Maximization of Power Density of Direct Methanol Fuel Cell for Greener Energy Generation Using Beetle Antennae Search Algorithm and Fuzzy Modeling.

Direct methanol fuel cells (DMFCs) are promising form of energy conversion technology that have the potential to take the role of lithium-ion batteries in portable electronics and electric cars. To increase the efficiency of DMFCs, many operating conditions ought to be optimized. Developing a reliable fuzzy model to simulate DMFCs is a major objective. To increase the power output of a DMFC, three process variables are considered: temperature, methanol concentration, and oxygen flow rate. First, a fuzzy model of the DMFC was developed using experimental data. The best operational circumstances to increase power density were then determined using the beetle antennae search (BAS) method. The RMSE values for the fuzzy DMFC model are 0.1982 and 1.5460 for the training and testing data. For training and testing, the coefficient of determination (R2) values were 0.9977 and 0.89, respectively. Thanks to fuzzy logic, the RMSE was reduced by 88% compared to ANOVA. It decreased from 7.29 (using ANOVA) to 0.8628 (using fuzzy). The fuzzy model's low RMSE and high R2 values show that the modeling phase was successful. In comparison with the measured data and RSM, the combination of fuzzy modeling and the BAS algorithm increased the power density of the DMFC by 8.88% and 7.5%, respectively, and 75 °C, 1.2 M, and 400 mL/min were the ideal values for temperature, methanol concentration, and oxygen flow rate, respectively.

Membrane-based carbon capture: Recent progress, challenges, and their role in achieving the sustainable development goals.

The rapid growth in the consumption of fossil fuels resulted in climate change and severe health issues. Among the different proposed methods to control climate change, carbon capture technologies are the best choice in the current stage. In this study, the various membrane technologies used for carbon capture and their impact on achieving sustainable development goals (SDGs) are discussed. Membrane-based carbon capture processes in pre-combustion and post-combustion, which are known as membrane gas separation (MGS) and membrane contactor (MC), respectively, along with the process of fabrication and the different limitations that hinder their performances are discussed. Additionally, the 17 SDGs, where each representing a crucial topic in the current global task of a sustainable future, that are impacted by membrane-based carbon capture technologies are discussed. Membrane-based carbon capture technologies showed to have mixed impacts on different SDGs, varying in intensity and usefulness. It was found that the membrane-based carbon capture technologies had mostly influenced SDG 7 by enhancement in the zero-emission production, SDG 9 by providing 38-42% cost savings compared to liquid absorption, SDG 3 through reducing pollution and particulate matter emissions by 23%, and SDG 13, with SDG 13 being the most positively influenced by membrane-based carbon capture technologies, as they significantly reduce the CO2 emissions and have high CO2 capture yields (80-90%), thus supporting the objectives of SDG 13 in combatting climate change.

Membrane-based water and wastewater treatment technologies: Issues, current trends, challenges, and role in achieving sustainable development goals, and circular economy.

Membrane-based technologies are recently being considered as effective methods for conventional water and wastewater remediation processes to achieve the increasing demands for clean water and minimize the negative environmental effects. Although there are numerous merits of such technologies, some major challenges like high capital and operating costs . This study first focuses on reporting the current membrane-based technologies, i.e., nanofiltration, ultrafiltration, microfiltration, and forward- and reverse-osmosis membranes. The second part of this study deeply discusses the contributions of membrane-based technologies in achieving the sustainable development goals (SDGs) stated by the United Nations (UNs) in 2015 followed by their role in the circular economy. In brief, the membrane based processes directly impact 15 out of 17 SDGs which are SDG1, 2, 3, 5, 6, 7, 8, 9, 11, 12, 13, 14, 15, 16 and 17. However, the merits, challenges, efficiencies, operating conditions, and applications are considered as the basis for evaluating such technologies in sustainable development, circular economy, and future development.

Role of microalgae in achieving sustainable development goals and circular economy.

