Journal of Renewable Energy and Environment
Volume:8 Issue: 1, Winter 2021

This study investigates a new double-stage single-phase Grid-Connected (GC) Photo-Voltaic (PV) system. This PV system includes a DC-DC Positive Output Super Lift Luo Converter (POSLLC) and a single-phase inverter connected to a grid through an RL filter. Due to its advantages, the POSLLC was used between PV panel and inverter instead of the conventional boost converter. The state space equations of the system were solved. By using two Sliding Mode Controls (SMCs), PV panel voltage and POSLLC inductor current were controlled and the designed controls were compared. Two of these SMCs included a simple Sign Function Control (SFC) and a conventional SMC. To control the power injected into the grid with a unity power factor, an SMC was used. Perturb and Observe (P&O) method was employed to reach maximum power of the PV panel. The Maximum Power Point Tracking (MPPT) control generated the voltage reference of the PV panel. Similar controls were used for the boost converter instead of POSLLC. The obtained results were compared.

In this experimental work, the energy efficiency and performance parameters of a coarse aggregate-assisted single-slope solar still were analyzed using Taguchi analysis. The preheated inlet saline water was sent to the solar still using thermal energy accumulated in coarse aggregate to enhance its productivity and energy efficiency. The daily distillate of the proposed model was observed to be about 4.21 kg/m2 with the improved efficiency of around 32 %. Furthermore, the parameters that influenced the performance of the solar stills and their levels were identified using Taguchi analysis. The Signal to Noise (S/N) ratios of the coarse aggregate temperature, saline water temperature, glass temperature and energy efficiency were observed to be about  45.4 °C, 41.4 °C, 36.7 °C and 20.07 %, respectively. The results revealed that, the percentage difference between predicted and experimental values was observed to be about 1.6 %, 0.6 %, 1.5 % and 3.3 %, respectively. The optimization method confirmed that there was good agreement between the predicted and experimental values.

Reliability is an essential factor in Photovoltaic (PV) systems. Solar power has become one of the most popular renewable power resources in recent years. Solar power has drawn attention because it is free and almost available worldwide. Moreover, the price of maintenance is lower than other power resources. Since there are no moving parts in PV systems, their reliability is relatively high. It is assumed that a typical PV system can operate 20–25 years with minimum possible interruptions. However, solar power systems may fail, the same as any other systems. It is indicated by several studies that the PV inverters are responsible for major failures in PV systems, as other components are almost passive. Hence, the reliability of the inverter has maximum impact on the reliability of the whole PV system. Thus, not only assessing and calculating the reliability value of inverter is highly crucial, but also increasing its value is essential, as well. This paper calculates and evaluates the reliability of PV single-stage inverters exclusively. Furthermore, there are suggestions that improve their reliability value.

Photovoltaic energy is a good alternative to fossil fuels due to the abundance of solar energy. In this research, the criteria for locating photovoltaic solar power plants were identified using previous studies and experts’ views and by using the Delphi method based on five socioeconomic, topographic, power generation and distribution issues, climatological, and environmental criteria. Then, by using the GIS software, the layers of sub-criteria were classified for locating photovoltaic solar power plants. Upon identifying the proposed decision-maker units for location finding, their efficiency was calculated using the full fuzzy data envelopment analysis method in three steps. The information extracted from the layers of the sub-criteria of GIS was coded using the MATLAB software in the first step of the full fuzzy data envelopment analysis model and the decision-making units were classified into three classes of efficient, weak, and inefficient. In the second step, the values of output shortages and input surplus were determined. Finally, in the third step, efficient decision-making units were ranked using Anderson-Pearson Super Efficiency Method in full fuzzy data envelopment analysis. In order to validate the proposed method, a case study was carried out. The results of calculations showed that the north, central, and southeast areas of Sistan and Baluchestan province were among the favorable areas for photovoltaic solar power plant construction. Therefore, approximately 66 % of the province’s area has appropriate efficiency matching the sub-criteria considered to construct a photovoltaic solar power plant.

The issue of renewable energy is an important one in Poland. The Polish economy heavily relies on coal. Polish cities are among the most polluted in Europe. Therefore, there is a considerable societal support for renewable energy projects. Some people, however, keep having objections, e.g. to windfarms. This paper analyzes social costs and benefits identified by representatives of municipalities in whose territories renewable energy investments have been carried out and by representatives of companies investing in renewable energy projects. The data come from a series of surveys conducted in the period of 2013-18. It has been found out that municipalities and companies significantly differ in their identification of the key social costs and benefits related to renewable energy projects. They are alike in one aspect: such problems like climate change, global warming, energy security, air pollution, energy diversification, etc. are replaced in their thinking by more parochial concerns of land price shifts, social tensions, and others. The article finishes with discussion of reasons explaining why the Poles declare to be staunchly pro-environmental in general and at the same time turn out to be benefit-seeking when asked about particular solutions.

