Abstract In order to achieve the goal of “carbon peak” in 2030 and “carbon neutrali zation” in 2060, the task of energy conservation has risen to the national strategic level, and its work is urgent. It focuses on energy saving and ener gy consumption in data center, 5G network and other fields. The gravity heat pipe double cycle air conditioning is a kind of room air conditioning which uses natural cooling source with high efficiency. According to the outdoor meteorological parameters of ten typical cities in China, the calcu lation model of unit hybrid refrigeration mode is established by using integral method. A simplified algorithm for statistical summation is proposed. Then it compares with the same type of refrigerant pump air conditioner, wa ter-cooled chiller and natural cooling plate. The results show that the an nual operation time of gravity heat pipe double cycle air conditioner is 50.8% longer than that of refrigerant pump air conditioner. Then the calculation model is verified by the annual actual operation data of a data center in Changsha. The results show that the double cycle air conditioner with grav ity heat pipe can save about 34% energy compared with the chiller. The ac curacy of the calculation model is 17.5%, which meets the engineering ac curacy requirements. The application of gravity heat pipe double cycle air conditioning in hot summer and cold winter area is a scheme worthy of popularization and application.

Abstract Photovoltaic (PV) modules have emerged as an ideal technology of choice for harvesting vastly available renewable energy resources. However, the efficiency of PV modules remains significantly lower than that of other renewable energy sources such as wind and hydro. One of the critical elements affecting a pho tovoltaic module’s efficiency is the variety of external climatic conditions un der which it is installed. In this work, the effect of simulated snow loads was evaluated on the performance of PV modules with different types of cells and numbers of busbars. According to ASTM-1830 and IEC-1215 standards, a load of 5400 Pa was applied to the surface of PV modules for 3 hours. An indige nously developed pneumatic airbag test setup was used for the uniform ap plication of this load throughout the test, which was validated by load cell and pressure gauge. Electroluminescence (EL) imaging and solar flash tests were performed before and after the application of load to characterize the per formance and effect of load on PV modules. Based on these tests, the maxi mum power output, efficiency, fill factor and series resistance were deter mined. The results show that polycrystalline modules are the most likely to withstand the snow loads as compared to monocrystalline PV modules. A maximum drop of 32.13% in the power output and a 17.6% increase in series resistance were observed in the modules having more cracks. These findings demonstrated the efficacy of the newly established test setup and the potential of snow loads for reducing the overall performance of PV module.

Abstract In this work, the potential for energy production in Jordan was explored using four distinct types of biomass samples (olive cakes, woods). The proximate analysis, oil content, and higher heating value were all determined experimentally and compared to other biomass previously published in the literature. The findings appear to be similar to other biomass materials utilized as solid biofuel feed-stock materials. Olive cake and wood samples have lower calorific values than anthracite coal, ranging from 25% to 40% lower. According to the results of this study, olive cake samples had the highest oil extractive content (14.5 wt%), followed by pine and beech woody samples with 8.9 wt% and 3.1 wt%, respectively. The calorific values of the biomass samples tested ranged from 18 to 22 MJ/kg, making them suitable for use as fuel. Moreover, the high volatile matter content (78% to 93%) was appropriate for chemical energy conversion by gasification or combustion process. Jordan can create roughly 8000 tons of pomace oil per year from the waste solid olive cake, based on existing results. Furthermore, the olive cake’s energy potential in Jordan is estimated to be 38 MW based on the higher heating value of the tested samples and the annual quantity of this resource. In the meantime, due to limited annual production, Jordanian firewood has the modest energy potential (2.4 MW).

