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Energy use, CO2 emission and foreign direct investment: Is there any inconsistence between causal relations?
Ertugrul YILDIRIM
Front. Energy. 2014, 8 (3): 269-278.
https://doi.org/10.1007/s11708-014-0326-6
In this study, the causal relations between inward foreign direct investment (FDI)-energy use per capita and inward FDI-CO2 emission per capita were analyzed and the inconsistency between the causal relations was investigated via bootstrap-corrected panel causality test and cross-correlation analysis. In this direction, data from 76 countries including the period of 1980–2009 was processed. No supportive evidence was found for changing causal relations to country group which was classified into income level. The findings indicated that while the pollution haven hypothesis was supported for Mozambique, United Arab Emirates and Oman, the pollution halo hypothesis was supported in the case of India, Iceland, Panama and Zambia. For other countries, energy use and CO2 emission were neutral to inward FDI flows in aggregated level. Furthermore, this study urged that increased (decreased) energy use due to the inward FDI flows did not necessarily mean an increase (decrease) in pollution level, and vice versa. For policy purpose, FDI attractive policy should be regulated by taking into account this possibility.
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Solving unit commitment problem using a novel version of harmony search algorithm
Roozbeh MORSALI,Tohid JAFARI,Amirhossein GHODS,Mohammad KARIMI
Front. Energy. 2014, 8 (3): 297-304.
https://doi.org/10.1007/s11708-014-0309-7
In this context, a novel structure was proposed for improving harmony search (HS) algorithm to solve the unit comment (UC) problem. The HS algorithm obtained optimal solution for defined objective function by improvising, updating and checking operators. In the proposed improved self-adaptive HS (SGHS) algorithm, two important control parameters were adjusted to reach better solution from the simple HS algorithm. The objective function of this study consisted of operation, start-up and shut-down costs. To confirm the effectiveness, the SGHS algorithm was tested on systems with 10, 20, 40 and 60 generating units, and the obtained results were compared with those of the simple HS algorithm and other related works.
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Hybrid optimization algorithm for modeling and management of micro grid connected system
Kallol ROY,Kamal Krishna MANDAL
Front. Energy. 2014, 8 (3): 305-314.
https://doi.org/10.1007/s11708-014-0308-8
In this paper, a hybrid optimization algorithm is proposed for modeling and managing the micro grid (MG) system. The management of distributed energy sources with MG is a multi-objective problem which consists of wind turbine (WT), photovoltaic (PV) array, fuel cell (FC), micro turbine (MT) and diesel generator (DG). Because, perfect economic model of energy source of the MG units are needed to describe the operating cost of the output power generated, the objective of the hybrid model is to minimize the fuel cost of the MG sources such as FC, MT and DG. The problem formulation takes into consideration the optimal configuration of the MG at a minimum fuel cost, operation and maintenance costs as well as emissions reduction. Here, the hybrid algorithm is obtained as artificial bee colony (ABC) algorithm, which is used in two stages. The first stage of the ABC gets the optimal MG configuration at a minimum fuel cost for the required load demand. From the minimized fuel cost functions, the operation and maintenance cost as well as the emission is reduced using the second stage of the ABC. The proposed method is implemented in the Matlab/Simulink platform and its effectiveness is analyzed by comparing with existing techniques. The comparison demonstrates the superiority of the proposed approach and confirms its potential to solve the problem.
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End-use energy utilization efficiency of Nigerian residential sector
Fidelis I. ABAM, Olayinka S. OHUNAKIN, Bethrand N. NWANKWOJIKE, Ekwe B. EKWE
Front. Energy. 2014, 8 (3): 322-334.
https://doi.org/10.1007/s11708-014-0329-3
In this paper, the end-use efficiencies of the different energy carriers and the overall energy efficiency in the Nigerian residential sector (NRS) were estimated using energy and exergy analysis. The energy and exergy flows were considered from 2006 to 2011. The overall energy efficiency ranges from 19.15% in 2006 to 20.19% in 2011 with a mean of (19.96±0.23)% while the overall exergy efficiency ranges from 4.34% in 2006 to 4.40% in 2011 with a mean of (4.31±0.059)%. The energy and exergy efficiency margin was 15.58% with a marginal improvement of 0.07% and 0.02%, respectively when compared with previous results. The contribution of the energy carriers to the total energy and exergy inputs were 1.45% and 1.43% for electricity, 1.95% and 3% for fossil fuel and 96.6% and 95.57% for bio-fuel. The result shows that approximately 65% of the residence use wood and biomass for domestic cooking and heating, and only a fraction of the residence have access to electricity. LPG was found to be the most efficient while kerosene, charcoal, wood and other biomass the least in this order. Electricity utilization exergy efficiency is affected by vapor-compression air conditioning application apart from low potential energy applications. In addition, this paper has suggested alternatives in the end-use application and has demonstrated the relevance of exergy analysis in enhancing sustainable energy policies and management and improved integration techniques.
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An improved delta-star switching scheme for reactive power saving in three-phase induction motors
P. RAJA,N. KUMARESAN,M. SUBBIAH
Front. Energy. 2014, 8 (3): 364-370.
https://doi.org/10.1007/s11708-014-0324-8
It is proposed that a capacitor can be connected permanently across each phase winding of a three-phase induction motor along with the conventional delta-star switching, for further saving in VARh at reduced loads on the motor. The method of choosing a suitable value for the capacitor and the criteria to be adopted for calculating the power output at which the star to delta switching is to be made are also explained. The experimental results on a 3-phase, 4-pole, 415 V, 50 Hz, 3.3 kW induction motor verify the advantages in adding the capacitor to the phase winding of the motor. Compared to using only a single delta connected stator winding or a delta-star switching, the advantages of the proposed addition of a capacitor, are also demonstrated through a case study conducted on a 400 V, 250 kW motor. Any further improvement in grid side power factor can be achieved by employing a static synchronous compensator (STATCOM) of reduced VAR rating.
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