Journal of Renewable Energy and Environment
Volume:10 Issue: 4, Autumn 2023

One of the environmental problems today is the rising land surface temperature and the formation of heat islands in metropolitan areas, which have arisen due to the unplanned expansion of these cities. Satellite imagery is widely used in urban environmental studies to provide an integrated view and reduce costs and time. In this study, Landsat satellite imagery in TM, ETM+, and OLI sensors from 1984 to 2020, remote sensing techniques, and GIS is used to analyze the data, and SPSS software is employed to examine the correlation between the data. The results indicate that the land surface temperature in District 1 of Tehran has increased during the last 38 years. Moreover, land use in District 1 has changed significantly over this period, and urban land use increased from 16 % (1984) to 35 % (2020) while vegetation declined from 32 % to 14 %. The results of linear regression analysis show a significant correlation between satellite images and weather station data. The significance coefficient (Sig) in all stations is less than 0.05 with a 95 % confidence interval. Besides, the coefficient of variation (R) for all stations is above 80 %, and the coefficient R2 has a desirable value. The findings suggest that the trend of rising temperatures in District 1 of Tehran has become an environmental problem and the changes in land use such as declining vegetation and increasing the acceleration of urbanization are among the factors that affect it.

Phase Change Materials (PCMs) have received much consideration as thermal energy storage systems due to their high storage capacity. However, their heat transfer rate is limited because of the low thermal conductivity. Incorporating of carbon-based nanoparticles into the matrix of PCMs with good dispersion can be an efficient way to solve their deficiency. In this research, graphite nanoparticles were homogeneously dispersed within the Eicosane PCM matrix to prepare a Nano-Enhanced PCM (NEPCM). The main objective is to determine the optimum amount of graphite to maximize the thermal properties of NEPCM composites. The Scanning Electron Microscopy (SEM) images of the prepared nanocomposites confirmed the excellent dispersion of graphite nanoparticles within the Eicosane layers through an ultrasonic bath-assisted homogenization procedure followed by solidification. In addition, Differential Scanning Calorimetry (DSC) and Thermal Conductivity Evaluation (TC) of the samples were conducted to determine their heat capacity and thermal diffusivity. The results illustrated that the more the number of graphite nanoparticles, the larger the number of collisions between graphite and Eicosane. As the nanoparticle content increased, the thermal conductivity and diffusivity were enhanced, as well. Numerically, the maximum thermal conductivity was 4.1 W/m K for the composite containing 10 wt% graphite, 15.66 times that of the pure Eicosane. Furthermore, increasing crystal growth and reducing heat capacity for the large number of nanoparticles in the composite were discussed. The significantly improved thermal properties of the prepared NEPCMs with an optimal nanoparticle content could make them applicable for different thermal management applications.

This study considers N-photovoltaic thermal-thermo electric cooler (PVT-TEC) air collectors connected in series for thermal and electrical performance. An improved Hottel-Whiller-Bliss (HWB) equation and mass flow rate factor were derived for the nth PVT-TEC air collectors. The derivation is based on energy balance equation for each component of N-photovoltaic thermal-thermo electric cooler (PVT-TEC) air collectors connected in series. Further, thermal energy and electrical energy from PV module and TEC were analyzed based on a given design and climatic parameters along with the overall exergy of the proposed system on the hourly and daily bases. Numerical computations were conducted using MATLAB under Indian climatic conditions. The proposed thermal model is valid for all climatic and weather conditions. Based on the numerical computations carried out, the following conclusions were made:The electrical power of PV module decreased with increase in the number of the n^th PVT-TEC air collectors as the electrical power of TEC increased.The overall instantaneous exergy efficiency decreased with increase in the number of the n^th PVT-TEC air collectors.Packing factor of TEC was found to be a very sensitive parameter for optimizing the number of PVT-TEC air collectors to ensure maximum overall exergy, and it was found to be β_tec=0.5. for N=7

In this research study, a cost-effective and reliable weather station using a microcontroller system containing instruments and sensors for measuring and recording ambient variables was designed, fabricated, and tested. The dataset recorded and stored in the meteorological system can be applied to conduct various research in the field of energy and environment, especially in solar systems. Employing a microcontroller system reduces costs and provides special features such as accessing data on the web-based spreadsheets and adding control devices. In this system, meteorological information including solar radiation, air temperature, wind velocity, and air relative humidity is measured and saved in user-defined time intervals such as 30 seconds. The total cost for measuring equipment, sensors, and microcontroller along with a data logger is about 110 USD. To demonstrate the importance of using local meteorological data, in the vicinity of the case studies, the dataset provided by the local weather station was compared with the meteorological data of two nearby national stations for one month. The results revealed that the values reported by the national stations were different from the actual values measured by the local weather station. The deviations for solar radiation, wind velocity, air temperature and humidity values were at least 5, 9, 7%, and more than 100%, respectively.

