Sustainable Energy Generation Research Articles

Optimal sizing of hybrid renewable energy systems using quasi-optimal control

This paper addresses the critical challenge of sizing hybrid renewable energy systems over their lifespan while accounting for uncertainties in energy sources and load demands. By leveraging stochastic programming, we introduce a novel modeling technique that ensures robust optimization without compromising numerical tractability. Unlike conventional methods, which determine system parameters for the entire project duration upfront, our approach enables annual adjustments to the renewable components’ sizing. This dynamic strategy alleviates early-stage under-utilization, aligning system capacity with evolving demand patterns. Central to our approach is the reformulation of the two-stage stochastic program as a quasi-optimal control. This reduces the number of optimization variables significantly, simplifying the solution process. Moreover, thousands of constraints are replaced with a system of differential equations, enhancing computational efficiency. By minimizing capital costs and dynamic operating expenses, we achieve an optimal system size. Through a real-world application in a rural area of South Africa, we demonstrate the effectiveness of our approach. The results showed a remarkable improvement in problem-solving efficiency, reduced under-utilization, and heightened adaptability to unpredictable weather conditions. This innovative framework represents a substantial leap forward in hybrid renewable energy systems design, offering a more agile and efficient solution for sustainable energy generation.

A data envelopment analysis based evaluation of sustainable energy generation portfolio scenarios

Generating secure, affordable, and clean energy requires careful evaluation of the costs and associated risks of different energy generation sources. Portfolio optimisation models are commonly used in this regard to help diversify risks associated with generation sources. In recent times, energy policies often require the consideration of the environmental and social effects of such activity. Consequently, sustainability has become a key factor in making energy mix planning decisions. To incorporate sustainability considerations in energy mix planning, the conventional approach has been to add indicators for environmental and social costs to the total generation cost for each available technology in a portfolio optimisation model. However, this approach to developing a sustainable generation mix may not effectively address all dimensions of sustainability. In most cases, the economic dimension is prioritised over social and environmental factors. We examine how various aggregation methods impact the preference among the sources and the optimal portfolio mix and propose aggregation methods that effectively incorporate all sustainability dimensions. We observed that technology ranking based on multiplicative, pairwise interaction, and multilinear aggregation options aligns better with our sustainability goals than additive aggregation. By adopting these methods of aggregation, we were able to include more renewable and clean energy sources in our optimal portfolios.

A new intelligently optimized model reference adaptive controller using GA and WOA-based MPPT techniques for photovoltaic systems

Recently, the integration of renewable energy sources, specifically photovoltaic (PV) systems, into power networks has grown in significance for sustainable energy generation. Researchers have investigated different control algorithms for maximum power point tracking (MPPT) to enhance the efficiency of PV systems. This article presents an innovative method to address the problem of maximum power point tracking in photovoltaic systems amidst swiftly changing weather conditions. MPPT techniques supply maximum power to the load during irradiance fluctuations and ambient temperatures. A novel optimal model reference adaptive controller is developed and designed based on the MIT rule to seek global maximum power without ripples rapidly. The suggested controller is also optimized through two popular meta-heuristic algorithms: The genetic algorithm (GA) and the whale optimization algorithm (WOA). These meta-heuristic approaches have been exploited to overcome the difficulty of selecting the adaptation gain of the MRAC controller. The reference voltage for MPPT is generated in the study through an adaptive neuro-fuzzy inference system. The suggested controller’s performance is tested via MATLAB/Simulink software under varying temperature and radiation circumstances. Simulation is carried out using a Soltech 1sth-215-p module coupled to a boost converter, which powers a resistive load. Furthermore, to emphasize the recommended algorithm’s performance, a comparative study was done between the optimal MRAC using GA and WOA and the conventional incremental conductance (INC) method.

