• Energy Research
• Closed Access close
• Open Source close
• Embargo close
• IR close
• Renewable Energy close

Abstract Sweet sorghum plant, containing starchy grain, juice, and bagasse, is a potential energy crop for biobutanol production as an advanced renewable fuel. This paper assesses the economy of production of butanol from the whole sweet sorghum plant based on available experimental results. Different scenarios, including separate hydrolysis and fermentation (scenarios 1 and 2), simultaneous saccharification and fermentation (scenario 3), and co-fermentation of the juice and pretreated stalk (scenario 4), were simulated using Aspen Plus®. Moreover, in scenarios 5 and 6, the stalk is directly fed to the fermenters without juice extraction and pretreatment. Gas stripping was used to enhance the recovery and fermentation yield in scenarios 2 to 6. Acetone, supplied from the process products, was used for bagasse pretreatment in scenarios 1–4. Economic viability was investigated using Aspen Process Economic Analyzer. The butanol production price was 0.62, 0.44, 0.45, 0.61, 0.39, and 0.56 US$/L for scenarios 1 to 6, respectively. The most profitable process was scenario 5, where US$47.75 million total capital is required for the production of 11,260 tonne/year butanol. The sensitivity analysis of butanol sales price showed that even in the case of its value reduction by 50%, scenario 5 can still be profitable.

Abstract The energy assurance and electricity supply are significant factors for progress and development of all countries. Low investment costs, reducing greenhouse emission, and high output efficiency for good performance of power plants are key factors in evaluating energy parameters for governments. This study is intended on determining and proving the compatibility of existing power plants in the country of Iran by applying observational data through the application of Multi-Criteria Decision-Making Analysis (MCDA). The obtained compromise solutions applied through a MATLAB code that helped in specifying which power plants are particularly suitable for establishment in the future work. Furthermore, it supports the generalization and validation of applying VIKOR method for thorough evaluation of power systems by comparing the results with real condition. The different types of power plants have been considered as alternatives. Multi-criteria evaluations of these diverse power plants were also carried out with respect to the environmental, technological, and economic criteria. It was concluded that hydropower plant is the best possible case for establishment, and the VIKOR method is a reliable technique for evaluating energy systems which can help to rank alternatives and determines the solution named compromise that is the closest to the ideal case.

Abstract Utilization of pump as turbine (PAT) systems is known as an economically beneficial method to harvest hydropower energy, especially in a remote area. Despite the extensive investigations on the operation and parametric study of the PAT components, the turbine mode of multistage PATs in case of a viscous working fluid is found as a literature gap. In this paper, a numerical simulation method is employed as a predicting tool to investigate the consequences of changing the fluid viscosity affecting the flow patterns within the multistage PATs. The commercial solver ANSYS CFX 16 was used for simulation. Validation of numerical solution was done for the single-stage pump considering water and 48 cSt viscous fluid. The numerical results in the single-stage PAT showed that increasing the viscosity causes an efficiency drop mainly at the part-load condition and translates the maximum efficiency point to higher flow rates, where the vortices at impeller passage and draft tube are weaker. Increasing the viscosity up to 48 cSt, results in 12.5% reduction of efficiency at the best efficiency point (BEP) in two stage PAT. Based on the two-stage PAT results, the total hydraulic efficiency at the BEP has been increased by 1% and 1.5% for water and the 48 cSt viscous fluid, respectively, in comparison with the single-stage PAT. According to the post-processed streamlines at different stages of the two-stage PAT, the undesired vortical structures were caused by the diffuser and the return channel, which were mainly designed for the pump mode. The hydraulic analysis of two-stage PAT shows that using multistage pumps in reverse mode is reasonable for power generation in high head and flow rate sites.

In recent years due to the decreasing fossil fuel reserves and the increasing social stress, complex power networks have no other choices except to seek for alternative energy sources to eliminate the environmental issues caused by the traditional power systems. Thus, the scheduling of energy sources in a complex Micro-Grid (MG) comprising Micro Turbine (MT), Photo Voltaic (PV), Fuel Cell (FC), battery units and Wind Turbine (WT) has been investigated in this paper. Furthermore, a multi-objective framework is presented to simultaneously handle the two objective functions including minimization of total operation cost and minimization of emission. In this regard, Normal Boundary intersection (NBI) technique is employed to solve the proposed multi-objective problem and generate the Pareto set. Besides, a fuzzy satisfying method is used for decision making process. Afterward, the results obtained from the presented method are compared to the ones derived from other methods. Finally, it is verified that the proposed solution method results in better solutions for operation cost, emission and the execution time.

Abstract In common parabolic trough solar collectors (PTC), solar irradiation is concentrated at the bottom of the absorber tube, causing high surface temperatures, thermal stresses, and deflections with subsequent damages and costs. Also, the performance improvement of PTCs is always of significant importance. The new idea of rotating the absorber tube is proposed, and its effects on the PTC performance are studied experimentally. The effects of the working fluid flow rate (Re number) and the rotational velocity of the absorber tube (Ta number) on the energy characteristics of the PTC are analyzed. Results indicate that the optimal selection of the rotational speed makes it possible to reduce and control the temperature of the absorber by about 60% reduction in the fluid-tube temperature difference, and 15% reduction in the maximum surface temperature. Furthermore, about 17% enhancement in the efficiency of the PTC is attained. The share of the natural and both the rotational and mass flow forced convection forces in the total heat transfer is analyzed through Gr, Re, Ta, and a convection evaluation parameter (CEP). Ta/Re ratio and CEP provide valuable information such that, CEP T a / R e ≈ 0.5 led to the highest efficiency (average and maximum efficiencies of 30% and 87% respectively).