In 2015, the United Nations General Assembly (UNGA) set out 17 Sustainable Development Goals (SDGs) to be achieved by 2030. These goals highlight key objectives that must be addressed. Each target focuses on a unique perspective crucial to meeting these goals. Social, political, and economic issues are addressed to comprehensively review the main issues combating climate change and creating sustainable and environmentally friendly industries, jobs, and communities. Several mechanisms that involve judicious use of biological entities are among instruments that are being explored to achieve the targets of SDGs. Microalgae have an increasing interest in various sectors, including; renewable energy, food, environmental management, water purification, and the production of chemicals such as biofertilizers, cosmetics, and healthcare products. The significance of microalgae also arises from their tendency to consume CO2, which is the main greenhouse gas and the major contributor to the climate change. This work discusses the roles of microalgae in achieving the various SDGs. Moreover, this work elaborates on the contribution of microalgae to the circular economy. It was found that the microalgae contribute to all the 17th SDGs, where they directly contribute to 9th of the SDGs and indirectly contribute to the rest. The major contribution of the Microalgae is clear in SDG-6 "Clean water and sanitation", SDG-7 "Affordable and clean energy", and SDG-13 "Climate action". Furthermore, it was found that Microalgae have a significant contribution to the circular economy.

Recent progress in renewable energy based-desalination in the Middle East and North Africa MENA region.

BACKGROUND: The Middle East and North Africa (MENA) countries are rapidly growing in population with very limited access to freshwater resources. To overcome this challenge, seawater desalination is proposed as an effective solution, as most MENA countries have easy access to saline water. However, desalination processes have massive demand for energy, which is mostly met by fossil fuel-driven power plants. The rapid technological advancements in renewable energy technologies, along with their gradually decreasing cost place renewable energy-driven power plants and processes as a promising alternative to conventional fuel-powered plants. AIM OF REVIEW: In the current work, renewable energy-powered desalination in the MENA region is investigated. Various desalination technologies and renewable energy resources, particularly those available in MENA are discussed. A detailed discussion of suitable energy storage technologies for incorporation into renewable energy desalination systems is also included. KEY SCIENTIFIC CONCEPTS OF REVIEW: The progress made in implementing renewable energy into power desalination plants in MENA countries is summarized and analyzed by describing the overall trend and giving recommendations for the potential amalgamation of available renewable energies (REs) and available desalination technologies. Finally, a case study in the MENA region, the Al Khafji solar seawater reverse osmosis (SWRO) desalination plant in the Kingdom of Saudi Arabia KSA, is used to demonstrate the implementation of REs to drive desalination processes.

Geopolymer concrete as green building materials: Recent applications, sustainable development and circular economy potentials.

Environmental degradation and increased greenhouse gas emissions force communities to achieve sustainable green building and construction materials. The environmental and financial aspects of sustainable development and circular economy strongly depend on the recycling of wastes into new products. Geopolymers gained increasing attention because of their eco-friendly and superior mechanical characteristics and their ability to utilize numerous wastes as precursors. Although there are numerous studies on geopolymer, little attention was focused on geopolymer concrete (GeoC). Hence, This review follows the Preferred Reporting Items for Systematic Reviews (PRISMA) investigated in detail GeoC. The first part of this study explores the recent synthesis processes, different precursors, and applications of geopolymer concrete (GeoC) in numerous sectors as well as the mechanical, microstructural, and physical related characteristics of GeoC developed from various wastes. The second part discusses in detail the contributions of GeoC to the sustainable development goals (SDGs) stated by the United Nations. The last part discusses the implementation of different wastes to develop GeoC-based circular economy to provide recommendations and prospects for GeoC science and technology. An eco-friendly, sustainable, structurally sound GeoC matrixes can be developed from numerous industrial, municipal, and agricultural wastes. Such GeoC is a good candidate to traditional concrete and some other building materials. GeoC is strongly contribute into 12 SDGs of the main 17 SDGs. Optimizing the elements of GeoC would decrease its cost and thus promote a green circular economy.

Impact of COVID-19 on the Renewable Energy Sector and Mitigation Strategies.

This review explores the impact of the COVID-19 pandemic on the renewable energy (RE) sector, especially in countries with the highest RE capacities, e.g., the USA, China, India, and the EU. It highlights stimulus packages put in place by governments worldwide and their sustainability to cushion the RE sector. Commissioning of RE projects has stalled due to lack of funding allocation and interruptions in the supply of equipment and components due to lockdown measures. Despite the need to fund COVID-19 vaccination programs and other related health services, the world must not neglect other sectors of the economy, creating more problems, such as worsening the climate change situation in the long run. This review aims to present the information needed to sustain future energy during the COVID-19 global pandemic.

