Major Energy Loss Research Articles

Investigation of plasma behavior during noble gas injection in the end-cell of GAMMA 10/PDX by using the multi-fluid code ‘LINDA’

The linear divertor analysis with fluid model (LINDA) code has been developed in order to simulate plasma behavior in the end-cell of linear fusion device GAMMA 10/PDX. This paper presents the basic structure and simulated results of the LINDA code. The atomic processes of hydrogen and impurities have been included in the present model in order to investigate energy loss processes and mechanism of plasma detachment. A comparison among Ar, Kr and Xe shows that Xe is the most effective gas on the reduction of electron and ion temperature. Xe injection leads to strong reduction in the temperature of electron and ion. The energy loss terms for both the electron and the ion are enhanced significantly during Xe injection. It is shown that the major energy loss channels for ion and electron are charge-exchange loss and radiative power loss of the radiator gas, respectively. These outcomes indicate that Xe injection in the plasma edge region is effective for reducing plasma energy and generating detached plasma in linear device GAMMA 10/PDX.

Slow hot carrier cooling in cesium lead iodide perovskites

Lead halide perovskites are attracting a great deal of interest for optoelectronic applications such as solar cells, LEDs, and lasers because of their unique properties. In solar cells, heat dissipation by hot carriers results in a major energy loss channel responsible for the Shockley–Queisser efficiency limit. Hot carrier solar cells offer the possibility to overcome this limit and achieve energy conversion efficiency as high as 66% by extracting hot carriers. Therefore, fundamental studies on hot carrier relaxation dynamics in lead halide perovskites are important. Here, we elucidated the hot carrier cooling dynamics in all-inorganic cesium lead iodide (CsPbI3) perovskite using transient absorption spectroscopy. We observe that the hot carrier cooling rate in CsPbI3 decreases as the fluence of the pump light increases and the cooling is as slow as a few 10 ps when the photoexcited carrier density is 7 × 1018 cm−3, which is attributed to phonon bottleneck for high photoexcited carrier densities. Our findings suggest that CsPbI3 has a potential for hot carrier solar cell applications.

Exergy Analysis of a Pilot Parabolic Solar Dish-Stirling System

Energy and exergy analyses were carried out for a pilot parabolic solar dish-Stirling System. The system was set up at a site at Kerman City, located in a sunny desert area of Iran. Variations in energy and exergy efficiency were considered during the daytime hours of the average day of each month in a year. A maximum collector energy efficiency and total energy efficiency of 54% and 12.2%, respectively, were predicted in July, while during the period between November and February the efficiency values were extremely low. The maximum collector exergy efficiency was 41.5% in July, while the maximum total exergy efficiency reached 13.2%. The values of energy losses as a percentage of the total losses of the main parts of the system were also reported. Results showed that the major energy and exergy losses occurred in the receiver. The second biggest portion of energy losses occurred in the Stirling engine, while the portion of exergy loss in the concentrator was higher compared to the Stirling engine. Finally, the performance of the Kerman pilot was compared to that of the EuroDish project.

Modeling and simulation of heat transfer phenomena in a semi-buried anaerobic digester

A transient thermal model has been developed for predicting temperature variations in semi-buried anaerobic digesters as a function of climatic conditions (ambient temperature, solar irradiation, rain intensity, etc.). Compared to literature, the modeling of several heat transfer terms was improved. Predicted operating temperatures were in good agreement with experimental observations. The simulation results allowed identifying phenomena leading to major energy losses from the reactor. Technical solutions were recommended to reduce heat losses in anaerobic digesters. The present model constitutes a powerful predictive tool for assisting engineers in determining the optimal design of digesters, as well as in the investigation of the influence of materials type on the reactor heating requirements.

Power Generation from Condenser Waste Heat in Coal-fired Thermal Power Plant Using Kalina Cycle

Abstract In any thermal power plant the major energy loss takes place in the condenser through its cooling water system. The objective of the present study is to convert this low grade waste heat from a 500 MWe subcritical coal-fired power plant into electricity by integrating Kalina Cycle System 11 (KCS 11) where ammonia-water binary mixture is used as working fluid. A computer simulation programme has been developed by MS-Excel and VBA to analyze the combined cycle plant configuration and parametric optimization based on thermodynamic equations. The parametric study is carried out based on variation of ammonia mass fraction and cooling water flow rate by keeping saturated vapour condition at turbine inlet. Result shows that the Kalina cycle is able to add about 13.49MWe electric power with a net cycle efficiency of 2.58%. There is an optimum cooling water flow rate that yields the maximum net cycle efficiency for a particular condenser design value in the Kalina cycle. Effect of ammonia mass fraction variations in the binary mixture is also studied by fixing turbine inlet temperature at 312.308K. The study shows that cycle performance improves with higher ammonia mass fraction. Effect of temperature rise across the main plant condenser increases the overall plant efficiency. Around 3.3 ton/h of CO2 emission can be reduced by electric power addition with the help of utilizing the condenser heat loss.