This study proposes a novel approach to fast and direct determination of the Maximum Power Point (MPP) at any value of solar irradiation and cell temperature, without applying further mathematical processing to operate at that point. The current approach aims to reduce algorithm complexity, time consumption during the iteration, and oscillation to reach the point at which the panel generates maximum possible power. For avoiding or eliminating these drawbacks, the chopper duty cycle (D) at which the panel-generated power should be the maximum is determined using the panel datasheet with respect to voltage and power at different irradiation rates (G). Mathematical equations are derived for MPP voltage and power at any value of solar irradiation using the manufacturer Photovoltaic (PV) specification. The simulation results obtained by MATLAB/SIMULINK platform showed that the power had a linear change, while the voltage had a nonlinear one with narrow variations.  The yield duty cycle controls the Modified Single Ended Primary Converter (MSEPIC) that regulates the load voltage through a wide range below and above the rated panel voltage. The simulation results showed the fast response of chopper operation with a negligible starting time required by the MPPT algorithm, no duty cycle oscillation, and shorter iteration time. Furthermore, the conducted approach is validated based on the data published in a reputed journal, and the obtained results gave rise to new aspects that helped reduce dependency on conventional MPPT algorithms and, consequently, enhance the system response, efficiency and cost reduction.

Paraffin waxes are widely used as commercial organic heat storage phase changes (PCM) for many applications due to their suitable properties. Significant heat from fusion, nonpoisonous and stable properties, no phase separation, and the phase process result in a small volume change. Meanwhile, they are subject to low thermal conductivity. The thermal conductivity of PCMs can be increased by different techniques such as the use of dispersion of particles or nanomaterials with high conductivity in PCM and the use of metal foams. The use of nanoparticles has such disadvantages as high cost and particle deposition after various cycles. Hence, in this study, some experiments were carried out to investigate the effect of porous media like copper foam and iron wool as the filler instead of nanomaterials on improving the heat conductivity of PCM. The results show that the porous foam increases the heat transfer and during the charging operation, the temperature of the porous plate wall increases continuously at the same rate as the paraffin. At 2400 s, the temperature of pure PCM, iron wool, and copper foam reaches 67.3, 72.5, and 73.27℃, respectively. The optimal mode is the one in which the copper absorber plate is connected to the copper foam, thus reducing the charging time by 600 s compared to pure PCM and saving 75% of energy. Connecting the copper absorber plate to the iron wool has a good thermal performance and stores 70.83% of energy. Thus, iron wool has an acceptable performance and is suitable for storage systems.

The use of Diesel Generators (DGs) and gas turbines to power oil rigs is characterized by pollution due to the emission of harmful gases like carbon dioxide, very high noise levels, high maintenance costs, and the inability to start the platform if the DG fails. Offshore wind energy generation system provides a viable alternative means of powering the oil rig and can also be integrated to operate in parallel with gas turbines. However, offshore wind energy might fail if not properly designed due to the high variability of wind resources. Hence, the objective of this work is to design offshore Wind Turbine Generator (WTG) energy generation system, DG, and hybrid DG-WTG for the black start of an offshore oil rig. The designed energy systems are simulated using HOMER Pro. Furthermore, the performance of the simulated systems was evaluated using the electrical production, unmet load, and emission profile as the performance metrics. The results of the hybrid DG-WTG powered black start revealed that 150kW DG generated 322,071kWh/yr representing 6.77% of the total generation and 1.5MW WTG generated 4,434,632kWh/yr representing 93.2% of the total generation. The comparison of the emissions from DG and DG-WTG revealed that 294,058kg/yr, 1,945kg/yr, 80.9kg/yr, 9.02kg/yr, 720kg/yr, and 688kg/yr of CO2, CO, UH, PM, SO2, and NO, respectively, were released into the atmosphere by DG-WTG which is very low compared to 969,129kg/yr, 6,109kg/yr, 267kg/yr, 37kg/yr, 2373kg/yr, and 5739kg/yr of CO2, CO, UH, PM, SO2, and NO, respectively, released into the atmosphere by DG. The sensitivity analysis revealed that while the electrical production of 100kW and 50kW DGs decreased with an increase in WTG height, the electrical production of 1.5MW WTG increased with an increase in WTG height. It was further revealed that the higher the WTG height the smaller the quantity of the emission released into the atmosphere.