Direct Z-scheme system of UiO-66 cubes wrapped with Zn0.5Cd0.5S nanoparticles for photocatalytic hydrogen generation synchronized with organic pollutant degradation

Optimized fabrication of Z-scheme photocatalyst based on MOF materials offers sustainable energy generation and environmental improvement due to their attractive properties. The Z-scheme heterojunctions consisting of UiO-66 cubes covered with Zn0.5Cd0.5S nanoparticles were fabricated by a facile solvothermal method. Thanks to the Z-scheme carrier transport under simulated sunlight irradiation, UiO-66@Zn0.5Cd0.5S exhibited enhanced photocatalytic performance of H2 generation synchronized with organic pollutant degradation in fluoroquinolone antibiotic wastewater. Synergistically, the highest comprehensive performance was obtained in ciprofloxacin solution. The H2 yield reached 224 μmol∙ g−1∙ h−1 and simultaneously the removal efficiency was up to 83.6 %. The degradation pathways revealed that the process of piperazine ring cleavage and decarboxylation also generates H protons, further promoting the production of H2. Therefore, the effective spatial separation and transfer of the photoinduced carriers are attributed to the good band structure, large specific surface area, and cooperative reduction and oxidation reactions of UiO-66@Zn0.5Cd0.5S, resulting in significant photocatalytic activity. The toxicity assessment of antibiotics and intermediate products during the photocatalytic reaction also verifies the reduction of environmental risk. This study highlights a promising way to expand the application of the MOFs-based photocatalyst in clean energy conversion coupling with water remediation.

Clustering-based assessment of solar irradiation and temperature attributes for PV power generation site selection: A case of Indonesia’s Java-Bali region

This study presents clustering-based assessments of solar attributes for locating potential solar photovoltaic (PV) power plant sites using k-means and density-based spatial clustering of applications with noise (DBSCAN) by examining the yearly average single-attribute and three-attribute clustering on a dataset of long-term hourly-based direct and diffuse irradiation, ambient temperature, and solar PV power output from 2005 to 2022. Three-attribute clustering enables stakeholders to better understand the characteristics of a cluster by collectively identifying three solar attributes and the magnitude of each attribute in an area or cluster. The presence of this information, which constitutes the clusters, suggests that these attributes have different effects on solar PV output power in different clusters. Although k-means is an effective method for investigating potential locations for PV power plant placements, DBSCAN offers users an alternative method for accomplishing a similar goal. In the case of three-attribute clustering of direct irradiation with k-means and DBSCAN, the 18-year mean value of clusters with the highest yearly average value is achieved at very similar values of 0.305 kW/m2 and 0.310 kW/m2, respectively. It turns out that only six years of direct irradiation had an annual mean value of less than 0.305 kW/m2. This finding implies that in the long run, the solar resources in terms of direct irradiation will typically surpass 0.3 kW/m2/MW installed capacity over all areas suitable for PV power plants. While focusing on the Java-Bali region, Indonesia, the findings, and methods appear to be of broader interest to policymakers, particularly in developing countries where solar PV is considered an option for sustainable energy generation.

CIEF-Carbon Induced Electric Fuel: A Revolutionary Approach to Sustainable Energy Generation

Carbon Induced Electric Fuel (CIEF) is an innovative solution in the sustainable energy landscape that has the potential to transform energy generation on Earth and propel space exploration. This review delves into the intricacies of its design, exploring its dual output system that generates electricity and extracts hydrogen. We examine the technical challenges and future prospects of CIEF, highlighting its efficiency and sustainability. As we navigate this technical odyssey, it becomes evident that CIEF is not just a technological marvel but a testament to human ingenuity and the relentless pursuit of a cleaner, more sustainable future. Furthermore, we have designed a prototype and compared its efficiency to other solutions.

Na-deposited TiO2 nanotubes for photo electrochemical water splitting with enhanced activity – A novel approach

Hydrogen generation using sunlight as an energy source in a photoelectrochemical (PEC) cell is one of the most challenging tasks, and it is an environmentally friendly method for sustainable energy generation. In this work, Na-doped TiO2 nanotubes (Na-TNT) are used as the photoanode and platinum as a cathode for photoelectrochemical hydrogen generation under AM 1.5 G light illumination, generating a photocurrent of up to 0.12 mA cm−2 at 1.23 V (vs. reversible hydrogen electrode (RHE)), which is six times greater than pristine TiO2 nanotubes (TNT), which is found to be 0.02 mA cm−2. The Na-TNTs were prepared via the effortless thermal treatment of anodized TNT sheets over sodium chloride (NaCl) in a furnace at 450 °C, improving the light absorption and decreasing the recombination rate. The reason for enhanced activity upon introducing Na was investigated with structural, optical, and electrochemical studies.

