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1 Nov 2012

Volume 4, Issue 6, Articles (06xxxx)

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Editorial: Energy and the U.S. Department of State

Devinder Mahajan

J. Renewable Sustainable Energy 4, 060401 (2012); http://dx.doi.org/10.1063/1.4772638 (2 pages)

Online Publication Date: 14 December 2012

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Abstract Unavailable
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01.30.Ww Editorials
88.05.Jk Policy issues; resource assessment
88.05.Lg Economic issues; sustainability; cost trends
88.05.Np Environmental aspects
88.05.Pq Emissions trading and CDM
88.05.Ec Renewable energy targets
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Comparative analysis of energy security in the Nordic countries: The role of renewable energy resources in diversification

Alireza Aslani, Erkki Antila, and Kau-Fui V. Wong

J. Renewable Sustainable Energy 4, 062701 (2012); http://dx.doi.org/10.1063/1.4765695 (11 pages) | Cited 3 times

Online Publication Date: 12 November 2012

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Security of energy supply has been one of the important debates among citizens and governments of the Nordic countries after the first energy crisis. In response, diversification was defined as the heart strategy to reach a certain level of energy supply. This article discusses about the level of energy security in the Nordic countries with comparison to other developed countries and their neighbors. Then, the support schemes and policies to achieve the energy security and diversification are reviewed based on the system thinking approach with especial focus on the renewable energy resources. This approach provides a unique and powerful tool to explain the complexity and the relationships among the elements of the support schemes in the energy security analysis.
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88.05.Jk Policy issues; resource assessment

Review of Spanish renewable energy policy to encourage investment in solar photovoltaic

Sana Zeeshan Shirazi and Syed Mohammad Zeeshan Shirazi

J. Renewable Sustainable Energy 4, 062702 (2012); http://dx.doi.org/10.1063/1.4766469 (13 pages)

Online Publication Date: 13 November 2012

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The Spanish renewable energy sector has experienced phenomenal growth over the past decade due to implementation of regulatory frameworks that have encouraged the rapid deployment of some renewable energy technologies particularly solar photovoltaic (PV), wind, and biomass. But the unstable regulatory frameworks, price, and quantity caps on renewable technologies and recent initiative of temporary suspension of subsidies for any new solar, wind, cogeneration or waste incineration projects have declined the growth of production of electricity from renewable energy sources (RES-E). The aim of this paper is to provide the current situation of promotion measurers for RES-E particularly for solar PV in Spain and regulatory changes since the feed-in-tariff was put in place in Spanish solar market. The paper also provides a critical analysis of the Spanish policy instruments and regulatory frameworks that contributed in the tremendous growth of solar PV. It also analyses the new policy instruments necessary to achieve declared 2020 RES-E targets.
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84.70.+p High-current and high-voltage technology: power systems; power transmission lines and cables
88.05.Lg Economic issues; sustainability; cost trends

A review on frequency tuning methods for piezoelectric energy harvesting systems

Sutrisno W. Ibrahim and Wahied G. Ali

J. Renewable Sustainable Energy 4, 062703 (2012); http://dx.doi.org/10.1063/1.4766892 (29 pages)

Online Publication Date: 13 November 2012

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Piezoelectric energy harvesting technologies have received a great attention during the last decade to design self-powered microelectronic devices such as wireless sensor nodes. Piezoelectric energy harvester is a resonant system that produces maximum power output when its resonant frequency matches the ambient vibration frequency. The deviation from the resonance causes significant decrease in the power output. There are two possible solutions to compensate the effect of frequency deviation: widening the operating frequency bandwidth and tuning the resonant frequency. Tuning the resonant frequency is a more efficient technique for applications with single time varying dominant frequency. This paper presents a comprehensive review of frequency tuning methods for piezoelectric energy harvesting systems. Two categories generally investigated in the literature include manual and autonomous tuning methods. The recent developments of many tuning strategies are discussed and summarized.
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84.60.-h Direct energy conversion and storage
85.50.-n Dielectric, ferroelectric, and piezoelectric devices

