Showing papers in "Energy Sources in 2006"

Global Renewable Energy Resources

Abstract: Renewable energy sources (RES) supply 14% of the total world energy demand. RES are biomass, hydropower, geothermal, solar, wind, and marine energies. The renewables are the primary, domestic and clean or inexhaustible energy resources. The percentage share of biomass was 62.1% of total renewable energy sources in 1995. Large-scale hydropower supplies 20 percent of global electricity. Wind power in coastal and other windy regions is promising as well.

Performance Characteristics of Sunflower Methyl Esters as Biodiesel

Abstract: This study is devoted to determining performance characteristics of biodiesel as a diesel engine fuel. An engine performance test using sunflower methyl esters exhibited characteristics very similar to regular diesel. The test values obtained from a 2.5 lt. 4 cylinder Peugeot XD3p157 engine shows that torque values obtained by the two types of fuels are 5%–10% in favor of regular diesel. Obviously, power values will be the engine revolutions times this percentage with regular diesel. Specific fuel consumption, however, is better with biodiesel. This means that a better combustion characteristic is achieved with biodiesel, which compensates for its lower calorific value. Soot emissions are slightly less with biodiesel, as expected, due to the improvement in specific fuel consumption.

New options for conversion of vegetable oils to alternative fuels

Abstract: Biodiesel from transesterification of vegetable oils is an excellent alternative fuel. There is, however, a need to develop a direct process for conversion of vegetable oils into gasoline-competitive biodiesel and other petroleum products. Methyl esters of vegetable oils have several outstanding advantages among other new-renewable and clean engine fuel alternatives. The purpose of the transesterification process is to lower the viscosity of vegetable oil. Compared to No. 2 diesel fuel, all of the vegetable oils are much more viscous, whereas methyl esters of vegetable oils are slightly more viscous. The methyl esters are more volatile than those of the vegetable oils. Conversion of vegetable oils to useful fuels involves the pyrolysis and catalytic cracking of the oils into lower molecular products. Pyrolysis produces more biogasoline than biodiesel fuel. Soap pyrolysis products of vegetable oils can be used as alternative diesel engine fuel. The soaps obtained from the vegetable oils can be pyrolyzed in...

Oil Consumption and Economic Growth: Evidence from Korea

Abstract: This article investigates the short- and long-run causality issues between oil consumption and economic growth in Korea by applying modern time-series techniques. It employs annual data covering the period 1968–2002. Tests for unit roots, cointegration, and a Granger-causality based on error-correction model are presented. The results show that bidirectional causality runs from oil consumption to economic growth in Korea. This means that an increase in oil consumption directly affects economic growth and that economic growth also stimulates further oil consumption.

Biogas Potential of Manure and Straw Mixtures

Abstract: Wheat straw or manure or both were converted to a methane-rich gas mixture. Anaerobic biomethane production is an effective process for conversion of a broad variety of lignocellulosic materials to methane to substitute natural gas and medium calorific value gases. Methane generating bacteria (methanogens) and other microbes help digest dying plants in anaerobic (without oxygen) conditions. Wheat straw wastes represent a potential energy resource if they can be properly and biologically converted to methane. The yields of methane from the materials used were found between 10.4% and 14.7%. The producing gas has an energy content of about 33%–50% of the higher heating value from the feedstock. The most important parameters for the biogas generation rates were the total solids (TS) concentration in the slurry, the digestion time, species of feeding substrate, and pH of the medium. The methane content of the biogas was in the range of 73%–79% for the runs, the remainder being principally carbon dioxide.

Global Solar Radiation Potential, Part 1: Model Development

Abstract: Solar engineers, architects, agriculturists, and hydrologists dealing with many applications of solar energy require a reasonably accurate knowledge about the availability of solar resources at any place. For this purpose, in the past, several empirical correlations have been developed in order to predict the solar radiation around the world. The present study, consisting of two parts, analyzes global solar radiation over the Central Anatolia Region (CAR) of Turkey along with its twelve provinces. Part 1 of this study includes the solar radiation models developed, while their statistical analysis is presented in Part 2. In the analysis, the data of the monthly average daily global solar radiation and sunshine duration measured by the Turkish State Meteorological Service in the period from January 1990 to December 1996 are used. Empirical models to estimate the monthly global solar radiation on a horizontal surface for each province are developed. The results obtained have indicated that the models develop...

