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Various strategies, including controls of morphology, oxidation state, defect, and doping, have been developed to improve the performance of Cu-based catalysts for CO2 reduction reaction (CO2RR), generating a large amount of data. However, a unified understanding of underlying mechanism for further optimization is still lacking. In this work, combining first-principles calculations and machine learning (ML) techniques, we elucidate critical factors influencing the catalytic properties, taking Cu-based single atom alloys (SAAs) as examples. Our method relies on high-throughput calculations of 2669 CO adsorption configurations on 43 types of Cu-based SAAs with various surfaces. Extensive ML analyses reveal that low generalized coordination numbers and valence electron number are key features to determine catalytic performance. Applying our ML model with cross-group learning scheme, we demonstrate the model generalizes well between Cu-based SAAs with different alloying elements. Further, electronic structure calculations suggest surface - negative center could enhance CO adsorption by back donating electrons to antibonding orbitals of CO. Finally, several SAAs, including PCu, AgCu, GaCu, ZnCu, SnCu, GeCu, InCu, and SiCu, are identified as promising CO2RR catalysts. Our work provides a paradigm for the rational design and fast screening of SAAs for various electrocatalytic reactions.

Hydrogen as an energy vector is seen as a key for the energy transition. Recently, more than 30 countries have launched their hydrogen strategies and roadmaps. Hydrogen storage and transportation are challenging steps of the hydrogen economy since all available options have significant drawbacks. This paper evaluates a power-to-liquid hydrogen process; the system is “charged” with electricity from renewable sources to produce hydrogen via water electrolysis; the produced hydrogen gas is liquefied and stored at ambient pressure and cryogenic temperature. The purpose of this paper is to report the first evaluation results of a system including a polymer electrolyte membrane electrolyser and a hydrogen liquefier. The evaluation was conducted using exergy-based methods, i.e. exergetic, exergoeconomic and exergoenvironmental analyses. The process of hydrogen liquefaction was simulated with the aid of the Aspen Plus software. The exergetic efficiencies for the liquefaction process and for the electrolyser are 42% and 47%, respectively. While the total exergetic efficiency of the power-to-liquid hydrogen system amounts to 44%. The total exergy destruction for the liquefier amounts to 9.3 MW and for the polymer electrolyser membrane electrolyser amounts to 19.3 MW. The electrolyser followed by the hydrogen compressors were identified as the components with the highest exergy destruction values and investment costs, while the compressors and the recuperators account for the highest exergoenvironmental impact. The sensitivity analysis shows that the specific liquefaction cost of hydrogen strongly varies with the electricity price and the cost of green hydrogen.

Radiative cooling without energy consumption and environmental pollution holds great promise as the next-generation cooling technology. To date, daytime radiative cooling performance is still slightly low, especially in humid areas. In this work, we demonstrated that nanoporous polyethylene (Nano PE) film can improve solar reflectivity from 96% to 99%, thus boosting radiative cooling performance. Moreover, the experimental results in humid areas indicate that Nano PE films can improve radiative cooling performance by ∼76% in a clear day and 120% in a day with few clouds. Additionally, compared with ordinary PE films, thin Nano PE films have significantly higher weather fastness and mechanical strength. More importantly, nano PE films can scatter part of visible light, thus suppressing the generation of light pollution in practical applications. Lastly, the modeling results reveal that with Nano PE films, more than 95% of China's areas can achieve daytime cooling performance. Our work can boost the development of radiative cooling technology with a very low cost.

Biogas, landfill gas, associated petroleum gas, and other tail gases accompanying various industrial processes are potential sources of hydrogen and carbon monoxide for solid oxide fuel cells via the reforming process. As these gases contain heavy hydrocarbons, fine-tuning of steam and carbon dioxide addition and specific temperature control are necessary to avoid carbon deposition during the reforming process. Numerical simulation plays a crucial role in designing miniaturized steam reforming reactors and optimal working conditions. All simulations of reforming processes must account for carbon deposition. The methods commonly seen in the open literature include Gibbs free energy minimization or parametric equations formalism. This paper utilizes Gaussian process regression as a tool for making predictions about which reforming parameters are suitable for carrying out this process without the danger of damaging the catalyst due to a carbon formation. Parametric equations formalism and Gibbs free energy minimization involve either the minimization of objective function or a search for roots of nonlinear functions. These tasks are sensitive to a choice of the starting points of the algorithm — wrong choice of starting points could lead to numerical instability. Unlike conventional methods, the Gaussian process regression approach bypasses the computation of equilibrium composition. It predicts carbon formation tendencies directly from the initial conditions which ensure stability.

The architecture, engineering, and construction (AEC) industry is undergoing a substantial change, and the technological advancements are shaping the future of this industry. Over years, numerous tools have been developed based on building information modeling (BIM) and the Internet of Things (IoT) to manage a variety of tasks and activities within different construction and operational phases in the AEC industry. Recently, with the advent of novel internet-enabled technologies in providing the ability of real-time connectivity, researchers have started to develop virtual design and construction (VDC) and digital twin approaches to remotely monitor, control, and optimize different work progresses and activities in real-time at any work level in the AEC industry. This paper presents a reference model to illustrates the main advantages and applications of VDC and digital twin, and to demonstrate their trends and anticipated cost savings in the AEC industry at a global level. These technological advancements along with augmented reality (AR) and virtual reality (VR) can offer the unique benefit of real-time monitoring of the current status as well as predicting the future of any physical structure at any level of work. The global demand and usage of these technological advancements will lead to great cost savings in the AEC industry which would be US$950 million in design and construction and US$400 million in operation and maintenance phases in the non-residential AEC industry in 2025. This paper also discusses the future challenges of VDC and digital twin in the industry. As a main line of future research, these technologies can simultaneously be utilized with artificial intelligence to enable human-centered decision making to automate and optimize work progresses. Such integrations of VDC, digital twin, artificial intelligence, and human-centered approaches will shape the future of the AEC industry and provide numerous research opportunities in this domain.