High energy storage quasi-solid-state supercapacitor enabled by metal chalcogenide nanowires and iron-based nitrogen-doped graphene nanostructures.

Transition metal selenides (TMS) have excellent research prospects and significant attention in supercapacitors (SCs) owing to their high electrical conductivity, superior electrochemical activity and excellent structural stability. However, the commercial utilization of TMS remains challenge due to their elaborate synthesis. Present study designed a hierarchical cobalt selenide (CoSe2) nanowire array on Ni-foam to serve as a positive electrode for asymmetric SCs (ASCs). The nanowires-like morphology of CoSe2 was highly advantageous for SCs, as it offered enhanced electrical conductivity, plenty of surface sites, and short ion diffusion. The as-obtained, CoSe2 nanowire electrode demonstrated outstanding electrochemical features, with an areal capacity of 1.08 mAh cm-2 at 3 mA cm-2, high-rate performance (69.5 % at 50 mA cm-2), as well as outstanding stability after 10,000 cycles. The iron titanium nitride@nitrogen-doped graphene (Fe-TiN@NG) was prepared as a negative electrode to construct the ASCs cell. The obtained ASCs cell illustrated an energy density of 91.8 W h kg-1 at a power density of 281.4 W kg-1 and capacity retention of 94.6% over 10,000 cycles. The overall results provide a more efficient strategy to develop redox-ambitious active materials with a high capacity for advanced energy-storage systems.

Faradic capacitive deionization (FCDI) for desalination and ion removal from wastewater.

Capacitive deionization (CDI) is one of the emerging desalination technologies that attracted much attention in the last years as a low-cost, energy-efficient, and environmentally-friendly alternative to other desalination technologies, such as multi-stage flash desalination (MSF) and multiple effect distillation (MED). The implementation of faradaic electrode materials is a promising method for enhancing CDI systems' performance by achieving higher salt removal characteristics, lower energy consumption, and better ion selectivity. Therefore, a novel CDI technology named Faradaic CDI (FCDI) that implements faradaic electrode materials arose as a high-performance CDI cell design. In this work, the application of FCDI cells in desalination and wastewater treatment systems is reviewed. First, the progress done on using various FCDI systems for saline water desalination is summarized and discussed. Next, the application of FCDI in wastewater treatment applications and selective ion removal is presented. A thorough comparison between FCDI and conventional carbon-based CDI is carried out in terms of working principle, electrode material's cost, salt removal performance, energy consumption, advantages, and disadvantages. Finally, future research consideration regarding FCDI technology is included to drive this technology closer towards practical application.

Effects of COVID-19 on the environment: An overview on air, water, wastewater, and solid waste.

The COVID-19 pandemic has hit the world hardly as of the beginning of 2020 and quickly spread worldwide from its first-reported point in early Dec. 2019. By mid-March 2021, the COVID-19 almost hit all countries worldwide, with about 122 and 2.7 million confirmed cases and deaths, respectively. As a strong measure to stop the infection spread and deaths, many countries have enforced quarantine and lockdown of many activities. The shutdown of these activities has resulted in large economic losses. However, it has been widely reported that these measures have resulted in improved air quality, more specifically in highly polluted areas characterized by massive population and industrial activities. The reduced levels of carbon, nitrogen, sulfur, and particulate matter emissions have been reported and confirmed worldwide in association with lockdown periods. On the other hand, ozone levels in ambient air have been found to increase, mainly in response to the reduced nitrogen emissions. In addition, improved water quality in natural water resources has been reported as well. Wastewater facilities have reported a higher level of organic load with persistent chemicals due to the increased use of sanitizers, disinfectants, and antibiotics. The solid waste generated due to the COVID-19 pandemic was found to increase both qualitatively and quantitatively. This work presents and summarizes the observed environmental effects of COVID-19 as reported in the literature for different countries worldwide. The work provides a distinct overview considering the effects imposed by COVID-19 on the air, water, wastewater, and solid waste as critical elements of the environment.

