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Energy Usage (energy + usage)
Selected AbstractsLocal authorities, climate change and small and medium enterprises: identifying effective policy instruments to reduce energy use and carbon emissionsCORPORATE SOCIAL RESPONSIBILITY AND ENVIRONMENTAL MANAGEMENT, Issue 3 2008Jaryn Bradford Abstract This paper discusses potential policy options available to local and municipal authorities, to achieve reductions in energy usage and greenhouse gas (GHG) emissions from small and medium-sized enterprises (SMEs). Researchers conducted surveys with 112 SMEs, and the results have been used to disaggregate the category of ,SME' into sub-sectors based on industrial sector, two measurements of employee size and annual turnover. A statistical analysis identifies key characteristics and behaviours of the sub-sectors of firms and discusses the type of policy measure these groups of SMEs would probably respond to. The key results of the research indicate that categories of firms differ in terms of energy use behaviours, internal constraints and attitudes toward possible policy options. The paper presents a ,policy matrix' to represent the most and least likely policy options to achieve energy savings from different categories of SMEs. Copyright © 2007 John Wiley & Sons, Ltd and ERP Environment. [source] Hydrodynamic Cavitation: Characterization of a Novel Design with Energy Considerations for the Inactivation of Saccharomyces cerevisiae in Apple JuiceJOURNAL OF FOOD SCIENCE, Issue 6 2008P.J. Milly ABSTRACT:, A Shockwave PowerÔ Reactor consisting of an annulus with a rotating pock-marked inner cylinder was used to induce hydrodynamic cavitation in calcium-fortified apple juice flowing in the annular space. Lethality on Saccharomyces cerevisiae was assessed at processing temperatures of 65 and 76.7 °C. Details of the novel equipment design were presented and energy consumption was compared to conventional and pulsed electric fields processing technologies. The mean log cycle reduction of S. cerevisiae was 6.27 CFU/mL and all treatments resulted in nonrecoverable viable cells. Induced lethality from hydrodynamic cavitation on S. cerevisiae exceeded the predicted values based on experimentally determined thermal resistance. Rotation of 3000 and 3600 rpm at flow rates greater than 1.0 L/min raised product temperature from 20 to 65.6 or 76.7 °C, respectively, and energy input was less than 220 kJ/kg. Conversion efficiency from electrical to thermal was 55% to 84%. Hydrodynamic cavitation enhanced lethality of spoilage microorganisms in minimally processed juices and reduced energy usage. [source] Optimization of energy usage for fleet-wide power generating system under carbon mitigation optionsAICHE JOURNAL, Issue 12 2009A. Elkamel Abstract This article presents a fleet-wide model for energy planning that can be used to determine the optimal structure necessary to meet a given CO2 reduction target while maintaining or enhancing power to the grid. The model incorporates power generation as well as CO2 emissions from a fleet of generating stations (hydroelectric, fossil fuel, nuclear, and wind). The model is formulated as a mixed integer program and is used to optimize an existing fleet as well as recommend new additional generating stations, carbon capture and storage, and retrofit actions to meet a CO2 reduction target and electricity demand at a minimum overall cost. The model was applied to the energy supply system operated by Ontario power generation (OPG) for the province of Ontario, Canada. In 2002, OPG operated 79 electricity generating stations; 5 are fueled with coal (with a total of 23 boilers), 1 by natural gas (4 boilers), 3 nuclear, 69 hydroelectric and 1 wind turbine generating a total of 115.8 TWh. No CO2 capture process existed at any OPG power plant; about 36.7 million tonnes of CO2 was emitted in 2002, mainly from fossil fuel power plants. Four electricity demand scenarios were considered over a span of 10 years and for each case the size of new power generation capacity with and without capture was obtained. Six supplemental electricity generating technologies have been allowed for: subcritical pulverized coal-fired (PC), PC with carbon capture (PC+CCS), integrated gasification combined cycle (IGCC), IGCC with carbon capture (IGCC+CCS), natural gas combined cycle (NGCC), and NGCC with carbon capture (NGCC+CCS). The optimization results showed that fuel balancing alone can contribute to the reduction of CO2 emissions by only 3% and a slight, 1.6%, reduction in the cost of electricity compared to a calculated base case. It was found that a 20% CO2 reduction at current electricity demand could be achieved by implementing fuel balancing and switching 8 out of 23 coal-fired boilers to natural gas. However, as demand increases, more coal-fired boilers needed to be switched to natural gas as well as the building of new NGCC and NGCC+CCS for replacing the aging coal-fired power plants. To achieve a 40% CO2 reduction at 1.0% demand growth rate, four new plants (2 NGCC, 2 NGCC+CCS) as well as carbon capture processes needed to be built. If greater than 60% CO2 reductions are required, NGCC, NGCC+CCS, and IGCC+CCS power plants needed to be put online in addition to carbon capture processes on coal-fired power plants. The volatility of natural gas prices was found to have a significant impact on the optimal CO2 mitigation strategy and on the cost of electricity generation. Increasing the natural gas prices resulted in early aggressive CO2 mitigation strategies especially at higher growth rate demands. