Green Energy Sources Research Articles

Vertical Takeoff and Landing for Distribution of Parcels to Hospitals: A Case Study about Industry 5.0 Application in Israel’s Healthcare Arena

To gain a sustained competitive advantage, organizations such as UPS, Fedex, Amazon, etc., began to seek for industry 5.0 innovative autonomous delivery options for the last mile. Autonomous unmanned aerial vehicles are a promising alternative for the logistics industry. The fact that drones are propelled by green renewable energy source fits the companies’ need to become sustainable, replacing their fuel truck fleets, especially for traveling to remote rural locations to deliver small packages, but a major obstacle is the necessity for charging stations which is well documented in the literature. Therefore, the current research embarks on devising a novel yet practical piece of technology adopting the simplicity approach of direct flights to destinations. The analysis showcases the application for a network of warehouses and hospitals in Israel while controlling costs. Given the products in the case study are medical, direct flight has the potential to save lives when every moment counts. Hydrogen cell technology allows long-range flying without refueling, and it is both vibration-free which is essential for sensitive medical equipment and environmentally friendly in terms of air pollution and silence in urban areas. Importantly, hydrogen cells are lighter, with higher energy density than batteries, which makes them ideal for drone usage to reduce weight, maintain a longer life, and enable faster charging, all of which minimize downtime. Also, hydrogen sourcing is low-cost and unlimited compared to lithium-ion material which needs to be mined. The case study investigates an Israeli entrepreneurial company, Gadfin, which builds a vertical takeoff-and-landing-type of drone with folded wings that enable higher speed for the delivery of refrigerated medical cargo, blood, organs for transplant, and more to hospitals in partnership with the Israeli medical logistic conglomerate, SAREL. An analysis of shipping optimization (concerning the number and type of drone) is conducted using a mixed-integer linear programming technique based on various types of constraints such as traveling distance, parcel weight, the amount of flight controllers and daily number of flights allowed in order to not overcrowd the airspace. Importantly, the discussion assesses the ecosystem’s variety of risks and commensurate safety mechanisms for advancing a newly shaped landscape of drones in an Israeli tight airspace to establish a network of national routes for drone traffic. The conclusion of this research cautions limitations to overcome as the utilization of drones expand and offers future research avenues.

A Novel Ag-MgFe2O4 nanocomposite based hydroelectric cell: Green energy source illuminating the future

Hydroelectric cells demonstrate their capacity to produce electricity via the dissociation of water molecules, eliminating the requirement of electrolytes. The objective of this research is to synthesize Ag-MgFe2O4 nanocomposite using low-cost method and to study the green electricity generation by hydroelectric cell via the dissociation of water molecules. The nanocomposite displayed a cubic crystalline structure with an average crystallite size of about 29 nm, as determined by XRD. The lattice strain and crystal defects resulted from the insertion of the Ag in spinel ferrite from the W-H plot. The theoretical porosity of 54 % was further evaluated by XRD analysis and visually confirmed by FESEM imaging. The FTIR spectroscopy revealed functional groups present in ferrite observed from 428 cm−1 to 3450 cm−1 spectra. Strong water absorption near 3450 cm−1 showed materials sensitivity to water. FESEM imaging displayed the morphology, revealing porous grains with an average size of 93 nm. BET analysis of the prepared nanocomposite confirmed mesoporosity within the nanocomposite. Photoluminescence study confirmed radiative defects and oxygen deficiencies, as evidenced by emitted light maximum at 483 nm and broad peak from 456 nm to 526 nm. The voltage-current (V-I) polarization diagram for the Ag- MgFe2O4 nanocomposite-based hydroelectric cell showed an offload current of 18 mA, an open circuit voltage of 1.404 V, and an output power of 25.27 mW. In this context, the hydroelectric cell based on Ag- MgFe2O4 nanocomposite demonstrated increased porosity, radiative defects, and oxygen vacancies, all contributing to efficient water molecule dissociation for power generation. This represents a significant development in sustainable energy and highlights the practical possibilities of clean and renewable resources.

Weld Zone Analysis Based on FCAW Mechanical Characteristics and Heat Transfer Analysis of 316L Stainless Steel for Liquefied Hydrogen Tanks.