Optimization of Fuel Cell Performance Using Computational Fluid Dynamics.

A low cost bipolar plate materials with a high fuel cell performance is important for the establishment of Proton Exchange Membrane (PEM ) fuel cells into the competitive world market. In this research, the effect of different bipolar plates material such as Aluminum (Al), Copper (Cu), and Stainless Steel (SS) of a single stack of proton exchange membrane (PEM) fuel cells was investigated both numerically and experimentally. Firstly, a three dimensional (3D) PEM fuel cell model was developed, and simulations were conducted using commercial computational fluid dynamics (CFD) ANSYS FLUENT to examine the effect of each bipolar plate materials on cell performance. Along with cell performance, significant parameters distributions like temperature, pressure, a mass fraction of hydrogen, oxygen, and water is presented. Then, an experimental study of a single cell of Al, Cu, and SS bipolar plate material was used in the verification of the numerical investigation. Finally, polarization curves of numerical and experimental results was compared for validation, and the result shows that Al serpentine bipolar plate material performed better than Cu and SS materials. The outcome of the investigation was in tandem to the fact that due to adsorption on metal surfaces, hydrogen molecules is more stable on Al surface than Cu and SS surfaces.

A critical review on environmental impacts of renewable energy systems and mitigation strategies: Wind, hydro, biomass and geothermal.

The annual growth of global energy demand and the associated environmental impacts (EIs) has an important role in the large sustainable and green global energy transition. Renewable energy systems have been attracting substantial economic, environmental, and technical attention throughout the last decade, while some have been in the market for almost a century. However, even renewable energy may negatively affect the environment, which is widely considered much less harsh than fossil energy resources. This, in return, requires more consideration and appropriate precautions to be taken. This work discusses the environmental impacts (EIs) of small and medium-sized wind, hydro, biomass, and geothermal power systems. The approach goes through all stages from planning and conception to construction and installation and throughout service life and decommissioning. For various circumstances and technically and ecologically viable guidelines for their effect on natural resources and wildlife, clear and comprehensive solutions have been given.

Environmental impacts of nanofluids: A review.

Nanofluids (NFs) have been expanding their applications in many areas as high-performance heat transfer fluid (HTF) for heating and cooling purposes. This is mainly due to the improved thermophysical properties relative to the base fluid (BF). The addition of nanoparticles (NPs) to BF, to obtain NFs, increases the thermal conductivity, hence better heat transfer properties and thermal performance. The properties of NFs can be considered somehow intermediate between those of the BF and the added solid NPs. The improved heat transfer using NFs results in increased energy conversion efficiency, which results in reduced energy consumption for heating or cooling applications. BF and their environmental impacts (EIs) have been widely discussed within the scope of their applications as a HTF, with most of the attention given to the improved energy efficiency. The IEs of NPs and their toxicity and other characteristics have been extensively studied due to the widespread applications on newly engineered NPs. However, with the evolution of expanding the applications of NFs, the different EIs were not well addressed. The discussion should consider both the base fluid and NPs added in combination as the NF constitutes. The current work presents a brief discussion on the EIs of NFs. The discussion presented in this work considers the NPs as the primary contributor to the EIs of different NFs. It was found that the EIs of NFs depend significantly on the type of NP used, followed by the BF, and finally, the loading of NPs in BF. The use of non-toxic and naturally occurring NPs at lower NPs loading in water as NF promises a much lower EIs in terms of toxicity energy requirements for production, and other EIs, while still maintaining high thermal performance. The production methods of both NPs, i.e., synthesis route, and NF, i.e., one-step or two-step, were found to have a significant effect on the associated EIs of the produced NF. The simpler NP synthesis route and NF production will result in much lower chemicals and energy requirements, which in turn reduce the EIs.

Fuel cells for carbon capture applications.

