According to the ANSI/ASHRAE Standard 55, thermal comfort is a subjective evaluation of thermal environment satisfaction. Therefore, the most challenging issue about thermal comfort is the assessment by subjective evaluation and addressing the case as a mental condition. Hence, The primary goal of the study is to determine which of the well-known thermal comfort indices is most suited for studying urban pedestrian movement. The present research method is based on the study of a wide range of research related to climatic comfort on the scale of urban space. The research has a review character and is set to analyze the different indices comparatively. In the analytical approach, the most significant factors which are compared are 1- PMV (predicted mean vote), 2- P4SR (four-hour predicted transpiration index), 3- HSI (heat stress index), 4- SET (standard effective temperature), 5- E.T.* (new effective temperature), 6- PPD (predicted percentage of dissatisfied) and 7- PET (Physiological Equivalent Temperature). The results show each component's advantages and disadvantages in analyzing thermal comfort in urban pedestrian pathways. The findings also underscored the importance of incorporating mixed methodologies to assist designers in making more accurate selections during urban planning. The most difficult issues that should be reconsidered in order to gain a better understanding of thermal comfort as an "adaptive" issue in urban pedestrian pathways are 1- Resetting the reference temperatures, 2- Readdressing the equations for upper and lower limits, 3- Providing more comprehensive databases (age, weight, gender, and thermal history), and 4- Reprogramming the acceptable temperature ranges based on individual expectations. Controls, layout, airflow, and humidity, among other design considerations, would be better emphasized by urban designers.

There is no doubt that Saudi Arabia exports the most oil. The country has considered notable investments in Renewable Energy to diversify its economy and decrease dependence on oil export. The research aims to analyze the key factors that have influenced Saudi Arabia's renewable energy policy. The main question of our article is: What are the influential factors in Saudi Arabia's energy policy on renewable energy sources? In response, the research hypothesizes that the growing energy consumption of Saudi Arabia and its favorable geographical location for renewable energy production caused the country to invest in renewable energy for its energy mix, economy, and carbon emission reductions. To investigate the research hypothesis, we have used the theoretical framework of energy security by Benjamin Sovacool. The findings show that Saudi Arabia’s capital investments in renewable energy provide opportunities for the government to create a modern industry that creates jobs and revenue with the support of the private sector. Furthermore, industries and residences use renewable energy for electricity. Therefore, renewable energy has decreased fossil fuel dependence and diversification of the country's energy mix consumption. Data are collected through the library method. The analysis method is descriptive.

Off-grid power production utilizing renewable sources of power has become more significant and viable to meet the limited demands of remote locations. The primary goal of this study is to develop an economic and optimal hybrid PV/Biogas configuration for power production for rural common facilities, including one Primary school, Junior school, and Panchayat Ghar buildings of Sarai Jairam village in Uttar Pradesh, India. Data on the electric load was gathered for two schools and Panchayat Ghar. The PV/biogas hybrid configuration was designed utilizing the Hybrid Optimization Model for Electric Renewable (HOMER), and techno-economic analysis is carried out to fulfill the load requirements. The available biomass potential and the data on solar irradiance of the study area were utilized in the HOMER software to carry out the analysis. The HOMER analysis produced a solution that included total net present cost (NPC) and cost of electricity (COE), and these results were then further improved using sensitivity analysis. The sensitivity analysis employed sensitivity parameters like biomass potential, biomass pricing, solar irradiance, and variation in loads. Based on the NPC and COE, this analysis evaluates the system performance and demonstrates that it is techno-economically feasible.

Combining heat and power (CHP) technology, which uses renewable energy sources as fuel, will be a promising solution to increase energy security. This report aims to examine CHP technologies based on renewable energy, seek to increase their efficiency and reduce the unsustainable nature of renewable resources, and then examine the existing articles from an economic and technical perspective. Heat and electricity are generated simultaneously in CHP technology; heat is the limiting factor in this issue. Therefore, it should be installed in a place requiring heat and population density because transmission losses are reduced in this case. Among renewable energy sources used as fuel for CHP power plants, biomass has the largest share, and among fossil fuels, natural gas and coal have the largest share in CHP, respectively. The United States, Russia, and China have the largest shares in renewable power plants, respectively. All the articles reviewed mention the need for heat storage for CHP power plants. If regional heating and cooling using CHP technology are used, biomass consumption can be reduced by 31.4% compared to single heating, and this amount can be used more in value-added sectors.