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source] Systems approach to reducing energy usage and carbon dioxide emissionsAICHE JOURNAL, Issue 9 2009David Glasser First page of article [source] Energy optimization for the design of corn-based ethanol plantsAICHE JOURNAL, Issue 6 2008Ramkumar Karuppiah Abstract In this work, we address the problem of optimizing corn-based bioethanol plants through the use of heat integration and mathematical programming techniques. The goal is to reduce the operating costs of the plant. Capital cost, energy usage, and yields,all contribute to production cost. Yield and energy usage also influence the viability of corn-based ethanol as a sustainable fuel. We first propose a limited superstructure of alternative designs including the various process units and utility streams involved in ethanol production. Our objective is to determine the connections in the network and the flow in each stream in the network such that we minimize the energy requirement of the overall plant. This is accomplished through the formulation of a mixed-integer nonlinear programming problem involving short-cut models for mass and energy balances for all the units in the system, where the model is solved through two nonlinear programming subproblems. We then perform a heat integration study on the resulting flowsheet; the modified flowsheet includes multieffect distillation columns that further reduces energy consumption. The results indicate that it is possible to reduce the current steam consumption required in the transformation of corn into fuel grade ethanol by more than 40% compared to initial basic design. © 2008 American Institute of Chemical Engineers AIChE J, 2008 [source] Catheter-Free 120W lithium triborate (LBO) laser photoselective vaporization prostatectomy (PVP) for benign prostatic hyperplasia (BPH)LASERS IN SURGERY AND MEDICINE, Issue 8 2008Massimiliano Spaliviero MS Abstract Introduction and Objective We evaluate the safety and efficacy of catheter-free LBO laser PVP for the treatment of lower urinary tract symptoms (LUTS) secondary to benign prostatic hyperplasia (BPH). Methods We prospectively evaluated our initial LBO laser PVP experience and the need for urethral catheterization. Results Seventy consecutive patients were identified. 49 (70%) were discharged without (C,) and 21 (30%) were discharged with (C+) a urethral catheter. There were no significant differences in pre-operative parameters, including age (C,: 65±10 vs. C+: 69±9 years), AUASS (C,: 22±6 vs. C+: 21±6), Qmax (C,: 10±4 vs. C+: 8±3 ml/second), PVR (C,: 62±105 vs. C+: 57±82 ml) and prostate volume (C,: 65±35 vs. C+: 86±53 ml). There were no significant differences in laser time and energy usage. AUASS, Qmax and PVR values showed significant improvement within each group (P<0.05), but there were no significant differences between the two groups. All were outpatient procedures. 2/70 (2.9%) patients required catheter reinsertion in C+. The overall incidence of adverse events was low and did not differ between the two groups. Conclusions Our experience suggests that catheter-free LBO laser PVP is safe and effective for the treatment of LUTS secondary to BPH. Lesers Surg. Med. 40:529,534, 2008. © 2008 Wiley-Liss, Inc. [source] Daily oscillations in liver function: diurnal vs circadian rhythmicityLIVER INTERNATIONAL, Issue 3 2004Alec J. Davidson Abstract: The rodent suprachiasmatic nucleus (SCN), a site in the brain that contains a light-entrained biological (circadian) clock, has been thought of as the master oscillator, regulating processes as diverse as cell division, reproductive cycles, sleep, and feeding. However, a second circadian system exists that can be entrained by meal feeding and has an influence over metabolism and behavior. Recent advances in the molecular genetics of circadian clocks are revealing clock characteristics such as rhythmic clock gene expression in a variety of non-neural tissues such as liver. Although little is known regarding the function of these clock genes in the liver, there is a large literature that addresses the capabilities of this organ to keep time. This time-keeping capability may be an adaptive function allowing for the prediction of mealtime and therefore improved digestion and energy usage. Consequently, an understanding of these rhythms is of great importance. This review summarizes the results of studies on diurnal and circadian rhythmicity in the rodent liver. We hope to lend support to the hypothesis that there are functionally important circadian clocks outside of the brain that are not light- or SCN-dependent. Rather, these clocks are largely