Hasil untuk "Renewable energy sources"

Saket Mathur, Victoria Bishop, Andrew Swindle et al.

Day to day energy production is shifting towards renewable energy sources as these sources become more economically viable while being less polluting to operate; solar energy has become one of the major sources of renewable energy. However, it currently relies on ultra-pure silicon ingots to produce commercial silicon photovoltaics, which prevents the cost of electricity being produced to compete with non-renewable energy production. A viable low-cost alternative for silicon based cells would be dye-sensitized solar cells (DSSCs), which are easier and cheaper to manufacture as they do not require expensive and delicate raw materials to make. Moreover, they could be made semi-flexible which allows for a greater variety of applications. A DSSC consists of three components, a photo-electrode, an electrolyte and a counter-electrode. When exposed to incident light, the complex photosensitizers in the photoelectrode release electrons which are transported to the external load, leaving the photoelectrode in an oxidized state. The electrons are collected by the counter electrode and used to reduce the electrolyte. This charged electrolyte then reduces the positively charged photoelectrode, allowing the process to begin again. To improve the efficiency of this process, we explore the use of bismuth sulfide (Bi2S3) and titanium oxide (TiO2) composite as photoelectrode material and investigate their impact on the efficiency of DSSC.

M. Hikmatul Ridho, Prabowo

The energy consumption pattern in the world, and in Indonesia today, is still dominated by fossil energy in oil, gas, and coal. It contradicts the reduced production of fossil energy, especially petroleum. Therefore, the government is trying to increase the role of new and renewable energy. One of the renewable energy sources that can be developed is wind energy. Indonesia has the potential for wind energy of 60.6 GW with an average wind velocity of 3–6 m/s. Given these conditions, it is expected that the installation of vertical axis wind turbines (VAWT) in buildings in urban areas and remote islands will be able to take advantage of the wind speed flowing above or beside buildings or skyscrapers, where the wind conditions do not have obstacles such as trees, houses, and so on. As a result, analysis and experimentation are required to design a wind turbine with good performance that can be used in cities or remote islands at relatively low wind speeds. The method used in this study is numerical analysis with computational fluid dynamics (CFD) with poly-hexacore meshing type, and the geometry sample is an H-Darrieus turbine. The input parameter is wind speed, which ranges from 2.5 to 9 m/s. The final goal of this study is to determine whether the CFD simulation modeling used is credible or valid.

Yungpil Yoo, Sang-Yup Lee, Seok-Ho Seo et al.

The feasibility of integrating a CCU (Carbon Capture and Utilization) plant into a green methanol production system was studied through detailed energy, exergy, and thermoeconomic analyses from process, economic, and environmental perspectives. In this system, wood chips are combusted with oxygen generated by an electrolyzer in a circulating fluidized bed boiler. Carbon dioxide, a primary component of flue gas, reacts with hydrogen produced by the electrolyzer to synthesize green methanol. The chemical formula for wood chip combustion was modeled and used in this study. Our thermodynamic modeling allows us to calculate the oxy-fuel combustion, carbon capture, and water electrolysis processes to obtain the amounts of carbon dioxide and hydrogen required to produce methanol. When the unit costs of wood chips and electricity are $0.15/kg and $0.120/kWh, respectively, and the system’s initial investment cost is $117.9 million, the production cost of green methanol is calculated to be $1.393/kg. Additionally, the unit costs of hydrogen and oxygen produced by the electrolyzer were $4.75/kg and $0.30/kg, respectively. However, if the unit cost of electricity is reduced by 50 %, the production cost of green methanol decreases to $0.90/kg, which is close to the market price. If the carbon dioxide produced is sold as carbon credits at $0.50/kg, the unit price of methanol drops to $0.89/kg. Using wind, solar, or nuclear energy to electrolyze water, the carbon emissions of this methanol plant are estimated to be around 0.11–0.45 kgCO2/kgMeOH.

Lakshmi Narayan Satheesh, Katerina Achilleos, Abdullah M. Abudayyeh et al.

