Photovoltaic energy has the potential to become one of the major energy sources used in the households in the tropical region of Africa, where the solar radiation intensity is abundant and almost constant over the year. Solar photovoltaic systems present many advantages when they are integrated in the building structure envelope and have a significant influence on the indoor air temperature of dwelling buildings due to the thermal resistance modification. In this paper, a simplified model of the photovoltaic system integrated on the roof of a residential building according to the building construction customs and materials has been designed and modeled. The heat transfer is studied in several situations: with and without a Building Integrated Photovoltaic (BIPV) system and for a building with and without false ceiling. The BIPV system installed over an effective area of 35 m2 increases the building indoor air temperature of approximately 5 °C which is corrected by the heat insulation optimization of the false ceiling made up with building local materials. The final indoor air temperature obtained is in good agreement with the ASHRAE standards and can, therefore, be applied to tropical regions.

In recent times, limitations and adverse effects of fossil fuels have significantly attracted researchers' attention to green fuels worldwide, especially in developed nations. As a way of assessing this actualization of biorefineries establishment in developing nations, this report surveys the works done by various researches towards this great course in terms of promoting and gaining the attention of both government and private investors about the technical and economic feasibility of embracing the use of biofuels, a case of bioethanol in Nigeria. Different classes of feedstocks were reviewed for the laboratory-scale, process scale-up, pilot plant, and techno-economic studies regarding ascertaining the technical and economic feasibility of local setup of a functional biorefinery in Nigeria, which would be beneficial environmentally and economically. The literature survey unveiled that the Bioethanol yield obtained from sugarcane-juice (72.7 %), banana-stems (84.0 %), and cassava (92.0 %) were found to be of highest potential amongst other sugar-based, lignocellulosic, and starch-based feedstock, respectively. The survey further unveils that the volume of process scale-up and economic feasibility studies does not correlate well with the laboratory-scale studies. The bulk of the research works on bioethanol has given preferential attention to laboratory studies. Only a few studies have looked into the commercialization (i.e., scale-up) of the laboratory findings and the economic implications. Presently, only sugarcane and a few cassavas are reported in the literature so far. It is, therefore, necessary for further studies to give attention to the investigation of the commercializing locally developed technologies and the exploration of their economic benefits.

The greenhouse problem has a significant effect on our communities, health, and climate. So, the capturing techniques for CO2 remain the focus of attention these days. In this work, a Chemical Looping Combustor (CLC) was designed and fabricated with the major geometric sizes at the Faculty of Engineering, Suez Canal University. The system involves two interconnected fluidized beds. Nickel powder with 150 µm diameter as well as brown coal and liquefied petroleum gas were used as oxygen carrier, solid fuel, and gaseous fuel, respectively. The temperature distributions along the fuel reactor for LPG flow rates of 11 and 18 LPM with and without using nickel powder as well as using preheated reactor were discussed and evaluated. The effects of brown coal diameter change with and without using nickel powder were studied. The CO and CO2 concentrations at combustion gases with and without using nickel powder were conducted for LPG and brown coal fuels. A mathematical model was used to simulate the combustion in CLC using combustion and energy code. The obtained results showed that using nickel powder improved the combustion process and in case of using LPG, the flame color changed to blue which is the color of the complete combustion flame. The CO was reduced by 48.4 % and CO2 was augmented by 66.5 %. In case of using brown coal as solid fuel, CO was reduced by 53.7 % and CO2 was increased by 71.9 %. Finally, there is good agreement between the experimental and numerical results based on the determination coefficient.

To investigate the possibility of using fuel for plant origin in a diesel generator, safflower methyl ester was prepared and used as a biodiesel. In this research, biodiesel was produced through a transesterification reaction using a hydrodynamic reactor, which increased the reaction efficiency and reduced fuel production time. Upon increasing the reaction time from 30 seconds to 60 seconds, the reaction performance increased by 5.5 %. Then, its important features complied with ASTM D-6751 standard. The performance and pollution indices of the diesel generator engine were tested with compounds B0, B20, B50, B80 and B100. The results of short-term engine tests showed that by increasing the share of biodiesel to 20 %, CO emissions were reduced by 21 % compared to pure diesel fuel, but the amount of NOX increased by 0.82 % compared to diesel. Also, the use of 20 % volume of biodiesel in the fuel composition increased the thermal efficiency of braking, braking power, and braking torque of fuel, compared to diesel. Also, the specific fuel consumption of B20 was reduced by 2 %, which is very important economically. Finally, the TOPSIS analysis illustrated that B50 fuel outperformed pure diesel fuel and other listed fuel combinations.

One of the best and most important types of concentrating solar power plants is the linear Fresnel collector. The thermal performance and application of absorber in a solar power plant can be enhanced using direct steam generation technology. A particular discrepancy between the present study and others lies in our attempt at applying a new method for calculating critical heat flux based on Look-up Table. In the current study, effects of nanofluid on the length of the critical heat flux and convection heat transfer coefficient were investigated. The nanoparticles considered in this study were aluminum, silver, nickel, and titanium dioxide at concentrations of 0.01, 0.1, 0.3, 0.5, 1 and 2 %. Modeling results revealed that the heat transfer coefficient increased upon enhancing the volumetric concentration of nanoparticles, thereby improving this coefficient at 2 vol. % nickel nanoparticles, which was 10.6 % above the value of pure water. On the other hand, thermal efficiency was enhanced when nickel nanoparticles were dispersed in pure water such that increase rates of thermal efficiency equaled 11.2, 10.8 and 11.3 % in the months of June, July, and August, respectively, when the volume concentration of nanoparticles was 0.5 %.

