Journal of Renewable Energy and Environment
Volume:11 Issue: 2, Spring 2024

Desalination stands out as a prominent method for obtaining fresh water from saltwater sources. The focus of this study revolves around a dehumidifier-dehumidifier system within a closed air-open water desalination framework, exploring two distinct modes: one without integration with solar collectors and the other incorporating solar collectors.Optimal conditions emerged with a fresh water circulation rate of 3 L/min and an incoming salt water flow rate of 1 L/min, resulting in a commendable maximum recovery ratio of 5.33%. Subsequently, in these optimal operating conditions, photovoltaic-thermal (PVT) panels were introduced to the desalination system, yielding insightful results. The output gain ratio (GOR), indicating the efficiency of converting heat to water evaporation, was 0.78 without connecting panels and 0.48 when panels were integrated. With panels connected, the desalination system achieved a peak fresh water production of 2.04 L/hr. Notably, the humidifier tower exhibited an impressive efficiency of 97%, while the dehumidifier tower operated at 40%. The solar collectors contributed significantly, meeting approximately 10% of the system's heating requirements and satisfying 7.3% of its electrical needs. The findings underscore the viability of integrating solar technology into desalination systems, showcasing not only increased fresh water output but also a noteworthy reduction in reliance on conventional energy sources. This innovative approach aligns with the global pursuit of sustainable and efficient water management solutions.

This experimental study investigates the performance of a single-slope solar desalination with a finned pond, considering varying glass cover angles, water depths, and the usage of sensible and latent heat materials for four different saline water types. Conventional solar stills (CSS) produce less distillate; therefore, some design changes were implemented by integrating a finned pond into the conventional solar still (CSS-FP). Additionally, paraffin wax and bricks were placed inside the solar still to enhance thermal storage capacity. The solar still is constructed with galvanized steel for the base and side walls, while the basin is covered with tempered glass. Thermal conductivity is improved by applying black paint on the sides. The finned pond enhances the heat absorption and distribution process, consequently increasing the evaporation rate within the still. The experiment was conducted in Pongalur, Tamil Nadu, India (10.9729° N, 77.3698° E). The maximum distillate production was achieved at a 35° glass cover angle and a 7 cm water depth. Desalination was performed on four saline liquids: bore water (BW), seawater (SW), leather industry wastewater (LW), and plastic industry wastewater (PW). BW exhibited the highest yield due to its lower density and salinity. Chemical analysis of the desalinated water suggests its suitability for home use. Economic research reveals a payback period of 230 days, confirming the financial feasibility of the solar still. Hence, it is concluded that the proposed CSS-FP can increase productivity compared to the CSS under different conditions.

The sun serves as the primary energy source, providing our planet with the essential energy for sustaining life. To efficiently harness this energy, photovoltaic cells, commonly known as PV cells, are employed. These cells convert the solar energy they receive into electrical energy. The operational point of the solar cell, delivering maximum output power, is referred to as the maximum power point (MPP). However, as light availability and temperature fluctuate throughout the day, the MPP also varies accordingly. To maintain constant operation at the MPP, Maximum Power Point Tracking (MPPT) algorithms are employed to trace the MPP during module operation. These algorithms can be categorized into four groups: classical, intelligent, optimization, and hybrid, based on the tracking algorithm utilized. Each MPPT algorithm, existing in these categories, comes with its own set of advantages and limitations. This paper extensively reviews fifteen algorithms categorized under different groups. The review concludes with a comparative analysis of these algorithms, considering various parameters such as cost, complexity, tracking accuracy, and sensed parameters in a succinct manner. The paper focuses on elucidating the necessity of MPPT algorithms, their classification as per existing literature, and a comparative assessment of the studied MPPT algorithms. This comprehensive review aims to address advancements in this field, paving the way for further research.

The widespread integration of wind energy poses numerous challenges, including ride-through capability issues, stability concerns, and power quality issues within the utility grid. Additionally, the inherent non-linear nature of wind energy systems, coupled with internal dynamics like model uncertainties, non-linearities, parametric variations, modeling errors, and external disturbances, significantly impacts system performance. Therefore, developing a robust controller becomes imperative to address the complexity, non-linearity, coupling, time variation, and uncertainties associated with wind energy systems, aiming to enhance transient performance in the presence of external and internal disturbances. The research presented in this manuscript focuses on devising a robust control scheme for a grid-tied Permanent Magnet Synchronous Generator (PMSG) wind turbine. The objective is to improve the wind turbine's performance under both normal and abnormal grid conditions. The innovation in Active Disturbance Rejection Control (ADRC) lies in its capacity to offer robust, adaptive, and disturbance-rejecting capabilities without relying on precise mathematical models. This quality makes ADRC a valuable and innovative tool for addressing challenges in complex and dynamic real-world applications where system parameters evolve over time. The wind energy system is inherently non-linear, time-varying, cross-coupled, and highly uncertain. It is also susceptible to parameter uncertainties, parametric variations, and external grid disturbances, all of which significantly influence its performance. The effectiveness of the proposed control scheme is validated to enhance ride-through capability and extract maximum power under internal disturbances, external grid disturbances, and parametric variations. To assess the proposed controller's efficacy, a comparative analysis is conducted using the Integral Time Absolute Error (ITAE) index for all abnormal grid disturbances. This analysis is performed in comparison to a Proportional Resonant Controller and a PI controller, providing evidence of the proposed controller's effectiveness. In summary, the incorporation of an Active Disturbance Rejection Controller emerges as a promising solution for enhancing the Low Voltage Ride-Through (LVRT) and High Voltage Ride-Through (HVRT) capabilities of grid-tied Permanent Magnet Synchronous Generator (PMSG)-based wind energy systems.