The exploitation of new energy plant from mangrove

Xu Hui-Min, Tam Fung-Yee, Li Peng-Yuan, Zan Qi-Jie, Liao Wen-Bo, and Xu Hua-Lin

J. Renewable Sustainable Energy 4, 062704 (2012); http://dx.doi.org/10.1063/1.4767838 (9 pages)

Online Publication Date: 28 December 2012

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In recent years, due to the scarcity of non-renewable resources, many researchers started to pay more attention to the exploitation of new energy plants and plant biomass as a renewable resource. Salt-tolerant and high-oil plants which can grow well on large areas of saline and alkaline land, such as coastal land, are becoming potential energy resources, since it is not possible to grow energy plants on limited fertile soil land. For instance, the mangrove and many associated plants, which are important in coastal ecosystems, could be considered as potential candidates as energy plants. The application of mangrove as energy plants is very feasible and promising. In this paper, we summarized the investigation of the typical salt-tolerant plants–mangroves and mangrove associates to demonstrate their capacity to become the resources of biomass energy.
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88.20.-j Biomass energy
84.60.Rb Thermoelectric, electrogasdynamic and other direct energy conversion
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Commentary: Powering America with sustainable energy in the 21st century

George Philippidis

J. Renewable Sustainable Energy 4, 062801 (2012); http://dx.doi.org/10.1063/1.4767906 (9 pages)

Online Publication Date: 13 November 2012

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The United States continues to rely heavily on foreign oil and coal-based electricity for its transportation and power generation needs, respectively. The perennial lack of a national energy policy has deprived the United States of strong direction towards the development of sustainable domestic energy resources, which are abundantly available, enhance the country's energy security, and reduce its carbon footprint. Technology innovation and economies of scale in the last ten years have made wind, solar thermal, biomass, and natural gas viable and cost-competitive alternatives to highly polluting coal. Biomass and natural gas can produce base-load electricity, whereas wind and solar can address peak demand, when combined with fossils or with energy storage systems like batteries. In vehicles, biofuels and electric motors can rather seamlessly replace gasoline and reduce significantly our dependence on foreign oil. While each form of alternative energy has its own advantages, they can all contribute to economic growth in the 21st century by attracting investment, creating jobs, generating tax revenues, and making the entire US economy more sustainable.
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89.30.ag Coal
89.30.aj Oil, petroleum
88.05.Lg Economic issues; sustainability; cost trends
84.50.+d Electric motors
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Power management strategies and energy storage needs to increase the operability of photovoltaic plants

H. Beltran, I. Etxeberria-Otadui, E. Belenguer, and P. Rodriguez

J. Renewable Sustainable Energy 4, 063101 (2012); http://dx.doi.org/10.1063/1.4765696 (14 pages)

Online Publication Date: 6 November 2012

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This paper analyzes the effect of introducing an energy storage (ES) system in an intermittent renewable energy power plant such as a photovoltaic (PV) installation. The aim of this integration is to achieve an improvement in the operability of these power plants by increasing their production predictability. This will allow a further PV integration within the electrical power system, facilitating the system's load–demand balance. In this manner, the paper proposes two power management strategies (PMSs), each with different configurations, for operating a PV power plant: the first focuses on fixing constant power production and the latter focuses on reducing the high frequency fluctuations of the production. Thereafter, this paper analyzes and quantifies the ratings of the ES system (ESS) required to ensure a reliable performance of the plant on an annual basis for each of the PMSs with their different possible configurations. The resulting ES ratings vary with these PMS configurations. It can be concluded that significant improvements in production predictability are achieved with an ESS energy capacity of approximately 50% of the average daily energy produced by the PV panels and a power rating of around 55% of the plant's rated power. All the results are based on 1-year-long simulations which used real irradiance data sampled every 2 min.
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84.70.+p High-current and high-voltage technology: power systems; power transmission lines and cables
84.60.Ve Energy storage systems, including capacitor banks

Studies on the effect of different solar dryers on the vitamin content of tomato (Solanum lycopersicon)

J. I. Eze and O. Ojike

J. Renewable Sustainable Energy 4, 063102 (2012); http://dx.doi.org/10.1063/1.4763563 (7 pages)

Online Publication Date: 6 November 2012

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Samples of tomato fruit were dried under four different conditions: open-air sun drying method and by using three different models of integral passive solar dryers which include green house solar dryer, sun-tracking solar dryer, and latitudinal box solar dryer. The fresh tomato samples and the dried samples were analysed for vitamins A, C, and E. The results showed a significant difference in the concentrations of vitamins A, C, and E between the fresh samples and the dried samples for all drying systems. While vitamin C is reduced in concentration for all dried samples, vitamins A and E are increased significantly with open-air system having the highest value in vitamin C concentration while latitudinal box dryer gives the best result in terms of vitamins A and E retention. All year round, availability of tomato could be enhanced by chipping and drying. Packaging and marketing of dried chips in small quantities could be a lucrative entrepreneurial endeavour for the business minded.
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89.20.Bb Industrial and technological research and development

Numerical study on aerodynamic performances of the wind turbine rotor with leading-edge rotation