In the context of increasing emission of greenhouse gasses in the environment due to fossil fuel burning, this paper attempts to describe the significance of Maximum Power Point Tracking (MPPT) by investigating the power performance of photovoltaic modules with MATLAB simulation. MPPT algorithm was employed to secure maximum power from PV module. The boost converter whose pulse is linked to MPPT algorithm restricts the flow of load power and controls the current and voltage of PV panels. The whole design of the solar model, boost converter, and MPPT controlled algorithms was done in the SIMULINK to prioritize the system in simulation. The main concept employed in this paper was to develop a power generation process with MPPT algorithm and to provide information for future use. In this paper, all simulations along with the PV power generation process were done in MATLAB. This research could potentially play a vital role in mitigating the world fuel crisis.

The use of small-scale Combined Heat and Power (CHP) to meet the electrical and thermal needs of buildings has grown exponentially and plans have been made in Iran to expand these systems. In view of the above, in the present work, for the first time, sensitivity analysis has been performed on the parameters of natural gas price, annual interest rate, and the price of pollutant penalties. The CHP system studied included fuel cell, biomass generator, solar cell, wind turbine, and gas boiler. The techno-econo-enviro simulations were performed by HOMER software and the study area was Abadan. The use of a dump load to convert excess electricity into heat and heat recovery in a biomass generator and fuel cell are other advantages presented by the present work. The minimum Cost of Energy (COE) is 1.16 $/kWh. The results also showed that the use of biomass generators was economical when the annual interest rate was 30 %. The significant effect of using dump load on the required heat supply and the lowest price per kg of hydrogen produced equal to $ 35.440 are other results of the present work. In general, the results point to the superiority of solar radiation potential over wind energy potential of the study area and the prominent role of dump load in providing heat on a residential scale is clearly seen. Also, for the current situation, using biomass is not cost-effective.

Studies on renewable energy are essential topics that help find new energy sources to replace fossil sources and promote environment friendliness. Hydrogen is the most practical alternative energy carrier source that meets the mentioned purposes. The mass of hydrogen element in the Earth's water was calculated and found to be about 2.1×1020 kg, which is greater than the mass of the world oil reserves by about 9×105 times. In addition, essential details of water molecular arrangement were investigated in order to better understand the electrolysis of water. Also, the energy of covalent and hydrogen bonds per molecule of water was theoretically calculated and found to be about 8.17×10-19 J/molecule and 3.87×10-20 J/molecule, respectively. In the electrolysis process, two stages should be undertaken: the first stage was to break hydrogen bonds between water molecules, in which all water eclectic dipoles would align in the direction of the Applied Electric Field across the electrolysis unit. The second stage was to break water covalent bonds to generate H2 and O2 gases. Moreover, the lowest cost to generate one kg of hydrogen (0.4 $/kg) by electrolysis method using solar energy was about 0.4 $, which has already been proven, while this value was about 2.8 $/kg upon considering the average price of electricity of Oman in comparison.

As a result of growing energy demand, shortage of fossil fuel resources, climate change, and environmental protection, the need for renewable energy sources has been growing rapidly. However, there is an urgent need to cope with intermittency and fluctuation of renewable energies. Various energy storage systems are considered as appropriate solutions to the above-mentioned problem. In the present manuscript, a novel compressed carbon dioxide energy storage system was proposed. Furthermore, an extra thermal energy storage with Therminol VP-1 as a working fluid, coupled with Parabolic Trough Collector (PTC), was added to the system. This integration is conducive to rising the inlet temperature of turbines and reducing the work load that should be done by the compressors. In the present study, a method based on software product including Engineering Equation Solver (EES) for determining thermodynamic characters per component and System Advisor Model (SAM) was employed to model the solar field for a desired location. Energy and exergy analyses were conducted to evaluate the whole cycle performance during charging and discharging periods. In this study, the city of Kerman located in the south-eastern part of Iran, with Direct Normal Incidence (DNI) of 950 , was selected for the present modeling. The results of a random day (June 22/2019) at time 15:00 represented the exergy efficiency of 66.98 % and the round trip efficiency of 93.14 %. High exergy efficiency and round trip efficiency of this system make this idea applicable to enhancing the total performance of the entire system.

Energy plays a vital role in all human life activities. Due to the problems caused by fossil fuels in recent decades such as global warming, greenhouse gas emissions, ozone depletion, etc., the use of renewable and clean energy has been considered. An experimental facility for the acquisition of reliable data from Parabolic Trough Solar Collectors (PTCs) was established to develop a robust analytical model. A wide range of Heat Transfer Fluid (HTF) flow rates (0.0372-0.1072 kg/s) and solar radiation (400-900 W/m2) were used to determine PTC parameters such as the outlet temperature of HTF loss and temperature distribution. Vacuum conditions in the receiver were considered effective in terms of thermal efficiency. Also, three types of HTF including two oil fluids (Syltherm 800 and S2) and water were examined. The temperature distribution showed that when Syltherm 800 or S2 passed through the absorber tube, the outlet temperature was higher than water: 2.84 % for Syltherm 800 and 3.72 % for S2. Since the absorber tube temperature was much higher than water, the heat loss in this condition was considered for oil HTF. Of note, the results demonstrated that use of the vacuum tube could diminish heat loss for the oil HTF. The effect of solar intensity increases from 600 W/m2 to 900 W/m2 on the maximum temperature of the receiver tube indicated that when Syltherm 800 was used as an HTF, this temperature increased by 35.1 % (from 167 °C to 219 °C), while this percentage was 32.7 % and 6.8 % for S2 and water, respectively.