This study investigates the dynamics and properties of non-premixed methane/air flames under three swirl numbers by segmenting flame images using the Otsu thresholding technique. Under three operating conditions, the lean blow out (LBO) and flame length, lift-off height, maximum width, flame angle, and flame pulsing displacements in terms of flame center of gravity, length, and width are measured and compared. A high-speed camera is used to record video of flames, and the image processing of frames collected from a high-speed video was accomplished by using the intermittency distribution method to quantitatively compare flame attributes. The findings show that increasing the swirl number from 0.5 to 0.7 generally has an unfavorable effect on the LBO at given fuel flow rates, and the LBO of flames under 35° (0.6 swirl number) and 40° (0.7 swirl number) swirlers has decreased up to about 15% and 40%, respectively when compared with a 30° swirler (0.5 swirl number). Additionally, observations indicate that the flame length (𝐿) and lift-off height (𝐿𝑂) drop as the swirl number rises, although the flame width (𝑊) and angle (𝛼) show an ascending tendency. Besides, flame lift-off reveals an increasing-decreasing trend with an increment in the airflow, and flame length decreases as the airflow rate increases. It was also observed that flame pulsating displacements in terms of center of gravity (𝛿𝐶𝐺), length (𝛿𝐿), and width (𝛿𝑊) increases with an increase in the fuel flow rate, and as the swirl number is increased, 𝛿𝐶𝐺 and 𝛿𝐿 lessens, while 𝛿𝑊 increases.

Among the types of renewable energy, solar energy has received more attention due to its ability to convert directly into electricity and heat, its ease of use, its possibility of storage, and its endlessness, so in recent decades, a lot of research has been done on solar energy systems in the world and in Iran. Considering Iran's potential in the field of solar energy and the country's need for this type of energy, it is necessary to locate and identify suitable sites for the use of solar energy. In this research, the potential of generating power from solar energy on the ocean coasts of south-eastern Iran has been investigated. The geographical data of the solar radiation map of Iran was used to estimate the power of electrical energy from spatial limiting criteria for the feasibility of installing photovoltaic panels at the power plant scale. Finally, the total power of electricity that can be extracted from suitable places in the region was calculated; results showed that 37.5% of the Makran area is exploitable as solar farms. With a conversion efficiency of 15% and an area factor of 70%, annual electricity production for the exploitable area is roughly 17200 GWh, which can be a driving force for the industrial, economic and social development of Makran region.

The consumption of hydrogen as an automotive fuel has been growing since the 1980s. It can be used both as a gasoline blend and as a pure fuel. All human activities involve the use of energy. Some examples are: fuels for transport and heating, electricity for various purposes, among others. It is a basic element for the production and commercialization of any goods or services and represents one of the main expenses of families. Thus, projected future trajectories for energy prices are of obvious interest to consumers and producers. The use of hydrogen generation and storage technology is an energy generation option to replace current fossil fuels, as it offers the opportunity to obtain energy with reduced environmental impacts and which does not pollute the environment. In this work, TiO2 fibers were obtained by the electrospinning technique and used as catalysts in the photodecomposition of water-ethanol mixtures for the production of hydrogen. The X-ray diffraction technique (XRD) was used to characterize the synthesized catalysts, the BET method provided measurements of the specific area, and scanning electron microscopy (SEM) analyzed the morphology of the samples. The results indicate that the fibers that contain the anatase phase in greater proportion have a high surface area and were the most effective in the production of hydrogen.

The world is searching to find alternatives to fossil fuels. The main criteria for an ideal future fuel are cleanliness, inexhaustibility, and independence from foreign control. Hydrogen fuel has indicated all these characteristics and is promoted worldwide as an environmentally friendly replacement for fossil fuels in the industrial and transportation sectors.

Sarawak is a state in Malaysia that has many potential sites for hydropower dams as Sarawak houses many hilly areas which are yet to be developed. As a result, many hydropower dams were proposed in Sarawak. This paper reviews the environmental and social impacts of hydropower projects in Sarawak. The murky river waters of Sarawak contributed to a high level of sedimentation in the hydroelectric plant reservoirs which increases the emission of greenhouse gases through mineralization and indirectly affects the lifespan of a hydroelectric plant. The ecosystem is adversely affected by the loss of trees, destruction of habitat for flora and fauna, and the narrowing of rivers due to sedimentation. The construction of hydropower plants forces nearby indigenous communities to relocate, which are given compensation by the Sarawak government. The issues behind the relocation process are explored in this paper with further details. The communities that are affected by the construction of the hydropower dams will have to be displaced from their original lands; thus, the approach by the government to compensate the affected locals in Sarawak is explored in this paper.

External-cooling indirect evaporative coolers with different configurations and working air sources are incomprehensively analyzed and compared so far. This paper investigates the mechanism and theory of operation of indirect flat-panel evaporative coolers based on X-analysis. Then, based on the second law of thermodynamics analysis, the entropy production rate of the flat-plate heat exchanger of the cooler is calculated. As a result of this analysis, the optimal energy efficiency-evaporation efficiency and cooling capacity values are presented in terms of effective parameters in the design.