The harmful effect of carbon pollution leads to depletion of the ozone layer, which is one of the main challenges confronting the world. Although progress is made in developing different carbon dioxide (CO2) capturing methods, these methods are still expensive and face several technical challenges. Fuel cells (FCs) are efficient energy converting devices that produce energy via an electrochemical process. Recently varying kinds of fuel cells are considered as an effective method for CO2 capturing and/or conversion. Among the different types of fuel cells, solid oxide fuel cells (SOFCs), molten carbonate fuel cells (MCFCs), and microbial fuel cells (MFCs) demonstrated promising results in this regard. High-temperature fuel cells such as SOFCs and MCFCs are effectively used for CO2 capturing through their electrolyte and have shown promising results in combination with power plants or industrial effluents. An algae-based microbial fuel cell is an electrochemical device used to capture and convert carbon dioxide through the photosynthesis process using algae strains to organic matters and simultaneously power generation. This review present a brief background about carbon capture and storage techniques and the technological advancement related to carbon dioxide captured by different fuel cells, including molten carbonate fuel cells, solid oxide fuel cells, and algae-based fuel cells.

Evaluation of the nanofluid-assisted desalination through solar stills in the last decade.

Remote areas and poor communities are occasionally deprived of access to freshwater. It is, therefore, critical to providing a cheap and efficient desalination system that encourages the development of those communities and benefiting society at large. Solar stills are an affordable, direct method of water desalination, but its productivity is the critical challenge hindering its application. To ease this, research has focused on the role of nanofluids to improve heat transfer. Other works have focused on improving the design in consort with utilizing the nanofluids. This review reports and discusses the substantial role of nanofluids to enhance the productivity and energy utilization efficiency of the solar stills. Specifically, the mechanism of energy transfer between the nanoparticles and the base fluid. This includes both plasmonic and thermal effects. It is evident that nanofluid utilization in small fraction enhanced the thermal conductivity compared to base fluid alone. Alumina was found to be the most suitable nanoparticle used as nanofluid inside the solar stills due to its availability and lower cost. Still, other competitors such as carbon nanostructures need to be investigated as it provides higher enhancement of thermal conductivity. Also, several aspects of energy utilization enhancement have been discussed, including innovative application techniques. The challenges of such integrated systems are addressed as well.

Environmental impacts of solar energy systems: A review.

The annual increases in global energy consumption, along with its environmental issues and concerns, are playing significant roles in the massive sustainable and renewable global transmission of energy. Solar energy systems have been grabbing most attention among all the other renewable energy systems throughout the last decade. However, even renewable energies can have some adverse environmental repercussions; therefore, further attention and proper precautional procedures should be given. This paper discusses in detail the environmental impacts of several commercial and emerging solar energy systems at both small- and utility-scales. The study expands to some of the related advances, as well as some of the essential elements in their systems. The approach follows all the stages, starting with the designs, then throughout their manufacturing, materials, construction or installation phases, and over operation lifetime and decommissioning. Specific solutions for most systems such as waste minimization and recycling are discussed, alongside with some technically and ecologically favorable recommendations for mitigating the impacts.

Environmental aspects of fuel cells: A review.

Fossil fuels represent the primary energy supply utilized worldwide. Despite this, fossil fuels are both limited resources and have severe environmental impacts that result in climate change and several health issues. Fuel cells (FCs) are efficient energy conversion devices, which can be used for energy conversion and storage. Although different types of FCs exhibit promising features for future usage, they also have some environmental aspects that ought to be addressed. This review summarizes the different types of FCs, including the advantages and disadvantages of each. The different environmental aspects of the common types of FCs are then comprehensively discussed. This review also compares FCs to conventional power generation systems to illustrate their relative environmental benefits. Although FCs are considered more environmental-friendly compared to conventional energy conversion systems, there are still evident operational and environmental setbacks among different FC types. These setbacks, however, must be compared in context of the intended application, fuel type, and all other involved factors in order to have a clear and fair comparison. FCs are considered environmentally friendly and more efficient. However, this is usually only when considering the operational phase or the operational perspective. The main challenge facing FCs still remains fuel sourcing, like, for example, in the case of obtaining hydrogen for hydrogen FCs, where hydrogen production causes environmental impacts. The same applies for electrode materials, where, in many cases, either a noble metal such as platinum, or other precious metals, or costly material. With this consideration, a life cycle assessment (LCA) is a useful tool that considers all of the manufacturing, fuel sourcing, and operational phases. Although using FCs shows evident environmental improvements compared to conventional energy sources, the LCA of FCs compared to that of conventional power sources shows a similar performance. This is mainly due to the EIs associated with fuel sourcing and material acquisition, either for precious metals used for low-temperature FCs, or thermally and chemically stable materials used for medium- and high-temperature FCs. Both of these also contribute largely to the cost of FCs. Developments in both areas will undoubtedly help to make FCs both more environmental-friendly and cost-efficient.