Major and Minor Element Distribution in Fly Ash from a Coal-Fired Utility Boiler in Kentucky

Abstract: Study of the combustion of a multiseam blend of southeastern Kentucky high volatile A bituminous medium sulfur coal in a 220-MW wall-fired utility boiler demonstrated that there is significant asymmetry in the distribution of major elements and oxides, including sulfur and carbon, and minor elements in the ash collection system. Partitioning of volatile elements, such as Zn and As, according to flue gas temperature is a well-known phenomenon. Hg distribution is related to both the flue gas temperature and the amount of carbon in the fly ash. In addition, many elements show a distinct lateral asymmetry within individual rows of the ash-collection system. Certain aspects of the element distribution appear to be related to the carbon distribution. Hg is an example of an element with a lateral distribution tied to carbon. Other elements, such as Mo, As, Mn, and Cr, may be incidental relationships, tied to the relative increase in glassy fly ash constituents in the absence of carbon.

Effect of Ash in Coal on the Performance of Coal Fired Thermal Power Plants. Part I: Primary Energy Effects

Abstract: This article reports the effect of ash content in raw coal on the energy performance of coal fired thermal power plants of capacity range 30–500 MW. The focus is on primary energy effects—combustion, heat transfer, and flow hydrodynamics. The effects of variation of ash in coal from 6% (taken as standard) up to 75% on component performance are studied and overall unit performance is quantified based on experimental data. When the ash content increases from 6% to 75%, the effects on the system (without fuel oil support) are as follows: (a) total boiler area requirement (excluding air preheater [APH]) increases by 69%, (b) efficiency of boiler fans drop by 22%–27%, (c) drum mills show an increase in SEC of 115% while ball-race mills and bowl mills show an increase in SEC of 30%, (d) induced draft (ID), forced draft (FD), and primary air (PA) fans show an increase in specific energy consumption (SEC) of around 30%, 6%–14%, and 2%–7% respectively, (e) the gross and net overall efficiencies are reduced to 77% ...

Electrical Power Production Facilities from Green Energy Sources

Abstract: Green power refers to electricity supplied from more readily renewable energy sources than traditional electrical power sources. Green power products have become widespread in many electricity mark...

Estimating Petroleum Exergy Production and Consumption Using a Simulated Annealing Approach

Abstract: This study deals with the development of the petroleum exergy production and consumption relations in order to better analyze exergy values and predict the future projections using the simulated annealing (SA) approach, which is a powerful technique used to solve many optimization problems. The exergy estimation is performed based on the indicators of gross domestic product (GDP) and the percentage of vehicle ownership figures in Turkey, which is given as an illustrative example. The so-called SA exergy production and consumption (SAPEX) model is developed, while the exergy values obtained using the SAPEX model are also compared with those using the genetic algorithm (GA) approach. It is determined that the SAPEX model developed predicts the exergy values better than the GA model. It may be concluded that the models proposed here can be used as an alternative solution and estimation technique to available estimation techniques in predicting the future energy and exergy utilization values of countries. Thi...

Biomass-Based Combined Heat and Power Systems

Abstract: This study aims to identify and evaluate the biomass utilization options and evaluate the sustainable biomass production for combined heat and power (CHP) in Turkey. The total biomass energy potential of Turkey is about 32 Mtoe. The amount of usable biomass potential of Turkey is approximately 17 Mtoe. Among the biomass energy sources, fuel wood seems to be one of the most interesting because its share of the total energy production of Turkey is high at 21%. The use of biofuels for CHP on a large scale is focused mainly on forest industry sites, where considerable quantities of biomass are available. Biomass available for energy can be converted to different types of final energy (e.g., electricity, heat), of these, the production of electricity appears to be particularly important. While CHP provides several environmental benefits by making use of waste heat and waste products, air pollution is a concern any time fossil fuels or biomass are burned.

Effect of Ash in Coal on the Performance of Coal Fired Thermal Power Plants. Part II: Capacity and Secondary Energy Effects

Abstract: This article reports the secondary energy effects (wear/erosion/abrasion, slagging, and fouling) of ash in coal on the energy performance of coal fired thermal power plants of capacity range 30–500 MW. It also gives the extent of capacity reduction in equipment due to firing of coals with higher ash contents. At an ash content of 75% in coal, the effects on the system (without fuel oil support) follow: (a) decrease in Hardgrove index from 80 to 44; (b) 20% of the specific energy consumption (SEC) of induced draft (ID) fans, 10%–12% of that of forced draft (FD) and primary air (PA) fans, 17% of that of drum mills, and 12%–13% of that of ball-race mills and bowl mills, are accounted for by wear/erosion/abrasion effects; (c) decrease of fan efficiencies by 5%–6% points due to wear/erosion/abrasion effects; (d) capacity loss originating from wear/erosion/abrasion effects alone is 8% due to ID fans, 1% due to PA fans, and 6% due to mills; (e) fouling effects are high fouling factor, decrease in boiler efficien...