Geothermal energy with abundance and large quantity can partially cover building heating/cooling loads and promote the carbon-neutrality transitions. Shallow geothermal ventilation (SGV) system, with a little initial investment cost, is one of promising technologies to partly replace the conventional air-conditioning system for air pre-cooling/pre-heating. This paper reviews applications of SGV system for improving thermal performance over latest two decades, which mainly includes the reclassification of SGV system, coupling with other advanced energy-saving technologies, application potentials for building cooling/heating under various weather conditions. Heat transfer mechanism and mathematical modelling techniques have been reviewed, together with in-depth analysis on current research trends, existing limitations, and recommendations of SGV system. Phase change materials, with considerable latent energy density, can stabilize the thermal performance with high reliability. The review identifies that optimization designs and advanced approaches need to be investigated to address the existing urgent issues of SGV system (e.g., large land occupation, difficulty in centralized collection of condensate water timely for horizontal buried pipe, bacteria growth, polluted supply air, and high construction cost for vertical buried pipe). A plenty of studies show that the SGV system could greatly expand the application scope and improve system energy efficiency by combining with other energy-saving technologies. This paper will provide some guidelines for the scientific researchers and engineers to keep track on recent advancements and research trends of SGV system for the building thermal performance enhancement and pave path for future research works.

The design of solid oxide fuel cells (SOFC) using biogas for distributed power generation is a promising alternative to reduce greenhouse gas emissions in the energy and waste management sectors. Furthermore, the high efficiency of SOFCs in conjunction with the possibility to produce hydrogen may be a financially attractive option for biogas plants. However, the influence of design variables in the optimization of revenues and efficiency has seldom been studied for these novel cogeneration systems. Thus, in order to fulfill this knowledge gap, a multi-objective optimization problem using the NSGA-II algorithm is proposed to evaluate optimal solutions for systems producing hydrogen and electricity from biogas. Moreover, a mixed-integer linear optimization routine is used to ensure an efficient heat recovery system with minimal number of heat exchanger units. The results indicate that hydrogen production with a fuel cell downstream is able to achieve high exergy efficiencies (65–66%) and a drastic improvement in net present value (1346%) compared with sole power generation. Despite the additional equipment, the investment costs are estimated to be quite similar (12% increase) to conventional steam reforming systems and the levelized cost of hydrogen is very competitive (2.27 USD/kgH2).

Energy independence and sustainable renewable energy sources are the two main components of energy security for Nepal. More than 2/3rd of energy consumed in Nepal comes from biofuels and waste and about 1/4th of energy consumed comes from coal and petroleum products. With increasing number of motor vehicles and rising demand for cooking gas, Nepal’s coal and petroleum import bills in recent years have reached over Rs. 200 billion. With its vast water resources, Nepal has a great potential for energy independence and sustainability and achieve energy security. Nepal’s current 1,689 MW hydroelectricity capacity is expected to reach over 5,000 MW in next three to five years, which means Nepal will have a large amount of clean energy in the market. This increased hydropower production will also require an increased domestic consumption by making hydroelectricity affordable, reliable, and high-quality energy by improving its distribution system. Nepal also has a very high potential for solar power, which need to be harnessed and brought to the national grid. Nepal needs to harness all energy sources, which consist of hydropower, solar power, wind power, biofuels, and biogas, in a sustainable way for its energy independence and security. Because Nepal is in a geologically active and natural disasters prone area, it is critical to ensure ecological balance of Asta-Ja elements, Nepali letter, Jal (water), Jamin (land), Jungle (forest), Jadibuti (medicinal and aromatic plants), Janashakti (manpower), Janawar (animal), Jarajuri (crop plants) and Jalabayu (climate) while developing energy resources. Asta-Ja Framework serves as the connecting bridge between the energy resources and the end users. Strategic planning for comprehensive energy development considering ecological balance of Asta-Ja resources, decarbonization and electrification of energy end uses, improvement of energy infrastructures, continuous monitoring and evaluation of energy sector, and development of hydropower plants and alternative energy sources such as solar and wind is suggested for energy security in Nepal.

A permanent assessment of climate regime in forest sites has a key role in forest resource conservation and preservation of ecosystem services, biodiversity and landscape multi-functionality, informing sustainable forest management. In this view, time-series of meteorological data relative to several monitoring sites from the ICP-Forest network in Italy, were analyzed with the aim to define the number of site-specific observations, which can be considered adequate for further analysis on forest resource management. The relative importance of each factor accounted in our analysis (season, year, variable, plot, sampling proportion) was investigated comparing results through the use of descriptive statistics.

This study aims to estimate and explore the experience of introducing renewable energy use in the context of the world’s smart cities. In this regard, the study points out that the use of green energy is an important part of sustainable development. Environmental problems are a matter of global concern. Hence sustainable development is one of the approaches to end the harmful anthropogenic impact. The work includes quantitative assessment methods, for example, statistics, quantitative analysis, analogy, and synthesis. As a result, the analysis confirms that the effective development of a smart green city is impossible without the introduction of several renewable energy sources, the integrated use of which will reduce the likelihood of problems with the city’s energy supply. Likewise, the outcome accentuates that the desire to fully switch to renewable energy sources (RES) can be accompanied by several problems as the creation of RES technologies does not always take the risk of abnormal situations into account. In conclusion, the research findings are recommended to be taken into consideration by researchers in the field of smart and sustainable cities development, as well as urbanists and economists for designing future smart green cities based on renewable energy sources.