Recent progress in environmentally friendly geopolymers: A review.

The manufacturing of cement demand burning of huge quantities of fuel as well as significant emissions of CO2 resulting from the decomposition of limestone that consequently resulted in severe environmental impact that is estimated by one ton of CO2 per ton of cement. Geopolymerization technology is an effective method for converting wastes (containing alumina and silica) into useful products. It can reduce CO2 emissions significantly from the cement industry. The geopolymerization process usually starts with source materials based on alumina/silicate in addition to alkaline liquids. The compressive strength, setting time, and workability of the final product depends mainly on the type and proportions of the precursors, the type and strength of the activator, the mixing and curing conditions. The structural performance of a geopolymer is similar to that of ordinary Portland cement (OPC). Therefore, geopolymer can replace OPC, and thus decreasing the energy consumption, reducing the cost of the building materials, and minimizing the environmental impacts of the cement industry. This review summaries the mechanism of geopolymerization, including the controlling parameters and different raw materials (fly ash, kaolinite and metakaolin, slag, red mud, silica waste, heavy metals waste, and others) with particular focus on recent studies and challenges in this area.

Progress in carbon capture technologies.

Human factors are one of the key contributors to carbon dioxide emissions into the environment. Since the industrial revolution, the atmospheric carbon dioxide levels have increased appreciably. This has been attributed to the utilization of fossil fuels for energy generation coupled with the clearing of forests and extensive manufacturing of some industrial products such as cement. The increase in atmospheric concentrations of carbon dioxide has been widely linked to climate change and the Earth's temperature. A drastic approach is therefore needed in terms of policy formulation to address this global challenge. Carbon capture and storage are reliable tools that can be introduced to the industrial sector to address this issue. Therefore, this review presents a thorough investigation of the various technologies that can be harnessed to capture carbon dioxide. The cost associated with the capture, transport, and storage of the carbon dioxide is discussed. Socio-economic aspects of carbon capture and storage technologies are also presented in this review. Factors influencing public awareness of the technology and perceptions associated with carbon capture and storage should be a point for consideration in future research activities relating to this novel technology. This, in effect, this will ensure effective expert knowledge communication to the general public and foster social acceptance of this technology.

Environmental impact of desalination processes: Mitigation and control strategies.

Freshwater supplies are in shortage relative to the high demand for different human activities, making desalination of saline water a must. Desalination to extract water from saline water has been well established as a reliable non-conventional water supply. However, desalination as any human-based process has resulted in many impacts on the environment. Brine loaded with chemicals being discharged back to the environment, along with greenhouse gases (GHGs) emissions being released to the atmosphere, are the most significant impacts, which has been extensively studied, with some efforts given to its mitigation and control. The current work discusses the mitigation and control strategies (M&CS) to the different environmental impacts (EIs) of desalination processes. The article compiles the M&CS in one work, instead of the distributed and separate treatment of the EIs of each desalination step and its respective M&CS as currently present in literature. The article tracks the water flow in an intake-to-outfall approach exploring how to minimize the impacts at each step and as a whole process. This starts from intake, pretreatment processes, desalination technology, and finally, brine discharge. The EIs associated with each desalination process element is thoroughly discussed with proposed M&CS. The work shows clearly that many EIs can be eliminated or minimized by incorporating specific design criteria and process improvements. The feedwater source has shown to have a great effect on EIs. Similarly, desalination technology has shown a considerable effect on the EIs related to brine characteristics and energy consumption. Hybrid and emerging desalination systems have shown reduced EIs relative to conventional thermal and membrane desalination technologies, while the utilization of renewable and waste energy sources has shown a significant reduction in EIs related to energy consumption.