A warm welcome for alternative CO2 fixation pathways in microbial biotechnology.

Biological CO2 fixation is a crucial process carried out by plants and a number of microorganisms, which can be harnessed for both agriculture and sustainable, biobased production of fuels and chemicals. Fixation of CO2 by plants enables the production of food, feed, fuels and chemicals. Additionally, fixation of CO2 by autotrophic microorganisms such as cyanobacteria and microalgae can be employed for converting CO2 into value-added products, such as commodity chemicals or fuels. However, a major challenge to fully realize sustainable autotrophic production of chemicals and fuels is the low growth rate, productivity and energy conversion efficiency of autotrophs. Excluding the energy loss photoautotrophs experience due to inefficient light-harvesting (Blankenship et al., 2011), another major energy loss occurs during the fixation of CO2 in both photoautotrophs and chemolithoautotrophs (Zhu et al., 2010). The large majority of autotrophs employ the relatively inefficient Calvin–Benson–Bassham cycle for CO2 fixation (Fig. 1A). After having a dominant role in nature for billions of years, in the coming years I expect synthetic biologists will replace the Calvin cycle in biotechnology with potentially better and more efficient alternatives. But what is the limiting factor of the Calvin cycle? The main issue is the key enzyme ribulose-bisphosphate carboxylase/oxygenase (RubisCO). RubisCO has a low catalytic rate, and therefore is generally expressed in high levels, which requires a considerable amount of cellular resources. This resource demand comes on top of the existing high ATP-demand of the Calvin cycle required to produce common metabolic precursors such as acetyl-CoA and pyruvate (Claassens et al., 2016). Furthermore, RubisCO has a major wasteful side-activity with O2 in atmospheric conditions. This side-activity results in the formation of 2-phoshpoglycoylate that has to be re-assimilated to the Calvin cycle through photorespiration pathways. These photorespiration pathways partly counteract CO2 fixation by releasing some CO2 and typically add ~40–50% extra NADPH and ATP to the costs of CO2 fixation (Bar-Even et al., 2010). In recent years, many ideas have been put forward and attempts have been made to increase the efficiency of the Calvin cycle including; improving catalytic properties of RubisCO by protein engineering (e.g. Parikh et al., 2006; Dur~ ao et al., 2015), introducing more efficient photorespiration pathways (e.g. Shih et al., 2014) and introducing CO2 concentrating mechanisms to increase the carboxylating activity of RubisCO (e.g. Bonacci et al., 2012; Kamennaya et al., 2015). Some of these attempts have slightly improved the performance of autotrophs employing the Calvin cycle. However, apart from fixing such inefficiencies of the Calvin cycle, future research should also seriously address the options to completely replace both the Calvin cycle and accompanying enzyme RubisCO by potentially more efficient alternatives. Fortunately, nature has evolved many carboxylases with more promising properties than RubisCO and more attractive novel carboxylases may be created by protein engineering (Erb, 2011). Some examples of attractive natural carboxylases are employed in alternative natural carbon fixation pathways, thus far five alternative autotrophic CO2 fixation pathways have been discovered (Berg, 2011). Moreover, attractive carboxylases can be embedded in synthetic CO2 fixation pathways, which have been extensively explored by computational analyses (e.g. Bar-Even et al., 2010; Volpers et al., 2016). Several of the alternative natural and synthetic CO2 fixation pathways have lower ATP costs than the Calvin cycle, however, some trade-offs exist. For example, the natural Wood–Ljungdahl pathway and the natural reductive tricarboxylic acid cycle have very low ATP costs. However, these pathways can have major drawbacks, as these pathways are mainly limited to anaerobic settings, due to oxygen-sensitive enzymes, and they require high CO2 concentrations to be thermodynamically feasible (Berg, 2011). Alternative to natural pathways, computational analysis identified several oxygen-tolerant Received 18 October, 2016; accepted 19 October, 2016. *For correspondence. E-mail nico.claassens@wur.nl; Tel. +31(0) 317481066; Fax +31 317 483829. Microbial Biotechnology (2017) 10(1), 31–34 doi:10.1111/1751-7915.12456

