Clean Technol., Volume 6, Issue 2 (June 2024) – 8 articles

Fuel cells represent an appealing avenue for harnessing eco-friendly energy. While their fuel supply traditionally stems from water electrolysis, an environmentally conscious approach also involves utilizing low-weight alcohols like methanol and ethanol. These alcohols, concentrated from sustainable sources within the enological by-product distillation process, offer a noteworthy contribution to the circular economy. This study delved into evaluating the efficacy of distillery fractions in powering methanol fuel cells. Beyond their energy-generation potential, the performed GC-MS analysis unveiled appreciable quantities of acetic acid resulting from the partial oxidation of ethanol. This revelation opens the door to intriguing possibilities, including the recovery and repurposing of novel compounds such as short-chain fatty acids (predominantly acetic acid), ketones, and aldehydes—establishing a link between sustainable energy production and the emergence of valuable by-product applications. Full article

Significant research endeavors have focused on microbial fuel cell (MFC) systems within wastewater treatment protocols owing to their unique capacity to convert chemical energy from waste into electricity while maintaining minimal nutrient concentrations in the effluent. While prior studies predominantly relied on empirical investigations, there remains a need to explore modeling and simulation approaches. Assessing MFC systems’ performance and power generation based on real wastewater data is pivotal for their practical implementation. To address this, a MATLAB model is developed to elucidate how MFC parameters and constraints influence system performance and enhance wastewater treatment efficiency. Leveraging actual wastewater data from a municipal plant in Guelph, Canada, six sets of MFC models are employed to examine the relationship between power generation and six distinct parameters (inflow velocity, membrane thickness, internal resistance, anode surface area, feed concentration, and hydraulic retention time). Based on these analyses, the final model projects a total power generation of 50,515.16 kW for the entire wastewater treatment plant in a day, capable of supporting approximately 2530 one-person households. Furthermore, the model demonstrates a notably higher chemical oxygen demand (COD) removal rate (75%) compared to the Guelph WWTP. This comprehensive model serves as a valuable tool for future simulations in similar wastewater treatment plants, providing insights for optimizing performance and aiding in practical applications. Full article

The paper presents the design and implementation of decentralized control for a PV–wind–battery hybrid off-grid system with limited power electronics devices and sensors. To perform well without using any maximum power point tracking (MPPT) technique from the wind turbine (WT) based on a permanent-magnet brushless DC generator (PMBLDCG) and solar panels (PVs) and balance the power in the system, a cascade control structure strategy based on a linear active disturbance rejection controller (LADRC) is developed for the two-switch DC-DC buck-boost converter. Moreover, to ensure an uninterruptible power supply to the connected loads with a constant voltage and frequency, a cascade d-q control structure based on LADRC is developed for the interfacing single-phase inverter. Furthermore, the modeling and controller parameters design are presented. The performance under all operation conditions of the hybrid off-grid configuration and its decentralized control is validated by simulation using MATLAB/Simulink and in real-time using a small-scale hardware prototype. Full article

The global shift from conventional energy sources to sustainable alternatives has garnered significant attention, driven by the promise of economic benefits and environmental sustainability. The current study rigorously investigated the economic advantages and sustainability achieved from the transition of households in Mauritania from liquefied petroleum gas (LPG) to biogas utilization. The study constitutes a robust case study that centers on assessing the multifaceted impacts of this transition on household finances and overall quality of life in Mauritania. This case focuses on biogas technology adoption and its role as a competitor of LPG in Mauritania. The energy poverty portfolio of the nation has been explored and livestock waste generation and biogas production potential have been estimated at 2451 million cubic meters annually. Biogas production can fulfill 50% of the energy requirement for cooking purposes within the country. The community scale fixed-dome-type biogas digesters have been recommended for Mauritania by considering a community of 100 families. The calculated payback period for the community project is 74 months, and after the payback period, continuous monthly benefits of USD 1750 will be started. Livestock manure is directly utilized for farming practices in Mauritania, which produces 10.7 Gg of methane emissions per year. Biogas production is a clean and economically viable option for Mauritania, which can also be beneficial for reducing the methane emissions footprints of the livestock sector. This case study will prove as a vital project for other African nations if successfully implemented. Multiple recommendations for the policy-makers of Mauritania have also been formulated, like tariffs on biogas production facilities and swift financing schemes, which can further strengthen the biogas production on a national scale. International funders should also take part in coping with the energy demand of Mauritania and its mission to mitigate climate change rather than utilizing LPG on a national scale. Biogas production and utilization are much cheaper compared with the fluctuating prices of LPG and ensure health when cooking. Full article

