An Overview of Scientific Production of Renewable Energies in GhanaRead the full article
Journal of Energy publishes research relating to the science and technology of energy generation, distribution, storage, and management. It also covers the environmental, societal and economic impacts of energy use and policy.
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Study of Vertical-Axis Wind Farm Layouts Using a 2D Actuator-Cylinder RANS Model
The actuator-cylinder RANS (Reynolds-averaged Navier-Stokes equations) model was used to study the performance of two different arrays of wind turbines. The staggered array proved to be more efficient than the fish-school array (grouped in pairs) in most directions; however, the fish-school array outperformed the conventional staggered array when the pairs of turbines were facing the wind. Increases in global power coefficient up to 16% were found when the wind speed was 8 ms-1 and up to 10% when the wind speed was 10 ms-1. Despite the fish-school array being slightly less efficient, this array yielded almost twice as much power density as the staggered array in almost all directions. The current methodology proves to be a fast tool for the estimation of vertical-axis wind turbine farms compared to full RANS simulations.
Institutional Involvement and Collaboration in Disseminating Biogas Technology in Ghana
Globally, biogas technology has been touted by academics, international organizations, United Nations, and pressure groups, among others, as an effective tool for protecting the planet against degradation. As such, stakeholders in the biogas technology sector have made some policy recommendations toward that goal. These include a global campaign in support of energy for sustainable development, climate financing by the international community, all countries adopting appropriate national strategies, innovative financial mechanisms, and encouraging private-sector participation in achieving the goal. Clearly, for countries to promote accessibility and create favorable perceptions on the adoption of biogas technology requires institutional involvement and collaboration. That is, institutions need to participate and contribute in terms of ideas and expertise as well as work together to ensure the dissemination and uptake of biogas technology in Ghana. This study is aimed at assessing the level of institutional involvement and collaboration and barriers to biogas technology dissemination in Ghana. A qualitative method was employed, and data were collected from 101 respondents through interviewing. The results indicated that the involvement of government and financial institutions in disseminating biogas technology was low, while biogas service providers showed moderate involvement. With regard to collaboration, it was revealed that institutions moderately collaborate in awareness creation but had low collaborations for promotion, monitoring, and evaluation. Furthermore, the lack of a national biogas policy, low government commitment towards biogas technology, and low financial support were key barriers to effective institutional involvement and collaboration in disseminating biogas technology in Ghana. It is recommended that the government shows a high commitment by providing the needed resources for dissemination activities and task the Ghana Energy Commission to formulate a national biogas policy to facilitate dissemination and adoption. Finally, a national biogas steering committee composed of all relevant stakeholders, including the Finance Minister or a representative from the Finance Ministry would create a good platform to help champion the dissemination of biogas technology in Ghana.
Technoeconomic Evaluation of Electricity Generation from Concentrated Solar Power Technologies in Ghana
This work estimates the annual energy that could be generated from a concentrated solar power (CSP) plant. The optimal location used for this analysis was selected based on a set of multicriteria decision-making (MCDM) methods employed in an earlier research. The paper also determines the financial viability of implementing a CSP plant within the selected location. A 100 MW CSP plant for the said location was modelled and simulated using the System Advisor Model (SAM) software with data from the online database of the National Renewable Energy Lab (NREL) available from the SAM software. Using a solar multiple of 2.0 with a TES of 6 hours, the plant generated an estimated annual energy of 306.850 GWh with a capacity factor of 35.10% and gross-to-net conversion of 89.10%. The months with the highest generation were from November to March while July to September had the least generation. Generation begins from 8 am, rising to a peak around 12 pm to 4 pm and gradually declines into the night. Results from the financial analysis produced a net present value (NPV) of USD 156,287,433.72 after the plant life of 25 years, indicating profitability of the project. Results from the sensitivity analysis showed that the project NPV became negative only when the base case capital cost, electricity price, and revenue were, respectively, increased by 15%, reduced by 10%, and reduced by 13%.