ABSTRACT Novel renewable alternatives to meet the needs of our current energy landscape are highly sought after. Photovoltaic solar cells (PV) are considered leading candidates for carbon neutrality due to their numerous benefits and good solar‐to‐energy conversion efficiency. However, the need is no longer solely focused on electric current generation but also on strategies to store that energy. This led, amongst other technologies, to the development of dye‐sensitized photoelectrosynthesis cells (DSPECs), the successor of dye‐sensitized solar cells (DSSCs). However, these cost‐effective solar cells mostly use photosensitizers based on scarce metals such as ruthenium. Iron‐based photosensitizers represent the holy grail due to their low toxicity, greater abundance, and versatile chemistry. However, they still suffer from drastic limitations: their photochemistry and extremely fast excited‐state deactivation processes lead to inefficient charge injection and/or fast charge recombination. This review gathers examples of iron‐based photosensitizers that have been successfully immobilized on metal oxide surfaces. A critical comparison of Fe‐based photosensitizers is made based on their photophysical properties, electrochemistry, and photovoltaic performances.

Katherine A Acord, Alexander D Dupuy, Qian Nataly Chen et al.

Additive manufacturing of solid-state batteries is advantageous for improving the power density by increasing the geometric complexity of battery components, such as electrodes and electrolytes. In the present study, bulk three-dimensional Li _1+ _x Al _x Ti _2− _x (PO _4 ) _3 (LATP) electrolyte samples were prepared using the laser powder bed fusion (L-PBF) additive manufacturing method. Li _3 PO _4 (LPO) was added to LATP to compensate for lithium vaporization during processing. Chemical compositions included 0, 1, 3, and 5 wt. % LPO. Resulting ionic conductivity values ranged from 1.4 × 10 ^−6 –6.4 × 10 ^−8 S cm ^−1 , with the highest value for the sample with a chemical composition of 3 wt. % LPO. Microstructural features were carefully measured for each chemical composition and correlated with each other and with ionic conductivity. These features and their corresponding ranges include: porosity (ranging from 5% to 19%), crack density (0.09–0.15 mm mm ^−2 ), concentration of residual LPO (0%–16%), and concentration and Feret diameter of secondary phases, AlPO4 (11%–18%, 0.40–0.61 µ m) and TiO2 (9%–11%, 0.50–0.78). Correlations between the microstructural features and ionic conductivity ranged from −0.88 to 0.99. The strongest negative correlation was between crack density and ionic conductivity (−0.88), confirming the important role that processing defects play in limiting the performance of bulk solid-state electrolytes. The strongest positive correlation was between the concentration of AlPO4 and ionic conductivity (0.99), which is attributed to AlPO4 acting as a sintering aid and the role it plays in reducing the crack density. Our results indicate that additions of LPO can be used to balance competing microstructural features to design bulk three-dimensional LATP samples with improved ionic conductivity. As such, refinement of the chemical composition offers a promising approach to improving the processability and performance of functional ceramics prepared using binderless, laser-based additive manufacturing for solid-state battery applications.

Nikita Goyat, Rajeev Kumar Kapoor, Baljeet Singh Saharan et al.

Trametes versicolor, a common upper polyporus fungus, demonstrates mycelial growth that is influenced by temperature, pH, and media composition. This study aimed to optimize these conditions, as well as carbon and nitrogen sources, to enhance the mycelial growth of the white-rot fungus T. versicolor HBB 7328. This fungus shows significant potential for green energy applications due to its enzymatic activities. The research found that the fungus achieved maximal mycelial growth at 30°C (8.24 mm/day) and pH 7 (6.34 mm/day). Among various carbon sources, maltose resulted in the highest growth rate of 10.62 mm/day, whereas malt extract proved to be the most effective nitrogen source, supporting a growth rate of 8.96 mm/day. Enzymatic activity screening showed that T. versicolor HBB 7328 was positive for laccase, cellulase, protease, and xylanase activities. Notably, it exhibited substantial laccase activity (50.167 U/mL). These results are pivotal for developing pure cultures and conducting further studies on the enzymatic activities of T. versicolor HBB 7328. The high laccase activity, in particular, underscores its potential in biotechnological applications such as pollutant biodegradation and biofuel production, advancing green energy solutions.

Yaqian Ren, Yanlong Kong, Yonghui Huang et al.