Negative environmental changes generally addressed as ‘syndromes’ areevaluated in the context of Soil Degradation (SD) and interpreted by usinga ‘Land-Use/Land Cover Changes’ (LULCCs) framework in order to dis-entangle ‘past trajectories’, ‘present patterns’, and ‘future changes’. Thisapproach allows to discuss the potential impact on SD processes and itrepresents an informed basis for identifying measurable outcomes of SD.This study focuses on the case of Emilia Romagna, a region located inthe North of Italy with high-value added agricultural productions. A multi-temporal analysis of land-use changes between 1954 and 2008 has been proposed, discussing the evolution of associated SD syndromes in EmiliaRomagna. The contributing information have been used as a baseline forSustainable Land Management (SLM) strategies. This framework of analysisprovides useful tools to investigate and to monitor the effects of SD in theMediterranean basin where several regions underwent common developmentpatterns yelding global pathological symptoms of environmental degradation.

The radiant systems consume less energy and provide better thermal comfort as compared to the conventional system, but the main drawback of radiant technology is inability to cater the latent load and condensation. This problem has engaged researchers to push their emphasis on Personalized Conditioning System (PCS). It forms a micro-climate region near the occupant. This study is aimed at PCS combined with a radiant conditioning system, which evaluates the performance of the PCS and compares it with different radiant cooling systems. A radiant cubicle was used to investigate the performance of the PCS for both heating & cooling modes. For heating mode, the Standard Effective Temperature (SET) was calculated with the help of thermal comfort surveys which were in a range of 23.4°C to 27.3°C. For cooling mode, four different cases compared the performance of the system which are: Conventional Air Conditioning System (CACS), Radiant Cooled Ceiling System (RCCS), Personalized Radiant Conditioning System (PRCS), and both PRCS-RCCS coupled. It was observed that PRCS alone reaches the thermal comfort criteria with low energy consumption. The energy-saving of RCCS-PRCS was achieved 38% when compared with CACS. It can be concluded that PRCS is a new step in the field of thermal comfort.

Enhancing the energy efficiency of structures has been a staple of energy policies. The key goal is to slash electricity usage in order to minimize the footprint of houses. This goal is sought by putting restrictions on the design specifications with respect to the properties of the raw materials and components as well as the exploitation of sustainable sources of energy. These facts for the basis for zero-energy building (ZEB) being established. This novel technology has faced several obstacles impeding its commercialization and future advancement. This investigation therefore holistically explored and evaluated the state of zero energy building and factors impeding their commercialization. The review further proposed some suggestion in terms of technology that can be considered by the sector to augment existing technologies. Similarly, the investigation touched on the effect of occupant's character in zero energy structures. Policies in terms of government subsidies and tax rebates were recommended to encourage more investors into the sector. Finally, the perception of zero energy building being more expensive compared to the traditional structures can equally be curbed via efficient and effective public sensitization.

This paper systematically describes the technical principles, evaluation indicators, system forms and research progress of air-side evaporative cooling air conditioning systems, water-side evaporative cooling air conditioning systems and freon-side evaporative cold coagulation heat air conditioning systems of Data center. In order to reduce the energy consumption of the refrigeration and air-conditioning system in the Data center, the application conditions and scenarios of the different forms of evaporative cooling air-conditioning systems should be considered comprehensively. Therefore, it is very important that the renewable energy-dry air can be used to the greatest extent. These efforts would contribute to China's 2030 "Carbon Peak" and 2060 "Carbon Neutral."

High light-harvesting efficiency and low interfacial charge transfer loss are essential for the fabrication of high-efficiency quantum dot-based solar cells (QDSCs). Increasing the thickness of mesoporous TiO2 films can improve the loading of pre-synthesized QDs on the film and enhance the absorbance of photoanode, but commonly accompanied by the increase in the unfavorable charge recombination due to prolonged electron transmission paths. Herein, we systematically studied the influence of the balance between QD loading and TiO2 film thickness on the performance of QDSCs. It is found that the relative thin photoanode prepared by the cationic surfactant-assisted multiple deposition procedure has achieved a high QD loading which is comparable to that of the thick photoanode commonly used. Under AM 1.5G illumination, Zn–Cu–In–Se and Zn–Cu–In–S based QDSCs with optimized 11.8 μm photoanodes show the PCE of 10.03% and 8.53%, respectively, which are comparable to the corresponding highest PCE of Zn–Cu–In–Se and Zn–Cu–In–S QDSCs (9.74% and 8.75%) with over 25.0 μm photoanodes. Similarly, an impressive PCE of 6.14% was obtained for the CdSe based QDSCs with a 4.1 μm photoanode, which is slightly lower than the best PCE (7.05%) of reference CdSe QDSCs with 18.1 μm photoanode.

