experimental results shows that the maximum efficiency is 95.97%, and the efficiency of full-load is 93.27%.

IrOx-MoO3 nano-heterostructure electrocatalysts for efficient acidic water oxidation

Rational design of Ir-based electrocatalyst with high performance and low cost remains as an urgent requirement to speed up the sluggish acidic water oxidation to produce hydrogen in renewable energy conversion and storage systems. In this work, the highly dispersed IrOx nanoparticles are fabricated on MoO3 sheets coated Ti meshes (c-IrOx-MoO3/Ti) as efficient electrocatalytic electrodes for acidic water oxidation. The heterogeneous c-IrOx-MoO3/Ti catalysts show much higher acidic oxygen evolution reaction activity (∼200 mV overpotentials at 10 mA cm−2) and long-term stability (longer than 130 h at 100 mA cm−2) with extremely low Ir content (∼28.35 μgIr cm−2) as compared to the IrOx/Ti and commercial IrO2 catalysts. The special intertwined formation of MoO3 sheets through electrodeposition effectively promotes the uniform dispersion of IrOx nanoparticles and the electrocatalytic performance. Theoretical calculations reveal that the electronic modulation on the MoO3-IrOx heterogeneous interface optimized the adsorbed energies for oxygen intermediates on the active Ir sites of the catalysts. The self-assembled proton exchange membrane single-cell electrolyzer test further verifies that the fabricated c-IrOx-MoO3/Ti catalysts demonstrate a greatly lower voltage and higher stability for water electrolysis than the commercial IrO2 catalysts. This work provides a new pathway to designing highly active and acid-resistant Ti-supported water oxidation catalysts with ultra-low Ir content.

Investigation on Thermophysical Properties of Multi-Walled Carbon Nanotubes Enhanced Salt Hydrate Phase Change Material

Thermal Energy Storage (TES) is a valuable tool for improving the energy efficiency of renewable energy conversion systems. One of the most effective methods for harnessing thermal energy from solar sources is through energy storage using phase change materials (PCMs). However, the thermal performance of PCMs is hindered by their low thermal conductivity. This research focuses on enhancing the thermal performance of salt hydrate PCM using multi-walled carbon nanotubes (MWCNTs) and surfactants. Through experimental investigations, a salt hydrate PCM with varying concentrations of MWCNTs (ranging from 0.1% to 0.9%) was prepared using a two-step technique and their thermophysical properties were thoroughly characterized. Various techniques such as field emission scanning electron microscope, thermal conductivity analyzer, ultraviolet-visible spectrum, thermogravimetric analyzer, and Fourier transform infrared spectroscopy were utilized to study the effect of surfactant on the nanocomposites and examine their morphology, thermal conductivity, optical properties, thermal stability, and chemical stability. The results indicated that the inclusion of MWCNTs with salt hydrate significantly improved the thermal conductivity by 68.09% at a concentration of 0.7 wt %, compared to pure salt hydrate. However, this enhancement in thermal performance was accompanied by a reduction in optical transmittance in the developed nanocomposite PCM. Additionally, the formulated nanocomposite demonstrated excellent thermal and chemical stability up to temperatures as high as 468 °C. As a result, this nanocomposite shows great promise as a potential candidate for solar TES applications, offering favourable characteristics for efficient energy storage from solar sources.

Nonlinear control strategies with maximum power point tracking for hybrid renewable energy conversion systems

AbstractThis paper addresses the problem of controlling and optimizing a hybrid renewable energy system, specifically consisting of a photovoltaic (PV) generator and a wind energy conversion system comprising a wind turbine and a permanent magnet synchronous machine. The primary control objectives involve maximizing power extraction from both the PV and wind turbine while ensuring efficient injection of the extracted energy into the electrical network and maintaining a suitable power factor. This study presents two key innovations that distinguish it from existing research. Firstly, it introduces a new hybrid PV/aerogenerator energy source that eliminates the need for a DC/DC converter in the PV structure. Secondly, unlike previous works that rely on various measurements such as wind speed, temperature, and irradiance, our approach only requires measurements of electrical variables. This advancement significantly reduces the number of sensors required and enhances the overall reliability of the system.

Optimization Strategies and Nonlinear Control for Hybrid Renewable Energy Conversion System

Optimization Strategies and Nonlinear Control for Hybrid Renewable Energy Conversion System

Oxygen-atom-bridged Ru–Sn–Ce heterojunction for enhanced oxygen evolution reaction in acidic media

Developing for highly active and stable electrocatalysts for oxygen evolution reaction (OER) is of significant importance for some renewable energy conversion and storage systems. While, the prerequisite for further optimizing the activity of electrocatalysts is whether their original composition has potential for development. Herein, we firstly managed to combine theoretical and experimental efforts to establish Ru0.4Sn0.3Ce0.3O2 (RSCO) as a promising electrocatalyst for acidic OER. The X-ray absorption and density functional theory studies reveal that the local coordination environment and electronic structure of Ru sites in RSCO is optimized by the oxygen atom bridged Sn and Ce at heterogeneous interfaces, thereby resulting in a low energy barrier. In addition, the electrochemical results indicate that the activity and stability of RSCO obviously surpasses that of the RuO2 prepared by same method as RSCO. Most encouragingly, the OER activity of RSCO can be substantially enhanced only by optimizing the calcination temperature, meaning the possibility of further improvement the intrinsic activity of such oxygen atom bridged Ru based complex by proper surface or interfacial engineering.