Abstract Large-scale ground source heat pump (GSHP) systems are increasingly used for space heating and cooling. In comparison with smaller ones, large GSHP systems are often coupled with much more borehole heat exchangers (BHEs). Because of the intense thermal interactions between BHEs, they are more susceptible to significant ground temperature changes. Meanwhile, they possess the advantage that their operational strategies can be applied with a high degree of freedom, which presents chances to alleviate intense thermal interactions. In this study, we used a new performance indicator to access the effectiveness of GSHP operational strategies on alleviating thermal anomalies. The Daxing Airport GSHP system, contains 10,497 BHEs and is the largest in the world; therefore, it was selected as the test case for performance enhancement through operational strategies. We established a 2D model to predict ground temperature changes during the 50-year operation of the BHEs. First, it was revealed that the most severe thermal anomalies in the study area mainly occurred both within and between the BHE arrays, which should be mitigated. To alleviate the thermal anomalies caused by the thermal interactions of BHEs, operational strategies were applied by adjusting the cooling/heating starting sequence, setting time-dependent thermal loads, and reallocating thermal loads according to the position of the BHEs. Our study demonstrates that only the operation strategy that adjusts the cooling/heating starting sequence is beneficial for different BHE layouts, while the operational strategy that reallocates the thermal loads depending on BHEs position may be only effective for specific BHE layouts. In addition, our new performance indicator can be used to evaluate the effectiveness of the operational strategies and determine the spacing of adjacent BHE arrays. Therefore, it benefits the operation management of BHE array and design of BHE layout, and further guarantees the sustainable operation of the GSHP system.

Martin Nagl, Oskar Haske-Cornelius, Wolfgang Bauer et al.

Abstract Background Pulp refining is an energy consuming, but integral part of paper production with the aim to increase tensile strength and smoothness of paper sheets. Commercial enzyme formulations are used to lower the energy requirements by pre-treatment of pulp before refining. However, a high number of different commercial enzyme products are available on the market containing enzymes of varying origin and composition, which complicates the prediction of their behavior, especially using different pulp types. Results Endoglucanase-rich enzyme formulations were characterized regarding enzyme activity at different temperatures, resulting in a significant decrease of activity above 70 °C. Some enzyme preparations additionally contained arabinosidase, xylanase and β-glucosidase activity consequently resulting in a release of xylose and glucose from pulp as determined by high-performance liquid chromatography. Interestingly, one enzyme formulation even showed lytic polysaccharide monooxygenase (LPMO) activity of 3.05 nkat mg−1. A correlation between enzyme activity using the endoglucanase specific derivatized cellopentaose (CellG5) substrate and enzyme performance in laboratory PFI (Papirindustriens forskningsinstitut) refining trials was observed on softwood pulp resulting in a maximum increase in the degree of refining values from 27.7°SR to 32.7°SR. When added to a purified endoglucanase enzyme (31.6°SR), synergistic effects were found for cellobiohydrolase II (34.7°SR) or β-glucosidase enzymes (35.7°SR) in laboratory refining. Comparison with previously obtained laboratory refining results on hardwood pulp allowed differences in enzyme performance based on varying pulp types to be elucidated. Conclusions Interestingly, the individual enzymes indeed showed different refining effects on softwood and hardwood pulp. This difference could be predicted after development of an adapted enzyme activity assay by combination of the derivatized cellopentaose CellG5 substrate with either softwood or hardwood sulfate pulp.

Teng Wen, Xiang Cui, Xuebao Li et al.

Abstract The working voltage of the high‐voltage high‐power electronic devices is the positive periodic square waveform (PPSW) voltage, which is much different from the conventional AC or DC voltage. For the composite insulation structure of devices, it is important to analyse the transient electric field under the PPSW voltage. However, the existing investigations are often conducted under the electrostatic field due to the high frequency of the PPSW voltage. Thus, the transient characteristics of the electric field are missed. To obtain some qualitative conclusions, this paper focusses on the theoretical analysis of the transient characteristics of electric field for the composite insulation structure under the PPSW voltage. First, the formula of the electric field intensity and the interfacial charge density are derived analytically. Second, the influence of the cycle and the duty cycle on the transient characteristics are investigated. Third, the maximum of the electric field intensity and the interfacial charge density in the positive square waveform steady‐state are discussed in detail. Besides, the engineering calculation methods for obtaining these maximum values are also suggested. Lastly, an actual model is employed to testify the validity of the analytical analysis. This work is significant for the numerical calculation of the transient electric field of composite insulation structure under the PPSW voltage in engineering.