Dust accumulation on PV surface panels is a crucial factor affecting their performance. It is more frequently noted in the desert zones. The effect of dust on the electrical behavior of damaged PV panels was investigated in this study. Three panels are used: the degraded panels (with and without dust) and the reference panels; they are located in an industrial zone with a continental climate (Bordj Bou Arréridj, Algeria). The I-V and P-V characterization and degradation mechanism visualization are used. Also, a numerical simulation was conducted to calculate the five parameters of the three modeled PV panels (diode ideality factor (a), series resistance (Rs), Shunt resistance (Rp), photocurrent (Ipv), and diode saturation current (I0)). These parameters were utilized for the first time to study the impact of dust on their degradation rate and the PV panel behavior. The degradation rate and the annual degradation rate of each parameter are affected by dust differently. The power degradation rate is increased by 5.45%. The Isc and Imax degradation rates are climbed by 6.97% and 6.0%, respectively. Vmax and Voc degradation rates decrease by 1.20% and 0.35%, respectively. Dust increased the rate of degradation for a, Iph, and I0 by 4.12%, 6.99%, and 68.17%, respectively. For Rs and Rp, the degradation rate was reduced by 4.51% and 20.01%, respectively. An appropriate netoiling approach must be considered because dust, even in non-desert areas and industrial zones, has a significant impact on the electrical characteristics degradation of a PV panel.

Oil Palm Frond (OPF) juice has been the focus of Malaysian bioenergy producers through acetone-butanol-ethanol (ABE) fermentation. However, due to the high concentration of phenolic compounds in the hydrolysate, usually gallicacid and ferulic acids, the fermentation medium turns acidic which hinders the growth of most microorganisms. A suitable method of phenolic compound removal with a minimal effect on the sugar stability of OPF juice has been employed using Amberlite XAD-4 resin. During the detoxification process, the effects of temperature and pH on the removal of phenolic compounds and sugar stability were also assessed. The Amberlite XAD-4 resin managed to adsorb about 32% of phenolic compound from the OPF hydrolysate at an optimum temperature of 50 °C and hydrogen ion concentration (pH) of 6. In addition, it maintained as much as 93.7 % of the sugar in the OPF juice. The effect of detoxifying OPF hydrolysate was further tested for biobutanol production in batch culture using strain Clostridium acetobutylicum SR1, L2, and A1. Strain L2 gave the highest improvement in biobutanol and total solvent production by 22.7% and 14.41%, respectively, in medium with detoxified OPF juice. Meanwhile, compared to non-detoxified OPF juice, the acid production of strain L2 significantly decreased by 2.99-fold when using detoxified OPF juice, despite a 1.2-fold increase in sugar consumption. Conclusively, using Amberlite XAD-4 resin to detoxify OPF hydrolysate at pH 6 and 50 °C removed the phenolic compound while increasing the strain L2 capability to improve biobutanol and total solvent production.

Researchers worldwide are studying thermal energy storage with phase change materials because of their substantial benefits in the enhancement of energy efficiency of thermal drying systems. A two-stage convective-vacuum impulsive drying plant is a technology for the manufacturing of chemical and food products with high quality and low energy costs. Energy consumption during the drying process is the main indicator in terms of economy. In this paper, a brief and focused review of the peculiarities of TEAs with PPCMs and opportunities of their application in such drying systems is done and discussed. The paper described the mentioned manufacturing system. The advantages of paraffin wax and thermal conductivity improvement techniques were demonstrated for their use as heat storage materials in CVID drying units. The results of similar previous studies were presented. The results of the experimental studies conducted by the researchers proved that the use of heat accumulators with PCMs increased the overall energy efficiency of drying systems. Finally, integration of TEAs based on modified PPCMs in the CVID system was recommended to intensify thermal energy, reduce thermal influence on the main indicators of the vacuum pump during the evacuation process, and decrease production costs.

