The Executive Yuan in Taiwan plans to install air-conditioning (A/C) in all elementary schools within two years. However, besides the associated energy consumption and environmental issues, the use of A/C will inevitably result in the doors and windows of the classroom being closed, which will increase the accumulation of carbon dioxide (CO2) within the classroom. An excessive indoor CO2 concentration can result in reduced cognitive performance and an impaired learning efficiency. Therefore, the moderate introduction of external air into the classroom is essential to increase the air exchange rate (AER) and reduce the CO2 concentration level. Accordingly, the present study conducts a numerical investigation into the effects of various A/C operation strategies on the CO2 concentration within the classroom given different proportions of students remaining in the classroom during the recess. Overall, the results indicate that the optimal usage strategy is to operate the A/C over the full... [more]

At present, with the intelligence that has been achieved in computer and communication technologies, vehicles can provide many convenient functions to users. However, it is difficult for a vehicle to deal with computationally intensive and latency-sensitive tasks occurring in the vehicle environment by itself. To this end, mobile edge computing (MEC) services have emerged. However, MEC servers (MECSs), which are fixed on the ground, cannot flexibly respond to temporal dynamics where tasks are temporarily increasing, such as commuting time. Therefore, research has examined the provision of edge services using additional unmanned aerial vehicles (UAV) with mobility. Since these UAVs have limited energy and computing power, it is more important to optimize energy efficiency through load balancing than it is for ground MEC servers (MECSs). Moreover, if only certain servers run out of energy, the service coverage of a MEC server (MECS) may be limited. Therefore, all UAV MEC servers (UAV MEC... [more]

Various human activities emit greenhouse gasses (GHGs) that contribute to global climate change. These include the burning of fossil fuels for energy production, transportation, and industrial uses, and the clearing of forests to create farmland and pasture, all for urban and industrial development. As a result, temperatures around the world are rising, extreme weather events are occurring more frequently, and human health is suffering because of these changes. As a result of massive traffic, agriculture, and urbanization, the natural environment is being destroyed, negatively affecting humans and other living things. Humanity plans to live in smart cities within this ecosystem as the world evolves around these mutations. A smart city uses technology and data to improve the quality of life of its citizens and the efficiency of its urban systems. Smart cities have the potential to be more sustainable because they use technology and data to improve the efficiency of urban systems and red... [more]

The idea of sustainable development (SD) forces companies to combine the quality development of products with the simultaneous care of the natural environment. These actions should start with the product design process. The aim of the study was to create a modified method of Quality Function Development (QFD-CE), which will support the design of new products or improve the existing products on the market. In the proposed method (QFD-CE), the method integrates techniques such as: SMARTER method, brainstorming (BM), the method of selecting a team of experts, kinship diagram, fixed sum scale, and Likert scale. A novelty compared to the traditional QFD methodology is that design goals are set not only based on customer expectations, but also considering the impact on the natural environment. The originality of this proposition comes to the practical inclusion of including sustainability development criteria. The proposed method can be used in companies that design new products and are focu... [more]

With the continuous development of conventional oil and gas resources, the strategic transformation of energy structure is imminent. Shale condensate gas reservoir has high development value because of its abundant reserves. However, due to the multi-scale flow of shale gas, adsorption and desorption, the strong stress sensitivity of matrix and fractures, the abnormal condensation phase transition mechanism, high-speed non-Darcy seepage in artificial fractures, and heterogeneity of reservoir and multiphase flows, the multi-scale nonlinear seepage mechanisms are extremely complicated in shale condensate gas reservoirs. A certain theoretical basis for the engineering development can be provided by mastering the percolation law of shale condensate gas reservoirs, such as improvement of productivity prediction and recovery efficiency. The productivity evaluation method of shale condensate gas wells based on empirical method is simple in calculation but poor in reliability. The characterist... [more]

Greenhouse gas (GHG) emissions have significantly increased in recent years as a result of population rise and the increase in the number of residences, with high levels of energy use in homes and household appliances. It is crucial to move the housing industry away from high-carbon sources and toward low-carbon sources in order to minimize greenhouse gas emissions as a precaution. One of the most crucial systems that needs to be provided in order to achieve energy efficiency is the electric water heater (EWH), as they rank among the top electricity consumers. In this study, a double-tank EWH model was developed and simulated at various tank sizes (100 L, 200 L, 300 L and 400 L) and power ratios (1 kW, 2 kW, 3kW and 4 kW) in order to demonstrate energy efficiency. To obtain information for the simulation analysis of the tanks, the hourly water usage of 25 houses was measured. The single-tank and the double-tank models created for this study were both run in the Matlab/Simulink environm... [more]