Yueqing Zhuang, Xiaojing Sun, Diangui Huang, and Guoqing Wu

J. Renewable Sustainable Energy 4, 063103 (2012); http://dx.doi.org/10.1063/1.4765697 (16 pages) | Cited 1 time

Online Publication Date: 12 November 2012

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The flow control using leading-edge rotating cylinder on both two-dimensional NACA 63418 airfoil section and three-dimensional two-bladed wind turbine rotor has been studied by means of numerical simulations. For the two-dimensional NACA 63418 airfoil with a fasting spinning cylinder at the leading-edge, flow separation occurs on the pressure side of the airfoil near the clearance between rotating cylinder and stationary airfoil at small angles of attack; however, flow separation on the suction side of the airfoil can be suppressed at large angles of attack. The aerodynamic performances of the leading-edge rotation (LER) wind turbine rotors with two twisted/non-tapered blades and with two twisted/tapered blades have been studied, respectively. The result shows that the power efficiency of the LER wind turbine with twisted/non-tapered blades is superior to the uncontrolled wind turbine rotor remarkably at high tip speed ratios. The aerodynamic control effects of the leading-edge rotating cylinder have also been studied under various wind speeds. On the basis of the aerodynamic characteristics of non-tapered LER wind turbine rotor, the power output of the rotor can be optimized through adjusting the cylinder rotational speed in various wind speeds.
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89.20.Kk Engineering
02.60.-x Numerical approximation and analysis
47.32.Ef Rotating and swirling flows
47.32.Ff Separated flows
47.85.Gj Aerodynamics

Effects of ocean thermal energy conversion systems on near and far field seawater properties—A case study for Hawaii

Yanli Jia, Gérard C. Nihous, and Kelvin J. Richards

J. Renewable Sustainable Energy 4, 063104 (2012); http://dx.doi.org/10.1063/1.4766820 (13 pages)

Online Publication Date: 12 November 2012

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In light of renewed interest and efforts in the development of ocean thermal energy conversion (OTEC) systems with a vision to provide mankind with a long-lasting energy resource, the potential environmental impacts of this technology should be considered from the perspective of sustainability. As an important step toward such a goal, we examine effects of OTEC effluent discharge on the physical aspects of the ocean environment near a Hawaiian Island in the North Pacific Ocean. We use modeling tools comprised of a mixing model that predicts the near field dilution of effluent plumes and a high-resolution ocean circulation model that simulates the dispersion of effluent in the far field. Numerical experiments are conducted to explore factors that influence effluent dispersal. We find that OTEC thermal resource is favorable and stable at the chosen location for the time period experimented. For a given OTEC design, the effluent discharge settles at a depth sufficiently far from the depths of discharge or intakes, and becomes dispersed quickly away from the site by highly variable ocean currents. Changes in ocean stratification and flow field are negligible for one OTEC device but are notable when multiple OTEC devices are present. These changes do not persist beyond 2 weeks after switching off OTEC activity.
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84.60.-h Direct energy conversion and storage
92.05.Hj Physical and chemical properties of seawater (salinity, density, temperature)

Statistical analysis of kinetic energy entrainment in a model wind turbine array boundary layer

Nicholas Hamilton, Hyung Suk Kang, Charles Meneveau, and Raúl Bayoán Cal

J. Renewable Sustainable Energy 4, 063105 (2012); http://dx.doi.org/10.1063/1.4761921 (19 pages)

Online Publication Date: 12 November 2012

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For large wind farms, kinetic energy must be entrained from the flow above the wind turbines to replenish wakes and enable power extraction in the array. Various statistical features of turbulence causing vertical entrainment of mean-flow kinetic energy are studied using hot-wire velocimetry data taken in a model wind farm in a scaled wind tunnel experiment. Conditional statistics and spectral decompositions are employed to characterize the most relevant turbulent flow structures and determine their length-scales. Sweep and ejection events are shown to be the largest contributors to the vertical kinetic energy flux, although their relative contribution depends upon the location in the wake. Sweeps are shown to be dominant in the region above the wind turbine array. A spectral analysis of the data shows that large scales of the flow, about the size of the rotor diameter in length or larger, dominate the vertical entrainment. The flow is less incoherent below the array, causing decreased vertical fluxes there. The results show that improving the rate of vertical kinetic energy entrainment into wind turbine arrays is a standing challenge and would require modifying the large-scale structures of the flow. Such an optimization would in the future aid recovery of the wind turbine wake towards conditions corresponding to the undisturbed atmospheric boundary layer.
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88.50.G- Wind turbines
02.50.-r Probability theory, stochastic processes, and statistics