Waleed I. Breesam, Ameer L. Saleh, Khearia A. Mohamad et al.

The direct-current (DC) motor has been widely utilized in many industrial applications, such as a multi-motor system, due to its excellent speed control features regardless of its greater maintenance costs. A synchronous regulator is utilized to verify the response of the speed control. The motor speed can be improved utilizing artificial intelligence techniques, for example fuzzy neural networks (FNNs). These networks can be learned and predicted, and they are useful when dealing with nonlinear systems or when severe turbulence occurs. This work aims to design an FNN based on a model reference controller for separately excited DC motor drive systems, which will be applied in a multi-machine system with two DC motors. The MATLAB/Simulink software package has been used to implement the FNMR and investigate the performance of the multi-DC motor. moreover, the online training based on the backpropagation algorithm has been utilized. The obtained results were good for improving the speed response, synchronizing the motors, and applying load during the work of the motors compared to the traditional PI control method. Finally, the multi-motor system that was controlled by the proposed method has been improved where its speed was not affected by the disturbance.

Huihong Zhu, Zhiwei Mao, Bin Liu et al.

Hydrotreating of vacuum residue by ebullated-bed shows tremendous significance due to more stringent environmental regulations and growing demand for lighter fuels. However, enhancing the catalyst stability still remains as a challenging task. Herein, two Ni–Mo/Al2O3 catalysts with distinct morphologies (i.e., spherical and cylindrical) were first designed, and the morphology effect on deactivation was systematically elucidated employing multi-characterizations, such as HRTEM with EDX mapping, electron microprobe analysis, FT-IR, TGA and Raman. It is found that spherical catalyst exhibits superior hydrotreating stability over 1600 h. The carbonaceous deposits on spherical catalyst with less graphite structure are lighter, and the coke weight is also smaller. In addition, the metal deposits uniformly distribute in the spherical catalyst, which is better than the concentrated distribution near the pore mouth for the cylindrical catalyst. Furthermore, the intrinsic reason for the differences was analyzed by the bed expansion experiment. Higher bed expansion rate together with the better mass transfer ability leads to the enhanced performance. This work sheds new light on the design of more efficient industrial hydrotreating catalyst based on morphology effect.

Al-Dabbagh Riadh

Population growth, social and industrial activities have increased significantly, resulting in an increase in the quantities of wastes in UAE in specific the Emirate of Ajman. Most of the waste is still not thoroughly treated and ends up in municipal landfills, where organic waste generates many gases such as methane, a potent greenhouse gas. Currently, little of the waste is burned, and the rate of municipal waste recycling has been rapidly rising. Waste management in the Ajman is coordinated through local authorities. For this purpose the UAE has set Key Performance Indicators (KPIs) to measure its performance against its targets of 2021. To support the national efforts, Ajman is continuously seeking to adopt vital initiatives and projects that are positively affecting all aspects of life. Waste issues are handled through recycling and converting waste to energy and resources, new technologies and improved waste separation and collection systems. Ajman Municipality and Planning Department has initiated plans and efforts in waste management, including converting waste to energy, treating wastewater, and controlling the movement of hazardous waste. The programs are implemented with the aim to reduce the adverse per capita environmental impact of the city, including by paying particular attention to air quality and all types of waste. The paper presents an overview of the waste situation and the management practices according to the Municipality's plans and strategies. It is concluded that Ajman still lacks an infrastructure for organic waste recycling for residents. This organic waste is a significant contributor to methane emissions from landfills. Challenges are to be solved, such as the lack of adequate waste sorting and recycling facilities in the Emirate and weak community culture to adopt waste sorting. Many practices started to be implemented by the Municipality, for instance, creating an incinerator used to treat non-chemical medical waste generated from hospitals & clinics. As a result, Ajman has witnessed a reduction in the quantity of waste dumped in the landfill.

Partha Pratim Das, Vijay Chaudhary

Pollution due to plastic waste is a major concern for the eco-friendly environment. These manmade waste release various toxins to the environment, which are harmful to mankind. To encounter the effect of the synthetic materials, bio fibre based polymer composites made from bio fibres (jute, hemp, flax, cotton etc.) are emerging as a suitable replacement as bio fibre based polymer composites are low cost, light in weight and eco-friendly. Green Economy is an important aspect of the environment that helps to promote environmentally friendly nature. The present article gives an insight into the various types of bio fibres available along with their mechanical and chemical properties. A detailed discussion on recycling and disposal mechanism and how the use of bio fibre based polymer composites will lead to a sustainable environment in the coming years has been included. At last, the future market trend and potential applications of bio fibre based polymer composites have also been addressed in this article.