A coal-based multifunctional membrane for solar-driven seawater desalination and power generation

Water evaporation systems driven by solar energy delivers great potential for seawater desalination and sustainable energy generation, which is of great significance to relieve the worldwide shortage of fresh-water and energy. However, the achievement of well-designed materials and configuration for water evaporation systems remains a great challenge, hindering the realization of high evaporation rates and stable energy output. Herein, conductive coal-based nanocarbon material was creatively fabricated to assemble a novel multifunctional membrane based evaporation system for simultaneous solar thermal desalination of seawater and power generation. The coal-based multifunctional membrane (CBMM) possesses a permanently asymmetric wetting structure, which can ensure high photothermal evaporation efficiency and stable energy output. The constructed device unit demonstrate a long and stable operation in seawater under one sun irradiance for 100 h, achieving a high evaporation rate of 1.81 kg m−2 h−1 and a large voltage output of 410 mV. Especially, multiple units of the devices can be easily connected in series or parallel to power small electronic devices. This work provides a cost-effective and large scale method for the fabrication of coal-based nanomaterials and the creative application in high-perforamnce water evaporation systems for seawater desalination and sustainable energy generation.

A template-assisted method for synthesizing TiO2 nanoparticles and Ni/TiO2 nanocomposites for urea electrooxidation

The exploration of electrocatalytic urea-assisted wastewater treatment as a method for sustainable energy generation presents a compelling approach within the domain of green chemistry. In this context, titanium dioxide (TiO2) and nickel-doped TiO2 (Ni@TiO2) nanocomposites were developed through an innovative organic template-assisted synthesis strategy. These were denoted as m-TiO2-org and Ni@m-TiO2-org, respectively, to create cost-effective and high-performance electrodes for urea electrooxidation in urea-based fuel cells. The structural and chemical properties of the fabricated m-TiO2-org and Ni@m-TiO2-org materials were meticulously analyzed using a suite of physicochemical characterization techniques, including Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), Thermogravimetric Analysis (TGA), and Energy-Dispersive X-ray Spectroscopy (EDX). These investigations revealed that both m-TiO2-org and Ni@m-TiO2-org materials predominantly consisted of irregular monolithic microparticles formed through the aggregation of spherical nanoparticles, with diameters ranging from 8.16 nm to 13.1 nm. Subsequent evaluations of these TiO2-based materials as electrocatalysts for urea electrooxidation demonstrated their efficacy, as evidenced by voltammetric and electrochemical impedance spectroscopy measurements. Notably, the Ni@m-TiO2-org variant exhibited enhanced electrochemical performance, attributed to the presence of Ni2+ sites. These sites facilitated electrochemical activation and the formation of active NiOOH sites, leading to a significant increase in the current density (0.78 mA/cm2 at 1.523 V vs. the Reversible Hydrogen Electrode (RHE)), as a fiftyfold enhancement compared to m-TiO2-org@Glassy Carbon Electrode (GCE) under similar conditions (3 M KOH containing 3 M urea), with a Tafel slope of 33 mV/decade. This research not only elucidates the potential of TiO2-based nanocomposites in the electrooxidation of urea but also heralds the development of innovative electrode materials for commercial electrochemical cells, marking a significant advancement in the field of electrocatalysis and sustainable energy technology.