In the past few decades, the solar energy market has increased significantly, with an increasing number of photovoltaic (PV) modules being deployed around the world each year. Some believe that these PV modules have a lifespan of around 25–30 years. As their lifetime is limited, solar panels wind up in the waste stream after their end of life (EoL). Several ecological challenges are associated with their inappropriate disposal due to the presence of hazardous heavy metals (HMs). Some studies have reported different treatment technologies, including pyrolysis, stabilization, physical separation, landfill, and the use of chemicals. Each proposed treatment technique pollutes the environment and underutilizes the potential resources present in discarded solar panels (DSPs). This review recommends thermal plasma pyrolysis as a promising treatment technology. This process will have significant advantages, such as preventing toxic HMs from contaminating the soil and groundwater, reducing the amount of e-waste from DSPs in an environmentally friendly and economical way, and allows the utilization of the valuable resources contained in EoL photovoltaic solar panel modules by converting them into hydrogen-rich syngas to generate thermal energy, electricity, and non-leachable slag that can be used as an additive in other treatment processes or as a conditioner to improve soil properties. However, plasma pyrolysis uses a high temperature to break down waste materials, a challenge which can be offset by the integration of this process in anaerobic digestion (AD), as the slag from plasma pyrolysis can be used as an additive in AD treatments to produce high yields of biogas and improve nutrient recovery. Moreover, the produced energy from both processes can operate the entire plant in which they take place and increase the net energy production, a resource which can be sold for an additional income. Future challenges and recommendations are also highlighted. Full article

The design and optimization of floating offshore wind turbines (FOWTs) pose significant challenges, stemming from the complex interplay among aerodynamics, hydrodynamics, structural dynamics, and control systems. In this context, this study introduces an innovative method for forecasting the dynamic behavior of FOWTs under various conditions by merging Convolutional Neural Network (CNN) with a Gated Recurrent Unit (GRU) network. This model outperforms traditional numerical models by delivering precise and efficient predictions of dynamic FOWT responses. It adeptly handles computational complexities and reduces processing duration, while maintaining flexibility and effectively managing nonlinear dynamics. The model’s prowess is showcased through an analysis of a spar-type FOWT in a multivariate parallel time series dataset using the CNN–GRU structure. The outcomes are notably promising, underscoring the model’s proficiency in accurately forecasting the performance of FOWTs. Full article

Amidst a growing global focus on sustainable energy, this study investigates the underutilization of renewable resources in the southern region of Saudi Arabia, with a specific emphasis on the Najran Secondary Industrial Institute (NSII). This research presents an in-depth analysis of installing a hybrid microgrid (MG) system on the roofs of NSII buildings, exploring six cases with varying tilt and azimuth angles. The study innovatively integrates architectural design and system administration, a novel approach for this location, and benchmarks the optimal angles against Hybrid Optimization of Multiple Energy Resources (HOMER) software defaults. The proposed system consists of solar photovoltaic (PV) panels, a battery storage system (BSS), a converter, a diesel generator (DG), and a grid. The selected model balances technological and economic viability with environmental considerations, ensuring a reliable power supply within the NSII’s roof area constraints. An extensive sensitivity analysis evaluates the system’s resilience across different scenarios. The current system, which is grid-only, has an estimated Net Present Cost (NPC) of about USD 7.02M and emits 1.81M kg/yr of CO₂. The findings point to installing a microgrid with a 20.97° tilt and 50° azimuth angle as optimal, demonstrating 54.69% lower NPC and 92% lower CO₂ emissions, along with zero kWh/year unmet electrical load when applying the resilience assessments. This outcome highlights Saudi Arabia’s southern region’s renewable energy potential, aligning with national mega-projects and energy initiatives. Full article