The International Maritime Organization (IMO) is currently rolling out more restrictive regulations in order to achieve net-zero GHG emissions by 2050. In response, the shipping industry is planning to pivot to green energy sources such as hydrogen fuel. However, since hydrogen has an extremely low boiling point (-253 °C), materials for storing liquid hydrogen must be highly resistant to low-temperature brittleness and hydrogen embrittlement. A 316L stainless steel is a typical material that meets these requirements, and various welds have been studied. In this study, 3 pass butt welding was performed by applying the FCAW (flux cored arc welding) process to 10 mm thick ASTM-A240M-316L stainless steel, with the size of the fusion zone and HAZ investigated by mechanical testing and heat transfer FE analysis according to process variables, such as heat input, welding speed, and the number of passes. In all cases, the yield and tensile strengths were about 10% and 3% higher than the base metal, respectively. Furthermore, heat transfer FE analysis showed an average error rate of 1.3% for penetration and 10.5% for width and confirmed the size of the HAZ, which experienced temperatures between 500 °C and 800 °C.

Advancing sustainability in mechanical engineering: Integration of green energy and intelligent manufacturing

Efficient energy utilization and waste reduction are imperative for sustainable mechanical engineering practices. This paper explores the integration of green energy sources and intelligent manufacturing techniques to enhance sustainability in the mechanical engineering sector. Through quantitative analysis and case studies, the efficacy of energy-efficient technologies, waste reduction strategies, and the adoption of green energy sources are examined. Additionally, the role of smart process automation and digital twin simulation in optimizing resource utilization and operational efficiency is discussed. The findings underscore the potential of integrating sustainable practices into mechanical engineering processes, contributing to environmental conservation, cost savings, and competitiveness.

Optimal sizing of a proposed stand-alone hybrid energy system in a remote region of southwest Egypt applying different meta-heuristic algorithms

Hybrid energy system (HES) is considered a solution to the energy supply issue, particularly in rural areas to achieve their sustainable development goals. The rise in energy consumption has increased the appeal of renewable resources, because of their potential to supply consumers with competitive, carbon-free electricity. This paper suggests strategies for managing energy and the most recently published optimizers for designing a stand-alone HES positioned in a remote region of southwest Egypt. This HES includes two green energy sources (wind and solar) and a storage system for energy (battery) as the first backup in addition to a second backup (diesel). The most recent sizing techniques employing the Chernobyl disaster optimizer, dynamic control cuckoo search (DCCS), and gold rush optimizer have been suggested to obtain the optimal design of the utilized HES. Furthermore, an in-depth evaluation of the applied optimization approaches has been achieved based on a comparative study. A detailed analysis of the studied algorithms aims to identify the optimum algorithm that provides the lowest possible cost at the highest level of reliability for the proposed HES. The simulation results verified that, the DCCS algorithm outperformed other algorithms, indicating its potential for achieving promising solutions.

Cross-Domain Knowledge Transfer for Sustainable Heterogeneous Industrial Internet-of-Things Networks.

In this article, a novel cross-domain knowledge transfer method is implemented to optimize the tradeoff between energy consumption and information freshness for all pieces of equipment powered by heterogeneous energy sources within smart factory. Three distinct groups of use cases are considered, each utilizing a different energy source: grid power, green energy source, and mixed energy sources. Differing from mainstream algorithms that require consistency among groups, the proposed method enables knowledge transfer even across varying state and/or action spaces. With the advantage of multiple layers of knowledge extraction, a lightweight knowledge transfer is achieved without the need for neural networks. This facilitates broader applications in self-sustainable wireless networks. Simulation results reveal a notable improvement in the 'warm start' policy for each equipment, manifesting as a 51.32% increase in initial reward compared to a random policy approach.

The impact of cleaner energy sources, advanced technology firms, and economic expansion on ecological footprints is critical in sustainable development

The environmental degradation accompanying economic growth, despite the potential mitigating effects of technological advancements and cleaner energy sources. This study examines the critical impact of cleaner energy sources, advanced technology firms, and economic expansion on ecological footprints within the context of sustainable development, focusing on the period between 2010 and 2022. By comparing the E7 (emerging seven) and G7 (Group of Seven) economies, the research aims to delineate how these factors collectively influence environmental sustainability in both developing and developed nations. Utilizing a robust panel estimation technique, the study systematically explores the relationship between the adoption of renewable energy technologies, the growth of high-tech industries, and macroeconomic expansion, alongside their respective effects on the ecological footprint, a key indicator of environmental impact. Our statistical analysis reveals significant differences between the E7 and G7 countries. For the G7, investments in cleaner energy and technology sectors have shown a more pronounced effect in reducing ecological footprints, attributed to higher efficiency standards and greater public awareness. In contrast, the E7 countries exhibit a delayed response, owing to varying stages of economic development and technological adoption, although promising trends are emerging. Notably, the G7 demonstrates a more pronounced inclination towards financial imperialism (0.043), while the E7 is significantly influenced by green energy sources (0.258). Policy implications drawn from the findings suggest that targeted investments in green technologies and renewable energy sources, coupled with robust policies supporting economic expansion in a sustainable manner, are crucial for both groups of countries. For the E7, accelerating technology transfer and adopting stricter environmental regulations are key, while the G7 should focus on innovation and the continuous improvement of energy efficiency standards. This dual approach is essential for mitigating the environmental impacts of economic growth and steering the global economy towards a more sustainable trajectory.