A new optimized ZV-ZCS non-isolated high-gain boost converter for renewable energy systems

Abstract This paper proposes a novel zero-voltage zero-current transition (ZV-ZCT) DC/DC high gain coupled inductor based boost converter for applications in renewable energy systems. It employs an auxiliary resonant network to soft-switch transition of semiconductor switches and soft-recovery of power diodes over wide input voltage and output power range of the converter with high efficiency. The auxiliary cell of the proposed converter has negligible impact on the converter’s overall dynamics and it doesn’t contribute any extra current stress to the semiconductor switches compared to classical hard switched boost converters. A thorough theoretical analysis of each operating mode has been presented together with the converter’s steady-state performance. The mathematical equations illustrating the dynamic behaviour of the converter have been used to design the auxiliary cell components. The circulating current loss has been minimized and simultaneously soft-switched operation of the converter is maintained through optimal selection of auxiliary cell components. Additionally, a power loss study and the proposed converter’s advantages over existing traditional converters are discussed. The converter’s soft-switching behaviour is established by hardware testing on a 400 W, 100 kHz prototype model. The theoretically predicted behaviour of the converter has been well corroborated by experimental observations.

Technical and economic appraisal for harnessing a proposed hybrid energy system nexus for power generation and CO2 mitigation in Cross River State, Nigeria

By creating hybrid energy systems and obtaining a framework that equally satisfies a continuous operation for renewable energy technology, this study presents renewable and sustainable energy options as an integral method to energy transitioning from non-renewable to renewable energy utilization in Cross River State, Nigeria. For a needed load of 2424.25 kWh/day in Cross River State, this study focused on proposing a designed hybrid energy system (HES) nexus, mitigating CO2, and appraisal of the technical and economic viability. To accomplish this, HOMER software was utilized in simulating the ideal components that suggested a HES nexus. The software enabled the selection of the optimal HES using various renewable energy sources since it predicts future electrical demand, wind speed, solar irradiation, and temperature. Economic results obtained showed that the proposed HES's Levelized cost of energy (LCOE), net present cost (NPC), and operating cost (OC) were $0.89/kWh, $10,138,702 and $134,084.37 respectively. Further technical appraisal showed that the renewable energy conversion systems (RECs) make up 78.74% of the proposed HES. The photovoltaic (PV) arrays were primarily responsible for the hybrid energy system's electricity output. The annual electrical energy output was 1,984,111kWh (89.4%), produced by the PV arrays. The generic fuel cell produced the least, at 29,957kWh/year, accounting for just 1.35% of the total electricity produced. However, the wind power plant produced 205,365kWh/year annually. Furthermore, comparing the HES with diesel-powered generators, the system achieves a net-zero carbon emission status. Therefore, it has proven to be the most reliable energy as it will solve the problem of energy demand and reduces carbon emissions in Cross River State, Nigeria

An Optimized Switching Strategy Based on Gate Drivers with Variable Voltage to Improve the Switching Performance of SiC MOSFET Modules

This paper proposes an optimized switching strategy (OSS) based on a silicon carbide (SiC) MOSFET gate driver with variable voltage, which allows simultaneous variations in several different parameters to optimize the switching performance of semiconductor devices. As a relatively new device, the SiC MOSFET shines in the field of high power density and high-frequency switching; it has become a popular solution for electric vehicles and renewable energy conversion systems. However, the increase in voltage and current slope caused by high switching speeds inevitably increases the overshoot and oscillation in a circuit and can even generate additional losses. The principle of this new control strategy is to change the voltage and current in the turn-on and turn-off stages by changing the gate driver’s voltage. That is, we reduced the drive’s voltage after a certain time delay and maintained it for a period of time, thus directly controlling the slopes of di/dt and dv/dt. This study focused on the optimization of the SiC MOSFET by changing the time delay preceding the decrease in the voltage of the gate driver, analyzing and calculating the optimal time delay before the decrease in the voltage of the gate driver, and verifying the findings using LTspice simulation software. The simulated results were compared and analyzed with hard-switching strategies. The results showed that the proposed OSS can improve the switching performance of SiC MOSFETs.

Coordination Engineering of Dual Co, Ni Active Sites in N-Doped Carbon Fostering Reversible Oxygen Electrocatalysis.