Coronavirus Disease 2019 (COVID-19) has been destructive in various sectors of Malaysia. In the renewable energy sector, Malaysia thrives in harvesting solar energy, biomass energy, and hydro energy, but despite years of development, the impacts of COVID-19 on these fields remain significant. This paper reviewed, analyzed, and summarized the effects of COVID-19 on the renewable energy sector in Malaysia. According to reviews, solar energy projects experience postponements as the import of solar panels is halted. At the same time, biomass saw its productivity reduced as workers were sent home as a measure to curb COVID-19. The same can be seen with the hydroelectric dams, where a single case may form a cluster which, once again, puts the entire project on hold. These are just some examples of the disastrous impact of COVID-19. However, there are positive impacts as well. The reduction in CO2 emission and the investment in the renewable energy sector once fossil fuel drops its price are the same example testimonies. The future of the renewable energy sector after COVID-19 and the lessons learned from the impacts of COVID-19 are reviewed and presented in this paper as well.

Improving perovskite solar cell (PSC) efficiencies would not have been possible without discovering and incorporating novel materials. More significant than materials usage is the compatibility of various material components in the entire device. Charge transport materials have been at the heart of this discussion to decide a PSC's functioning fundamentally. This review highlights various high-efficiency examples using alternate charge transport materials, bringing us one step closer to commercializing this technology. The article also elaborates on recent innovations in Bismuth and Copper-based PSCs. These are possible candidates to replace the conventional materials used in a standard PSC and affirmatively yield favorable results through extensive research.

These days, one of the major threats in the world is climate change. It is already proven by a large number of strong evidence that human activities are responsible for these sudden changes. It is expected that in the future mankind will witness more severe consequences of climate change on the amount of precipitation and temperature levels in different regions of the world, and as a result of that, more both physical and economic water scarcity is anticipated to be seen. Each year food production industry produces a considerable amount of greenhouse gases which are the number one factor for global warming. By fluctuations in the groundwater, surface water, CO2 fertilization, and extreme weather conditions such as floods and droughts, a drastic impact on agricultural practices is expected to occur in Iran if the current trends are not slowed down or reversed. Any disturbance in food security and quality could lead to malnutrition, food-borne illnesses, or even death. Crop cultivation and livestock have their own unique impact on the total emitted GHGs. Given this, in this study, we analyzed the food production (both animal-based and plant-based), consumption, and global warming potential (CO₂e) of 11 main dietary categories in the Iranian food industry from 2010 to 2019. Moreover, the population growth in the decade was included in the study. The results of this article revealed that vegetable consumption faced a downward trend in the decade while animal protein sources remained almost intact and animal-based food items produce a considerably higher amount of greenhouse gases than plant-based dietary options.

Energy is a sector of production of considerable interest. Today's era is particularly dependent on energy. Both continuous technological upgrading and the increase in living standards require ever-greater energy security. Many countries in the world are formulating their policies in order to secure energy resources. Energy security is one of the most important objectives of any country in the international economic system. All countries are trying to secure energy resources whether they are endowed or through trade. However, the main issue that arises is the production of energy. Energy production has a direct and indirect impact on a country's economy. It is therefore essential to properly investigate those factors that determine energy production. What are those factors determining energy production? There are many factors that can determine energy production. This study will attempt to set an analytical framework that can analyze the factors that determine energy production. The methodology applied is the construction of a composite index (CI).

World energy consumption is constantly rising; therefore, it is essential to investigate different possibilities to produce power in the medium and long term. The sun is a clean source of power that is virtually inexhaustible. Photovoltaic (PV) power stations are used to harness this energy, but they are not completely reliable since they depend on weather patterns. To overcome this problem, large satellites with extensive solar panel surfaces can be placed in orbit. These satellites, known as Solar Power Satellites (SPS), would be positioned in geostationary orbit (GEO) thus constantly providing energy while avoiding meteorological conditions and erosive factors. These benefits make solar power station an appealing option for the energy of the future. Therefore, in this paper, the possibility and challenges of using solar-powered satellites are explored. The mechanisms regarding microwave transmission, photovoltaic collection, radiation impact, and propulsion are discussed. The advantages and disadvantages of solar-powered satellites are discussed regarding cost and practicality, and the current race between different countries to achieve this technology was examined. It was found that power could be collected with an efficiency of over 30% using gallium-arsenide photovoltaic cells. To minimize radiation effects, the use of a 100-micron transparent Pilkington Borosilicate Glass (commercially known as CMG cover glass) could be employed. For spacecraft propulsion, Hall thrusters provide the optimal combination between efficiency and thrust. Finally, the cost analysis indicates that to make the SPS viable, launch costs to GEO must be decreased by a factor of 10, solar panel efficiency must be increased to 40%, panel density must be minimized, and international cooperation must be achieved.