The photovoltaic-thermal collector is one of the most interesting technology for solar energy conversion, combining electric and thermal energy production in a single device. Vapour-compression heat pump is already considered the most suitable clean technology for buildings thermal energy needs. The combination of these two technologies in an integrated ”photovoltaic-thermal solar-assisted heat pump” (PVT-SAHP) system allows reaching a high fraction of the building thermal needs covered by renewable energy sources and to improve the performances of both the photovoltaic-thermal collector and the heat pump. The first is cooled down increasing its energy conversion efficiency, while providing low-temperature thermal energy to the second, which benefits from a higher evaporation temperature. The review study presents the state-of-art of photovoltaic-thermal solar-assisted heat pump systems intended to cover thermal energy needs in buildings, with a particular focus on the integration methodologies, the possible configurations, the use of different sources and the design of sub-system components. These issues are addressed by much scientific research, to improve the reliability and applicability of this technology, as an option for the building decarbonization. This study aims to present PVT-SAHP systems in an organic and critical way to propose a useful tool for future research developments. More in detail, the work highlights the fact that the integration of photovoltaic-thermal collectors as evaporator of the heat pump in direct-expansion systems allows the highest heat recovery and performances. However, the distinction of the two circuits lead to more reliable, flexible and robust systems, especially when combined with a second heat source, being able to cover both heating and cooling needs. The implementation of real-time control strategy, as well as the continuous development of the compressor and refrigerant industries is positively influencing this technology, which is receiving more and more attention from scientific research as a suitable solution for nearly zero energy buildings.

This paper deals with the experimental investigation of hygrothermal behavior of wooden-frame building envelope. The experiment was based on in-situ monitoring of a full size experimental monozone house built at the University of Lorraine. Variations in temperature and relative humidity inside and outside the envelope were logged simultaneously with local meteorological data. Results showed the high coupling between temperature and relative humidity variations within the envelope materials. An overall hygrothermal response of the wall highlighted an interesting hygrothermal dynamic behavior of the envelope which may contribute to mitigate variations of relative humidity inside the building. Nevertheless, relative humidity evolves within a range of values ​​that can lead to mold growth at a certain position which may alter wooden envelope life.

The aim of this study is to investigate the ongoing energy management and energy efficiency practices in the industries of Peshawar division of Khyber Pakhtunkhwa, Pakistan. The outcomes of this research shows that Khazana Sugar Mills, Caliph Pharmaceutical, Naguman Flour Mill have no or low awareness of energy management practices (awareness level mainly includes barriers to energy efficiency and drivers for energy efficiency) except FF steel mill. The major paces observed in lacking the awareness are (1) “understanding level of staff and workers about energy savings due to energy management practices” (2) “interest level of top managers for energy management implementation” (3) “awareness level regarding energy efficiency” (4) “lack of technical competence” (5) “use of standardized procedures”. When the industry managers were inquired about the relationship with energy service providers it is found that there is absolute absence of energy engineers, relationship with energy consultancies and long-term energy strategy in all the industries. It was also found that there is lack of using renewable energy technologies in all industries as they were relying upon using the generators during the blackout hours. In terms of percentage, the energy saving factor of 36 kWh/day has also observed with the replacement of fluorescent tube lights with light emitting diode (LED) tube lights. Proper maintenance and energy management practices in the heating, ventilation and air conditioning system (HVAC) would also save energy in a significant amount. The study shows that there is an overall improvement factor of 4% to 8% if the inclusion of energy management and energy efficiency practices would have been applied in all the stated industries.

In this research, canola meal was densified using bio-additives including alkali lignin, glycerol, and l -proline. The fuel pellet's formulation was optimized. The best fuel pellet demonstrated relaxed density and mechanical durability of 1015 kg/m3 and 99.0%, respectively. Synchrotron-based computer tomography technique indicated that lack of water in pellet formulation resulted in a twofold increase in pellet porosity. Thermogravimetric analysis showed that ignition temperature (240 °C) and burn-out temperature (640 °C) for fuel pellet were smaller than those for coal. Impacts of process parameters were evaluated on the quality of the gas product obtained from pellet's steam gasification and hydrothermal gasification. The gasification experiments showed production of untreated syngas with a suitable range of H2/CO molar ratio (1.3–1.6) using steam gasification. Hydro-thermal gasification produced a larger molar ratio of H2/CO (1.8–51.2) for the gas product. Modeling of pellet's steam gasification showed an excellent agreement with experimental results of steam gasification.

This study uses three data envelopment analysis models to determine the production efficiency of biohydrogen which is produced from macroalgae and other sources by dark fermentation. The efficiency of macroalgae is greatest in batch mode for S. Japonica using a sDFMEC process at pH 5.3, 35 °C, 1 g COD/L and a hydrogen production rate (HPR) of 0.34 L/L/h. The highest efficiency is using an internal circulation batch reactor in continuous mode for beverage waste water. The HPR and substrate concentration are the most important factor of biohydrogen efficiency, and efficiency and temperature are the most important factors of HPR. Malaysia and India are the two economies that most benefit from increased production efficiency due to the use of macroalgae. Increasing biohydrogen yield efficiency will improve macroeconomic growth and establish a renewable hydrogen and biohydrogen industry, which is especially efficient related to the economic recovery during the COVID-19 pandemic.

Usage of plastics in the form of personal protective equipment, medical devices, and common packages has increased alarmingly during these pandemic times. Though they have served as an excellent protection source in minimizing the coronavirus disease (COVID-19) spreading, they have still emerged as major environmental pollutants nowadays. These non-degradable COVID-19 plastic wastes (CPW) were treated through incineration and landfilling process, which may lead to either the release of harmful gases or contaminating the surrounding environment. Further, they can cause numerous health hazards to the human and animal populations. These plastic wastes can be efficiently managed through thermochemical processes like pyrolysis or gasification, which assist in degrading the plastic waste and also effectively convert them into useful energy-yielding products. The pyrolysis process promotes the formation of liquid fuels and chemicals, whereas gasification leads to syngas and hydrogen fuel production. These energy-yielding products can help to compensate for the fossil fuels depletion in the near future. There are many insights explained in terms of the types of reactors and influential factors that can be adopted for the pyrolysis and gasification process, to produce high efficient energy products from the wastes. In addition, advanced technologies including co-gasification and two-stage gasification were also reviewed., Graphical abstract Image 1

