Fonio is an underutilized cereal from West Africa, recognized for its exceptional nutritional profile and ability to thrive under climate stress. However, its processing, including drying, remains labor-intensive in rural areas. This study therefore aimed to design and evaluate the performance of a chamber-type solar dryer, considering the specific constraints of fonio drying in rural contexts. The dryer consists of a 10 m × 5 m concrete chamber with a sloped roof (3.0 m to 2.2 m). It is covered with translucent fiberglass sheets and powered by a photovoltaic system. Experimental trials were conducted in northern Benin during both rainy and dry seasons, to compare the dryer’s technical performance with traditional sun drying. Furthermore, economic and environmental assessments were carried out. Results showed that the new dryer significantly accelerated the drying process in both seasons. Fonio moisture content was reduced from 40% to below 9% (w.b.) in 4 hours during the dry season and 22 hours during the rainy season. This corresponds to a drying time reduction of 86% and 59%, respectively, compared to natural sun drying. Moreover, the dryer preserved nutrients and protected fonio from dust, insects, and other contaminants. The net annual profit was estimated at 54,224 USD (42.7% of revenue), with a payback period of 58 days. Over a 20-year lifespan, the system could mitigate 757.31 tons of CO₂ emissions, with an energy payback time of 1.27 years. The carbon credit value was estimated at 11,359.65 USD. This dryer offers a cost-effective and sustainable alternative to traditional fonio drying.
In this paper, we present a cost-effective and efficient design for a single-phase solar power inverter system aimed at converting solar energy into high-quality alternating current (AC) power. The primary objective of this design is to enable the reliable integration of renewable energy into residential and industrial electrical systems. A PIC16F876A micro-controller was employed to generate a sinusoidal pulse-width modulation (SPWM) signal, which precisely controls the operation of the H-bridge inverter circuit. This configuration allows the system to convert direct current (DC) from solar panels into a stable AC output. To further improve power quality, a lowpass LC filter was incorporated at the inverter output to eliminate high-frequency harmonics, producing a waveform that closely resembles a pure sine wave. Simulation and practical hardware testing confirm that the inverter delivers a consistent and stable AC output with minimal harmonic distortion. Due to its simplicity, scalability, and low cost, this design is highly suitable for renewable energy applications, including powering sensitive electronic equipment, off-grid systems, and energy-efficient smart homes or small industrial setups. It offers a promising solution for enhancing energy access and sustainability, particularly in regions where conventional grid connectivity is limited or unreliable.
Microbial Fuel Cells (MFCs) represent a promising biotechnology for green energy production and wastewater reclamation. These bio-electrochemical processes harness the metabolism of microbes to oxidize organic matter and generate electricity. A widespread energy crisis is the result of the current global situation, which is characterized by high energy demand and finite resources. Depletable resources are eroding rapidly, while clean energy sources remain overlooked. Thus, there is a pressing need for alternative energy-generating techniques. MFCs have received a lot of attention because of their advantageous working conditions and the availability of a wide range of environmentally safe fuel substrates. Through active breakdown of substrates by microorganisms, bioelectricity is produced, offering a durable solution to intensify energy challenges. Rigorous research has yielded new insights into fuel cells, revealing that various carbon sources, including numerous types of biomass, can be utilized proficiently. Consequently, in wastewater treatment, conversion of waste by microbes through cutting-edge bioremediation techniques, such as using MFCs, offers a potentially attractive substitute for traditional treatment processes, enabling the direct production of electricity. In addition to being in line with current technological developments, this lowers overall process costs. This review provides an overview of fundamental principles underlying MFC operation, discusses the various configurations and components, highlights their diverse applications, addresses current challenges, and outlines future research directions in the field.
This study investigates the use of lime as a buffer solution to optimize pH and temperature for the fermentation of bioethanol from elephant grass (Pennisetum purpureum), a non-edible biomass. Bioethanol is an environmentally friendly alternative to fossil fuels, produced through the fermentation of starches, sugars, or cellulose. This study emphasizes the importance of controlling pH and temperature during fermentation, noting that enzymatic hydrolysis typically requires higher temperatures than fermentation. Samples of elephant grass were incubated at different pH levels (4.0, 4.5, 5.0, 5.5, and 6.0) and temperatures (25, 35, and 40 ℃) for one week. Following acid hydrolysis using lime—which also serves as a mildly acidic substance—as the nutrient medium, fermentation was conducted using baker’s yeast, selected for its cost-effectiveness and wide availability. The ethanol yields were measured and recorded using a digital refractometer. The results were analyzed using the Gompertz method to verify the accuracy of the experimental findings. The results showed that lime not only increased ethanol production efficiency but also affected the enzymes by maximizing yeast growth at temperatures above 30 ℃, specifically 35 ℃ in this study, with a total yield of 8 % (v/v) ethanol concentration and 12 % (v/v) ethanol concentration on the peak day (day 3) at a pH of 4. These findings indicate that temperature enhances ethanol concentration, whereas higher pH levels inhibit it.
The physical characteristics of a school building have a significant impact on student learning. Daylight is one of the most important elements in architecture. Adequate lighting has a significant effect on the physical and physiological health, comfort, and performance of students. Therefore, a considerable proportion of the visual quality of educational environments depends on the quality of lighting within their spaces. Nowadays, due to population growth and the extensive demand for schools, the construction of school buildings often proceeds with minimal standards, frequently without adequate consideration of daylighting. Therefore, it is crucial to design schools with sufficient and high-quality lighting. The quality of daylight within a building is directly related to windows, which serve as the primary gateways for daylight entry. Consequently, it is essential for designers to recognize the various window parameters and the impact of each on daylight metrics, and to optimize window configurations during the early design stages. The aim of this research is to identify the physical parameters of windows and the metrics used for daylight calculation, to evaluate the interaction between these components, and ultimately to present a general template for the design of windows without shading control strategies in schools in Tehran, considering the LEED v4.1 standard. In this study, the Rhinoceros-Grasshopper software was used to simulate a total of 132 classroom models located in Tehran city (BSk Köppen climate). Subsequently, the Ladybug and Honeybee plugins were employed to investigate static and dynamic daylight metrics (DF, DA, SDA, CDA, UDI, and ASE) by modifying five main physical properties of windows (orientation, position, window-to-wall ratio, shape, and number) and analyzing their mutual impacts. In general, when the use of shading control elements is not feasible, placing windows on the north facade is more advantageous due to very low annual sunlight exposure (ASE). For both north- and south-facing windows, window position has the greatest influence on daylight performance, improving UDI by up to 62.9%. After window position, the number and shape of windows have a significant impact on the ASE and SDA metrics, which are among the most commonly evaluated daylight metrics in standards. The required window size to achieve the minimum daylight level on the south facade is nearly 50% smaller than that on the north facade. Ultimately, this paper presents 18 optimal window types for schools based on the LEED v4.1 rating system.