responsive to stimuli involved in nutrient intake. The interaction between these two systems may be very important for the ability of organisms to synchronize their internal physiology. [source] Correlation between energy usage and the rate of economic developmentOPEC ENERGY REVIEW, Issue 1 2006Salman Saif Ghouri This paper reviews the correlation between per capita GDP and per capita consumption of different sources of energy for OPEC Member Countries, the G-7 and three Asian countries, both with and without natural logarithm. In addition, the paper estimates the ratios for total GDP and total energy consumption of different sources of energy and also estimates GDP energy consumption elasticities. The paper concludes that on a per capita basis most OPEC Countries exhibit negative and weak relationships for all forms of energy, including electricity. For the G-7 and Asian countries, this relationship is positive and strong, with the exception of oil for G-7 countries, where there is a weak correlation. Surprisingly, most OPEC Countries showed a comparatively strong and positive correlation when tested for total GDP in relation to total energy consumption of the respective energy sources. The relationship for the rest of the countries remains unchanged. Population might have distorted the results in OPEC Countries. These results suggest that one should be cautious when drawing conclusions and not ignore the aggregate comparison, as this could otherwise lead to wrong results. For G-7 countries, there has been a significant shift in the pattern of energy consumption in relation to GDP when comparing 1960,73 and 1973,2001. All adjusted downward in the later period. However, the greatest adjustment was associated with petroleum consumption. The general conclusion is that wealth creation in G-7 countries is directly associated with the efficient use of all forms of energy. In contrast, most OPEC Countries exhibit a weaker linkage between energy consumption and economic development on a per capita basis, probably due to inefficient usage of resources or due to disproportionate distribution of wealth and thus energy usage. [source] An exergy calculator tool for process simulationASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 5 2007Juan M. Montelongo-Luna Abstract The constant tightening of environmental regulations and the ongoing need to reduce operating costs have posed a challenge for the design of any chemical process. Process engineers use process simulators to help them perform calculations that will, ultimately, result in design parameters or operating conditions for a plant or process. Exergy is a potential indicator that can aid in the design of energy efficient chemical processes and plants. The exergy concept has been increasingly used as a tool to locate the critical energy use in many industrial processes, both chemical and non-chemical. However, currently most process simulators in the market do not offer the capability of calculating the exergy of a process. An open-source exergy calculator has been created by embedding the calculation procedure in an open-source chemical process simulator. This improves process simulation by including a potential tool for design teams to quickly evaluate several process options in detail in order to understand their energy utilisation. A simple exergy analysis for a gas processing facility is used to demonstrate the capabilities of the tool. The analysis shows where the largest quantities of exergy are being consumed within the plant, thus pointing to areas where improvement in energy usage can be made. The use of exergy as a potential design and retrofit tool is also discussed. Copyright © 2007 Curtin University of Technology and John Wiley & Sons, Ltd. [source] Status of Microbial Modeling in Food Process ModelsCOMPREHENSIVE REVIEWS IN FOOD SCIENCE AND FOOD SAFETY, Issue 1 2008Bradley P. Marks ABSTRACT:, Food process models are typically aimed at improving process design or operation by optimizing some physical or chemical outcome, such as maximizing processing yield, minimizing energy usage, or maximizing nutrient retention. However, in seeking to achieve these objectives, one of the critical constraints is usually microbiological. For example, growth of pathogens or spoilage organisms must be held below a certain level, or pathogen reduction for a kill step must achieve a certain target. Therefore, mathematical models for microbial populations subjected to food processing operations are essential elements of the broader field of food process modeling. However, the complexity of the underlying biological phenomena presents special challenges in formulating, validating, and applying microbial models to real-world applications. In that context, the narrow purpose of this article is to (1) outline the general terminology and constructs of microbial models, (2) evaluate the state of knowledge/state of the art in application of these models, and (3) offer observations about current limitations and future opportunities in the area of predictive microbiology for food process modeling. [source] | ||||||||||||||||