Fossil fuels are associated with problems such as resource depletion and pollution, necessitating the exploration of alternatives. Giant miscanthus (Miscanthus × giganteus Greef et Deu), a perennial that can be harvested yearly, requires a low production energy input. It has less ash content and high heat efficiency and has attracted attention as an energy source. An on-site processing equipment, powered via a tractor and equipped with a chipper and a two-stage compression roller, was developed that can harvest 1000 kg of giant miscanthus per hour and simultaneously produce compressed pellets eliminating unnecessary processes such as transportation and processing. With its use, 33−74.5 kWh/t of electrical energy can be saved by producing pellets. The changes in moisture content between the produced compressed pellets and two samples of the ground product were measured immediately before compression for 24 h at relative humidity ranging from 65% to 80%. The moisture content was 6% initi... [more]

Building automation and the advancement of sustainability and safety in internal spaces benefit significantly from occupancy sensing. While particular traditional Machine Learning (ML) methods have succeeded at identifying occupancy patterns for specific datasets, achieving substantial performance in other datasets is still challenging. This paper proposes an occupancy detection method using non-intrusive ambient data and a Deep Learning (DL) model. An environmental sensing board was used to gather temperature, humidity, pressure, light level, motion, sound, and Carbon Dioxide (CO2) data. The detection approach was deployed on an edge device to enable low-cost computing while increasing data security. The system was set up at a university office, which functioned as the primary case study testing location. We analyzed two Convolutional Neural Network (CNN) models to confirm the optimum alternative for edge deployment. A 2D-CNN technique was used for one day to identify occupancy in rea... [more]

This article provides a detailed analysis of issues related to the complications while drilling in hydrate-bearing rocks of permafrost areas. The goal of the paper is to develop recommendations for preventing gas occurrence while drilling gas hydrate deposits and to eliminate gas leakiness of the intercasing space of the well. The results of modeling the effect of drilling mud injection on the temperature field of the well are presented. It is revealed that the most significant role is played by the injection rate of drilling mud and its temperature. The recommended flow rate of the process fluid should be within 0.30−0.45 m3/s, and its temperature should not exceed 20 °C. Controlling the parameters of drilling mud and its flow rate allows for avoiding intensive gas occurrence while drilling in gas hydrates. The presence of gas hydrates may be the cause of gas leakiness of the intercasing space in the permafrost area. One of the ways to eliminate leakiness is colmatation (clogging). A... [more]

While international trade drives countries’ economic growth and promotes employment, it also has some environmental impact. To investigate the impact of trade on carbon emissions and employment, this study performs a detailed decomposition and measurement of embodied carbon emissions and employment in value-added trade between China, Japan, and Korea from 2007−2019. The current study established that, while China’s trade with Japan and Korea created many domestic jobs, it also resulted in significant domestic carbon emissions. While Japan and Korea’s trade with China reduced carbon emissions, employment in their own countries was reduced and replaced by employment in China. At the value chain route level, trade among the three countries through each value chain route either achieves employment promotion at the cost of increased carbon emissions or promotes domestic emissions reduction at the cost of employment loss. However, it is worth noting that, when trade between Japan and Korea w... [more]

The co-combustion of dry coal and sludge was carried out in a self-built laboratory scale fluidized bed furnace. We used FTIR spectroscopy, high-resolution gas chromatography, high-resolution mass spectrometry, and XRF to capture and dynamically observe the flue gas fly ash and bottom ash. The sludge sample was taken from a municipal sewage treatment plant and its mixing ratio was below 20%. The temperature distribution of the furnace was observed and the emissions of the main gaseous pollutants such as SO2, NOx, and dioxins were measured in the combustion process. The heavy metal contents of fly ash and bottom ash were later detected to analyze the migration characteristics. The results showed that all of the gaseous pollutants measured increased linearly with the sludge mixing ratio. However, it could also meet the 1 metal content of bottom ash and fly ash did not change much. Through the elaboration of the above points, this study can provide guidance for future research on the co-c... [more]