Torrefaction is a pretreatment method that converts biomass to a fuel-like substance that can replace coal for sustainable power generation. In this work, a thermodynamic-based process simulation model was developed to simulate the gasification of empty fruit bunch (EFB), with torrefaction as pretreatment, to determine the optimum conditions; equivalence ratio, reactor temperature, torrefaction medium concentration, steam-to-biomass (S/B) ratio and system configuration were studied to determine their influence on hydrogen concentration, higher heating value (HHV), syngas ratio and cold gas efficiency (CGE). The highest hydrogen yield was obtained at an S/B ratio of 1.3 at 800 °C, with a syngas ratio of 2.5 and a CGE of 84%. Concentration of torrefaction medium showed no effect on hydrogen concentration due to the simplicity of the model used, but work is in progress in this direction. Therefore, steam gasification is more suitable than air gasification in hydrogen production.

This research aims to evaluate the hydrogen production and removal ability of impurity (e.g. tar and NH3) generated from sewage and textile sludge co-gasification using lab-scale fluidized-bed gasifier with an integrated hot-gas cleaning system. The gasification temperature and equivalence ratio (ER) were controlled at 850 °C and 0.2, as well as the hot gas cleaning system operated at 250 °C with the combination of zeolite, calcined dolomite, and activated carbon. Experimental results indicated that the H2 and CO yield in co-gasification of the tested sludge ranged from 2.12 to 2.45 mol/kg and from 2.83 to 3.98 mol/kg, respectively. The overall energy content of produced gas ranged between 2.40 and 2.63 MJ/kg, and cold gas efficiency (CGE) was nearly 15%. The impurities of produced gas were effectively mitigated by the hot-gas cleaning system, which could remove approximately 90% of the heavy fraction tar, up to 77% of total tar, and about 35% of ammonia. In summary, the combination of the fluidized-bed gasifier and the hot-gas cleaning system had been well developed for purifying the syngas produced from the tested sludge, and it could be applied to other organic wastes in the future.

Graphitic carbon nitride (g-C3N4) is considered a potential photoactive semiconductor for photocatalytic hydrogen evolution (PHE). Although being active in producing hydrogen, it is in general suffering from severe charge recombination rate, low mobility of charge and narrow visible light response range largely, which has restricted its greater application. Existing reviews on g-C3N4 are lacking of systematic and summative view on the effects of the physical-chemical structure-activity relationship between g-C3N4 and the modification involving phosphorus (P). Many studies indicate that adding P into g-C3N4 could effectively elevate the photo-activity. Underlying reasons for the observed improved photo-activity are discussed in this review. Here, P-containing g-C3N4 photocatalysts are grouped into the categories of P elemental doping, composite with elemental P, as well as the addition of metal phosphide as cocatalysts. These P-containing g-C3N4 possess novel properties demonstrating favorable photocatalytic activities as compared with the other elemental (such as O, S, B)-based materials. Therefore, in this mini review, we summarize and discuss the advances on the P-containing g-C3N4 photocatalysts, including the preparation strategies, physicochemical properties, the application for hydrogen production as well as the related reaction mechanism. Importantly, the physical-chemical structure-activity relationship between g-C3N4 and the integrated P is revealed. Finally, an overview of the current research status and challenges on future is presented, which would be helpful in designing and developing other P-containing photocatalysts for various photocatalytic applications.

An interesting phenomenon was found that fluorophore was introduced into ionic liquid (IL) to magnify fluorescence signal via the thermally activated delayed fluorescence process; thus up to 15 fold enhancements were achieved. Hence, we reported a succinct enhanced luminescence strategy to reduce single-triplet energy split by the tunability of ILs. This strategy could be extended to more kinds of ILs by the virtue of a preliminary DFT calculation screening. Moreover, the optical feature of IL sensor made it a promising candidate as a gas fluorescence sensor.

Clean and renewable energy plays important role in achieving carbon neutrality and nature sustainability, especially the application of green hydrogen in new energy system. Hydrogen (H2) produced from visible light has attracted attention owing to its high conversion efficiency and cleaner process. In this review, different photocatalyst preparation methods which can directly design the same structure were clarified. Also, different mechanism design which can realize different electron transfers were also proposed. Thus, various morphologies and different mechanisms of electron transfer have been summarized and evaluated. Also, the methods of photocatalysts’ construction were mentioned, all H2 production reactions depend on the amount of reaction sites and photo-generate electrons. It was evident that the concentration of reaction sites and photo-generate electrons play important roles in efficient H2 production. This review provides fundamental knowledge to design and construct variable morphologies with different electron transfer processes to enhance efficiency of H2 production.

The worldwide energy demand is steadily increasing and estimated to be doubled by the year 2050 due to a continuous hike in economies and population. A large part of the global energy requirement procures using traditional energy sources such as fossil fuels, which are non-renewable. Also, their excessive consumption imparts negative impacts on the environment by CO2, and CO emissions, which constantly increase the average global temperature. Therefore, the need for a more reliable, sustainable, inexpensive, renewable and environmentally-friendly form of energy is imperative. From these perspectives, hydrogen energy is emerging as one of the most promising alternatives to overcome rising energy demand with a zero-carbon footprint. Herein, various layered double hydroxides (LDH) nanocomposite owing to their attractive physicochemical properties and synergistic effect with other materials in the field of hydrogen production are reviewed. Why the class of LDHs materials is critical and their ideographic properties which make them promising materials in the field of water splitting via photocatalysis and electrocatalysis are also discussed. The synthetic methods of LDHs based nanocomposites fabrication are summarized. Various challenges and strategies from the viewpoint of a different method of hydrogen production through LDHs are reported. Additionally, multiple techniques like surface plasmon resonance (SPR), heterojunction formation, and doping with co-catalyst to increase the efficiency for photocatalytic hydrogen production are also presented. Hopefully, this review will help the readers explore highly efficient, inexpensive and stable LDH catalysts toward photocatalytic water splitting.

