Abstract:The kinetic analysis method using the non-isothermal technique was proposed to determine the kinetic parameters for the transesterification reaction of waste vegetable oil (WVO) in supercritical alcohols. To investigate the transesterification of WVO, experiments have been carried out with WVO and alcohols at three molar ratios of 1:6, 1:12 and 1:18 for both supercritical ethanol (SCE) and supercritical methanol (SCM) at temperatures between 210 °C and 350 °C in a 25 mL batch reactor. The products were analyzed by gas chromatography mass spectrometry (GC-MS). To verify the effectiveness of the proposed kinetic analysis method, the experimental values were compared with the values calculated using the kinetic parameters obtained from this work. It was found that the proposed kinetic analysis method gave reliable kinetic parameters for the transesterification of WVO in supercritical alcohols. It was also seen that SCM was a better solvent than SCE for the transesterification of WVO.
Transesterification of waste vegetable oil is one of the promising partial substitutes for fossil fuels. The degradation characteristics of waste vegetable oil using supercritical alcohols (ethanol and methanol) have been studied in this research. The elementary target was to conduct comparative analysis of the effect of supercritical methanol and supercritical ethanol as solvents on the transesterification along with the analysis of product obtained in terms of carbon number. The experiments were carried out at transesterification temperatures of 250, 270 and 290 • C, retention time of 0 to 60 min at an interval of 15 min and oil to alcohol molar ratios of 1:6, 1:12 and 1:18 for both alcohols. The conversion increased with increase in transesterification temperature and retention time. At 290 • C, almost 99% conversion was achieved for 60-min holding time for both alcohols. Increase in conversion of waste vegetable oil was observed as the molar ratio increased. Supercritical transesterification resulted into ester yield higher than 95% with non-ester composition and glycerol collectively less than 5%.
Abstract:Comparative analysis of transesterification of virgin cooking oil (VCO) and waste cooking oil (WCO) in catalyzed and supercritical transesterification process using methanol and ethanol as solvents has been conducted in this study. The luminous point of this research was the direct comparison of catalytic and supercritical process using the ester composition obtained from virgin cooking oil and waste cooking oil transesterification. Oil to alcohol molar ratio of 1:6 and reaction condition of 65 • C and 1 bar pressure were considered for the catalytic process, while 260 • C and high pressure (65 and 75 bar for methanol and ethanol, respectively) were accounted for the supercritical process. Distinct layer separation was observed for both processes. Ester, fatty acid and glycerol composition was studied for both the upper and lower layers separately, from which 100% ester composition in the upper layer and a mixture of ester and other composition in the lower layer was obtained for the catalytic process owing to succeeding filtration and washing. However, mixture of ester (>75%) and other composition was obtained in both layers for the supercritical process where purification process was not implemented. The similarity in the result obtained demonstrates the superiority of waste cooking oil compared to virgin cooking oil, taking cost into consideration.
Remote areas of Nepal suffer from limited or no access to electricity. Providing electricity access in remote areas is one of the foremost challenges of any developing country. The purpose of this study is to develop and propose a reliable and low-cost model for electrification. The study presents an optimized choice between decentralized renewable-energy systems and grid expansion. Opting for an analytical method for the modelling and analysis of electrification options based on life-cycle cost (LCC) and economic distance limit, each energy system for varied load conditions is compared for a better option. A framework for energy-system selection based on available resources is proposed. It compares the grid-expansion option with potential isolated renewable-energy systems to ensure energy access to the area under consideration. Additionally, off-grid configurations that rely on renewable energy sources are also considered for the necessity of backup supply to ensure continuous power to the research area. Techno-economic assessment is carried out for different off-grid and hybrid configurations proposed in this study and their feasibility checks are carefully examined. Commercial efficacy of the proposed hybrid energy systems is assessed by comparing the life cycle and energy cost and by performing different additional sensitivity analyses. The study concludes that reduced generation cost supports the increasing penetration of electrification. The LCC for grid expansion is the most economical under high-load conditions, whereas for the isolated and sparsely settled populations with low-load conditions, photovoltaic power backed up with a diesel generator is the most economical.
