Renewable Energy Research and Applications
Volume:3 Issue: 2, Summer-Autumn 2022

The present study investigated appropriate tree species for biomass energy utilization by determining trees' dry biomass and fuel value index, taking into account that developing countries rely heavily on fuelwood for energy consumption. In Ethiopia, biomass currently meets more than 89.5% of total energy consumption. Despite this reliance on biomass, there is a scarcity of fuelwood as well as data on dry biomass potential and fuel value indices of tree species utilized in various parts of the country. This study was done on the selection of trees for fuelwood purposes based on their dry biomass potential and fuel quality characteristics. Five highly performed Eucalyptus tree species were selected and aboveground biomass was measured using the destructive approach, whereas the fuel value index was computed using the effective method with four parameters (Calorific Value, Wood density, Ash content and Moisture content). These parameters were determined following the American Society for Testing and Materials method. Finally, aboveground biomass and carbon content varied from 13.96kg to 87.47kg and 6.03kg to 37.86 kg Tree-1, respectively. The biomass and carbon content of E. globulus and E. viminalis were both high. The maximum fuel value index was 276.34 for E. saligna. The computed fuel characteristics were statistically varied among tree species at (P ≤0.0001). Based on the tree fuel characteristics findings, E. globulus, E. viminalis, and E. saligna were identified as the best fuelwood species and were suggested for future plantations.

The request to improve electric supply in Eritrea has motivated the country to look for alternative energy resources to enhance existing power. Eritrea, being in tropics, is well situated to harvest solar energy to improve its power supply status. Although several solar energy projects have been initiated, very small has been done in the country. Therefore, this research paper aims to evaluate and investigate the regional solar energy potential (SEP) in Eritrea using remote sensing data and ArcGIS applications. The digital elevation model (DEM) data was adopted to estimate the SEP and suitability of energy in the country. In addition, areal solar radiation method is applied in ArcGIS 9.3 to extract the SEP and to evaluate suitability of this energy for the development of photovoltaics (PVs) power. The results revealed that approximately 69.03%, and 30.96% of the country was excellent and highly suitable to harness SEP, respectively, and only about 0.004% was considered as unsuitable. Therefore, this research may be useful as reference for future study and to motivate the country to improve its power supply using this alternative energy.

Renewable energy and energy sustainability are vital in meeting the exponential growth of energy demand due to increasing population and industrial needs. However, the renewable energy source unpredictability is still a concern for continuous energy supplies. United Arab Emirates (UAE) has been investing in renewable energy technologies over the years particularly in solar, nuclear, wind, waste to energy and hydropower. However, this seems insufficient still and the shortage of fossil fuels has triggered an alarming energy discussion. Therefore, this work aims at looking for tidal energy feasibility in the UAE apart from reviewing the shortcomings of the existing renewable energy sources in the country. Tidal energy is new but is highly predictable and if applied properly, it could add to the sustainable solutions. Based on the preliminary study, tidal lagoons with the area of 102 km2 integrated with double cycle reversible turbines can be installed at the Saqar Port in Ras Al Khaimah, UAE. The location has an average of 1.6 m head difference is sufficient to meet 1% of the total UAE’s energy demand.

The low bulk density of wood wastes causes handling, storage, and transportation issues, limiting its large-scale application. Pelletization can solve this inherent problem by converting biomass into dense and compact pellets with regular shape and size. To evaluate the effect of particle size and binding agents on pellets of carbonized Pinus patula sawdust, the particle size of 0.6 mm, 1.18 mm and 2.3 mm and binding agents of cow dung, molasses and wastepaper were used. The experimental results indicated that the addition of cow dung and molasses into the carbonized sawdust resulted in increase of calorific value, decrease of ash content and increase of fixed carbon. As a result, the maximum calorific value of 28.47 MJ/kg, ash content of 2.93%, and fixed carbon of 59.32% were obtained by using molasses.The calorific value of 25.8 MJ/kg, ash content of 6.03% and fixed carbon of 52.77% were obtained by using cow dung. Whereas, addition of wastepaper into carbonized sawdust resulted in lower calorific value of 22.3 MJ/kg, highest ash value of 8.35% and low fixed carbon of 43.2%. Therefore, the use of cow dung and molasses as a binder can be considered as a sustainable approach to improve the physicochemical properties of biomass pellets.