Biocarbon-Enhanced Flexible Nanofiber Mats for Sustainable Energy Generation and Wearable Device Applications

A broad diversity of nanofillers and polymers have been used to prepare polymer nanocomposites having potential applications in transportation, sports materials, aerospace, electronics, communication, energy, environment, and biomedical. Polyvinylidene fluoride (PVDF) finds a remarkable place in energy applications attributed to its highest known piezo- and pyroelectric properties. Like most carbon materials, Biochar has excellent electrical conductivity, since it comprises graphene layers with a great amount of carbon content. This study explores the behavior of composite nanofibers fabricated from rice straw-derived biochar-PVDF as wearable mats to harvest body energy into electricity. The composite nanofiber mats were fabricated using the electrospinning technique to get the benefit of both the piezoelectric properties of PVDF and the excellent electric properties of Biochar. The research found that incorporating 12 wt % of Biochar greatly enhances the piezoelectric content of the nanofiber mats without noteworthy loss in flexibility. In addition, the effects of membrane thickness (0.5, 0.9, and 1 mm) on their output voltages as a performance factor of the nanogenerator were measured. Results indicated that the effect of thickness was most influential in the thickness of 1 mm of PVDF/biochar nanofibers generator. The results of this work imply promising application development of such flexible composite piezoelectric nanofibrous membranes for environmentally sustainable energy generation and wearable self-powered electrical devices.

Performance enhancement of savonius hydrokinetic turbine using split airfoil blade: A numerical investigation

There is a concerted global effort to advance technology in the field of renewable energy sources due to the escalating energy crisis and escalating environmental pollution. One promising avenue for small-scale power generation is hydrokinetic technology. Among the various hydrokinetic turbines, the Savonius Hydrokinetic Turbine (SHT) stands out due to its specific advantages, but it has faced challenges in terms of performance. To address this, a novel blade design for the SHT has been developed, aiming to enhance its performance. This new turbine is referred to as the Split Airfoil Savonius Hydrokinetic Turbine (SASHT). To evaluate and compare the performance of both the conventional SHT and the newly developed SASHT, a Computational Fluid Dynamics (CFD) analysis has been conducted. This analysis encompasses a range of Tip Speed Ratios (TSR) from 0.7 to 1.2, with an inlet velocity of 0.8 m/s. The results reveal that the SASHT demonstrates a notable improvement, with a maximum Coefficient of Power that is 17% higher than that of the conventional semi-circular bladed SHT. This research offers valuable insights into the flow physics and performance parameters of these hydrokinetic turbines, showcasing the potential for more efficient and sustainable energy generation.

Triboelectric Energy Harvesting from Highly Conjugated Fused Aromatic Ladder Structure Under Extreme Environmental Conditions.

Practical application of triboelectric nanogenerators (TENGs) has been challenging, particularly, under harsh environmental conditions. This work proposes a novel 3D-fused aromatic ladder (FAL) structure as a tribo-positive material for TENGs, to address these challenges. The 3D-FAL offers a unique materials engineering platform for tailored properties, such as high specific surface area and porosity, good thermal and mechanical stability, and tunable electronic properties. The fabricated 3D-FAL-based TENG reaches a maximum peak power density of 451.2 µW cm-2 at 5 Hz frequency. More importantly, the 3D-FAL-based TENG maintains stable output performance under harsh operating environments, over wide temperature (-45-100°C) and humidity ranges (8.3-96.7% RH), representing the development of novel FAL for sustainable energy generation under challenging environmental conditions. Furthermore, the 3D-FAL-based TENG proves to be a promising device for a speed monitoring system engaging reconstruction in virtual reality in a snowy environment.

Optimal design and operation of a wind farm/battery energy storage considering demand side management

AbstractBalancing electricity demand and sustainable energy generation like wind energy presents challenges for the smart grid. To address this problem, the optimization of a wind farm (WF) along with the battery energy storage (BES) on the supply side, along with the demand side management (DSM) on the consumer side, should be considered during its planning and operation stages. An optimization framework with two levels to simultaneously decide the layout and operation of the WF/BES is put forward in this paper. The first‐level model consists of determining the WF/BES capacities, the WF configuration, and the connection buses. It is tackled by the mixed‐discrete particle swarm optimization algorithm. The multi‐objective optimization problem (MOOP) model in the second level determines the operation schedule of the WF/BES and other generators taking the DSM into consideration. The MOOP model in the second level is transformed to a single‐objective optimization problem via the maximum fuzzy satisfaction method, and is then solved by the genetic algorithm. The proposed model and the strategy are verified by the Barrow offshore WF test case, which is integrated into the IEEE‐118 system. Simulation results indicate that the wind and load patterns, the DSM and the BES price are the three key factors influencing the WF/BES design optimization.