Power Control of Wind Energy Conversion System with Doubly Fed Induction Generator
Wind power is one of the most efficient, reliable, and affordable renewable energy sources. The Doubly Fed Induction Generator (DFIG) is the most commonly used machine in wind power systems due to its small size power converter, reduced cost and losses, better quality, and the ability for independent power control. This research work deals with the power control of this machine by modeling and designing a suitable controller. Vector control is used to control the stator and grid active and reactive powers along with the proportional integral (PI) controller, fuzzy logic controller (FLC), and PI-fuzzy controllers. Modeling and simulation of the system are done using MATLAB Simulink, and the behavior of the machine with each controller is examined under variable wind speeds. Comparative analysis based on reference power tracking, stability, and grid code requirement fulfillment has been conducted. The obtained results show that among the three controllers, the PI-fuzzy controller meets the required specification with better performance, small oscillation, minimum overshoot, better reference tracking ability, and creating a stable and secure system by fulfilling grid code requirements. This study can be important to further insight into DFIG-based wind turbine systems.
Optimization of Concentrated Sulphuric Acid Hydrolysis of Gadam Sorghum Stalks Found in Kenya for Fermentable Sugar Production
Gadam sorghum stalks are agricultural residues which can be hydrolyzed into fermentable sugars that can be used to produce bioethanol which is a renewable source of energy. In order to produce bioethanol from lignocellulosic biomass such as Gadam sorghum stalks, several processes including hydrolysis are involved. However, the use of lignocellulosic biomass for bioethanol production is hindered by the low yield of fermentable sugars obtained during hydrolysis. The lack of sufficient information on optimal conditions governing hydrolysis of lignocellulosic biomass leads to inefficient process which hinders the economic viability of large-scale bioethanol production. The objective of this study was to optimize reaction conditions involved in concentrated sulphuric acid hydrolysis of Gadam sorghum stalks. During hydrolysis, the conditions that were varied included temperature (40°C–80°C), time (30-90 minutes), and concentration of acid (30%-70%, ). Central composite rotatable design was used to optimize and establish optimum level of hydrolysis conditions. Response surface methodology and analysis of variance were used to interprete the results. The results of hydrolysis revealed that the highest yield of glucose was 87.54% () which was realized at 60°C hydrolysis temperature, 60 minutes hydrolysis period, and 50% () concentration of sulphuric acid. In addition, the lowest glucose yield was 45.59% () which was realized at 60°C hydrolysis temperature, 60 minutes hydrolysis period, and 16.36% () sulphuric acid concentration. Concentrated sulphuric acid hydrolysis of Gadam sorghum stalks results in high yield of fermentable sugars. These results reveal that Gadam sorghum stalks are viable substrates for the production of fermentable sugars.
A Master-Slave Salp Swarm Algorithm Optimizer for Hybrid Energy Storage System Control Strategy in Electric Vehicles
Pure electric vehicles provide an enticing ecofriendly alternative to traditional fossil fuel combustion engine locomotives. Batteries have primarily been used to store energy in electric vehicles; however, peak load demand and transient power leading to decreased battery lifespan have bred interest in hybrid energy storage systems in electric vehicles. Management of energy drawn from a hybrid energy storage system (HESS) in electric vehicles is a real-time multistage optimization problem aimed at minimizing energy consumption while aptly distributing energy drawn from the battery and capacitor to enhance the battery life cycle. This paper explores the feasibility of a master-slave salp swarm optimization algorithm (MSSSA) (metaheuristic algorithm) in a HESS control strategy for electric vehicles. Introducing a master-slave learning approach to the salp swarm algorithm (SSA) improves its performance by increasing its convergence rate while maintaining a balance between exploration and exploitation phases of the algorithm. A comparison of the MSSSA results with the SSA (salp swarm algorithm), DA (dynamic algorithm), WOA (whale optimization algorithm), MFO (moth flame optimization algorithm), GA (genetic algorithm), and PSO (particle swarm optimization algorithm) on benchmark test functions and dynamic program simulation of an electric vehicle’s HESS control strategy and shows preeminence of the MSSSA control strategy for HESS.