The development of affordable and non-noble-metal-based reversible oxygen electrocatalysts is required for renewable energy conversion and storage systems like metal-air batteries (MABs). However, the nonbifunctionality of most of the catalysts impedes their use in rechargeable MAB applications. Moreover, the loss of active sites also affects the long-term performance of the electrocatalyst toward oxygen electrocatalysis. In this work, we report a simplistic yet controllable chemical approach for the synthesis of dual transitional metals such as cobalt, nickel, and nitrogen-doped carbon (CoNi-NC) as bifunctional electrode materials for rechargeable zinc-air batteries (ZABs). The spatially isolated Ni-N4 and Co-N4 active units were rendered for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), respectively. The individual efficacy of both reversible reactions enables an ΔE value of ∼0.72 V, which outperforms several bifunctional electrocatalysts reported in the literature. The half-wave potential (E1/2) and overpotential were achieved at 0.83 V and 330 mV (vs RHE) for ORR and OER, respectively. The peak power density of ZAB equipped with the CoNi-NC catalyst was calculated to be 194 mW cm-2. The present strategy for the synthesis of bifunctional electrocatalysts with dual active sites offers prospects for developing electrochemical energy storage and conversion systems.

Combination of Mn-Mo Oxide Nanoparticles on Carbon Nanotubes through Nitrogen Doping to Catalyze Oxygen Reduction.

An efficient and low-cost oxygen catalyst for the oxygen reduction reaction (ORR) was developed by in situ growth of Mn-Mo oxide nanoparticles on nitrogen-doped carbon nanotubes (NCNTs). Doped nitrogen effectively increases the electron conductivity of the MnMoO4@NCNT complex and the binding energy between the Mn-Mo oxide nanoparticles and carbon nanotubes (CNTs), leading to fast charge transfer and more catalytically active sites. Combining Mn and Mo with NCNTs improves the catalytic activity and promotes both electron and mass transfers, greatly enhancing the catalytic ability for ORR. As a result, MnMoO4@NCNT exhibited a comparable half-wave potential to commercial Pt/C and superior durability, demonstrating great potential for application in renewable energy conversion systems.

Measurements and modeling of water levels, currents, density, and wave climate on a semi-enclosed tidal bay, Cádiz (southwest Spain)

Abstract. Estuarine dynamics are highly complex as a result of the temperature and salinity gradients, as well as the multiple interactions between atmospheric, maritime, and hydrological forcing agents. Given the environmental and socioeconomic importance of estuaries and their current and future threats due to human interventions and climate change, it is of vital importance to characterize these dynamics, monitor their evolution, and quantify the expected impacts derived from climate change. This paper presents a hybrid database combining data obtained in six field surveys (in 2012, 2013, and 2015) and results from a physically based 3D numerical model for the Bay of Cádiz (southern Spain), a highly anthropized mesotidal estuary. The 3D dataset includes water levels, currents, density, and wave climate, allowing for an analysis of bay dynamics at different timescales ranging from intratidal processes to seasonal variabilities. The results offer an example of the potential uses of the dataset and include (1) an assessment of the spatial and seasonal variability of the estuarine dynamics and (2) an analysis of the effects of severe weather events. These examples provide convincing evidence regarding how the dataset can be employed in multiple research fields and applications, including ocean–bay interactions, water exchange between basins, longwave and shortwave propagation along creek systems, and energy extraction of tidal waves. Therefore, this hybrid dataset may be of significant interest for stakeholders and scientists from different sectors (water engineering, ecology, urban development, energy, etc.) working on the environmental management of the Gulf of Cádiz and other tidally dominated shallow bays. It can also serve as a benchmark test for numerical hydrodynamic models, infrastructure intervention assessments (e.g., dikes or breakwaters), or renewable energy conversion system models. The dataset is available at https://doi.org/10.5281/zenodo.7484186 (Zarzuelo et al., 2022b).

Facilitating Reconstruction of the Heterointerface Electronic Structure by the Enriched Oxygen Vacancy for the Oxygen Evolution Reaction

Exploring high-performance non-precious metal-based electrocatalysts for the sluggish oxygen evolution reaction (OER) process is fundamentally significant for the development of multifarious renewable energy conversion and storage systems. Oxygen vacancy (Vo) engineering is an effective leverage to boost the intrinsic activity of OER, but the underlying catalytic mechanism remains anfractuous. Herein, we realize the construction of oxygen vacancy-enriched porous NiO/ln2O3 nanofibers (designated as Vo-NiO/ln2O3@NFs hereafter) via a facile fabrication strategy for efficient oxygen evolution electrocatalysis. Theoretical calculations and experimental results uncover that, compared with the no-plasma engraving component, the presence of abundant oxygen vacancies in the Vo-NiO/ln2O3@NFs is conducive to modulating the electronic configuration of the catalyst, altering the adsorption of intermediates to reduce the OER overpotential and promote O* formation, upshifting the d band center of metal centers near the Fermi level (Ef), and also increasing the electrical conductivity and enhancing the OER reaction kinetics simultaneously. In situ Raman spectra proclaim that the oxygen vacancy can render the NiO/ln2O3 more easily reconstructible on the surface during the OER course. Therefore, the as-obtained Vo-NiO/ln2O3@NFs demonstrated distinguished OER activity, with an overpotential of only 230 mV at 10 mA cm-2 and excellent stability in alkaline medium, surmounting the majority of the previously reported representative non-noble metal-based candidates. The fundamental insights gained from this work can pave a new path for the electronic structure modulation of efficient, inexpensive OER catalysts via Vo engineering.