In this research, technical and economic analysis of the use of storage devices in the hybrid system of wind and solar is performed with the aim of providing a maximum electrical load of residential buildings. To this aim, two scenarios of grid-connected and off-grid system have been studied. two parameters of high reliability and cost per production capacity were used. According to these two parameters, due to the low cost of grid energy and the high cost of purchasing the second scenario cell was selected with the grid-connected system approach. Based on this system, the final generation that has a surplus of production sells the energy to the network and uses the network to supply the load when there is a lack of power to supply the load. According to the cases mentioned in the second scenario, more than 50% of the requested load is supplied by the photovoltaic cell, which indicates the high potential of the study area. For the selected system, the return on investment was 7.53 years, considering the cost of energy is 0.13 $/kWh

In order to systematically reduce the risk of SARS-CoV-2 infection in indoor space, it’s important to understand the building design strategies and air quality enhancement methods that set to mitigate this threat. This paper aims to introduce the different HVAC technologies used to mitigate the spread of COVID-19 in university settings in particular. Many of these technologies came to be as an outcome of scientific interest in the enhancement of indoor environmental quality. Thus, it is important to understand where airborne pathogens fit in the overall scheme of Indoor Air Health. Similarly, this paper set to reimagine architectural methods as solutions to the problem of airborne transmission of diseases. Based on the urgency of the problem and the demand of the market this paper discusses a summary of applicable technologies and strategies to combat airborne viruses, particularly COVID-19, in ventilation systems and enclosed spaces. By presenting an overview of the problem and the solutions that integrate engineering controls, design strategies and, indoor air sanitization techniques aim to create healthier indoor environments this paper aspires to move the research forward.

Energy is one of the most critical factors in economic development, but achieving sustainable development is impossible without environmental protection and improving economic conditions. If a country is dependent on energy, any structural reform policies to reduce energy consumption may reduce economic growth. Saving energy consumption and the development and application of alternative technologies, especially renewable energy, has a significant role in controlling and reducing the consumption of fossil energy carriers and, consequently, reducing the emission of environmental pollutants and achieving sustainable development. This article deals with the feasibility of constructing renewable energy power plants in Khoy city. First, using RETSCREEN software, the economic and environmental conditions of the construction of renewable energy power plants in Khoy city are examined. Using PVSYST software, the requirements for constructing solar power plants are discussed in a specialized way. In this article, the inflation rate is 12%, and the interest rate is 4%. The construction of solar and geothermal power plants in this city can be prioritized based on the results. The solar power plant has a production capacity of 30 MW. 212194 meters of land, and a capital of 40 million dollars are needed to construct this solar power plant. The payback period of this project in Khoy city is estimated at 25 years.

This paper is dealt with energy hub systems in order to evaluate the sensitivity analysis of output power carriers in terms of input electricity and natural gas. Unlike the recent works which were solitary concentrated at operational cost minimization, in this research not only the energy carriers of proposed hub are being modeled, but also the sensitivity analysis of each power supplier are investigated. Since some of input power carriers in the hub, are decreased slightly or immediately according to unsolicited situations, the output electrical or thermal profile may not be supplied completely. Therefore the network operator must make a proper decision to utilize the best carriers not to reduce the system efficiency if possible. In this regard, the objective function including the energy costs for electrical, thermal and cooling demand carriers is optimized and the best solution will be extracted based on conditional value at risk (CAVR) of electricity market actors, using GAMS/CPLEX software, results in the higher the risk the network operator takes, the higher the profit from futures contracts. In the next step, the electricity price is predicted using ARIMA approach for the next four weeks and the sensitivity analysis for the future of the energy hub will be examined. The simulation results and changes in the share of energy carriers show that the importance of passive defense must be considered in the planning for energy supply of office buildings and the percentage of unsupplied energy must be studied.