The intensification of countries’ growth causes the depletion of natural resources, biodiversity degradation, ecological imbalances, damage, and disasters. The aggravation of ecological issues requires the development of mechanisms for simultaneous achievement of economic, social, and ecological goals. The energy sector is the core direction of economic decarbonization. Therefore, green economic growth requires economic development due to the extension of innovative technologies for renewable energies and relevant investment for that. The study aims to test the hypothesis on the impact of green field investment on green economic growth. The object of the research was countries in the European Union (EU) for 2006−2020. This study applied the Malmquist-Luenberger Global Productivity Index to estimate green economic growth. It considers the resources available for the production process in the country (labor, capital, energy), the desired outcome (gross domestic product) and undesirable r... [more]

Treating municipal wastewater is a complex and costly process. With rising energy costs and sustainability targets, wastewater treatment plants (WWTPs) are looking for alternatives to reduce operating costs and carbon dependence. Anaerobic digestion is the most common and established technology used in WWTPs to treat sludge since it can potentially improve energy recovery and reduce sewage treatment costs, mainly due to the generation of biogas. Biogas is a renewable energy resource and can be used in several applications, including heating and producing electricity. By exploring the biogas potential, WWTPs can reduce their operating costs and energy demands. The objective of this paper is to conduct a scoping literature review in order to provide the key concepts underpinning alternatives to improve biogas production and utilisation in WWTPs. In addition, this study aims to provide an overview of the current state-of-the-art that may serve as a quick reference for the research communi... [more]

Hydrogen has been identified as an ideal sustainable energy carrier to meet the ambitious targets of reducing greenhouse gas emissions and the dependence on fossil fuels [...]

This study aimed to systemize global scholarly publications on corporate social responsibility and renewable energy to detect their influence on green brand development within the SDGs. The initial data are retrieved from the Scopus database. To operate with the most relevant publications, several limitations were applied. The research sample consists of the 2000 most cited articles in the subject areas of (1) Social Sciences, (2) Business, Management, and Accounting, and (3) Economics, Econometrics, and Finance. This study is carried out in the following logical sequence. The first stage involves searching, collecting, and preprocessing articles representing the investigated topic. Then, several bibliometric techniques were employed to analyze and map the findings. The third stage integrated the obtained results and discussed future research directions. This paper offers some theoretical implications by analyzing and visualizing the investigated scientific output, particularly publica... [more]

Coffee, as one of the most consumed beverages, generates a wide variety of waste materials that can be used as biofuels and bio-products. Conventional pyrolysis can be used in rural areas, improving the circular bioeconomy of these places. In this work, the characterization and slow pyrolysis of specialty coffee residues, coffee silverskin (CSS), and spent coffee (SC) were conducted at temperatures from 300 to 600 °C. Physico-chemical and thermal analysis were carried out. In addition, the quantification of individual compounds as acetic, formic, and levulinic acids, caffeine, and other minor compounds was performed. The results indicate the differences between both waste materials in the obtained pyrolysis fractions. The biochar fraction for SC is lower at all temperatures and the liquid fraction higher, reaching maximum values of 62 wt.% in the liquid at 600 °C compared to 47% in CSS. The higher yield in the liquid fraction of SC corresponds to the higher contents of hemicellulose an... [more]

The cooling capacity needed by ultra-low temperature apparatus cannot be reached economically with a single vapor compression refrigeration cycle due to the constraint of the high compressor pressure ratio. The auto-cascade refrigeration cycle is a good alternative. In this work, a novel concept that applies the principle of the auto-cascade refrigeration cycle to store cold energy is conducted. The environment-friendly refrigerants of R600a/R290/R170 zeotropic mixtures are used to study the performance of the modified auto-cascade refrigeration cycle (MACRC) as an alternative for cold-energy applications. The simulation results show that a cooling capacity of 500 W can be provided below −60 °C. The mixture with a mass fraction of 0.25/0.35/0.40 yields a COP of 0.695 and an exergy efficiency of 0.262 at −66 °C. The performance of the MACRC system was investigated at an ambient temperature of 20 to 40 °C for indoor small-scale applications. It is concluded that the performance would be... [more]

Due to the emission of carbon dioxide and other greenhouse gases, the global climate is warming. As the world’s biggest emitter of carbon emissions, China faces a more severe challenge in reducing carbon emissions than developed countries. A reasonable prediction of the carbon peak in China will help the government to formulate effective emission reduction paths. This paper analyzes the changes in carbon emissions in China from 2004 to 2020, uses the STIRPAT model and scenario analysis method to predict carbon emissions from 2021 to 2030, and then calculates the carbon efficiency during carbon peaking to select the most effective carbon peak path for China. The results show that China’s carbon emissions increased year by year from 2004 to 2020. Under the baseline scenario, China is unlikely to reach its carbon peak before 2030. Under the regulatory scenarios, China can reach its carbon peak before 2030. The peak values from high to low are seen with the rapid development-weak carbon co... [more]

The excess carbon dioxide emissions generated by the use of fossil fuels cause serious environmental problems and hinder the sustainable development of our society [...]