Sandeep Singh, Parteek Thind, Manpreet Kaur Verma et al.

In the preceding times, the number of enclosed parking garages has increased significantly in developing nations. The toxic emissions from vehicular exhausts are expected to drastically compromise the environmental conditions of the parking garages. Subsequently, exposure of humans to these accumulated pollutants is also expected to degrade their health. Therefore, in the present investigation, efforts were made to estimate the applicability of TiO2-mediated UV photocatalysis in degrading the concentration of vehicular emissions, viz., NOx and SO2, in the enclosed parking garages (EPGs). In this regard, an artificial EPGs’ environment was created and experiments were designed using the Box-Behnken design in combination with response surface methodology. The process parameters chosen for maximizing the degradation of the pollutants were a concentration of TiO2 emulsion (20 to 120 ml/m2), UV irradiance (1 to 5 mW/cm2), and relative humidity (10 to 50%). Optimization of the laboratory experiments revealed that at optimal conditions of the process parameters, i.e., a concentration of TiO2emulsion=77.50 ml/m2, intensity of UV irradiance=3 mW/cm2, and relative humidity=43.2%, maximum degradation of the NOx and SO2, i.e., 61.24% and 55.05%, respectively, was achieved. Further, it was revealed that relative humidity may prove to be the limiting factor while using the TiO2-mediated UV photocatalysis in humid areas. Findings of this study may prove beneficial in urban planning as it may assist scientific auditory and local authorities in identifying the applicability of TiO2-based photocatalysis in mitigating the impacts of vehicular emissions.

Piotr Olczak, Dominik Kryzia, Dominika Matuszewska et al.

There are a lot of studies that show the legitimacy of subsidizing renewable energy; however, some mechanisms are defective, and there are problems with the appropriate allocation of funds. Therefore, this paper aims to look at the situation of allocating funds to photovoltaics (PV) micro-installations in Poland through the “My Electricity” program. The article presents the results of analyses aimed at identifying inequalities between provinces in the use of funds available under the “My Electricity” program and verifying whether these inequalities are getting worse and whether the intensity of support should not be territorially conditioned in terms of maximization an electricity production. As part of two editions of the “My Electricity” program (until 1 August 2020), over 64,000 PV micro-installations were created with an average power of approximately 5.7 kWp. The total installed PV capacity was 367.1 MWp (1st edition: 159.3 MWp, 2nd edition: 207.8 MWp). Financial resources (as a whole), in the second edition of “My Electricity” program, were distributed better than in the first edition. In the first edition, as much as 7.60% of funds were allocated inefficiently; in the second edition, it was only 3.88%. Allocation surpluses occur in provinces where the average disposable income is low and where there are a small number of households. There is a potential to introduce a territorial project selection criteria. The analysis shows that the criteria should promote provinces with higher disposable income and a larger number of households.

Jingqi Wang, Musen Zhou, Diannan Lu et al.

Stable isotopes have been routinely used in chemical sciences, medical treatment and agricultural research. Conventional technologies to produce high-purity isotopes entail lengthy separation processes that often suffer from low selectivity and poor energy efficiency. Recent advances in nanoporous materials open up new opportunities for more efficient isotope enrichment and separation as the pore size and local chemical environment of such materials can be engineered with atomic precision. In this work, we demonstrate the unique capability of nanoporous membranes for the separation of stable carbon isotopes by computational screening a materials database consisting of 12,478 computation-ready, experimental metal-organic frameworks (MOFs). Nanoporous materials with the highest selectivity and membrane performance scores have been identified for separation of 12CH4/13CH4 at the ambient condition (300 K). Analyzing the structural features and metal sites of the promising MOF candidates offers useful insights into membrane design to further improve the performance. An upper limit of the efficiency has been identified for the separation of 12CH4/13CH4 with the existing MOFs and those variations by replacement of the metal sites.