Straw is an abundant natural bioresource, especially in developing and agricultural countries. Bio-hydrogen production from this renewable biomass through biological methods is an active research area. Because of its distinctive characteristic of being rich in cellulose, straw has been extensively considered as a promising raw material for clean energy production. In this paper, the recent progress of bio-hydrogen production from straw was reviewed with the emphasis on the advances in pretreatment and hydrolysis technologies. The future development of straw-based biohydrogen production was also analyzed. Based on the physicochemical properties of straw biomass and mechanisms of bio-hydrogen fermentation, various pretreatment procedures have been developed to make the straw substrate more available for hydrogen-producing bacteria to realize large-scale bio-hydrogen production from straw. This review summarized the recent technologies of straw pretreatment and hydrolysis as well as elaborated on the bottlenecks in the field of straw biotransformation in great detail. Furthermore, based on the current technology status and potential, the challenges, prospects and future directions of the production methods were further proposed.

Distributed electricity generation technologies, like solar photovoltaic (PV), have achieved rapid development in recent years, but are constrained by some problems such as low marketization and lag in public services. The peer-to-peer (P2P) electricity trading, which allows direct electricity transactions between local consumers and prosumers, has the potential to efficiently distribute the profits coming from self-consumption of PV electricity among all participants. This study proposes a three-layer P2P electricity trading system for communities with high penetration of household distributed PV. The trading system includes a physical layer based on the power grid, an information layer based on a virtual agent network, and a market layer based on a continuous double auction (CDA) mechanism combined with market clearing. By using simulation of trading experiments, a community with 60 houses and 50% PV occupancy is studied as a case. Results show that in one day, 62.5% of the surplus PV electricity of all prosumers actually can be consumed within the community. Through P2P electricity trading of this part of electricity, total incomes of prosumers can increase by 11.5%, and total expense of all users decrease by 7.5%, resulting in that the net expenses of the whole community decrease by 13.8%. It is concluded that P2P electricity trading can unite the whole PV community as a bigger prosumer, and make every residential house in the community share the profits from local PV consumption, which could promote the subsidy-free development and grid parity of household distributed PV in the future.

There are prototypes of social housing massively built in contrasting climatic conditions, generating thermal comfort needs that are difficult to satisfy by the users themselves. Variation of indoor air volume in living spaces where the use of air conditioning and natural ventilation strategies provides elements to improve thermal comfort conditions. This research shows the thermal performance located in a representative social housing according to Mexico's National Housing Commission. Operative temperature results from a benchmark case were compared to six Virtual Evaluation Models, using the Dynamic Thermal Simulation tool Design Builder® from the perspective of probability. The main objective was to determine the minimum use of active systems with different indoor air volumes and improve comfort conditions to promote sustainable living in social housing. The analysis was conducted under an adaptive comfort range according to three different climate conditions in Mexico adopting a Numerical Theoretical Method. The main findings can be divided into two parts: a) the impact of the indoor air volume on thermal performance was evidenced in a proportion of time in three representative climates of the central region of Mexico, and b) no relationship was found between indoor air volume and thermal comfort in sub-humid cold climate; in sub-humid temperate climate, the same number of comfort hours was found in two different models, and in sub-humid warm climate, an inversely proportional relationship was found between indoor air volume and the comfort hours. This findings implies a greater knowledge relative to what we know about sub-humid cold, temperate and warm climates.

Metal–organic frameworks (MOFs) containing open metal sites are important materials for acetylene (C2H2) adsorption. However, it is inefficient or even impossible to search suitable MOFs by molecular simulation method in nearly infinite MOFs space. Therefore, machine learning (ML) methods are adopted in the material screening and prediction of high-performance MOFs. In this paper, architecture, chemical and structural features are used to analyze the C2H2 adsorption performance of the MOFs. Different ML algorithms are applied to perform classification and regression analysis to the factors affecting material adsorption. By decision tree (DT) algorithm, it is found that only PV, GSA, and Cu-OMS are sufficient to determine the high adsorption of the MOFs. Furthermore, the influence of topology on the performance of MOFs is obtained. Gradient Boosting Decision Tree (GBDT), Support Vector Machine (SVM), and Back Propagation Neural Network (BPNN), are introduced to analyze the quantitative structure–property relationship (QSPR) between C2H2 adsorption and the features of MOFs. The prediction of the GBDT model is found to have the highest accuracy, with R2 as 0.93 and RMSE as 11.58. In addition, the GBDT model is used for feature analysis, and the contribution of each feature to the performance is obtained, which is of great significance for the design and analysis of MOFs. The successful application of ML to MOFs screening greatly reduce the calculation time and provides important reference for the design and synthesis of new MOFs.