Use of solar thermal energy in the hydrodistillation of essential oil

Subarna Maiti, Chitrangi Bhatt, Pankaj Patel, and Pushpito K. Ghosh

J. Renewable Sustainable Energy 4, 063106 (2012); http://dx.doi.org/10.1063/1.4766819 (14 pages)

Online Publication Date: 13 November 2012

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There has been rising demand in recent years for environment friendly technologies which has spurred interest in sustainable energy solutions. The use of solar radiation in place of fossil fuel-derived thermal energy to extract essential oils in decentralized manner is one such potentially attractive proposition. The present work reports such a study for hydrodistillation of essential oil from fresh orange peels. The distillation was carried out in the absorber tube of a square parabolic trough concentrator of 1.3 m2 collector aperture area. 400–500 g of fresh peels was processed per batch and the limonene content in the crude oil was in the range of 86% to 90% while the yield of the oil varied from 0.49% to 2.16% (w/w). The volume of distillate was found to correlate nicely with the average absorber tube temperature over the duration of the experiment and the maximum hydrodistillation efficiency was computed to be 8.37%. The yield of oil also showed a good correlation with the absorber tube temperature. The tube temperature, in turn, was controlled by the beam radiation, ambient temperature and wind speed.
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88.40.-j Solar energy
89.30.aj Oil, petroleum

Assessment of hydrokinetic energy near Rose Dhu Island, Georgia

Sandeep Bomminayuni, Brittany Bruder, Thorsten Stoesser, and Kevin Haas

J. Renewable Sustainable Energy 4, 063107 (2012); http://dx.doi.org/10.1063/1.4766884 (16 pages)

Online Publication Date: 13 November 2012

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The presented study reports on numerical simulations of flows in tidal channels near Rose Dhu Island, GA, which is used to identify hotspots of hydrokinetic energy and to assess the tidal stream energy potential at this site. The numerical simulations are complemented with field measurements of local current velocities and water surface heights, which are used to validate the simulations. Both velocity distributions and water surface heights as predicted by the numerical model are in good agreement with observed data. The simulations reveal a tidal asymmetry in the encompassing Ogeechee estuary with the ebb tide currents dominating over the flood tide ones. The model is able to successfully predict the distribution of discharge into the smaller creeks around Rose Dhu Island and thereby capturing the location of local hotspots of hydrokinetic energy. It is found that local hotspots do exist near the island, and the analysis suggests the maximum available annual power of 4.75 MW, with a peak estimated extraction surpassing 4 KW during Spring tides.
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88.60.nh Tidal energy
47.60.Dx Flows in ducts and channels

Radial p-n junction macroporous silicon solar cell on p-type upgraded metallurgical-grade silicon substrate

L. Zhao, Z. C. Li, H. W. Diao, H. L. Li, C. L. Zhou, and W. J. Wang

J. Renewable Sustainable Energy 4, 063108 (2012); http://dx.doi.org/10.1063/1.4766885 (8 pages)

Online Publication Date: 13 November 2012

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Macroporous silicon was fabricated on p-type upgraded metallurgical-grade (UMG) c-Si substrate with the resistivity of about 0.1–3 Ω cm, by metal-catalyzed electrochemical etching (MCECE). Ag nanoparticle catalyst was first fabricated on the c-Si substrate. Then, the electrochemical etching was performed. By optimizing the MCECE processes carefully, the macroporous silicon was successfully obtained with the pore width up to about 400 nm and the pore depth of 2–5 μm. After that, the radial amorphous/crystalline silicon heterojunction (SHJ) structure was prepared by conformally depositing a-Si:H i-layer and n-layer on the macroporous silicon via plasma-enhanced chemical vapor deposition (PECVD) at 200 °C, followed by depositing indium tin oxide front contact and Ag back contact via magnetron sputtering and thermal evaporation, respectively. As a result, the demonstrated radial p-n junction macroporous silicon solar cell with the unoptimized SHJ structure gave out a conversion efficiency of 3.67% under the standard AM1.5 illumination, which indicated a potential to make high performance radial p-n junction solar cell on UMG c-Si substrate.
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88.40.J- Types of solar cells
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
81.65.Cf Surface cleaning, etching, patterning

Point of common coupling voltage recovery capability improvement of offshore wind farm connected to a weak grid through high voltage direct current link