The cooling process of photovoltaic (PV) panel is one the main issue in in the field of solar systems. The temperature of solar cells increases when solar radiation and also ambient temperature increase. Increasing the cell temperature reduces the electrical output power of the panels as well as their lifetime. To solve this problem, various methods have been provided for cooling the panels. One of these methods is the application of heat pipes. In this research, a PV panel equipped with thermosyphon heat pipe is introduced. The thermosyphon was connected to the back sheet of the panel to enhance the cooling effect of the PV system. Instead of using polyvinyl fluoride polymer, unlike conventional panels, an aluminum plate was used to connect the heat pipe to the back of the panel to have better cooling. In addition, to increase the heat transfer area between heat pipe and back surface of the panel, a special groove was drilled on the aluminum plate. Three different filling ratios (25, 45 and 65%) of distilled water as the working fluid were used in thermosyphon. The best performance of the systems was obtained at 45% of filling ratio, in which, the electrical power of the PV panel equipped with heat pipe was around 3.2% better than the conventional PV panel. In this case, 6.8 °C temperature difference was observed in the water tank connected to the condenser section of heat pipe which means that 54 kJ heat was transferred to the water in the tank.

The propulsion system of an Unmanned Aerial Vehicle (UAV) plays an essential role in its performance, stability and flight endurance. In this study, two types of propulsion systems for UAV (differentiated based on fuel type) are studied to determine their characteristics and advantages. These proposed propulsion systems are using a solid oxide fuel cell (SOFC) to generate the heat required for the operation of the turbine and generating thrust. To achieve the best operating condition, a multi-objective Non-Dominated Sorting Genetic Algorithm (NSGA-II) in MATLAB is used to decide key design parameters. For reaching the best conditions where the acceptable thrust is accompanied by reasonable flight duration, the TOPSIS decision-making method was considered. Results indicated that the efficiency and generated power of the propulsion system will increase by higher flight altitude or compressor pressure ratio. Also, due to the recirculation of fuel in the SOFC’s anode, the higher efficiency is observed in comparison when hydrogen is used; since anode-recirculation causes higher fuel utilization. The optimization result shows that the efficiency and fuel consumption for the hydrogen-fueled system is 48.7% and 0.0024g/s, respectively, and 67.9% and 0.0066kg/s for methane-fueled engine. It was also found that, maximum efficiency for both hydrogen- and methane-fueled systems are available with the stack temperature of 1025 K; however maximum thrust for these systems is at the stack temperature of 1075 K. In addition, increasing fuel rate of the SOFC power unit helps the process of generating extra power and thrust for UAVs.

The widespread growing of electric vehicles (EVs) in distribution networks could be a variety of challenges and opportunities for the electricity network. This issue is important because the owners of electric vehicles are trying to maximize their profits, which in turn can cause many problems such as increased losses, congestion, increase network costs, etc. in distribution networks. Therefore, it is required to study different aspects of this new technology such as reliability and failure rate. For this purpose, the presented paper introduces a reliability model based on the Markov theory for different types of electric vehicles, and the main novelty is to determine the impact of the failure rate of the composed components of the each electric vehicle on the overall failure of the vehicle. In the proposed reliability models for these electric vehicles, the failure of the main composed components is considered. To compare different types of electric vehicles from reliability point of view, numerical results associated with the reliability evaluation of these vehicles are given. It is deduced from the numerical results associated to the reliability evaluation of different types of electric vehicles that the reliability of the compound plug-in hybrid electric vehicle is more than the other technologies.

The outbreak of Coronavirus disease (COVID-19) in late 2019 and its eventual transformation into a global pandemic caused a shock wave across countries. The renewable energy (RE) sector, which has always been one of the leading areas for promoting environmental sustainability, has not been spared from the epidemic. The integration of the effects of the epidemic on the global economy and the fluctuation of oil prices due to global quarantines around the world increased the impact of this disease on the RE industry. Although the COVID-19 crisis has had a negative effect on efforts to develop RE, analysts believe that in the future, more of the world's energy needs will come from RE sources. The International Energy Agency (IEA) has claimed that RE consumption is likely to increase because people tend to have clean and sustainable energy sources such as wind, water, and solar energy more than before. In the present work, the effects of the COVID-19 outbreak on environmental changes, energy consumption, the need to use RE, investments made in the field of RE, and the well-being of the people of the world are examined and details and results will be discussed. The main aim of the present work is to review the studies of researchers on the impact of COVID-19 disease on the environment and RE.