Some chemical processes, like the chlor-alkali industry, produce a considerable amount of hydrogen as by-product, which is wasted and vented to the atmosphere. Hydrogen waste can be recovered and utilized as a significant clean energy resource in the processes. This paper describes the thermodynamic analysis of hydrogen recovery at an industrial chlor-alkali plant by installation of hydrogen boiler and alkaline fuel cell. In addition, emission reduction potentials for the proposed systems were estimated. However, the goal of this work is to analyze the techno-economic feasibility and environmental benefits of using utilization systems of hydrogen waste. The results showed that hydrogen boiler scenario could produce 28 ton/hr steam at pressure of 25 bar and temperature of 245 °C, whereas the alkaline fuel cell system could produce 7.65 MW of electricity as well as 3.83 m3/h of deionized water based on the whole surplus hydrogen. In comparison, the alkaline fuel cell scenario has negative IRR (Internal Return Rate) and NPV (Net Present Value) due to cheap electricity and high cost of capital investment. However, regarding the steam price, the hydrogen boiler project has reasonable economic parameters in terms of IRR and NPV. Therefore, the hydrogen recovery scenario is proposed to install a hydrogen boiler as a feasible and economic idea for steam production in our case. Furthermore, in terms of emission reduction, hydrogen boiler and alkaline fuel cell techniques can significantly reduce greenhouse gas emission by 49300 and 58800 tons/year, respectively, whereas other pollutants can also be reduced by 141 and 95 tons/year in hydrogen boiler and alkaline fuel cell scenarios, respectively.

The performance characteristics and exhaust emission of a diesel engine using Water Emulsion Fuel (WEF) have been investigated under different engine speeds (1600 to 2400 rpm) and load conditions (25 to 100 %). The experiments were carried out on an air-cooled diesel engine of single cylinder using the WEF containing 5 % water, 2 % surfactant with Hydrophilic-Lipophilic Balance (HLB) of 6.8. The engine performance and exhaust emission using WEF were also compared with the Neat Diesel Fuel (NDF). According to the results, average reduction of 9.7 % in the engine torque and brake power was observed using WEF at all engine speeds. In addition, a 7.9 % increase in the Brake Specific Fuel Consumption (BSFC) and a 3.7 % increase in the Brake Thermal Efficiency (BTE) were observed for WEF in comparison with NDF in all loading conditions. In case of emission, significant lower hydrocarbon emission (i.e., 14.6 % on average) was observed for WEF comparing to NDF at all engine speeds. Moreover, a considerable reduction in the NOx emission (i.e., 31.1 % on average) was observed for the WEF comparing to the NDF in every engine load. In summary, the application of WEF leads to the reduction in the emission of different pollutants with a positive impact on the environment.

The present study is concerned with the development, estimation and validation of sunshine hours models (SHM) in Uganda. The SHM is based on geographical (latitude) and climatological (clearness index) indices. The meteosat data (1984-2018) acquired from the National Aeronautics and Space Administration were used to compute the coefficients of the models which, yielded a coefficient of determination close to unity, signifying a good association between the sunshine hours (SH) and the associated indices. The models become distributed by introducing a longitudinal function of clearness index into the primary SHM developed. Moreover, the models were subjected to statistical validation using; mean absolute relative error (MARE), root mean square error (RMSE) and mean absolute percentage difference (APD). Consequently, the primary SHM showed strong agreement with the measured SH data in the three regions with the exception of the northern region with flawed on-station data. Also, validation of the models by; {MARE, RMSE, APD} for Eastern, Central and Western regions, yielding the following results; {0.0788,0.5441,7.8778},{0.0390,0.1453,3.9013} and {0.0124,0.0528,1.2436}, respectively. The following maximum SH; 11.16, 7.87, 9.52, 8.86 and 6.06 h were recorded for Non-regional, Northern, Eastern, Central and Western regions, respectively. Further, comparative validation with redeveloped global SHM showed that the present model stands in all the regions, whereas the global models validated only in the Eastern region. This is attributed to the synergy of geographical and climatological indices against the global models only based on climatological index. The model results show the order of regional SH distribution; eastern>northern>central>western region. These results could be employed in solar power, exploitation and agrometeorology development. This study further recommends for adoption of the present model to non-equatorial regions upon redevelopment as a meaningful extension of this work.