Polyaniline based highly selective electrochemical sensor for ascorbic acid determination: Performance studies towards real sample analysis

The electrocatalytic behavior of polyaniline (PAni) towards the electro-oxidation of L-ascorbic acid (L-AA) was studied by using cyclic voltammetry. PAni synthesized by oxidative polymerization method, and characterized by using high resolution-transmission electron microscopy (HR-TEM), scanning electron microscopy coupled with energy dispersive X-ray analysis (SEM-EDAX) confirms large globular structures, X-ray diffraction (XRD) analysis revealed that PAni with amorphous nature, whereas Fourier-transform infrared spectroscopy (FTIR) of PAni shows C-N stretching, X-ray photoelectron spectra (XPS) attributes the peaks C1s, N1s and O1s. UV–visible spectra revealed PAni is conducting and its Brunauer–Emmett–Teller (BET) surface area is 343.67 m2/g demonstrates it has high surface area and good adsorption ability. The PAni electrocatalyst showed an excellent selectivity towards L-AA in presence of different inorganic and biological expedients under similar conditions. A limit of detection (LOD) and limit of quantification (LOQ) were calculated found to be 5.1 µM and 17.2 µM respectively. Furthermore, the electrocatalyst activity towards L-AA were also validated for real sample analysis like lemon juice and vitamin-C tablet by quantifying the L-AA. The exceptionally higher conductivity and good electrocatalytic performance of PAni make it a promising material for sustainable energy generation and environmental protection without relying on metals or harmful chemicals.

A review on ultra‐small undoped MoS2 as advanced catalysts for renewable fuel production

AbstractMolybdenum disulfide (MoS2) has garnered significant attention in the field of catalysis due to the high density of active sites in its unique two‐dimensional (2D) structure, which could be developed into numerous high‐performance catalysts. The synthesis of ultra‐small MoS2 particles (<10 nm) is highly desired in various experimental studies. The ultra‐small structure could often lead to a distinct S–Mo coordination state and nonstoichiometric composition in MoSx, minimizing in‐plane active sites of the 2D structure and making it probable to regulate the atomic and electronic structure of its intrinsic active sites on a large extent, especially in MoSx clusters. This article summarizes the recent progress of catalysis over ultra‐small undoped MoS2 particles for renewable fuel production. Through a systematic review of their synthesis, structural, and spectral characteristics, as well as the relationship between their catalytic performance and inherent defects, we aim to provide insights into catalysis over this matrix that may potentially enable advancement in the development of high‐performance MoS2‐based catalysts for sustainable energy generation in the future.

Reviewing Air Pollutants Generated during the Pyrolysis of Solid Waste for Biofuel and Biochar Production: Toward Cleaner Production Practices

The production of biofuels and biochar through pyrolysis is a promising avenue for sustainable energy generation and waste management. However, this process can inadvertently release various air pollutants into the atmosphere, potentially compromising its environmental benefits. This article provides a comprehensive overview of the gas pollutants associated with pyrolysis for biofuel and biochar production, as well as different variables affecting gas emissions. Key pollutants such as particulate matter (PM), volatile organic compounds (VOCs), polycyclic aromatic hydrocarbons (PAHs), carbon monoxide (CO), and nitrogen oxides (NOx) have been discussed in terms of their formations and emissions during pyrolysis processes. Furthermore, major factors influencing pollutant emissions, including feedstock composition, pyrolysis conditions, and combustion technologies have been examined with up-to-date examples. The review highlights the significance of emission control strategies, such as advanced reactor design, catalyst utilization, and the integration of realtime monitoring systems, in mitigating air pollution from pyrolysis processes. By shedding light on the environmental challenges associated with pyrolysis-based biofuel and biochar production, this article aims to encourage the development of cleaner and more sustainable approaches to harness the potential of solid waste conversion technologies.