Abstract Investments in the exploitation of the continent’s raw material reserves have resulted in little (positive) impact on the energy security situation within Africa. This paper attempts to explore factors influencing the level of energy security of Small Medium Enterprises (SMEs) in the Greater Accra Region of Ghana, and from the dimension of availability, affordability, economic efficiency and environmental stewardship or sustainability of energy. The cross-sectional survey design was employed as the design for the collection and analysis of data. The study applied a quantitative research method in examining the indicators of energy security for SMEs in Accra Metropolis in the Greater Accra Region of Ghana. The population covered about 500 SMEs who have about 100 employees and total revenue of $1 million or the equivalence in Ghana Cedis. A sample of 246 was selected through a cluster and simple random sampling. The analysis adopted statistical techniques to conduct descriptive, exploratory and inferential analysis of the data collected. Factors that influence the level of energy security of SMEs are broadly categorized into the environment and economic change, political factors, physical disruptions and market conditions. Generally, the level of energy security under the availability dimension is medium among the SMEs. Issues of affordability, economic efficiency and environmental stewardship provide high medium interventions on energy security for SMEs. It is recommended that managers of Ghana’s energy sector should ensure prudent management of the country’s energy resources since the disruption of supply lines or sources form the key conditions that influence the energy security level of SMEs. SMEs should adopt energy efficiency measures to ensure that energy is conserved for future use.

Abstract Machines are growth engines of the economy; each sector of the economy achieves its demand by the use of the machine. They are installed in various establishments for the purpose of using them to perform certain functions or others. However, as a result of the kind of forces, dynamic and static loads, they transmitted to their adjoining surroundings when used, they are often mounted on supporting structures, foundations or a combination of them to achieve adequate or appropriate safe operation and stability. When a machine is operating, it is subjected to several time-varying forces and as a result of which it tends to exhibit vibrations. In such a situation or process, a certain quantity of this force is transmitted to the foundation, which could undermine the life of the foundation and also affect its performance and the operation of any other machines on the same foundation. Hence, it makes sense to minimize this force transmission. This research aimed at developing an adjustable steel framed structure for supporting the major components of a 5.0 kW microsteam power unit (steam, turbine and alternator) and evaluating the performance of the unit with or without the vibration isolator when they are axially connected with flexible flange coupling or transversely connected with sets of belts and pulleys, in succession, respectively. The results showed that reduction in the force transmitted to the supporting structure occurred when the vibration produced by the unit is isolated from its base by the use of a vibration isolator,maximum reduction of 99.95% achieved when axially coupled and 99.91% when transversely connected with belt and pulley system. The results also showed that better performance would be attained when the steam turbine is axially coupled to the alternator than when connected with belt and pulley; The maximum voltage of 52 V and speed of 1000 rpm at 77 dB sound level attained with coupling connection, and voltage of 20 V and speed of 752 rpm at 75 dB with belt and pulley connection.

Abstract Recently the concern about energy consumption across the globe has become more severe due to global warming. One essential way to address this problem is to maximize the efficiency of existing renewable energy resources and effectively eliminate their power losses. The previous studies on energy harvesting of photovoltaic (PV) modules try to cope with this problem using gradient-based control techniques and pay little attention to the significant loss of solar energy in the form of waste heat. To reconcile these waste-heat problems, this paper investigates hybrid photovoltaic-thermoelectric generation (PV-TEG) systems. We implement the generalized particle swarm optimization (GEPSO) technique to maximize the power of PV systems under dynamic conditions by utilizing the waste heat to produce electricity through embedding the thermoelectric generator (TEG) with the PV module. The removal of waste heat increases the efficiency of PV systems and also adds significant electrical power. As a control method, the proposed GEPSO can maximize the output power. Simulations confirm that GEPSO outperforms some state-of-the-art methods, e.g., the perturb and observe (PO), cuckoo search (CS), incremental conductance (INC), and particle swarm optimization (PSO), in terms of accuracy and tracking speed.

Abstract In this paper, we utilized villared rectifier technique to harvest wireless energy to overcome previously used RF-WEH rectenna. Our design focuses mainly on a multiple-stage Villard voltage multiplier model to rectify the output voltage of the rectenna and transferred it to a dc load. As a starting point, optimization and parameter analysis offer a novel and small antenna for the 2.45 GHz ISM band that precisely matched. Moreover, the fabricated prototype has measured and simulated results have confirmed the antenna’s accuracy in the reflection coefficient. Second, a highly efficient antenna may effectively harvest the electrical energy by combining with the two-stage voltage multiplier circuit presented at the ISM band. Furthermore, the proposed rectenna has the optimum performance compared to state of art rectennas in terms of efficiency, power range, and impedance bandwidth showing pronounced achievement and increasing the DC output power significantly. The prototype is fabricated and experimentally tested to confirm the concept. Measurement results show that the proposed rectenna can be used for RF energy harvesting applications.