Complex suppression patterns distinguish between major energy loss effects in Quark–Gluon Plasma

Interactions of high momentum partons with Quark-Gluon Plasma created in relativistic heavy-ion collisions provide an excellent tomography tool for this new form of matter. Recent measurements for charged hadrons and unidentified jets at the LHC show an unexpected flattening of the suppression curves at high momentum, exhibited when either momentum or the collision centrality is changed. Furthermore, a limited data available for B probes indicate a qualitatively different pattern, as nearly the same flattening is exhibited for the curves corresponding to two opposite momentum ranges. We here show that the experimentally measured suppression curves are well reproduced by our theoretical predictions, and that the complex suppression patterns are due to an interplay of collisional, radiative energy loss and the dead-cone effect. Furthermore, for B mesons, we predict that the uniform flattening of the suppression indicated by the limited dataset is in fact valid across the entire span of the momentum ranges, which will be tested by the upcoming experiments. Overall, the study presented here, provides a rare opportunity for pQCD theory to qualitatively distinguish between the major energy loss mechanisms at the same (nonintuitive) dataset.

Gross vs. net energy: Towards a rational framework for assessing the practical viability of pressure retarded osmosis

Although significant technological advances have been made in recent years on pressure retarded osmosis (PRO), its practical viability remains unclear as few studies have been conducted at an integrated system level to quantify the potential of net energy output. In this study, we develop a framework to assess the net energy output of a PRO system by first quantifying the gross energy output via solving the mass transfer equations for a full-scale PRO module, and then incorporating the major energy losses from pretreatment, flow circulation, and inefficient energy recovery. We also propose a novel concept called net membrane power density that is strongly relevant to the capital cost of a PRO system. Finally, we describe an approach, based on the quantifiable specific net energy and net membrane power density, for assessing the economic viability of a PRO system. Albeit using seawater/river water PRO as the context for illustrating our approach, the assessment framework developed is universally applicable to PRO systems with any solution pairing. The results from this study clearly show the impacts of various parameters on the practical performance of a PRO system, thereby providing important guidance to the improvement of its design and operation.

Dyes and Redox Couples with Matched Energy Levels: Elimination of the Dye-Regeneration Energy Loss in Dye-Sensitized Solar Cells.

In dye-sensitized solar cells (DSSCs), a significant dye-regeneration force (ΔG(reg)(0)≥0.5 eV) is usually required for effective dye regeneration, which results in a major energy loss and limits the energy-conversion efficiency of state-of-art DSSCs. We demonstrate that when dye molecules and redox couples that possess similar conjugated ligands are used, efficient dye regeneration occurs with zero or close-to-zero driving force. By using Ru(dcbpy)(bpy)2(2+) as the dye and Ru(bpy)2(MeIm)2(3+//2+) as the redox couple, a short-circuit current (J(sc)) of 4 mA cm(-2) and an open-circuit voltage (V(oc)) of 0.9 V were obtained with a ΔG(reg)(0) of 0.07 eV. The same was observed for the N3 dye and Ru(bpy)2(SCN)2(1+/0) (ΔG(reg)(0)=0.0 eV), which produced an J(sc) of 2.5 mA cm(-2) and V(oc) of 0.6 V. Charge recombination occurs at pinholes, limiting the performance of the cells. This proof-of-concept study demonstrates that high V(oc) values can be attained by significantly curtailing the dye-regeneration force.

Surface Modification of CoOx Loaded BiVO4 Photoanodes with Ultrathin p-Type NiO Layers for Improved Solar Water Oxidation

Photoelectrochemical (PEC) devices that use semiconductors to absorb solar light for water splitting offer a promising way toward the future scalable production of renewable hydrogen fuels. However, the charge recombination in the photoanode/electrolyte (solid/liquid) junction is a major energy loss and hampers the PEC performance from being efficient. Here, we show that this problem is addressed by the conformal deposition of an ultrathin p-type NiO layer on the photoanode to create a buried p/n junction as well as to reduce the charge recombination at the surface trapping states for the enlarged surface band bending. Further, the in situ formed hydroxyl-rich and hydroxyl-ion-permeable NiOOH enables the dual catalysts of CoO(x) and NiOOH for the improved water oxidation activity. Compared to the CoO(x) loaded BiVO4 (CoO(x)/BiVO4) photoanode, the ∼6 nm NiO deposited NiO/CoO(x)/BiVO4 photoanode triples the photocurrent density at 0.6 V(RHE) under AM 1.5G illumination and enables a 1.5% half-cell solar-to-hydrogen efficiency. Stoichiometric oxygen and hydrogen are generated with Faraday efficiency of unity over 12 h. This strategy could be applied to other narrow band gap semiconducting photoanodes toward the low-cost solar fuel generation devices.