Batch Sorption of Divalent Metal Ions onto Brown Coal

Abstract: Brown coal, a relatively abundant and inexpensive material is currently being investigated as an adsorbent to remove some contaminants from aqueous solution. The adsorption of some heavy metals from aqueous solutions on the brown coals was studied as a function of pH, contact time, adsorbent dosage and concentration of metal solutions. A carboxyl, phenolic hydroxyl, and metoxyl functional group present on the coal surface was the adsorption site to remove metal ions from solution by means of ion exchange and hydrogen bonding. Effective removal of heavy metals was achieved at pH values of 4.0–5.0. The experimental data have been analyzed using the Langmuir on isotherm models. Under optimized conditions, the percentage of metal removal by brown coal adsorption was over 80%.

Autothermal Fluidized Bed Pyrolysis of Cuban Pine Sawdust

Abstract: Oxidative pyrolysis of Cuban pine sawdust was investigated using an autothermal fluidized bed reactor. Biomass particles were fed continuously (8.13 Kg/h) in a bed, fluidized by air gas. Experiments were conduced at three different dimensionless air factors 1, 1.5, and 2 (defined as ratio of actual air flow rate to stoichiometric air flow rate). The various physical and chemical characteristics of the pyrolysis products acquired in these conditions were identified. The results indicated that (1) the operating temperature can be correlated with the air factor; (2) the higher air factor promotes high temperature and contributes to the secondary reactions, which lead to less liquid; (3) the physicochemical characterization of the pyrolysis products indicated that the air factor, in the range studied, does not have a notable influence in their properties; (4) the liquid and char products obtained may be a potentially valuable source of chemical feedstocks.

Selecting an appropriate Multi-Criteria Decision Aid Technique for renewable energy planning

Abstract: Selecting an appropriate Multi-Criteria Decision Aid Technique for renewable energy planning

Role of Surfactants in Photogalvanic Cells for Solar Energy Conversion and Storage

Abstract: Photogalvanic effect was studied in photogalvanic cells containing toluidine blue as photosensitizer, ethylenediamine tetra acitic acid as reductant and sodium lauryl sulphate, cetyl pyridinium chloride, Tween-80 as surfactants in different systems The photopotential and photocurrent generated were 7430 mV and 700 μA in EDTA-TB-NaLS system, 7620 mV and 350 μA in EDTA-TB-CPC system, and 4300 mV and 500 μA in EDTA-TB-Tween-80 system, respectively The effects of different parameters on electrical output of the cell were observed, and a mechanism has been proposed for the generation of photocurrent in photogalvanic cell

Cogeneration and trigeneration applications

Abstract: Combined heat and power cogeneration, or “autoproduction” as it is known in Turkey, is the simultaneous production of heat and electricity, while trigeneration includes the cold production in addition to cogeneration. This technology has been advanced by governmental support and the continuing need for additional electricity generation within Turkey. The present study deals with cogeneration and trigeneration applications in Turkey, giving the electricity market development. Only four cogeneration plants with a total capacity of 30 MW e were operated up to 1994, while trigeneration applications have started for the last two years. The total installed cogeneration capacity is expected to reach up to 6,000 MW e by 2005, which would represent about 20% of Turkey's total installed electricity generating capacity. In this context, cogeneration and trigeneration have had, or will have, a significant and increasing role in dictating the energy strategies for Turkey.

An Application of Genetic Algorithm Search Techniques to the Future Total Exergy Input/Output Estimation

Abstract: Since 1975, there has been a great deal of interest, particularly during the past decade, in the promising genetic algorithm (GA) and its application to various disciplines from medicine to cogeneration. However, the studies performed on energy-related GA modeling are relatively low in numbers. The main objective of the present study is to develop the exergy input/output estimation equations in order to estimate the future projections based on the GA notion. In this regard, the GA Future Total EXergy Input/Output Estimation Models (GAFTEXIEM/GAFTEXOEM) are used to estimate total exergy input/output demand of Turkey, which is selected as an application country, based on the economic and social indicators of gross domestic product (GDP), population, import, export and house production figures. The future prediction of Turkey's total exergy input/output values are projected between 2003 and 2023. It may be concluded that the models proposed here can be used as an alternative solution and estimation technique...