The output power of a Solar Photovoltaic (SPV) plant depends mainly on the solar irradiance on the photovoltaic (PV) modules. Therefore, short-term variations in solar irradiance cause variations in the output power of solar power plants, making solar photovoltaic grid integration unstable. Solar irradiance variations mainly occur due to the weather conditions of a given location, especially the movement of clouds and seasonal effects. Consequently, assessing the variability of solar irradiance over the course of a year is essential to identify the extent of these variations. Geographical dispersion and cloud enhancement are two important factors affecting output power variations in a PV plant. Geographical dispersion reduces such variations, while cloud enhancement increases them. This study utilizes two ground station-based solar Global Horizontal Irradiance (GHI) datasets to assess the viability of solar irradiance in the Chittagong division of Bangladesh. The analysis reveals a significant number of days with high short-term solar irradiance variation. In addition to solar irradiance, the frequency and voltage at the interconnection point are important for safe grid integration. It was observed that the grid frequency exceeded the range specified by the International Electrotechnical Commission (IEC), but remained within the grid code range of Bangladesh. Grid voltage variation at the interconnection substation was found to be within the standard range during the daytime, but low voltage was observed at the grid level during the rest period. Therefore, it is crucial to implement necessary preventive measures to reduce short-term variations for the safe grid integration of large-scale variable SPV plants.

Several researchers have reported the prospects of biofuel commercialization in several countries across the globe. With over 400 million tons of biomass and 150 million tons of agro-waste produced annually in most developing countries, the prospect of biofuel commercialization looks promising. However, it is crucial to adopt a forward-thinking approach and anticipate potential challenges that may arise, building upon the lessons learned from current obstacles. This paper review addresses the current issues that have discouraged some developing countries against embracing biofuels as an economical tool to mitigate poverty. Also, future challenges that may scuttle biofuel commercialization in developing countries was discussed to provide a workable blueprint towards wealth creation. This review identified policies and political unwillingness as fundamental challenges that must be overcome in developing countries to attract investors. Other identified salient challenges include mono-economy, poor technical know-how, poor technology, government hypocrisy, lack of funds, sustainable biomass resources, inadequate farmland, poor policies, and weak infrastructure. It is recommended that conscious short- and long-term planning be implemented to actualize biofuel commercialization in developing

Clean solar energy is one of the best sources of energy. Solar power plants can generate electricity in Iran due to their large number of sunny days. This paper presents a short-term forecasting approach based on artificial neural networks (ANNs) for selected solar power plants in Iran and ranks the input variables of the neural network according to their importance. Two solar power plants in Hamadan province (Amirkabir and Khalij-Fars) were selected for the project. The output of solar power plants is dependent on weather conditions. Solar radiation on the horizontal plane, air temperature, air pressure, day length, number of sunny hours, cloudiness, and airborne dust particles are considered input variables in this study to predict solar power plant output. Forecasting model selection is based on considering zero and nonzero quantities of target variables. The results show that solar production forecasting based on meteorological parameters in the Khalij-Fars is more accurate than Amirkabir. The global solar radiation, air temperature, number of sunny hours, day length, airborne dust particles, cloudiness, air pressure, and dummy variables[1] are the order of the most important inputs to solar power generation. Results show simultaneous influences of radiation and temperature on solar power plant production.
 
[1]. The first half of the year is counted as one, and the second half is counted as zero.

This research reviews various studies on the effect of using nanofluids in evacuated tube solar collectors (ETSC). The initial segment of this study elaborates on the importance of using the ETSCs and categorizes these collectors in terms of classification and application. The second segment evaluates the physical properties of nanofluids incorporated in the solar system collector and presents some applications of nanofluids. The last segment of the research reviews the works of a group of researchers who have already applied nanofluids to evacuated tube solar collectors for various purposes, including increasing the heat transfer coefficient and improving efficiency. Among the prevalent nanofluids employed in solar applications, Al2O3, CuO, and TiO2 feature prominently, whereas Ag, WO3, and CeO2 find limited application in the solar context. Furthermore, nanofluids within the size range of 1–25 nm, 25–50 nm, and 50–100 nm constitutes 54%, 25%, and 11% of the applications, respectively. Particularly noteworthy, the single-walled carbon nanotubes/water (SWCNT/water) heat pipe showcases the most remarkable efficiency enhancement, achieving an impressive 93.43% improvement.

In this research, a piece of copper scrap was placed in the 1m × 1m base of a single-slope solar still. An automated system steadily dripped salt water into the basin of the solar still. The experiment utilized dripping salt water and energy storage materials such as copper and brass scrap. Research has shown that the presence of copper scrap in the basin, combined with a shallow layer of salt water, has a significant impact on the distillate output. However, the high thermal capacity of the salt water in the basin can lead to reduced production. As more salt water is added to the basin, the temperature difference between the water inside and the glass cover increases. Based on the experimental results, the calculated yield is satisfactory, and the overall thermal efficiency remains at 71.3%. The production rate is also influenced by the diffusion process on the south-facing condensing cover. The temperatures of water, glass, and air, as well as their combined effects, are measured and analyzed.