Techno Press
Tp_Editing System.E (TES.E)
Login Search


You have a Free online access.
eri
 
CONTENTS
Volume 1, Number 2, June 2013
 

Abstract
This study designs and tests a photovoltaic system with distributed maximum power point tracking (DMPPT) methodology using a field programmable gate array (FPGA) controller. Each solar panel in the distributed PV system is equipped with a newly designed DC/DC converter and the panel\'voltage output is regulated by a FPGA controller using PI control. Power from each solar panel on the system is optimized by another controller where the quadratic maximization MPPT algorithm is used to ensure the panel's output power is always maximized. Experiments are carried out at atmospheric insolation with partial shading conditions using 4 amorphous silicon thin film solar panels of 2 different grades fabricated by Chi-Mei Energy. It is found that distributed MPPT requires only 100ms to find the maximum power point of the system. Compared with the traditional centralized PV (CPV) system, the distributed PV (DPV) system harvests more than 4% of solar energy in atmospheric weather condition, and 22% in average under 19% partial shading of one solar panel in the system. Test results for a 1.84 kW rated system composed by 8 poly-Si PV panels using another DC/DC converter design also confirm that the proposed system can be easily implemented into a larger PV power system. Additionally, the use of NI sbRIO-9642 FPGA-based controller is capable of controlling over 16 sets of PV modules, and a number of controllers can cooperate via the network if needed.

Key Words
module integrated converter (MIC); field programmable gate array (FPGA); partial shading; maximum power point tracking (MPPT); quadratic maximization; distributed photovoltaic system

Address
(1) Ru-Min Chao, Shih-Hung Ko and Po-Lung Chen: Department of Systems and Naval Mechatronics Engineering, National Cheng Kung University, Tainan, Taiwan 701, ROC;
(2) Ru-Min Chao: Research Center for Energy Technology and Strategy, National Cheng Kung University, Tainan, Taiwan 701, ROC.


Abstract
This study was to investigate the composition and characteristics of long-chained alcohols extracted from the algal strain Monoraphidium 3s35. The production of biomass was optimized using different cultivation methods. Under the aerated growth condition, this strain yielded up to 37.26% extracts of dry weight and 576 mgL-1 biomass. The major compounds of the extracts are mainly long-chained alcohols (89.24%), with carbon chain length ranging from 12 to 20. Interestingly, or the long-chained alcohols, 3-(2-Methoxyethyl)-1-nonanol, 3,7,11, 15-Tetramethyl-2-hexadecen-1-ol and oleyl alcohol accounted for 53.68%, 23.45%, and 12.11%, respectively. Because of their amphipathic nature, these long-chained alcohols have been widely used in bioenergy production and cosmetics industry. Furthermore, Monoraphidium 3s35 produced 9.73% of C17 and C20 alkanes, which can be used as an important supplement for the petrodiesel-like fuel.

Key Words
Microalgae; Monoraphidium sp.; long-chained alcohols; 1H-NMR; GC/MS

Address
(1) Xuewei Yang, Xin Dai, Rui Zhang, Cong Shao, Shu Geng and Guangyi Wang: Key Engineering Laboratory for Algal Biofuels, School of Environment and Energy, Peking University Shenzhen Graduate School, Shenzhen 518055, China;
(2) Guangyi Chen, Xianhua Liu and Guangyi Wang: Tianjin University Center for Marine Environmental Ecology, school of Environmental Science and Engineering, Tianjin University, Tianjin 300072, China;
(3) Guangyi Wang: Department of Microbiology, University of Hawaii at Manoa, Honolulu, HI 96822, USA.


Abstract
In this paper, core-shell semiconductor quantum dots (QDs) CdSeS/ZnS with emission at 490 nm and 450 nm were investigated for their use in luminescent down-shifting (LDS) layers. Luminescent quantum yield (LQY) of the QDs measurements in solution proposed that they were suitable candidates for inclusion in LDS layers. QDs were encapsulated in poly(methyl,methacrylate) (PMMA) polymer matrix and films were fabricated of 134

Key Words
spectral losses; solar cell efficiency; down‐shifting; luminescent materials; quantum dots; organic dyes

Address
(1) Hind A. Ahmed, James Walshe, Manus Kennedy, Thomas Confrey and John Doran: Dublin Energy Lab, Dublin Institute of Technology, Dublin, Ireland;
(2) Sarah. J. McCormack: Trinity College Dublin, Dublin, Ireland.