Thermal Analysis of Water-Cooled Permanent Magnet Synchronous Motor for Electric Vehicles

In order to study heat generation and dissipation of water-cooled permanent magnet synchronous motor in electric vehicle, the major energy loss was calculated and the finite element model for interior heat transfer simulation was established based on appropriate simplification and equivalent processing. The fluid-solid-thermal coupling simulation was accomplished by CFD method and the steady state temperature field of the motor under rated condition was obtained. The simulation is verified by experiment and gives an effective support in motor’s cooling system design.

Reflectance Studies in Silicon Nanowires Grown By Electroless Etching

One of the major energy loss mechanisms of solar cells is optical reflection. Utilization of nanostructures in solar cells may eliminate the need for antireflective coating [1]. The antireflective nature of Silicon nanowires (SiNW’s) revealed by their black color and dull appearances have drawn the attention of researchers [2]. Highly oriented SiNWs arrays prepared by electroless etching method can significantly suppress light reflection across a broad spectrum. Reflectivity studies on these show a significantly decrease in optical reflectivity down to 1.3% for 10 µm long SiNWs arrays [3]. Electroless etching is a top-down technique for growing SiNWs and does not need costly and expensive equipment to grow SiNWs as bottom-up methods usually do.The electroless process begins with the cleaning of silicon substrates. They were cleaned in acetone, methanol and deionized water, then blow-dried with N2. They are dipped in hydrofluoric acid (HF) 49% solution for 1 min to remove any remaining oxide.The silicon (Si) wafers are dipped for 45 minutes at room temperature in an electroless solution prepared in a petri dish containing silver nitrate (AgNO3) and hydrofluoric acid (HF) [4].The substrates are dipped and galvanic reactions disperse silver ions on their surface, losing silicon as SiF6. As a consequence of this etching process, the removal of Si via Ag ions results in vertically aligned arrays of SiNWs covered with silver dendrites. Varying the heights of the SiNWs(fig. 1). changes their optical reflectance. A target optical reflection would be 0.8.Fig 1. Cross sectional SEM images of the vertically standing Si NW arrays obtained by electroless etching.REFERENCES[1] Jin-Young Jung, Han-DonUm, Sang-WonJee, Kwang-TaePark, JinHoBang, Jung-HoLee, “Optimal design for antireflective Si nanowire solar cells,” Solar Energy Materials & Solar Cells, 2013.[2] Baris Ozdemir, Mustafa Kulakci, Rasit Turan and Husnu Emrah Unalan, “Effect of electroless etching parameters onthe growth and reflection properties ofsilicon nanowires,” IOP Science, 2011.[3] Hua Bao and Xiulin Ruan, "Optical absorption enhancement in disorderedvertical silicon nanowirearrays for photovoltaic applications," OPTICS LETTERS, 2010.[4] R. G. Mertens and K. B. Sundaram, “Recession and Characterization of Patterned Nanowires Grown by Electroless Etching of Silicon”. ECS Journal of Solid state Science and Technology, 2012.

Mathematical modelling and simulation of the thermal performance of a solar heated indoor swimming pool

Buildings with indoor swimming pools have a large energy footprint. The source of major energy loss is the swimming pool hall where air humidity is increased by evaporation from the pool water surface. This increases energy consumption for heating and ventilation of the pool hall, fresh water supply loss and heat demand for pool water heating. In this paper, a mathematical model of the swimming pool was made to assess energy demands of an indoor swimming pool building. The mathematical model of the swimming pool is used with the created multi-zone building model in TRNSYS software to determine pool hall energy demand and pool losses. Energy loss for pool water and pool hall heating and ventilation are analyzed for different target pool water and air temperatures. The simulation showed that pool water heating accounts for around 22%, whereas heating and ventilation of the pool hall for around 60% of the total pool hall heat demand. With a change of preset controller air and water temperatures in simulations, evaporation loss was in the range 46-54% of the total pool losses. A solar thermal sanitary hot water system was modelled and simulated to analyze it's potential for energy savings of the presented demand side model. The simulation showed that up to 87% of water heating demands could be met by the solar thermal system, while avoiding stagnation.