Spray Characterization of Direct Hydrogen Injection as a Green Fuel with Lower Emissions

A viable green energy source for heavy industries and transportation is hydrogen. The internal combustion engine (ICE), when powered by hydrogen, offers an economical and adaptable way to quickly decarbonize the transportation industry. In general, two techniques are used to inject hydrogen into the ICE combustion chamber: port injection and direct injection. The present work examined direct injection technology, highlighting the need to understand and manage hydrogen mixing within an ICE’s combustion chamber. Before combusting hydrogen, it is critical to study its propagation and mixture behavior just immediately before burning. For this purpose, the DI-CHG.2 direct injector model by BorgWarner was used. This injector operated at 35 barG and 20 barG as maximum and minimum upstream pressures, respectively; a 5.8 g/s flow rate; and a maximum tip nozzle temperature of 250 °C. Experiments were performed using a high-pressure and high-temperature visualization vessel available at our facility. The combustion mixture prior to burning (spray) was visually controlled by the single-pass high-speed Schlieren technique. Images were used to study the spray penetration (S) and spray volume (V). Several parameters were considered to perform the experiments, such as the injection pressure (Pinj), chamber temperature (Tch), and the injection energizing time (Tinj). With pressure ratio and injection time being the parameters commonly used in jet characterization, the addition of temperature formed a more comprehensive group of parameters that should generally aid in the characterization of this type of gas jets as well as the understanding of the combined effect of the rate of injection on the overall outcome. It was observed that the increase in injection pressure (Pinj) increased the spray penetration depth and its calculated volume, as well as the amount of mass injected inside the chamber according to the ROI results; furthermore, it was also observed that with a pressure difference of 20 bar (the minimum required for the proper functioning of the injector used), cyclic variability increased. The variation in temperature inside the chamber had less of an impact on the spray shape and its penetration; instead, it determined the velocity at which the spray reached its maximum length. In addition, the injection energizing time had no effect on the spray penetration.

Cobalt-Based Nanoscale Material: An Emerging Electrocatalyst for Hydrogen Production.

Modern civilization has been highly suffering from energy crisis and environmental pollutions. These two burning issues are directly and indirectly created from fossil fuel consumption and uncontrolled industrialization. The above critical issue can be solved through the proper utilization of green energy sources where no greenhouse gases will be generated upon burning of such materials. Hydrogen is the most eligible candidate for this purpose. Among various methods of hydrogen generation, electrocatalytic process is one of the most efficient methods because of easy handling and high efficiency. In these aspects Co-based nanomaterials are considered to be extremely significant as they can be utilized as efficient, recyclable and ideal catalytic system. In this article a series of Co-based nano-electrocatalysts has been discussed with proper structure-property relationship and their medium dependency. Therefore, such type of stimulating summary on recently reported electrocatalysts and their activity may be helpful for scientists of the corresponding field as well as for broader research communities. This can be inspiration for materials researchers to fabricate active catalysts for the production of hydrogen gas in room temperature.

Investigation of structural, electronic, optical and thermoelectric properties of hallide double perovskite Rb2AlAgX6 (X = Cl, I): A first-principles DFT study