Pavel Atănăsoae, Radu Dumitru Pentiuc

This paper presents a method for choosing the energy sources that are needed for the following building utilities following building: lighting, domestic hot water, heating, ventilation, and air conditioning. The novelty of this paper consists of applying the concept of the energy hub and considering the cost of carbon dioxide emissions when selecting the available energy sources in the building’s location. The criterion for selecting the energy sources is the minimum overall cost of all forms of energy that are consumed in the building over its estimated lifetime. In order to estimate the overall costs, it is necessary to know the power that is installed and provided by the energy production technologies that are inside the building, as well as the capacity of energy that is required from outside energy sources. An office building that was proposed for refurbishment has been investigated as a case study. In the paper, we have analysed four scenarios. The results indicate that more favourable alternative solutions can be obtained compared to the traditional scenario (Scenario 4—heat and electricity by public utility networks). The overall costs are 46.17% (212,671 EUR) lower in Scenario 1, 25.35% (116,770 EUR) lower in Scenario 2, and 10.89% (50,150 EUR) lower in Scenario 3. Additionally, the carbon dioxide emissions are 22.98% (49 tonnes CO2/year) lower in Scenario 1 and 8.91% (19 tonnes CO2/year) lower in Scenario 2. Thus, renewable energy sources can occupy a growing share of the total energy consumption of the building. The proposed algorithm can be used for both the refurbishment of existing buildings and the design of new buildings.

Mohammed Saad Dwiddar, Ibrahim El-Osery

<span style="line-height: 150%; font-family: 'Calibri','sans-serif'; font-size: 11pt; mso-ascii-theme-font: minor-latin; mso-fareast-font-family: Calibri; mso-fareast-theme-font: minor-latin; mso-hansi-theme-font: minor-latin; mso-bidi-font-family: Arial; mso-bidi-theme-font: minor-bidi; mso-ansi-language: EN-US; mso-fareast-language: EN-US; mso-bidi-language: AR-SA;">A methodology of evaluating the economics of the front-end nuclear fuel cycle with a price change sensitivity analysis for a VVER-1000 reactor core as a case study is presented. The effect of increasing the fuel enrichment and its corresponding reactor cycle length on the energy cost is investigated. The enrichment component was found to represent the highly expenses dynamic component affecting the economics of the front-end fuel cycle. Nevertheless, the increase of the fuel enrichment will increase the reactor cycle length, which will have a positive feedback on the electricity generation cost (cent/KWh). A long reactor operation time with a cheaper energy cost set the nuclear energy as a competitive alternative when compared with other energy sources.</span>

Cheng-Hung Tai, Chu-Hsuan Lin, Chih-Ming Wang et al.

Many defects exist within amorphous silicon since it is not crystalline. This provides recombination centers, thus reducing the efficiency of a typical a-Si solar cell. A new structure is presented in this paper: a three-terminal a-Si solar cell. The new back-to-back p-i-n/n-i-p structure increased the average electric field in a solar cell. A typical a-Si p-i-n solar cell was also simulated for comparison using the same thickness and material parameters. The 0.28 μm-thick three-terminal a-Si solar cell achieved an efficiency of 11.4%, while the efficiency of a typical a-Si p-i-n solar cell was 9.0%. Furthermore, an efficiency of 11.7% was achieved by thickness optimization of the three-terminal solar cell.

Elias Stathatos, Panagiotis Lianos

Dye-sensitized photoelectrochemical cells based on TiO2 mesoporous films, a ruthenium bipyridyl derivative as photosensitizer and a SiO2/poly(ethylene glycol)-200 nanocomposite thin film as electrolyte support, have been constructed. TiO2 films have been deposited on conductive transparent Indium-Tin Oxide glass slides by means of a sol-gel procedure carried out in reverse-micellar solutions. The photosensitizer has been adsorbed on titania films from ethanolic solutions while the electrolyte layer has been synthesized by a sol-gel procedure. The presence of silica in the nanocomposite electrolyte gel provides the gelifying agent, the compound that holds the cell together in a sandwich form and the sealing agent that protects the cell and secures its long-term function. PEG-200 makes the organic subphase which provides the ionic conductivity. The present work describes the construction of the cell and the study of its efficiency. A variant of the cell has also been made by incorporating Ag+ and Ru3+ ions into titania particles, but these dopants did not improve cell efficiency, either in their oxidized or in their reduced form.