Dinh Chung Phan and Kyoung-Soo Ro

J. Renewable Sustainable Energy 4, 063109 (2012); http://dx.doi.org/10.1063/1.4766887 (13 pages)

Online Publication Date: 13 November 2012

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Large offshore wind farms using high voltage direct current transmission system have been considered and exploited in a few countries in the world. Maintaining stable operation of the wind farm is an important issue. Previous studies only proposed some methods to improve the fault ride-through capability of the wind farm as it is connected to a quite strong system, resulting in recovery of the voltage at the point of common coupling (PCC) after clearance of onshore grid-fault. This paper will evaluate the PCC voltage recovery ability of the wind farm when it is connected to a weak grid and suggest a new method to overcome unrecoverable voltage problem. The effectiveness of the proposed control strategies is proven by simulation results.
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88.50.J- Wind farms
84.70.+p High-current and high-voltage technology: power systems; power transmission lines and cables

Woodchip drying in a screw conveyor dryer

Ozgur Kaplan and Cenk Celik

J. Renewable Sustainable Energy 4, 063110 (2012); http://dx.doi.org/10.1063/1.4766890 (12 pages)

Online Publication Date: 13 November 2012

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Moisture content of raw biomass materials is a crucial parameter for system efficiency and the main purpose of the drying process is to reduce moisture content of the wet biomass. In this study, the drying characteristics of woodchip dried in a screw conveyor dryer had investigated experimentally. The experimental results demonstrated that drying rate had increased with the increasing drying air temperature and flow rate; however, the amount of volatile organic matters in the sample has kept constant. Furthermore, the results have showed that the best drying conditions in this study is 30 m3/h drying airflow rate, 200 °C drying air temperature, and co-current dryer type. With these conditions, moisture content of woodchip decreased from 60% to 27% (wet basis, mass %).
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89.20.Kk Engineering

Feasibility analysis of megawatt scale solar thermal power plants

K. S. Reddy, K. Ravi Kumar, and Vikramaditya A. Devaraj

J. Renewable Sustainable Energy 4, 063111 (2012); http://dx.doi.org/10.1063/1.4766891 (23 pages)

Online Publication Date: 13 November 2012

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In this article, feasibility analysis of solar thermal power plants is carried out for large scale power generation. Three different configurations of concentrating solar power technologies such as linear Fresnel reflector collector (LFRC), parabolic trough collector (PTC), and power tower (PT) are analyzed for power generation in stand-alone mode and various plant capacities such as 1 MWe, 5 MWe, 10 MWe, 30 MWe, and 50 MWe. The maximum achievable steam conditions in LFRC system has been considered for all the power plant capacities as 55 bar and 270 °C. In case of parabolic trough and power tower, the steam parameters have been considered as 60 bar, 370 °C for 1 MWe, 65 bar, 400 °C for 5 MWe, 65 bar, 410 °C for 10 MWe, 100 bar, 410 °C for 30 MWe, and 100 bar, 410 °C for 50 MWe. The feasibility of stand-alone solar power plants (SASPPs) is compared with coal fired power plant (CFPP) and solar aided coal fired power plant (SACFPP). The feasibility analysis in terms of performance and levelised electricity cost (LEC) is carried out for various technologies with capacities. It is observed that the LFRC power plants are relatively less efficient than others due to lower optical and thermal efficiency. The energy and exergy efficiencies of a 50 MWe LFRC power plant are found as 12.17% and 17.21%, respectively. The efficiency of 50 MWe solar PTC power plants is found as 23.16% which is higher than other technologies. The net exergy efficiency of PTC power plants increases from 23.14% to 32.76% for the plant capacity increases from 1 MWe to 50 MWe. It is observed that the exergy efficiency decreases from 22.57% to 19.65% as plant capacity increases from 1 MWe to 10 MWe due to shading and blocking for PT power plants and then increases to maximum of 23.33% for the 50 MWe power plant. The exergy efficiencies of 50 MWe CFPP and SACFPP have been estimated as 28.17% and 28.21%, respectively. The environmental benefits of stand-alone solar power plants are estimated in terms of CO2 mitigations and compared with CFPP. The LEC of CFPP, SACFPP, and SASPP is found as INR 3.56/kWh, INR 3.60/kWh, and INR 8.48/kWh, respectively. The discounted payback period, benefit-to-cost ratio, and net present value of all the power plants are also estimated.
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84.70.+p High-current and high-voltage technology: power systems; power transmission lines and cables
92.60.Ry Climatology, climate change and variability
92.60.Sz Air quality and air pollution
88.40.F- Solar concentrators
42.79.Ek Solar collectors and concentrators