Abstract
Torrefaction technologies convert assorted biomass feedstocks into energy- concentrated, carbon neutral fuel that is economically transported and easily ground for blending with fossil coals at numerous power plants around the world without needs to retrofit. Utilization of torrefied biomass in conventional electric generating units may be an increasingly attractive alternative for electricity generation as aging power plants in the world need to be upgraded or improved. This paper examines the economic feasibility of torrefaction in different scenarios by modeling torrefaction plants producing 136,078 t/year (150,000 ton/year) biocoal from wood and corn stover. The utilization of biocoal blends in existing coal-fired power plants is modeled to determine the demand for this fuel in the context of emerging policies regulating emissions from coal in the U.S. setting. Opportunities to co-locate torrefaction facilities adjacent to corn ethanol plants and coal-fired power plants are explored as means to improve economics for collaborating businesses. Life cycle analysis was conducted in parallel to this economic study and was used to determine environmental impacts of converting biomass to biocoal for blending in coal-fired power plants as well as the use of substantial flows of off-gasses produced in the torrefaction process. Sensitivity analysis of the financial rates of return of the different businesses has been performed to measure impacts of different factors, whether input prices, output prices, or policy measures that render costs or rewards for the businesses.

Key Words
torrefaction; economics; biomass; LCA; coal-fired power plant

Address
(1)Douglas G. Tiffany and Won Fy Lee: Applied Economics, University of Minnesota, Twin Cities, Minnesota, USA;
(2) Vance Morey and Nalladurai Kaliyan: Bioproducts and Biosystems Engineering, University of Minnesota, Twin Cities, Minnesota, USA.


Abstract
The world faces several issues of energy crisis and environmental deterioration due to over-dependence on single source of which is fossil fuel. Though, fuel is needed as ingredients for industrial development and growth of any country, however the fossil fuel which is a major source of energy for this purpose has always been terrifying thus the need for alternative and renewable energy sources. The search for alternative energy sources resulted into the acceptance of a biofuel as a reliable alternative energy source. This work presents the study of optimization of process of transesterification of vegetable oil to biodiesel using NaOH as catalyst. A 24 factorial design method was employed to investigate the influence of ratio of oil to methanol, temperature, NaOH concentration, and transesterification time on the yield of biodiesel from vegetable oil. Low and high levels of the key factors considered were 4:1 and 6:1 mole ratio, 30 and 60oC temperatures, 0.5 and 1.0 wt% catalyst concentration, and 30 and 60 min reaction time. Results obtained revealed that oil to methanol molar ratio of 6:1, tranesetrification temperature of 60oC, catalyst concentration of 1.0wt % and reaction time of 30 min are the best operating conditions for the optimum yield of biofuel from vegetable oil, with optimum yield of 95.8%. Results obtained on the characterizzation of the produced biodiesel indicate that the specific gravity, cloud point, flash point, sulphur content, viscosity, diesel index, centane number, acid value, free glycerine, total glycerine and total recovery are 0.8899, 4, 13, 0.0087%, 4.83, 25, 54.6. 0.228 mgKOH/g, 0.018, 0.23% and 96% respectively. Results also indicate that the qualities of the biodiesel tested for are in conformity with the set standard. A model equation was developed based on the results obtained using a statistical tool. Analysis of variance (ANOVA) of data shows that mole ratio of ground nut oil to methanol and transesterification time have the most pronounced effect on the biodiesel yield with contributions of 55.06% and 9.22% respectively. It can be inferred from the results various conducted that vegetable oil locally produced from groundnut oil can be utilized as a feedstock for biodiesel production.

Key Words
vegetable oil; biodiesel; optimization; alternative energy; characterization

Address
(1) Amina T. Mustapha, Saka A. Abdulkareem, Abdulfatai Jimoh, David O. Agbajelola and Joseph O. Okafor: Department of Chemical Engineering, School of Engineering and Engineering Technology, Federal University of Technology, PMB65, Gidan Kwano, Minna, Niger State, Nigeria;
(2) Saka A. Abdulkareem: Centre for Genetic Engineering and Biotechnology, Federal University of Technology, PMB65 Bosso, Minna, Niger State, Nigeria.



Techno-Press: Publishers of international journals and conference proceedings.       Copyright © 2017 Techno-Press
P.O. Box 33, Yuseong, Daejeon 34186 Korea, Tel: +82-42-828-7996, Fax : +82-42-828-7997, Email: info@techno-press.com