Design and Testing of an Adjustable Linkage for a Variable Displacement Pump

A variable displacement hydraulic pump/motor with high efficiency at all operating conditions, including low displacement, is beneficial to multiple applications. Two major energy loss terms in conventional pumps are the friction and lubrication leakage in the kinematic joints. This paper presents the synthesis, analysis, and experimental validation of a variable displacement sixbar crank-rocker-slider mechanism that uses low friction pin joints instead of planar joints as seen in conventional variable pump/motor architectures. The novel linkage reaches true zero displacement with a constant top dead center position, further minimizing compressibility energy losses. The synthesis technique develops the range of motion for the base fourbar crank-rocker and creates a method of synthesizing the output slider dyad. It is shown that the mechanism can be optimized for minimum footprint and maximum stroke with a minimum base fourbar transmission angle of 30 deg and a resultant slider transmission angle of 52 deg. The synthesized linkage has a dimensionless stroke of 2.1 crank lengths with a variable timing ratio and velocity and acceleration profiles in the same order of magnitude as a comparable crank-slider mechanism. The kinematic and kinetic results from an experimental prototype linkage agree well with the model predictions.

Spin-dependent electronic processes and long-lived spin coherence of deep-level trap sites in CdS nanocrystals

Carrier trapping in colloidal nanocrystals represents a major energy loss mechanism for excitonic states crucial to devices. Surprisingly little is known about the influence of the spin degree of freedom on the nature of these intrinsic trap centers or the types of coupling that these states experience. Here, a pulsed microwave optically detected magnetic resonance study is presented that aims to probe the interaction pathways existing between shallow band-edge trap states and the deep-level emissive chemical defect states responsible for the broad, low-energy emission common to CdS nanocrystals. Due to long spin coherence times (${T}_{2}$) of these states, Rabi flopping detected in the luminescence under magnetic resonance provides access to information regarding the modes of coupling of shallow-trapped electron-hole pairs, both of isolated species and of those in proximity to the emissive defect. Corresponding optically detected spin-echo experiments expose an extraordinarily long intrinsic spin coherence time (${T}_{2}\ensuremath{\approx}1.6$ \ensuremath{\mu}s) for colloidal nanocrystals, and an electron spin-echo envelope modulation indicative of local spin interactions. This effect provides opportunities for gaining the detailed chemical and structural information needed in order to eliminate energy loss mechanisms during the synthetic process.

Flow in a Single Stage Centrifugal Fan With Vaneless Diffuser and Peripheral Louver Outlets

This paper presents an analysis on the air flows in a single stage centrifugal fan with a vaneless diffuser and peripheral louver outlets. The performance data of the fan are obtained experimentally. A numerical fluid flow model is developed. The agreements between the numerical and experimental results are reasonably good. The performances of the fan under various working conditions are explained by the flow structures and pressure distributions. Flow energy analysis shows that the major energy losses in the fan are the impeller loss, the diffuser loss, and the gap leakage loss. Suggestions on the design and application of fans with such architecture are given.

Rare-earth doped materials enhance silicon solar cell efficiency

In silicon solar cells, the mismatch between the incident solar spectrum and the spectral absorption frequencies results in a major energy loss. Photons with energies smaller than the silicon band gap are not absorbed, and their energy is totally wasted. Photons with energies larger than twice the silicon band gap are absorbed, but the excess energy is lost to heating. Down-conversion and up-conversion mechanisms are usually exploited to modify the incident solar spectrum. Figure 1 illustrates the process schematically. In down conversion, multiple low-energy photons are generated to exploit the energy of one incident high-energy photon. In up conversion, two or more incoming photons generate at least one photon with a higher energy than the incoming photons. We focus on the down-conversionmechanism. Rare earth (RE) ions, in which absorption and emission occur through a number of energy levels, allow down-conversion processes, as shown in Figure 2. Different mechanisms based on energy transfer between a RE3C (absorbing ion) and Yb3C (emitting ion) were investigated recently: Pr3C/Yb3C; Tb3C/Yb3C; Tm3C/Yb3C. Most studies of down conversion to date have been performed on single crystals characterized by a low phonon cut-off energy to minimize non-radiative transitions from the RE ions to the host matrix. Recent studies, however, have demonstrated that some glasses and transparent glass ceramics (GCs) could be valid alternative systems for supporting an effective quantum cutting process.1 Figure 1. Solar spectrum showing the band gap and twice the band gap of silicon.2 Down conversion shifts photons from a high-energy band (blue) to the maximum absorption band of silicon (white). Up conversion shifts photons from a low-energy band (red) to the maximum absorption band of silicon.