Current study deals with performance evaluation of the solar power tower driven recompression with main compressor intercooling (RMCIC) supercritical CO2 cycle incorporating the parallel double evaporator organic Rankine cycle (PDORC) as bottoming cycle using low global warming potential fluids to reduce the global warming and ozone depletion. Using the PDORC instead of the basic organic Rankine cycle, waste heat from the intercooler and cycle exhaust were recovered simultaneously to enhance performance of the standalone RMCIC cycle. Exergy, thermal efficiency, efficiency improvement and waste recovery ratio were considered as performance parameters. A computer program was made in engineering equation solver to simulate the model. It was concluded that by the incorporation of the PDORC thermal efficiency was improved by 7–8% at reference conditions. Maximum combined cycle's thermal and exergy efficiency were found 54.42% and 80.39% respectively of 0.95 kW/m2 of solar irradiation based on R1243zf working fluid. Among the results it was also found that maximum waste heat was recovered by the R1243zf about 54.22 % at 0.95 effectiveness of low temperature recuperator.

Mechanical Ventilation with Heat Recovery (MVHR) systems are gaining increasing interest in buildings with low energy demand, for improvement of the Indoor Air Quality (IAQ) and reduction of the ventilation energy loss. In retrofitted buildings, MVHRs are often integrated with an additional air heater to cover space heating demand. Hence, evaluation of the interactions between MVHR and heat emitter, and their effects on indoor airflow characteristics is of significant importance. The present study aims to investigate effects of a combined MVHR-fan-coil system in heating mode on IAQ and thermal comfort parameters inside a retrofitted room, by means of a computational fluid dynamic (CFD) code. The proposed CFD model is validated by comparing the numerical results with experimental data. The results yielded by numerical simulations allow evaluating the indoor environmental quality characteristics as well as addressing the MVHR and fan coil interactions. The results indicate that the airflow discharged from the fan coil could have a significant impact on the age of the air; while it provides a desirable thermal comfort condition within the room, it may hinder to some extent delivery of the fresh air to the occupied zone due to creation of counterflow fields. Furthermore, it is shown that although increasing the fan speed (ON mode) would slightly enhance the air change efficiency, the OFF mode yields not only a better distribution of the fresh air but also a higher ventilation efficiency than when fan coil operates.

This study proposes a group control system optimization strategy coupled with a refrigeration plant model for a primary pump variable flow system, in order to improve the automation level of the refrigeration plant and maximize the energy saving potential. First, the control variables, optimization objectives, and operational constraints of the entire system were analyzed. Then, by collecting the operational data for each component and combining these data with theoretical analysis, the sub models were designed and the input parameters, output parameters, and optimization variables of each sub-model were defined. Next, the sub-models were coupled and the control variables of the operational combination, leading to the lowest overall system energy consumption, were obtained using a particle swarm optimization algorithm. Finally, considering a medical building in North China as an example, the application effectiveness of the optimal control strategy of the refrigeration plant was analyzed. The results showed that the energy-savings of the group control system after the optimization of the refrigerator, chilled water pump, cooling water pump, and cooling tower could reach 9.42, 8.04, 5.67, and 14.64%, respectively. This is a remarkable energy-savings benefit. The research described in this study also provides some reference for the design of group control systems in refrigeration plants.

To meet fast growing in energy demand, all energy sources have to be exploited. Renewables energies are unlimited and clean but the most problem with them is their intermittent aspect. To overcome this problem a mixture of several energy sources is made to obtain what called hybrid renewable energy system. This paper aims at presenting and analyzing a deep literature review of the recent paper published in hybrid renewable energy field. This review focuses on four essential categories of hybrid renewable energy system which is sizing (using software or using traditional methods), optimization (classical, artificial and hybrid methods), control (centralized, distributed and hybrid control) and energy management (technical objective, economic objective and techno-economic objective). Furthermore, this paper compares between different methods used in each category.

Thermal comfort inside classrooms located in an institutional building is examined as a function of air temperature, relative humidity and wind velocity. The effect of east-west orientation on the thermal comfort inside the classrooms located in different floor levels is understood based on field experiments and validated using computational fluid dynamics simulations. The air temperature inside the classrooms shows an increasing trend with the floor level. Air temperature and relative humidity inside the classrooms reveal an inverse relationship as a function of east-west orientation with different floor level. As time progresses, the air temperature inside classrooms located on the eastern side of the building is apparently higher than rooms situated on the western side of the building, both field experiments and simulation acknowledge the same. Appropriate reasons have been proposed behind the discussed phenomenon using computational fluid dynamics simulation.

Hydrogen is a renewable gas, efficient to produce energy that makes it a suitable alternative and effective solution for a carbon-free environment. Unlike other fossil fuels, combustion of hydrogen does not produce toxic compounds, such as greenhouse gases, carbon monoxide, hydrocarbons, etc., resulting in less environmental pollution. Agro-industrial residues contain several lignocelluloses that favor the growth of microorganisms to produce valuable products such as hydrogen. Of the diverse techniques in hydrogen production, bioconversion proves to be an efficient method in permuting agro-industrial residues into hydrogen. This review provides detailed information on the bioconversion processes and factors involved in hydrogen production from agro-industrial residues including different fermentation processes such as dark fermentation and photo-fermentation, and fuel cell systems such as microbial electrolysis cell and microbial fuel cell. Different pretreatment techniques to enhance the availability of lignocellulose for hydrogen production have been elaborated in this review. Various factors including pH, temperature and nutrient composition of feed, affecting the production efficiency and purity of the products during fermentation have been discussed.

Electrospun nanofibers show great potential in biomedical applications. This mini review article traces the recent advances in electrospun nanofibers for wound management via various approaches. Initially, we provide a short note on the four phases of wound healing, including hemostasis, inflammation, proliferation, and remodeling. Then, we state how the nanofiber dressings can stop bleeding and reduce the pain. Following that, we discuss the delivery of therapeutics and cells using different types of nanofibers for enhancing cell migration, angiogenesis, and re-epithelialization, resulting in the promotion of wound healing. Finally, we present the conclusions and future perspectives regarding the use of electrospun nanofibers for wound management.