The study aims to present the analysis of Economic Distance Limit (EDL) of conventional grid extension and some renewable energy systems for Gorkha District based on Life Cycle Cost (LCC) analysis. The study is an attempt to prepare a framework for the evaluation of a least cost electricity master plan which may be applied to other districts in future. An analytical tool has been followed to carry out the least cost electrification planning. The least cost planning has been done for the load forecast for the 5th year, which is 965 kW in aggregate. Accordingly, to meet this demand, it has been assumed that there will be 40 numbers of 25 kVA transformers feeding the settlements in the study Village Development Committee (VDCs), and an alternative option of electrifying these villages will consist of 40 Micro-Hydro Power plants (MHPs) of 25 kW capacities each. The result shows that extension from the existing grid points up to additional 22.41 km (economic distance limit, or EDL) is more economical than supplying through the installation of MHPs. A similar comparison was attempted with grid vs commercial scale solar photovoltaic (PV) for a theoretical load of 25 kW; the EDL for grid-extension has been worked out to be 47.96 km with battery storage. Furthermore, the costs of low voltage lines have not been included in comparison assuming they are common costs to both options. Reliability from the grid supply, MHPs and commercial solar PV has been assumed to be similar.
The electrical supply system in most underdeveloped nations is incredibly undependable. The country’s existing distribution system has experienced regular power outages due to population growth, industrial expansion, rough terrain, and a long-distance transmission network. The conventional approach to centralized generation and transmission is failing to address this challenge and as a response, the utilization of renewable energy sources is expanding day by day to alleviate the energy crisis. The purpose of this study is to perform a techno-economic analysis of a 100% renewable off-grid and on-grid hybrid energy system for the electrification of Thakle Namuna Basti, a small communal village in Melamchi, Sindhupalchwok. The HOMER Pro 3.14 program is used to analyze the feasibility of the suggested hybrid power system. The available resources are provided as an input parameter along with load data and HOMER Pro optimizes the list of system architecture for that specific site. In addition, sensitivity analysis is performed for the proposed HES (Hybrid Energy System). The main outcome of the project is to find out the best system architecture based on various economic parameters such as NPC (Net Present Cost), LCOE (Levelized cost of electricity) and Operating and Maintenance Cost. The system having lowest NPC and LCOE makes the best system architecture.
The article reviews the options of renewable energy technologies with the background of long-lasting power shortages that Nepal has been facing and examines the energy-related policies of Nepal and provisions to promote renewable energy technologies in Nepal and its regulatory framework. It analyses the pertinent energy policies related to energy generation and distribution. The research focuses on the context of the renewable energy sector of Nepal and its future. The research has found a positive role in renewable energy policies for adoption of renewable energy technologies and poses a positive impact on electricity generation. The article has also reviewed and analyzed the trend of electricity generation, peak demand and the resulted import to meet the gap. The almost linear electricity generation of Nepal Electricity Authority (including generation of Individual Power Producers against the steep gradient of peak power demand has ultimately increased the power purchase from India pushing towards unsustainability. It shows that energy policies are not up to the optimal. The research has further analyzed the impact of per capita GDP on electricity per capita by regression analysis. The analysis has found, higher the GDP per capita would increase the consumption of electricity per capita. The paper discusses issues and barriers for promotion of rural electrification and suggested economical, technical and geographical to be the three most pertinent barriers in developing countries.
Worldwide, nearly more than half a billion people will still not have a reliable and affordable electricity till 2040 and nearly 1.8 billion may compel to rely on traditional fuel sources for day to day activities. Specially the case is even more critical in remote areas of developing countries. Energy planning models (EPMs), approaches and optimization techniques play an important role in energy sectoral policy formulation. Long term energy planning through energy modelling and optimization techniques of energy technologies have a better impact to mitigate the issue of energy access. Varieties of energy planning approaches, energy modelling and planning tools and techniques are available at global context. Energy demand forecasting and the subsequent planning is one of the most important aspect when dealing with long-term energy planning. The study has focused on energy trend of Nepal, energy planning methodologies, analysis of prevailing energy modelling and optimization techniques in context of developing and under developed countries.
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