Effects of volumetric dilution on anaerobic digestion of food waste

Xian Fang Lou, Jaya Nair, and Goen Ho

J. Renewable Sustainable Energy 4, 063112 (2012); http://dx.doi.org/10.1063/1.4764935 (10 pages)

Online Publication Date: 13 November 2012

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Despite the increasing number of small scale digesters operating, there remains a lack of information with regards to performance optimization from an everyday user's standpoint. The objective of this study was to determine the effects of volumetric dilution and food waste composition on digester performance. Batch experiments utilizing food waste majoring in carbohydrate, protein, lipid, and cellulose, subjected to five concentrations of volumetric dilution (3.7%–17.1% total solids (TS)), were conducted. Irregardless of volumetric dilution, all assays achieved substrate degradation higher than 82.5% and did not suffer methanogenic inhibition, when provided with retention times comparable to those used in small scale digesters. Protein rich and cellulose rich waste achieved the highest methane potential varying between 0.410–0.539 m3/kg volatile solids (VS) and 0.450–0.535 m3/kg VS, respectively. Protein rich assays were also observed to be the first to achieve 50% of its Bo irregardless of concentrations, followed by carbohydrates and cellulose, and lipids having a considerably longer methanation time. Results saw an increase in total methane generated but a decrease in specific yield as % total solid increased. To successfully digest lipid rich waste a dilution no lesser than 1:4 was required.
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89.20.Kk Engineering
88.20.dr Food wastes

Development of an improved sawdust gasifier stove for industrial applications

Indraneel J. Bhanap and Ramchandrada D. Deshmukh

J. Renewable Sustainable Energy 4, 063113 (2012); http://dx.doi.org/10.1063/1.4765694 (16 pages)

Online Publication Date: 26 November 2012

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For decades and even today (though comparatively less), many people from rural India continue to use traditional cook stoves to satisfy their daily cooking needs [S. Kohli, in “New Initiative for Development and Deployment of Improved Cookstoves: Recommended Action Plan,” Indian Institute of Technology-Delhi, The Energy & Resources Institute, New Delhi, May 2010, p. 2]. These cook stoves run on solid fuels, which include biomass fuels such as fire wood, agricultural waste, charcoal, and cow dung [E. Duflo, in “Up in Smoke: The Influence of Household Behavior on the Long-Run Impact of Improved Cooking Stoves,” April 2012, p. 2]. While they achieve their purpose of cooking the food, they also release copious amounts of carbon monoxide and various other poisonous gases. Since these people often tend to cook their food indoors, they tend to inhale these gases, which lead to various respiratory diseases and complexities. This term is defined as “indoor air pollution (IAP)” and is one of the major problems that continue to plague the rural population in developing countries around the world [E. Duflo, in “Up in Smoke: The Influence of Household Behavior on the Long-Run Impact of Improved Cooking Stoves,” April 2012, p. 3], which continue to use the traditional cook stove. Therefore, it has become necessary to develop technologies (more specifically cook stoves), so that they continue to use these sources of fuel before ensuring that they produce minimal indoor air pollution. Appropriate Rural Technology Institute (ARTI) is a non-governmental organization (NGO) located in Phaltan, Maharashtra, India, which develops various cook stoves that run on various sources of biomass, which are not only significantly more powerful and efficient than the traditional stoves but also produce lower levels of CO than their traditional counterparts. It trains rural entrepreneurs on how to use it who distribute these cook stoves to the rural population. The stove, on which this paper is based, is the “Vivek” stove developed by ARTI. It is a portable, cylindrical gasifier stove designed for the rural people to carry it wherever they go and to cook a meal for a family of four. ARTI, however, also planned to develop a sawdust gasifier stove that can be utilized in small-scale industrial processes. The current “Vivek” stove is inadequate for such applications that require a long and stable power output, while maintaining low emissions. For this purpose, different design configurations of the sawdust gasifier stove were tested and evaluated. This paper aims to analyze the results of each of the stove design configurations and how each of the stoves performed and to select the most ideal design among them for developing an industrial sawdust gasifier stove, which also serves as the groundwork for the stove to be further optimized.
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89.20.Kk Engineering
89.60.-k Environmental studies
92.60.Sz Air quality and air pollution

Chemical composition and bioethanol potential of different plant species found in Pacific Northwest conservation buffers

Deepak Kumar, Ankita Juneja, William Hohenschuh, John D. Williams, and Ganti S. Murthy