In order to meet the demands of the energy consumption, double perovskites (DP) are a dependable green energy source. Consequently, there is a great deal of promise for thermoelectric and optoelectronic device applications when studying these perovskite halides. Our work examined the thermoelectric and optoelectronic properties of Rb2AlAgCl6 and Rb2AlAgI6 halides using Density Functional Theory (DFT). The tolerance factor and energy of formation for the halides that were examined show that they are stable in the cubic phase, structurally and thermodynamically. We calculated the bandgaps for Rb2AlAgCl6 (Eg = 3.82 eV) and Rb2AlAgI6 (Eg = 1.321 eV) using mBJ potentials, and compared them to the reported values. The optical characteristics of the materials under investigation were revealed through the use of a complicated dielectric function. The computed optical findings show that the materials are suitable for optoelectronic applications, with maximal light absorption occurring in the ultraviolet (UV) and infrared (IR) ranges. Optical parameters obtained includes large values of absorption coefficients (∼105cm−1), low reflectivity (∼1–15 %), and high optical conductivity (∼1015 sec−1). Thermoelectric properties revealed enhanced power factor for Rb2AlAgI6 as compared to Rb2AlAgCl6. These results imply that these materials are appropriate for application in optical and thermoelectric devices.

Transition metal oxide catalytic abilities for fuel cell applications: Density functional theory (DFT) studies

Because of its heavy reliance on fossil fuels, the world's existing energy supply releases pollutants into the atmosphere. Researchers have conducted extensive studies on greener energy sources, particularly fuel cell technology, which generates power from electrochemical energy while emitting minimal carbon. But there are obstacles to fuel cell efficiency and commercialization, such as the slow oxygen reduction reaction (ORR) and the expensive and unstable platinum (Pt) catalysts used in fuel cell membranes. This work explores the use of tungsten oxide, cobalt, and titanium oxide nanoparticles as inexpensive, active electrocatalysts. Despite extensive research on the monoxides of these metals, their bimetallic compositions when combined with oxygen to function as fuel cell catalysts remain poorly understood. This work evaluates the catalytic capabilities of the crystallographic surfaces of these oxides using Density Functional Theory (DFT) via CASTEP and DMol3, as well as the Adsorption Locator module. These surfaces, which include CoWO4, Co3WO8, and TiWO4, have different levels of stability and reactivity when it comes to absorbing hydrogen and oxygen. This makes them potentially useful for changing the hydrogen oxidation and oxygen reduction reactions in fuel cells.

Substantial Electrocatalytic Oxygen Evolution Performances of Activated Carbon-Decorated Vanadium Pentoxide Nanocomposites

Developing the ecofriendly and high-fidelity electrocatalysts for the oxygen evolution reaction (OER) is essential to foster effective production of environmentally friendly hydrogen. Herein, we fabricated the highly efficient OER electrocatalysts of the activated carbon-decorated vanadium pentoxide (AC-V2O5) nanocomposites using a facile hydrothermal technique. The AC-V2O5 nanocomposites displayed an aggregated structure of the AC nano-sheet-anchored orthorhombic V2O5 nanorods. When performing the OER process in an alkaline electrolyte at 10 mA/cm2, AC-V2O5 exhibited the low overpotential (~230 mV), small Tafel slope (~54 mV/dec), and excellent stability. These substantial OER performances of AC-V2O5 could be ascribed to the synergistic effects from both the electrochemically active V2O5 nanorods and the highly conductive AC nanosheets. The results infer that the AC-V2O5 nanocomposites possess a substantial aptitude as a high-performance OER electrocatalyst for production of the future green energy source—hydrogen.

USE OF RENEWABLE SOLAR-WIND HYBRID ENERGY SOURCES TO MEETLOCAL ELECTRICITY DEMAND: CURRENT STATUS AND PROSPECTS

Renewable energy sources are those which are abundantly available in nature. These are solar, wind, sea, geothermal and biomass and energy generated from these sources are carbon free with less pollution and capable enough to compensate the energy generated from coal and other fossil fuels. Wind and solar energy are becoming popular owing to abundance, availability and ease of harnessing for electrical power generation. It is very common to use these two aforementioned sources to generate electricity independently, i.e. solar power acting alone or wind power alone. Sometimes, though, it is desired that two of these renewable energy resources are combined together to generate electricity and these types of systems are called a Hybrid Power System (HPS). Hybrid power systems therefore, provide increased system efficiency and greater balance in supply of energy. The presentation will be a brief overview of research conducted around the world to design and implement HPS-s that combine wind and solar energy to produce reliable and sustainable electricity for local purposes. Also, information about the research conducting in these directions at the “Novel Alloys Design and Development Lab” (NOVALAB) of Metallurgical and Materials Engineering Department in Middle East Technical University (MetE-METU) and "New Materials and Nanotechnology" Center of Excellence of Azerbaijan Technical University (AzTU) and the details of joint research project proposal within the framework of the Japan-Azerbaijan technical cooperation program in the designing and implementation of solar-wind hybrid energy system at main campus and Techno-park of AzTU in order to supply full electricity demand from green energy sources will be given.