Fundamentals, Operation and Global Prospects for the Development of Biogas Plants—A Review

As the global demand for renewable energy continues to rise, biogas production has emerged as a promising solution for sustainable energy generation. This review article presents the advantages of biogas technologies (mainly agricultural, based on waste of animal and plant origin) and extensively discusses the main principles of biogas production in the anaerobic digestion (AD). In this respect, the main parameters of the process, which require monitoring and decisive for its efficiency are described, therefore: temperature, pH value, retention time and organic loading rate (OLR). The principles of substrate selection are also discussed and the necessity and advantages of the use of organic waste according to the model of a circular economy and the concept of sustainable development, are indicated. It is emphasized that according to the new European regulations, the crops classified as food cannot be considered energy crops. The part on biogas production is summarised with an explanation of the necessity to treat and purify biogas. Biogas purification is important from the point of view of the efficiency of its conversion into electricity. A special place in this paper is devoted to the design, construction, functioning and operation of biogas plants, based on both scientific and practical aspects. In conclusion of this chapter, the economic aspects and profitability of operating biogas plants are discussed. Cost and benefit analyses are the major tool used for the systematic evaluation of the financial costs and potential benefits associated with the operation of biogas plants. The important fact is that the return on investment can be achieved within a few years, provided the activities are well-planned and executed. In addition to the fundamental issues of the operation of biogas plants, this article presents the global situation regarding the development of biogas plants, discussing in detail the specific needs and limitations on different continents. It is a interesting and extensive part of this article. The global agricultural biogas market is at very different levels of development. Most such installations are located in Asia and Europe. China has the highest number of biogas plants, with more than 100,000 biogas plants, followed by Germany with over 10,000 plants. In addition to the 100,000 biogas plants, China also has a large number of household biogas units, which gives a total of approx. 40 million operating units. The article concludes with a discussion of opportunities and barriers to the development of biogas plants, pointing to: financial issues, access to feedstock, political regulations, public awareness and the geopolitical situation. The most frequently cited reasons for investment failure include economic problems, lack of professional knowledge.

Green Solvent Strategies toward Sustainable Perovskite Solar Cell Fabrication

The shift towards ecofriendly solvents in perovskite solar cell (PSC) production represents a significant leap towards sustainable renewable energy generation, effectively addressing concerns related to the harmful nature of conventional solvents employed in PSC manufacturing. This review assesses the toxicity of traditional solvents utilized in the PSC fabrication process as well as recent studies and challenges related to substituting toxic solvents with less harmful or green alternatives. Although considerable efforts have been made to adopt greener solvents, this review underscores the variations in evaluations based on specific criteria, highlighting the need for thorough consideration to ensure the viability and sustainability of each solvent replacement. This study offers a comprehensive exploration of the transition to greener solvents in PSC fabrication and elucidates the associated challenges and opportunities in this pivotal shift towards a more environmentally sustainable approach to renewable energy production.

A technical appraisal of solar photovoltaic-integrated single slope single basin solar still for simultaneous energy and water generation

In the contemporary era, the availability of energy and water stands as an essential foundation for human survival, with water's significance underscored by its role in shaping habitats. However, the modern world faces the pressing challenge of water scarcity, exacerbated by factors like air and water pollution, leading to ecological imbalances. Water, an indispensable resource for various daily human activities, necessitates the generation of freshwater. Simultaneously, the imperative of sustainable energy generation has taken precedence on the national agenda for growth. In this context, the integration of solar photovoltaic (PV) technology with solar stills emerges as the most viable solution. Within these integrated systems, electrical energy generated by solar PV is strategically employed to preheat inlet feeds, enhance air temperature, and optimize the evaporation and condensation processes within the solar still, thereby augmenting its overall performance. This study delves into the integration of solar PV collectors/systems with solar stills, distinguishing between thermal and electrical energy utilization in solar PV systems. The review underscores the pivotal role of solar PV integration in addressing critical issues of water scarcity and sustainable energy generation, contributing to the nation's growth.

Sustainable Energy Generation: Biodiesel Production from Rapeseed Oil

Sustainable Energy Generation: Biodiesel Production from Rapeseed Oil