J. Renewable Sustainable Energy 4, 063114 (2012); http://dx.doi.org/10.1063/1.4766889 (14 pages)

Online Publication Date: 26 November 2012

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Lands producing mixed lignocellulosic ethanol feedstocks may be able to produce more biomass with fewer resources than conventional monoculture crops, but lignocellulosic ethanol production processes and efficiencies can be highly dependent on feedstock composition. In this study, plants were collected from areas planted to simulate conservation buffers alongside stream channels within three common resource areas the interior Pacific Northwest. Two grasses (tall wheatgrass and alfalfa) and seven forb species (fiddleneck tarweed, dog fennel, kochia, downey brome, tall annual willowherb, prickly lettuce, and tumble mustard) commonly found in these buffers were examined to determine their chemical composition, potential bioethanol yields, and difficulties that may arise if they were to be harvested and processed in a single facility. Potential ethanol yields calculated on the basis of sugar monomer composition in the biomass ranged from 181.5 to 316.5 l/dry ton of biomass. Significant differences were noted in terms of structural sugars (cellulose 19%–33% w/w; hemicellulose 14%–26% w/w), lignin (10%–18% w/w), extractives (20%–40% w/w), and ash content (4.0%–13.8% w/w). These composition variations could vary the processing efficiency in terms of sugar recovery and eventual ethanol production yield.
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88.20.F- Renewable alternative fuels from biomass energy

New method to assess the loss parameters of the photovoltaic modules

M. Bencherif and A. Chermitti

J. Renewable Sustainable Energy 4, 063115 (2012); http://dx.doi.org/10.1063/1.4767812 (19 pages)

Online Publication Date: 26 November 2012

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The determination of an effective method able to estimate the parameters of a photovoltaic panel is essential for the development and the performance of analysis of such equipment. In this paper, we present a new simple and effective method in order to extract the parameters of the photovoltaic (PV) modules by using the standard diode model. This model requires the five parameters be known, the photocurrent Iph, the reverse saturation current Is, the resistance Rs, the shunt resistance Rsh, and the curve fitting parameter A (the ideality factor) or the thermal voltage a. In order to find the five parameters, we formulated an equation binding only the two loss parameters Rs and Rsh. In order to solve this equation and to determine the shunt resistance and the thermal voltage, we expose the computation models of the series resistance Rs, which give excellent approximations. While the other parameters Iph and Is depend exclusively on the parameters Rs, Rsh, a, and the short circuit current Isc, and the open circuit voltage Voc. This method is validated experimentally by three different flat plat PV modules of various technologies (monocrystalline, polycrystalline, and thin film panels) and manufacturers.
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84.60.Jt Photoelectric conversion
02.60.Ed Interpolation; curve fitting

Analysis on performance, emission and combustion characteristics of diesel engine fueled with methyl–ethyl esters

A. Murugesan, D. Subramaniam, C. Vijayakumar, A. Avinash, and N. Nedunchezhian

J. Renewable Sustainable Energy 4, 063116 (2012); http://dx.doi.org/10.1063/1.4767911 (12 pages)

Online Publication Date: 26 November 2012

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In this experimental study, performance, emissions, and combustion characteristics of methyl/ethyl esters of pongamia, ethyl esters of neem and diesel blends in a diesel engine were experimentally investigated. For this study, methyl esters of pongamia, ethyl esters of pongamia, and ethyl esters of neem were added to diesel by volume of 20% (B20), 40% (B40), 60% (B60) and 80% (B80), as well as pure blend (B100). Fuels were tested in single cylinder, water-cooled, direct injection kirloskar diesel engine loaded by eddy current dynamometer. The effect of blends on engine performance, exhaust emissions, and combustion were examined at different loads. It was clear, up to 40% of methyl/ethyl ester did not affect the brake thermal efficiency. On the other hand, HC emission decreased by 1.3% for B40 in comparison with base diesel operation in engine. At the same time, smoke emissions were also reduced by 1.2% compared to diesel engine fuelled with B40 blend. It was proved that B40 is a best blend ratio compared to B60, B80, and B100. The overall combustion characteristics of B40 bio diesel were similar to base diesel. The maximum cylinder pressure for B40 bio diesel was slightly less compared to maximum cylinder pressure of base diesel at the same operating condition. The heat release rate and cumulative heat release rate are higher for base diesel compared to B40 bio diesel operating at full load condition.
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88.05.Xj Energy use in transportation
88.20.ff Ethanol
88.20.fg Methanol
88.20.ft Vegetable oils

The wind-wave tunnel test of a tension-leg platform type floating offshore wind turbine