Left Ventricular Vortex Under Mitral Valve Edge-to-Edge Repair

Mitral valve (MV) edge-to-edge repair (ETER) changes MV geometry by approximation of MV leaflets, and impacts left ventricle (LV) filling fluid mechanics. The purpose of this study was to investigate LV vortex with MV ETER during diastole. A computational MV-LV model was developed with MV ETER at the central free edges of the anterior and posterior leaflets. It was supposed that LV would elongate apically during diastole. The elongation deformation was controlled by the intraventricular flow rate. MV leaflets were modeled as a semi-prolate sphere with two symmetrical circular orifices and fixed at the maximum valve opening. MV chordae were neglected. FLUENT was used to simulate blood flow through the MV and in the LV. MV ETER generated two jets deflected laterally toward the LV wall in rapid LV filling. The jets impinged the LV wall obliquely and moved apically along the LV wall. Jet energy was primarily lost near the impingement. The jet from each MV orifice was surrounded by a vortex ring. The two vortex rings dissipated at the end of diastole. The total energy loss increased inversely with the MV orifice area. The atrio-ventricular pressure gradient was adverse near the end of diastole and possibly in diastasis. Reduction of the total orifice area led to more increment in the transmitral pressure drop than in the transmitral velocity. In conclusion, during diastole, two deflected jets from the MV under ETER impinged the LV wall. Major energy loss occurred around the jet impingement. Two vortex rings dissipated at the end of diastole with little storage of inflow energy for blood ejection in the following process of systole. MV ETER increased energy loss and lowered LV filling efficiency. The maintaining of a larger orifice area after ETER might not significantly increase energy loss in the LV during diastole and the transmitral pressure drop. The adverse pressure gradient from the atrium to the LV might be the mechanism of MV closure in the late diastole.

An Approach to Energy Balance Analysis Application with Co-Generation: The Plant of Erdemir

Eregli Iron and Steel Works Co. (Erdemir) began its activities on May 15, 1965 with an annual production capacity of 450.000 t and has made important contributions to Turkey's economy ever since. Today, with a total amount of crude steel production capacity exceeding 3.000.000 t, it is the largest iron and steel factory and the sole producer of flat steel in the country. Erdemir produces hot and cold rolled coils, zinc, tin, and chromium plated steel. Erdemir has attained the production potential of its entire power requirement amounting to 1.2 billion Kwh/y in the power plant. However, it continues to purchase electricity amounting to 15% of its total production capacity from the Turkish Electricity Authority national system in order to meet the fluctuating loads, which occur during the hot rolling process. The installed energy production capacity of Erdemir has reached 155 MW (195 MW in 2008) with two steam turbine generators, which were put into service in 1965 with a 10 MW capacity each; a steam turbine, which was put into service in 1978 with a 30 MW capacity; two gas turbine generators, each of which was put into service in 1997 with a 40 MW capacity; and a steam turbine generator/motor blower which was put into service in 2001 with a 25 MW capacity. The steam production capacity is 750 t/hr of which 600 t/hr is produced in five steam boilers and 160 t/hr is produced in two co-generation facilities. In this study, as the control volume, the limits of co-generation plant No. 1 in Erdemir have been chosen for a detailed energy balance analysis. By the identification of the energy sources that move in and out of the control volume, the energy output sources have been categorized as fractioned. For the implementation of the method, the balance study has been chosen. Thanks to this study, major energy losses have been determined. According to our calculations energy efficiency of the furnace was founded as 77,2%. It seems that Erdemir co-generation plant No. 1 has a highly energy-efficient production for sustainable energy generation. Erdemir co-generation plant has also been rewarded as the second most-efficient co-generation plant of Turkey by the Ministry of Energy in 2002. This study also aimed to show the importance of the energy balance of plants, in order to find energy losses from the process. The losses can be recovered to use primary energy sources effectively.

Modeling the photovoltaic potential of a site

Measurements of the power produced by a photovoltaic (PV) system are important for technical as well as financial reasons, especially in large installations. The energy produced by a PV system is modeled through its nominal power, the incoming irradiance and the major energy loss mechanisms. These mechanisms involve the temperature of the cells, the response of a cell to low intensity light, the spectrum and polarization of the light, the deviation from maximum power point tracking, module mismatch and ohmic losses. The experimental quantities needed by the model are the solar irradiance at the plane of the array, the cell temperature and the nominal power of the system. In this work, we present part of the results of the theoretical calculations and their comparison with actual experimental measurements.