Coordinating electric vehicle charging with multiagent deep Q-networks for smart grid load balancing

Integrating EVs (Electric Vehicles) with the electrical system presents essential load distribution difficulties because EV recharging structures are unpredictable and variable. The article presents an innovative technique employing multiple-agent deeper Q-Networking (MADQN) to coordinate electric automobiles and improve the electricity system balance of load. The suggested MADQN simulation rapidly optimizes battery charge plans by utilizing the capabilities of multiple agent networks as well as deeper reinforced learning. The framework adjusts to current network situations utilizing cooperative decision-making between substances, considering variables like a need for power, accessibility to green energy sources, and protection of the arrangement. Beneficial load distribution is made possible when reducing expenses and ecological damage because of the system's capacity to gather data from and modify intricate, changing circumstances. The findings from the modelling indicate how well the suggested MADQN method works to enhance network efficiency, lower peak usage, and use more sustainable power resources. These factors help build a more robust, adaptable, intelligent grid environment.

Advancements and challenges in BaTiO3-Based materials for enhanced energy storage

Numerous researchers worldwide have been motivated to develop highly effective, environmentally acceptable green energy sources as a result of the recent sharp increase in energy use and the need for low emission levels. The energy generated from various renewable sources can be stored efficiently with a system that has a high energy density and high energy efficiency. Due to their enhanced dielectric, ferroelectric, and breakdown strength characteristics, BaTiO3 based dielectric/ferroelectric ceramic materials have received a lot of interest for energy storage applications in the past tw decades. In the present work, a thorough analysis of recent advancements in composites and single-phase BaTiO3 materials with enhanced energy storage performance. This review's main focus is on the crucial tactics and theoretical frameworks for improving the energy efficiency and recovered energy storage density of various BaTiO3-based materials. A thorough summary has been provided with the most recent developments in BaTiO3 based materials for multi-layered ceramic capacitors (MLCCs), pulse power capacitors, piezoelectric transducers, energy harvesting, electric vehicle batteries, and high-power electronic devices in order to confirm the commercial applications of BaTiO3 based single phase as well as multi-phase layered structures and composites.

Appraisal of Green Communication Technology Deployment in Nigeria

The idea behind “green” processes and technologies is the use of upgraded, ecologically friendly processes and technologies in a way that preserves natural resources and doesn’t disturb the environment. Clean technology and environmental technology are other names for green technology. These days, most governments take steps to promote these technologies because of their value. Governments therefore suggested a number of financial incentives that produce electricity using renewable resources. As its primary objective, green technologies seek to address societal demands while minimizing the use of natural resources and causing no harm to them. The idea is to create materials that are entirely recyclable or reusable. Green technology generates energy through novel and inventive methods. The goal of green communication is to explore sustainability in relation to energy efficiency, the environment, and communication goals. Green communications have an obligation to promote ecological network equipment and systems and to fortify corporate environmental responsibility. The paper presents Nigeria renewable green energy sources, green electronics, recycling, communication technology areas of application. The paper also presents a careful consideration of materials and methods to ensure the chosen deployment are environmentally sustainable. Despite the challenges, utilizing green ICT methods in Nigeria is not just a choice, it is essential for a number of advantageous causes as people throughout the world become more environmentally aware, implementing green ICT practices can improve Nigeria’s standing internationally. It will demonstrate the nation’s dedication to sustainability.

Binder-free phosphor-coated multiphase bismuth cobalt-selenide electrode for solar-charged quasi-solid-state hybrid supercapacitors

The enormous utilization of fossil fuels and the accelerated progression of global warming have irreversible destructive consequences on Earth's biodiversity. In response to this concern, there is a growing need to adopt green and renewable energy sources as effective strategies for mitigating environmental challenges. Herein, we report the novel synthesis and electrochemical properties of a binder-free phosphorus-coated multiphase bismuth-cobalt selenide/nickel foam (P@BCS/NF) electrode. Phosphorization was performed under an N2 atmosphere in a tube furnace to cover the electrodes. The synthesized electrode exhibited a porous nanorod morphology, which enhanced its electrochemical and energy storage properties. The P@BCS/NF electrode delivered a high areal capacity value of 836.4 µAh cm−2 in 1 M KOH electrolytic solution with excellent cycling stability, 81.4 % capacity retention, and 98.8 % coulombic efficiency over 10,000 cycles. A quasi-solid-state hybrid supercapacitor (QHSC) device was constructed using P@BCS/NF as the positive electrode and activated carbon as the negative electrode. The QHSC device showed maximum areal energy and power density values of 384.37 μWh cm−2 and 21750 μW cm−2, respectively, together with high stability of 94.4 % capacitance retention after 10,000 cycles. The practical application of the QHSC device was demonstrated in a PVA-KOH electrolytic environment by powering various electronic devices.