Nianxin Ren, Yugang Li, and Jinping Ou

J. Renewable Sustainable Energy 4, 063117 (2012); http://dx.doi.org/10.1063/1.4767928 (13 pages)

Online Publication Date: 26 November 2012

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In this work, a tension-leg platform (TLP) type floating offshore wind turbine (FOWT) system was proposed, which was based on the National Renewable Energy Laboratory 5 MW offshore wind turbine model. Taking the coupled effect of dynamic response of the top wind turbine, support tower structure, and lower mooring system into consideration, the 1/60 scale model test for investigating the coupled wind-wave effect on performance of the floating wind turbine system was done in Harbin Institute of Technology's wind tunnel and wave flume joint laboratory. In addition, numerical simulations corresponding to the scale model tests have been performed by advanced numerical tools. The results of model tests and numerical simulations have a good agreement, so the availability of the numerical model has been verified. Furthermore, to improve the performance of the TLP system, one tentative strategy adding mooring lines to the TLP system was proposed, and the model test results of the two TLP systems were compared with each other. As a result, the motion responses of the floating platform and the force levels of tension legs were effectively reduced by the additional mooring chains. The new TLP FOWT system might play an active and instructive role in the development of future FOWT system.
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88.50.G- Wind turbines
02.60.-x Numerical approximation and analysis

A new static lighting concentrator with optical coupler

Allen Jong-Woei Whang, Chia-Min Lin, Nai-Lun Ku, and Ming-Cheng Wang

J. Renewable Sustainable Energy 4, 063118 (2012); http://dx.doi.org/10.1063/1.4767929 (9 pages)

Online Publication Date: 26 November 2012

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Currently, energy-saving and carbon dioxide reduction are the most critical issues faced by the globe. Therefore, solar energy should be used as much as possible. A possible use is to illuminate a solar cell so as to transform light energy directly into electricity. However, due to its low efficiency and high cost, the solar cell is not presently economically feasible. Utilization of solar energy, which is considered one of the most important renewable energy sources, not only reduces consumption of fossil fuel but also slows down the pace of global warming. In addition to the use of solar cells, daylight illumination is also an important access to solar energy. Our team has developed a technique that can guide the natural light to the interior for indoor illumination. It is called the “Natural Light Guiding System.” Our system can guide sunlight to the interior, but the distribution of light at the exit of the system is disordered. To solve this problem, we have proposed an optical coupling transmission structure with right-angled prism collecting modules. We analyzed the mathematical model of coupling transmission. And, we also analyzed the efficiency of this cascade structure at the exit surface of the concentrator. In this paper, we provide a high efficiency new concentrator coupled to a transmission device. We save 75% of the optical fiber cable expense usage and we improve efficiency by 47.46% when we add an optical coupling transmission structure to our static lighting concentrator. It is better than the original cascade prism static concentrator. Taking the fiber cost into consideration, we defined a key performance index—it is a ratio of luminous flux on an illuminated area. Our system can provide more powerful light for indoor illumination than existing methods The optical coupling can provide high transmission efficiency and provide parallel light beams at the export from the optical coupling module. We used optical simulation tools to design and simulate the efficiency of the active module. We can use this system as an ecological illumination system to offer steady illumination in indoor space to provide healthy illumination, save energy, and meet safety requirements.
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42.79.Ek Solar collectors and concentrators
89.30.A- Fossil fuels
88.40.-j Solar energy
88.05.Gh Energy conservation; electricity demand reduction
88.40.mx Day lighting/natural lighting of buildings
42.79.Bh Lenses, prisms and mirrors

Stochastic generation scheduling considering wind power generators

Taher Niknam, Hamid Reza Massrur, and Bahman Bahmani Firouzi

J. Renewable Sustainable Energy 4, 063119 (2012); http://dx.doi.org/10.1063/1.4767930 (19 pages)

Online Publication Date: 26 November 2012

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This paper presents a model for the computation of costs of the generation of the electrical power in a power system. It is based on the stochastic optimization of mid-term generation scheduling wind integrated power system with respect to the uncertainty on both wind generation and load forecast. The uncertainty of the two above mentioned elements is modeled by scenario-based method. In the previous works, the impact of the generation of wind power on the generation scheduling (GS) problem using stochastic methods has been studied on daily basis. However, this study assesses the effect of the generation of wind power on the GS problem on a yearly manner. The problem of GS is solved under the various constraints of the power system. These constraints embrace the thermal and wind units' constraints, power balance, available wind power, and reserve requirements. A population-based method called teaching-learning-based-optimization (TLBO) is proposed to solve the stochastic generation scheduling problem. TLBO is a robust and effective search algorithm. The most salient advantage of this algorithm is that it does not require the tuning of any kind of controlling parameters. The efficiency of the proposed formulation is studied by employing the three test cases. Numerical results are presented for these case studies.
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88.50.-k Wind energy
84.70.+p High-current and high-voltage technology: power systems; power transmission lines and cables
88.05.-b Energy analysis
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