A hybrid renewable energy system is a feasible solution for off-grid electrification where grid electricity is not available due to economic or technical limitations. In this study, rural electrification is performed on a small longhouse settlement, Long Moh, in Sarawak, Malaysia, with a population of 308 from 70 households. Initially, a hybrid PV/Hydro/DG/Battery system is proposed due to the abundance of solar and hydro resources in the village. There have been a lot of studies based on PV/DG/Battery systems in Malaysia but less with the inclusion of hydropower. Through simulation and optimization process, the most optimal system in terms of Net Present Cost (NPC) is found to be a hybrid Hydro/DG/Battery system which provides a total NPC of $213,694.90, cost of electricity of $0.08/kWh, and operating cost of $9,495.56/year. The most environmentally friendly system is the proposed PV/Hydro/DG/Battery system due to less fuel consumption (12,863.63 L/year) and its high renewable penetration. The standalone diesel generator (DG) system was the least economic and most polluting system. The best system overall for rural electrification at the case study location is a hybrid Hydro/DG/battery system due to its relatively low NPC and emissions output compared to a standalone DG system.

Copter drone use has been on a steady increase over the last couple of decades. The main obstacle that has slowed down the widespread use of these systems is the limited flight time. This research paper will focus on implementing a hybrid system that includes a hydrogen fuel cell (HFC) along with a battery in a hex-copter configuration to determine its effectiveness and if possible, increase its flight time. Additionally, the different projects and studies that can be performed by students with this system were also discussed. The reason for the use of hydrogen relies on the fact that it has a higher energy density (120 kJ/g) than commercial lithium-ion polymer batteries (Li-Po), the type of batteries most commercial drones currently use, which only have an energy density of 1 kJ/g. This article was divided into two main experiments for its completion: testing the HFC and batteries with a parallel circuit composed of lightbulbs and testing both the HFC and LiPo batteries on the drone by spinning the motors without propellers. The data used for the analysis of the performance of the drone was the power drawn over the duration of each test. In addition, the fuel cell temperature and IV/IP curves were also studied. The results show a delay of less than 1 second between the transition from the fuel cell power to battery power. Additionally, it was found that both fuel cell and battery supplied energy at the same time, but the latter was almost negligible when the HFC was operating. However, the battery effectively supplied the drone with almost the same amount of power as the fuel cell when hydrogen was exhausted. Finally, it was found that the battery system plays an important role when the fuel cell is being turned on or off.

Co-firing biomass and fossil fuels in industrial furnaces is a suitable way to reduce the environmental impact of human activities with acceptable investment. In this paper, the results of numerical simulation co-firing of sulfide concentrate and three auxiliary fuels, including gasoil, kerosene, and sawdust biomass, are compared in the flash furnace copper smelting. For modeling of turbulent flow and combustion, RNG, k-ε model, and probability density function model (pdf) have been used, respectively. This study has been carried out to investigate the furnace temperature and combustion pollutants distribution. The numerical simulation results show that the flame temperature resulting from the combustion of diesel fuel and sawdust as auxiliary fuel is the highest and lowest, respectively. In biomass combustion, despite that the flame temperature is low, but the NOx mass fraction increases because there is nitrogen in the sawdust chemical composition. Also in sawdust combustion, the oxygen content is high, the SO2 and SO3 sulfur pollutants increase in the high temperatures regions of the furnace and the lower temperature of the auxiliary fuel burner, respectively. Because SO2 is formed at high temperatures (> 1273K), oxygen-rich and SO3 species are produced at relatively low temperatures with excess oxygen. The amount of CO emissions in sawdust combustion is much lower than the amount of combustion of diesel and oil. In the peak of the flash furnace for sawdust and diesel auxiliary fuels, the temperature is 2.29E+03 K, and the distribution of NOx, CO2, O2, SO2, and SO3 are 1.51E-04, 9.72E-02, 2.33E-03, 1.71E-01 and 2.45E-02 respectively.

The development of thin-film thermoelectric generators (TEG) is hampered by the lack of a new approach to their design. A new structure of thin-film TEGs has been proposed. The new structure is made by inverting flat thermocouples of the same name each other, generating electricity from adjacent rows of electrical circuits with the formation of narrow zones between the junctions on the substrate of each layer of a plurality of layers. Formed uniform alternation alternately areas of hot and cold junctions of thermocouples, which are connected in series in electrical circuits located on the substrate of each layer in uniform and parallel rows. The heat flow is brought to the areas of hot junctions, and heat is removed from the areas of cold junctions, respectively, by elements of the heat supply and heat removal circuits. The average temperature difference between hot and cold junctions is more than 100 ℃, which increases the thermo electromotive force. TEG ensures the achievement of several tens of kW of power. The new TEG structure makes it possible to fabricate thermocouples and substrates on the nanoscale.