With the worldwide rapidly increasing urbanization, the demand for heating increases too. To meet the substantially higher heating-demand, traditionally, the number of gas-fired boilers is simply increased. Unfortunately, this also causes severe air pollution. A viable alternative is solar heating systems that could be added to the existing gas-fired boilers system. This study investigates a heating system, which combines solar heating and existing gas-fired boiler heating into one system. The optimal individual capacity of the system is determined and the operation characteristics, energy saving, and economics are analyzed. The results showed that the combined heating system has a clear advantage with respect to both energy saving and economics over the traditional solution (gas-fired boiler-capacity expansion). For an expansion rate of 20%, for example, the average energy-saving rate is as high as 69%. With increasing capacity, the difference per unit heating-area cost between the two systems increases. This means that the combined heating system is even more beneficial when the capacity increase is high. This study shows a new way to meet increased heating demand effectively, which is especially useful for cities that require a significantly-increased heating capacity.

In the scope of the rapid technological advancements, nanoparticles (NPs) have gained prominence due to their excellent and tunable biological, and physicochemical properties. Nowadays, different methods are used for their synthesis. In particular, the green synthesis of metal precursors for the synthesis of NPs, represents a cost-effective, environmentally friendly, and hazardous chemical-free method for developing a large variety of NPs. By exploiting plant extracts, the production rate of NPs is relatively faster. Due to fossil reserves and high fuel consumption, renewable and clean energy materials are urgently needed to improve environmental sustainability. With outstanding electrochemical and physicochemical characteristics, molybdenum-based NPs (Mo-NPs) are gaining increasing attention in the fields of energy conversion and storage. Considering the significance of Mo-NPs synthesized from greener routes and their energy applications, it is necessary to review recent trends and developments in this field. This review summarizes important research studies and future research guidelines for the preparation of Mo-NPs through green routes and their applications to meet global energy and environmental demands. Moreover, future research directions are also highlighted to achieve sustainable greener precursors and Mo-NPs based energy storage devices.

Ice detection of wind turbine and estimating the resultant production losses is challenging, but very important, as wind energy project decisions in cold regions are based on these estimated results. This paper describes the comparison of a statistical (T19IceLossMethod) and numerical (Computational Fluid Dynamics, CFD) case study of wind resource assessment and estimation of resultant Annual Energy Production (AEP) due to ice of a wind park in ice prone cold region. Three years Supervisory Control and Data Acquisition (SCADA) data from a wind park located in arctic region is used for this study. Statistical analysis shows that the relative power loss due to icing related stops is the main issue for this wind park. To better understand the wind flow physics and estimation of the wind turbine wake losses, Larsen wake model is used for the CFD simulations, where results show that it is important to use the wake loss model for CFD simulations of wind resource assessment and AEP estimation of a wind park. A preliminary case study about wind park layout optimization has also been carried out which shows that AEP can be improved by optimizing the wind park layout and CFD simulations can be a good tool.

Countries enact environmental regulations to achieve sustainable development andecological sustainability. However, environmental regulations do not guarantee envi-ronmental sustainability unless implemented efficiently. Furthermore, political institu-tions play a key role in the formulation and management of environmentalregulations. This research examines the relationship between democracy, environ-mental regulations, economic growth, and ecological footprint (EF) in the panel of G7nations from 1985 to 2017. Second generation econometric techniques are used toanalyze the data. The empirical evidence indicates that economic growth enhancesEF while democracy and environmental regulations positively contribute to ecologicalsustainability by reducing EF. The causal outcomes reveal that democracy Grangercauses EF and renewable energy indicating that democracy curbs environmental deg-radation and stimulates the share of renewables. Further, democracy and environ-mental regulations Granger cause each other. Lastly, the implication of these findingsfor sustainable development and ecological sustainability are discussed.

Hydrogen is widely used in many industries, yet its role in the clean energy transition goes beyond being an element of these industries. Near-term practical large-scale clean hydrogen production can be made available by involving nuclear, solar, and other renewable energy sources in the process of hydrogen production, and coupling their energy systems to sustainable carbon-free hydrogen technologies. This requires further investigation and assessment of the different alternatives to achieve clean hydrogen using these pathways. This paper assesses the technoeconomics of promising hydrogen technologies that can be coupled to nuclear and solar energy systems for large-scale hydrogen production. It also provides an overview of the design, status and advances of these technologies.

Photocatalysts for harvesting solar energy to either electricity or chemical fuels have attracted much attention recently, but they have big obstacles such as wide bandgaps and rapid charge recombinations to overcome for final applications. In this study, we investigates a useful method to utilize vanadium redox pairs, which are commonly applied for vanadium redox flow batteries, to diminish charge recombinations and thus to enhance photocurrent response in regenerative solar energy storage. The results reveal significant improvements in photocurrent density by forming cuprous and cupric oxides in TiO2/CuxO electrodes under solar AM 1.5 illuminations using the vanadium photoelectrochemical storage cell at 0.025M of vanadium redox species in the acid electrolytes. In addition, the stabilized photocurrent density of the copper content optimized TiO2/CuxO electrodes is almost tripled from the TiO2 only electrode because the charge recombinations can be mitigated with the content optimized TiO2/CuxO electrodes. Therefore, the optimized TiO2/CuxO electrode results in the highest charge storing performance in the catholyte chamber, and the roles of vanadium redox species are also clearly demonstrated.