A Phenomenological Energy Model of Biomass Pyrolysis Under Autothermal Fluidized Bed Conditions

Abstract: In Cuba a variety of types of biomass is being investigated for energy conversion through thermochemical processes into solid, liquid, and gas products. A continuous bench fluidized bed pyrolysis has been designed and is currently under testing. In this article, a transport model has been developed to simulate the axial temperature fields in a bench. The model and experimental results indicated that (1) two zones exist inside of the fluidization column, the dense bed where the exothermic and endothermic reactions are active, and the freeboard zone where the temperature of the pyrolysis product decreases continuously; (2) the bed temperature increases with an increase in the air factor. The predicted temperature is in quantitative agreement with experimental measurements.

Utilization of Fly Ash to Prepare Adsorbent for SO2 Removal in Flue Gas

Abstract: The possibility of preparing formed active coke using fly ash from a fluidized bed coal gasifier for flue gas desulfurization was investigated. The study shows that fly ash can be utilized as the feedstock with the addition of some raw coal. The obtained formed active coke exhibits an almost equivalent desulfurization capacity to that from raw coal. In addition, the effects of the pore properties and surface chemical properties of different formed cokes on SO 2 removal were analyzed and discussed. The effect factors on the mechanical strength of formed coke and optimal preparation conditions were also discussed.

Carbonization Index and Energy Intensity in the Formation of Worldwide CO2 Emissions, 1971–2000

Abstract: This study uses three methods to explore the roles of the carbonization index and energy intensity in the formation of CO 2 emissions throughout the world based on statistics from 1971 to 2000. The finding is that the role of both the carbonization index and energy intensity is the same in the formation of CO 2 emissions. That is, they decreased CO 2 emissions. However, the decrease of CO 2 emissions caused by energy intensity is larger than the decrease of CO 2 emissions caused by the decarbonization index. The estimated rates of the former to the latter are four times larger.

Experimental Design in Petrophysical Studies: Passive and Active Petrophysical Experiments

Abstract: This article describes examples of experimental design, which is the procedure and pattern for obtaining mathematical description or mathematical model of a process or parameter under study as linear or nonlinear regression equation based on the limited number of reproducible experimental data. The examples are related to petrophysical studies of the influence of clay and carbonate contents in clastic rocks and depth of burial on porosity (passive experiment), and the influence of temperature and pressure on some principal petrophysical parameters (active experiment).

Evaluation of Polyurethanes as Potential Mud Loss Control Agents

Abstract: In this article, polyurethanes have been selected as potential lost circulation materials (LCMs) that will be introduced in wellbores having experienced serious drilling mud losses. The chemicals will be mixed at surface, pumped downhole, let to bridge/foam and seal open fractures/channels. Different tests have been carried out to investigate better ways of mixing and handling polyurethanes before pumping. In that, prospects of slowing down polyurethane reactions by decreasing the amount of activator and adding different proportions of diesel were investigated. Testing the effect of moisture on polyurethanes also was tested. Furthermore, testing using diesel, toluene, xylene, Musol, acetone, glycol, light crude oil, Safrasol as carrier fluids was undertaken. The mixing sequence of diluents and polyurethanes also was thought of and the effect of mixing water on foaming reaction also was investigated. Placement under pressure of pumped polyurethanes also was investigated. It was revealed that pressure enhan...

Adjustments of Microwave-Based Measurements on Coal Moisture Using Natural Radioactivity Techniques

Abstract: The use of nonconventional on-line measurements of moisture and ash content in coal is presented. The background research is briefly reviewed. The possibilities of adjusting microwave-based moisture measurements using natural radioactive techniques, and vice versa, are proposed. The results obtained from the simultaneous analysis of moisture and ash content as well as the correlation improvements are shown.

Preparation of Polymeric Pour Point Depressants for Shale Oil

Abstract: The melt esterification of acrylic acid and higher alcohols without solvent is carried out and the effects of factors on the production efficiency of acrylic higher alcohol ester are investigated. Optimum reaction conditions are obtained at molar ratio of acrylic acid to higher alcohol 1.2:1.0 and reflux time 7 h at 110–140°C in stepwise heating. At this point the acrylic higher alcohol ester will be polymerized with maleic anhydride, phenylethylene, and vinyl acetate, and formed into four components. Copolymer shale oil pour point depressant and the polymerization condition are also studied by orthogonal method. The effect of pour point depressants is best when the monomer molar ratio is 8:1:1:1 at 80°C for 8 h for reflux and the benzoyl peroxide is added. The pour point of Fushun shale oil reduces by 9°C when only 0.5% copolymer is added.