Abstract Improving solar cell performance by increasing solar cell efficiency by various process optimization had always been a simple straight-forward methodology followed in a R&D or in a solar cell manufacturing company. This is also the most cost-effective practice to improve a product performance using the same technology without the need to procure alternative or expensive raw materials or by adopting advanced solar cell processing techniques. Aluminium Back Surface Field (Al-BSF) technology using multi-crystalline wafers (mc-Si) had been a well-established and a dominant product in the solar industry for more than two decades. However, as the industry progresses, the demand for high efficiency solar cells and modules started going up and full area Aluminium BSF based cells suffers from a lot of inherent limitations on cell efficiency. This is primarily due to the intrinsic high density of crystal lattice defects or otherwise called as grain boundary defects present dominantly only in mc-Si wafers. These grain boundaries tends to accumulate several defects and become trap centres which cause high recombination for minority carriers thereby exhibiting lower conversion efficiency and higher dispersion in electrical parameters in batches of tested cells. Years of research using this material have helped to derive the maximum benefits using this mc-Si wafer in producing industrial full area BSF cells and we can say with certainty that the efficiency potential has reached the saturation point with this technology. An interesting development that happened in the area of improving the final product performance using mc-Si wafers at both cell and module level, is by replacing the conventional acid texturing process with an introduction of a nano-texturing process called Metal Catalysed Chemical Etching (MCCE) using specialized chemicals which improves the light trapping capabilities by creation of inverted pyramid texture on the silicon wafer surface and thereby enabling the wafers to absorb sunlight over a broader range of wavelength and incident angle. With this development done in mc-Si wafers in recent past, it is still a daunting task to surpass cell efficiencies beyond 19.0% using this wafer source. Hence for cell manufacturing lines which use mc-Si wafers, there is always a constant need to improve the cell manufacturing processes to reduce the impact of poor intrinsic quality of mc-Si wafers and improve the final product performance without adding any significant cost factor.

Abstract Al-Baha region, located in Saudi Arabia, is one of the main tourism and leisure areas. The authority at Al-Baha Governorate plans to use clean and renewable energy in its tourism facilities. The importance of this study is to assess the possibility of building a wind farm in Al-Baha and to select the best site for this purpose. This paper presents an analysis of long-term wind data for the annual and monthly variability in Al-Baha region of southwestern Saudi Arabia. Al-Baha region has an area of 9921 square kilometers and is divided into seven regions (groups) based on their similar measurements and wind speed values. The analysis used 40 years of annual and monthly wind speed data between 1981 and 2020. The analysis showed that Group III has the highest mean wind speed values in the northeastern part of the Al-Baha region, ranging from 5.4 m/s to 5.9 m/s at 50 m above the surface. Group VI (5.1 - 5.6 m/s) east of the Al-Baha area recorded the second-highest mean wind speed, while group V southwest of the Al-Baha area recorded lower values. The maximum wind speeds observed in Group III in January, February, March, and July were 6 m/s or higher. A frequency analysis ensures that 79% of the year’s wind speeds exceed 4 m/s at 50 m above the surface of the Group III site. Wind power was considered for 17 wind turbines of different sizes. The Soyut Wind 500 machine was found to produce maximum energy of 1420 MWh/year. The highest performance values for the Soyut Wind 500 machine occurred in winter and summer, while the calculated capacity factor values at a hub height of 50 m were 41% and 32%, respectively. The assessment concluded that generating electricity from wind at G III in the northeast of the Al-Baha region is a good decision.

Abstract In this study, the goal is to increase the efficiency of a high-pressure hydraulic turbine. The goal is achieved by numerical flow simulation using CFX-TASCflow. This approach reduces costs and time compared to the experimental approach and allows for improving the turbine productivity and its design. The analysis of energy losses in the flow part of the turbine Fr500, as well as the analysis of the influence of the opening of the guide vanes on changes in energy losses. The results showed that the greatest losses occur in the guidevane 3.02% based on the two-dimensional model and 2.5% based on the 3D model, which significantly affects the efficiency. The analysis was carried out using programs for calculating fluid flow in two-dimensional and three-dimensional formulations. With the help of the study, the main energy problem is solved—increasing efficiency.