This research explores biomass gasification for power generation in rural areas of developing countries, utilizing a 20 kW U-flow-shaped gasification system developed at Ashikaga University. While small-scale power systems typically rely on reciprocating or modified diesel engines, which face issues due to tar produced by biomass gasifiers, this study employed a piston-less rotary engine. Performance evaluations were conducted at various engine speeds and gasifier operational modes, demonstrating continuous power generation for approximately six hours. Improved maintenance of rotary engines could benefit rural users, with potential efficiency gains through thermal energy recovery, although tar filtration needs enhancement. The experimental findings reveal continuous power generation for approximately six hours under both operational conditions, with the closed-top operation outperforming the open-top counterpart in terms of power output. However, control over power output and gasifier temperatures is more straightforward in the open-top operation. Gasifier performance was assessed based on fuel consumption rate and system efficiency, with consumption rates varying by rotary engine speed, measuring 2.0 kWh/kg at 2800 rpm and 2.3 kWh/kg at 3200 rpm, and 2.9 kWh/kg at 3600 rpm. Cold gas efficiency of the U-shaped gasifier was 63.4%, and energy conversion efficiency reached 9.4% at 2800 rpm operation. At 3200 rpm operation, cold gas efficiency improved to 79.8%, but energy conversion efficiency decreased to 7.3%. The rotary engine's energy conversion efficiency was lower than that of a gas engine. Nonetheless, if the rotary engine reduces maintenance needs, it could benefit rural users. Efficiency can be improved through thermal energy recovery.

Evacuated tube solar collectors (ETSC) are widely utilized in both domestic and industrial solar water heaters (SWH) due to their commendable thermal performance and straightforward installation. However, a significant challenge associated with ETSC lies in the fact that half of the collector remains unexposed to sunlight. To overcome this limitation, parabolic reflectors can be employed as a viable solution. The primary objective of this study is to assess the performance of a compound parabolic concentrator (CPC) in conjunction with ETSC, taking into account a specific ratio between the areas of the CPC and ETSC. To achieve the desired configuration, the CPC was meticulously designed, fabricated, installed, and subsequently tested. Moreover, the energy performance of the absorber tube was scrutinized both with and without the integration of a parabolic trough collector. The experiments and data collection were conducted on two selected days for both the conventional ETSC device and the system incorporating the CPC. Meteorological data and operational conditions were measured and digitally stored for subsequent analysis. A noteworthy outcome of the study is the revelation that the energy efficiency of the system with a concentrator exhibited a notable improvement of 2.8% compared to the conventional system. Offline results further indicated that the performance of a single absorber tube with a concentrator increased by approximately 2.7 times when compared to the standard system. This suggests that the energy performance of the solar water heater, with a capacity of about 200 liters and featuring 7 absorber tubes with a concentrator, is comparable to that of the conventional system equipped with 18 absorber tubes.

In the present study, a modified pyramid-solar-still (MPSS) with new multiple stepped basin areas was investigated in the weather conditions of Qena, Egypt, at a location of (Latitude: 26.16°, Longitude: 32.71°). Boosting the output of the pyramid solar still is the primary focus of the proposed strategy. To achieve this, four basins were built and integrated into the pyramid solar still, with their size increasing in proportion to the surface area of the condensing glass. A 25% increase in basin area per square meter of solar still was achieved compared to conventional pyramid solar still (CPSS) with the same condensing cover area. The thermal performance and productivity of the suggested solar still were demonstrated by developing energy balance equations for temperature components and then analytically computing their solutions. The results showed compatibility between theoretical and experimental results. The highest yields for CPSS were 2524 mL/m2, and for MPSS, they were 3415 mL/m2. The stepped area enhanced the yield by 35.3% compared with CPSS. Moreover, the efficiency of CPSS and MPSS was recorded as 23.5% and 31.7%, respectively. Furthermore, the maximum yield of freshwater was obtained for the northern condensing cover, with the recorded value reaching 1174 mL/m2. Distilled water under the proposed system would cost $0.0179 per liter. Finally, the TDS and pH levels are in accordance with WHO recommendations for the quality of drinking water.