Physicochemical Study of Ethanol Ratio in the Transesterification Process for Biodiesel Synthesis from Kesambi (Schleichera Oleosa) Seed Oil

The demand for energy, particularly for fossil fuels, has been increasing in line with the growing number of transportation units. However, natural resource conditions such as fossil fuels are not always fulfilled. This is because fossil fuels are categorized as non-renewable resources. Moreover, all countries in the world are required to reduce the use of fossil resources and increase the use of green energy. Therefore, alternative green energy sources are needed to replace fossil fuels. Biodiesel is a green energy source that could be produced from renewable resources. Biodiesel could be obtained from non-food sources such as kesambi oil. In this research, the biodiesel production process was carried out by esterification and transesterification methods. The transesterification process was performed by varying the molar ratio between ethanol and kesambi oil. The molar ratio used in the transesterification process were 4:1, 6:1, 8:1, 10:1, and 12:1. The results showed that the molar ratio of 12:1 produced the lowest values of density, viscosity, and flash point, which were 0.839 g/ml, 3.98 CST, and 109.4°C, respectively, but the highest values of calorific value and yield, which were 9,040 cal/g and 91.30%, respectively.

Finance and the environment: The eco‐impact of market‐ and institution‐driven development in Africa using land‐use‐adjusted metrics across sources of greenhouse gases

AbstractAfrica must ensure that its development trajectories are sustainable. In pursuit of viable policy pathways, this study examines the eco‐impact of the energy mix (Te) and financial development (FD) in selected African countries. The Te path is defined using the emission‐intensity paradigm, where positive trends indicate a strong dependence on fossil fuels, while negative trends suggest a shift toward greener energy sources. The FD impact is disaggregated to recognize the separate effects of market‐based (FM) and institution‐based (FI) development. This study utilized land‐use metrics across major greenhouse gas (GHG) sources, drawing data from a panel of 33 countries spanning from 1982 to 2021. It employs a novel instrumental‐variables approach for fitting panel‐data models, addressing cross‐sectional dependence issues and incorporating heterogeneous slope coefficients using the mean‐group estimator. Empirical findings reveal that positive trends in Te have a significant and positive impact on total GHG emissions (GHGe), whereas FM has a negative and significant effect on GHGe, suggesting its active role in mitigating climate impacts. The disaggregation of GHGe highlights the distinct impacts on CO2 (CO2e), nitrous oxide (N2Oe) and methane (CH4e) emissions. Economic affluence positively impacts CH4e, while positive trends in Te primarily increase CO2e. FI significantly reduces N2Oe, while FM notably decreases CO2e. Furthermore, FI has a significant negative impact on the emission intensity of Te, indicating its role in promoting green energy transition. These findings underscore the necessity for nuanced policy interventions that integrate FD with environmental objectives, promote green energy transition and address land‐use challenges.

Green moisture-electric generator based on supramolecular hydrogel with tens of milliamp electricity toward practical applications.

Moisture-electric generators (MEGs) has emerged as promising green technology to achieve carbon neutrality in next-generation energy suppliers, especially combined with ecofriendly materials. Hitherto, challenges remain for MEGs as direct power source in practical applications due to low and intermittent electric output. Here we design a green MEG with high direct-current electricity by introducing polyvinyl alcohol-sodium alginate-based supramolecular hydrogel as active material. A single unit can generate an improved power density of ca. 0.11 mW cm-2, a milliamp-scale short-circuit current density of ca. 1.31 mA cm-2 and an open-circuit voltage of ca. 1.30 V. Such excellent electricity is mainly attributed to enhanced moisture absorption and remained water gradient to initiate ample ions transport within hydrogel by theoretical calculation and experiments. Notably, an enlarged current of ca. 65 mA is achieved by a parallel-integrated MEG bank. The scalable MEGs can directly power many commercial electronics in real-life scenarios, such as charging smart watch, illuminating a household bulb, driving a digital clock for one month. This work provides new insight into constructing green, high-performance and scalable energy source for Internet-of-Things and wearable applications.