Abstract High energy requirement of vapor compression cooling systems in addition to harmful refrigerants further necessitates the increasing need for more reliable, flexible, environmentally friendly, and cost-efficient cooling systems options. Adsorption cooling technology could be a better option in terms of huge energy saving potential, Carbon emission reduction, flexibility, and waste heat utilization. There are, however, some setbacks that hindered adsorption cooling technology from real mass production and commercialization. This work seeks to study, evaluate and compare the energy requirement and coefficient of performance of solar-powered adsorption cooling system (as an application of renewable energy) in relation to vapor compression system. Adsorbate/adsorbent equilibrium test (using a test rig) was used to predict the performance of thermal driven adsorption cooling system using methanol/activated carbon (as adsorbate/adsorbent pair) in relation to similar data obtained from laboratory vapor compression refrigeration test rig (same mass of refrigerant). For the adsorption cooling system and vapor compression system, the energy requirements were found to be 1913.57 kJ and 8932.02 kJ while the coefficient of performance (COP)s were found to be 0.39 and 1.2 respectively. Presumably, the adsorption cooling system has an energy requirement that could be powered by direct solar thermal heating using a flat plate collector, however, the COP is relatively lower indicating lower cooling capacity, and hence takes a longer period of time to overcome the same cooling load as vapor compression system. It is recommended among other things that research should focus on developing better adsorbate/adsorbent pairs for an increased adsorption/desorption time.

Abstract The paper proposes a model for a micro-grid architecture incorporating the role of aggregators and renewable sources on the prosumer side, working together to optimize configurations and operations. The final model takes the form of a mixed-integer linear programming model. This model is solved using the CPLEX solver via GAMS by having a consistent data set .

Abstract A large part of the energy savings in the building sector comes from the choice of materials used and their structures. We are interested, through a numerical study, in establishing the link between the thermal performance of composite materials and their microstructures. The work begins with the generation of a two-phase 3D composite structure, the application of the Random Sequential Addition (RSA) algorithm, and then the finite element method (FE) is used to evaluate, in steady-state, the effective thermal conductivity of these composites. The result of the effective thermal conductivity of composite building material based on clay and olive waste at a volume fraction of 10% obtained by simulation is 0.573 W·m−1·K−1, this result differs by 3.6% from the value measured experimentally using modern metrology methods. The calculated value is also compared to those of existing analytical models in the literature. It can be noticed also that the effective thermal conductivity is not only related to the volume fraction of the inclusions but also to other parameters such as the shape of the inclusions and their distribution. The small difference between the numerical and experimental thermal conductivity results shows the performance of the code used and its validation for random heterogeneous materials. The homogenization technique remains a reliable way of evaluating the effective thermal properties of clay-based building materials and exploring new composite material designs.

Abstract Briquette technology is an alternative green energy source to offset the increasing demand for charcoal and firewood to save the forests and the environment while creating employment for youth and women. Using the scoping and realistic review techniques, a review study was conducted to establish the briquette technology’s existence, and its value chain, identify stakeholders and challenges along the value chain and explore the policies supporting the technology and potential employment opportunities for youth in the green energy sector. The review results indicated that the briquette technology value chain consists of sourcing raw materials, production process, distribution, and consumption as its components while transportation, storage or packaging, marketing, and training are its supporting services. In addition, it was found that stakeholders in the value chain are manufacturers, producers, and supporting service providers who differ based on their formalities, such as groups, companies, government organizations, Non-Governmental Organizations (NGOs), institutions, and enterprises. Furthermore, five challenges were identified that impair the briquette adoption. They include the technology, raw materials, and the quality of briquettes, promotion, and marketing. Also, the study found that there are limited policies that provide a conducive environment for briquette technology to flourish. The study concludes that briquette technology exists in Tanzania. However, it is not yet matured as compared to the developed countries, and the technology is not backstopped by existing policies. The study recommends the briquette technology as a viable employment opportunity, especially for youth and women; therefore, the formulated briquette value chain should be utilized for easy coordination of stakeholders and deployment of the technology. Also, there is a need to create awareness and innovative strategies for promoting and engaging more stakeholders in the technology through the policies that explicitly insist on adopting the briquette technology.