The application of proton-exchange membrane fuel cells (PEMFCs) in maritime transportation is currently in the spotlight due to stringent emissions regulations and the establishment of a carbon trading system. However, salt in the marine environment can accelerate the degradation of proton-exchange membranes (PEM), which are the core component of PEMFCs. In this study, the effect of the NaCl concentration and temperature on the degradation of Nafion, the benchmark PEMFC membrane, was analyzed ex situ by accelerated degradation using Fenton’s test. The membrane properties were studied by mass change, fluoride ion emission, FTIR spectroscopy, and tensile test. The results showed that the degradation of Nafion membranes increased with the increase in temperature and NaCl concentration. Further studies revealed that Nafion produces C=O bonds during the degradation process. Additionally, it was found that sodium ions replace hydrogen ions in degraded Nafion fragments based on analysis of th... [more]

Presently, the rapid urbanization and industrialization have generated a great amount of waste around the world, which has led to increasing environmental pollution and greenhouse gas (GHG) emissions [...]

In this study, modeling and thermodynamic analysis of the combined double flash geothermal cycle generation was conducted using zeotropic fluid as the working fluid in the Organic Rankine Cycle (ORC). The analysis was performed based on the first and second laws of thermodynamics. Hexane, cyclohexane, isohexane, R245fa, and R236ea exhibit good performance at higher temperatures. In this study, three fluids—hexane, cyclohexane, and isohexane—were used. First, the model results for the pure fluids were compared with those of previous studies. Then, the important parameters of the cycle, including the efficiency of the first law of thermodynamics, the efficiency of the second law of thermodynamics, net productive power, and the amount of exergy destruction caused by changing the mass fraction of the refrigerant for the zeotropic fluids (investigated for the whole cycle and ORC), were obtained and compared.

As automobiles are major contributors to greenhouse gas emissions, the technological shift towards vehicle powertrain systems is an attempt to lower problems such as emissions of carbon dioxide and nitrogen oxides. Patent data are the most reliable measure of business performance for applied research and development activities when investigating knowledge domains or technology evolution. This is the first study on Japanese patent citation data of the green vehicle powertrains technology industry, using the social network analysis method, which emphasizes centrality estimates and community detection. This study not only elucidates the knowledge by visualizing flow patterns but also provides a precious and congregative method for verifying important patents under the International Patent Classification system and grasping the trend of the new technology industry. This study detects leading companies, not only in terms of the number of patents but also the importance of the patents. The e... [more]

In recent years, coal mine methane measurement techniques in mines have been gaining importance as poor firedamp control in work can cause the interruption of production and even fatal accidents. Since there is currently a variety of methane measurement equipment with different functional characteristics and measurement principles, a study is needed to indicate which type of equipment has the highest degree of confidence. This research presents the results of a study carried out by the Official Laboratory J. M. Madariaga (LOM) of the Polytechnic University of Madrid that aims to analyze the reliability of methane detection systems used in underground mining. Therefore, a series of portable and non-portable methane detectors with different measurement principles have been selected to subject them to laboratory tests following the methods described in the applicable regulations, such as time of response, dust effect, temperature, pressure, etc. The test equipment is usually the one used... [more]

In Japan, mechanical plastic recycling has been widely practiced. In recent years, the chemical recycling method has been gaining interest, especially due to its high-quality products similar to virgin materials. Understanding the environmental impact of both methods from the energy consumption standpoint is crucial so that attempts to preserve plastic resources can be based in the most energy-sustainable way. This research aims to determine the environmental impact of mechanical recycling and two types of chemical recycling technologies (coke oven and gasification) by analyzing their energy usage and environmental loads. The results relating to the electricity consumption and water usage show that mechanical recycling results in a 17% share of global warming potential (GWP), coke oven 51%, and gasification 32%. Although mechanical recycling results in a lower GWP, chemical recycling yields highly valuable products and byproducts that can be reused in its processes, such as steam and i... [more]