The rapid rise in electrical energy demand and the depletion of fossil fuels have created a market for renewable energy. Among all the renewable energy resources, the most popular is solar energy, perceived as pollution-free, easily accessible, and low maintenance. In non-uniform solar irradiation or partial shading conditions (PSC), the photovoltaic characteristics (PVC) of a solar panel system (SPS) exhibit multiple minor peaks (MP) with one global peak power point (GPPP). To extract the utmost energy from the SPS, the authors proposed an efficient hybrid algorithm integrating the advantages of machine learning and the classical algorithm fractional open circuit voltage (FOVA) to track the GPPP. To follow the GPPP of SPS under unstable environmental surroundings, this study tests ML-based hybrid MPPT algorithms, specifically squared multiple variable linear regression algorithms (SMVLRA), using Matlab/Simulink. Simulation through Matlab is employed to validate the efficiency of the SMVLRA-MPPT approach compared to existing popular conventional and modern MPPT algorithms, namely the Perturb and Observation algorithm (P&OA), the variable step size incremental conductance (VINC) algorithm, and an intelligent algorithm, Decision Tree Regression Algorithm (DTRA). The simulation results demonstrate that SMVLRA offers higher peak power and mean peak power efficiency in less tracking time, with lower error and almost negligible steady-state fluctuation under PSC. The proposed algorithm achieves 99.99% efficiency under standard test conditions (1000w/m2, 25°C), 99.95% under PSC1 (1000w/m2, 800w/m2, 25°C), and 98.89% under PSC2 (1000w/m2, 800w/m2, 600w/m2, 25°C)

The drive to move away from fossil fuels and related products has drawn significant attention to biomass and biomass-related products in recent times. This study reports the effect of three forest biomass sources namely acacia auriculiformis, terminalia randii, and delonix regia as combustion fuels in a retort heated, low-temperature and top-lit updraft gasifier on biochars produced from two agricultural wastes: corn husk and corn cob. The combustion fuels were characterized using Thermogravimetric/Differential thermogravimetric analysis. Their TGA data were fitted to 16 kinetic models using the Coats-Redfern method. Characterization of the products was performed using Scanning Electron Microscopy/Energy Dispersive X-ray Spectroscopy and Fourier Transform Infra-Red Spectroscopy. Results revealed similar decomposition trends for combustion fuels. Different kinetic models predicted decomposition mechanisms of combustion fuels for the regions considered. Negative correlation was found between biochar yields and increasing carbonization temperatures with yields ranging from 64.6-37.8 % and 28.4-24.5% for corn husk and cob, respectively. Results indicate similar effects of combustion fuels on functional groups contained in biochar samples.

The concentration of India's population has presented the country with various challenges regarding the exponential growth of Municipal Solid Waste (MSW). Globally, the increasing volumes of rubbish have made waste management both environmentally and socially burdensome. The development of safe and renewable resources has assisted in municipal solid waste management. Garbage-to-energy conversion has proven to be an effective method for reducing municipal waste. Biofuel and biogas generation from municipal solid waste are among the renewable energy possibilities within the broader framework of waste management. The review examines sustainable treatment methods for managing municipal waste. It provides an overview of the characteristics and environmental impacts of municipal solid waste. To enhance energy generation, pretreatment approaches have been integrated into waste conversion processes. The review underscores the significance of thermal and biological conversion-based approaches to municipal waste management. Biological treatment technologies have emerged as a significant focal point for energy recovery while maintaining environmental sustainability. Additionally, the review assesses the applicability of various Indian policies for Municipal Solid Waste Management.

Building insulation stands out as one of the most widely employed strategies to enhance energy efficiency in the building sector. Increasing the thickness of thermal insulation is a conventional approach to meet the design requirements of these structures. In this study, a novel approach to augment the thermal resistance of external building walls is explored by simultaneously employing multiple thermal insulation materials, comparing this with a single-layer insulation setup. Three typical insulation materials with varying thicknesses are utilized to create a three-layer insulation system, which is applied to a case study involving a house-like cubicle situated in the 3B climate zone per ASHRAE 169-2006. The findings indicate that merely increasing the thickness of a single-layer insulation does not invariably yield optimal solutions. A comparison of two non-dominated solutions, both with a thickness of 15 cm, reveals that both alternatives achieve approximately 70 percent energy savings compared to the base model lacking wall insulation. Furthermore, the environmental impact of the three-layer solution is 45%, and its cost is 43% lower than that of the single-layer solution. In summary, multi-layer thermal insulation emerges as an effective and environmentally friendly method. The results emphasize that the consideration of multi-layer insulation systems can establish a continuous decision-making space, enabling the identification of at least one insulation scenario aligned with design requirements. To facilitate designers in the initial stages of thermal insulation design, a rapid and simplified design model has been developed based on the results. The methodology proposed in this study is generalizable and can be applied to all climate zones, offering a comprehensive design tool without the need for intricate calculations.