971 resultados para final energy
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The aim of this study was to evaluate the effects of a Gallium Arsenide (GaAs) laser, using a high final energy of 4.8J, during muscle regeneration after cryoinjury. Thirty Wistar rats were divided into three groups: Control (C, n=10); Injured (I, n=10) and Injured and laser treated (Injured/LLLT, n=10). The cryoinjury was induced in the central region of the tibialis anterior muscle (TA). The applications of the laser (904nm, 50mW average power) were initiated 24h after injury, at energy density of 69Jcm(-1) for 48s, for 5days, to two points of the lesion. Twenty-four hours after the final application, the TA muscle was removed and frozen in liquid nitrogen to assess the general muscle morphology and the gene expression of TNF-, TGF-, MyoD, and Myogenin. The Injured/LLLT group presented a higher number of regenerating fibers and fewer degenerating fibers (P<0.05) without changes in the collagen remodeling. In addition, the Injured/LLLT group presented a significant decrease in the expression of TNF- and myogenin compared to the injured group (P<0.05). The results suggest that the GaAs laser, using a high final energy after cryoinjury, promotes muscle recovery without changing the collagen remodeling in the muscle extracellular matrix.
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In this paper, we measure the degree of fractional integration in final energy demand in Portugal using an ARFIMA model with and without adjustments for seasonality. We consider aggregate energy demand as well as final demand for petroleum, electricity, coal, and natural gas. Our findings suggest the presence of long memory in all of the components of energy demand. All fractional-difference parameters are positive and lower than 0.5 indicating that the series are stationary, although with mean reversion patterns slower than in the typical short-run processes. These results have important implications for the design of energy policies. As a result of the long-memory in final energy demand, the effects of temporary policy shocks will tend to disappear slowly. This means that even transitory shocks have long lasting effects. Given the temporary nature of these effects, however, permanent effects on final energy demand require permanent policies. This is unlike what would be suggested by the more standard, but much more limited, unit root approach, which would incorrectly indicate that even transitory policies would have permanent effects
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In this paper, we measure the degree of fractional integration in final energy demand in Portugal using an ARFIMA model with and without adjustments for seasonality. We consider aggregate energy demand as well as final demand for petroleum, electricity, coal, and natural gas. Our findings suggest the presence of long memory in all of the energy demand variables, that the series are stationary, although the mean reversion process will be slower than in the typical short run processes. These results have important implications for the design of energy policies. The effects of temporary policy shocks on final energy demand will tend to disappear slowly. This means that even transitory shocks have long lasting effects. Given the temporary nature of these effects, however, permanent effects require permanent policies. This is unlike what would be suggested by the more standard but much more limited unit root approach, which would incorrectly indicate that even transitory policies would have permanent effects.
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Tese de doutoramento, Sistemas Sustentáveis de Energia, Universidade de Lisboa, Faculdade de Ciências, 2015
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468 p.
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Concern over the global energy system, whether driven by climate change, national security, or fears of shortage, is being discussed widely and in every arena but with a bias toward energy supply options. While demand reduction is often mentioned in passing, it is rarely a priority for implementation, whether through policy or through the search for innovation. This paper aims to draw attention to the opportunity for major reduction in energy demand, by presenting an analysis of how much of current global energy demand could be avoided. Previous work led to a "map" of global energy use that traces the flow of energy from primary sources (fuels or renewable sources), through fuel refinery, electricity generation, and end-use conversion devices, to passive systems and the delivery of final energy services (transport, illumination, and sustenance). The key passive systems are presented here and analyzed through simple engineering models with scalar equations using data based on current global practice. Physically credible options for change to key design parameters are identified and used to predict the energy savings possible for each system. The result demonstrates that 73% of global energy use could be saved by practically achievable design changes to passive systems. This reduction could be increased by further efficiency improvements in conversion devices. A list of the solutions required to achieve these savings is provided.
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EU Directive 2009/28/EC on Renewable Energy requires each Member State to ensure 10% of transport energy (excluding aviation and marine transport) comes from renewable sources by 2020 (10% RES-T target). In addition to the anticipated growth in biofuels, this target is expected to be met by the increased electrification of transport coupled with a growing contribution from renewable energy to electricity generation. Energy use in transport accounted for nearly half of Ireland’s total final energy demand and about a third of energy-related carbon dioxide emissions in 2007. Energy use in transport has grown by 6.3% per annum on average in the period 1990 – 2007. This high share and fast growth relative to other countries highlights the challenges Ireland faces in meeting ambitious renewable energy targets. The Irish Government has set a specific target for Electric Vehicles (EV) as part of its strategy to deliver the 10% RES-T target. By 2020, 10% of all vehicles in its transport fleet are to be powered by electricity. This paper quantifies the impacts on energy and carbon dioxide emissions of this 10% EV target by 2020. In order to do this an ‘EV Car Stock’ model was developed to analyse the historical and future make-up of the passenger car portion of the fleet to 2025. Three scenarios for possible take-up in EVs were examined and the associated energy and emissions impacts are quantified. These impacts are then compared to Ireland’s 10% RES-T target and greenhouse gas (GHG) emissions reduction targets for 2020. Two key findings of the study are that the 10% EV target contributes 1.7% to the 10% RES-T target by 2020 and 1.4% to the 20% reduction in Non-ETS emissions by 2020 relative to 2005.
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Energy intensity of the total primary energy supply (TPES), total final energy consumption (TFC) and LOSSES in the conversion from TPES to TFC were analyzed for the World, OECD and Rest of the World (ROW) countries. LOSSES increased significantly for all groups of countries due to the increase of electricity production from coal in the period studied (1971-2008). Electricity share final consumption almost doubled, increasing from 8.8% to 17.2% in the period studied. However the energy intensity of LOSSES remained practically constant, which reflects the fact that the efficiency of electricity generation from coal (the main source of electricity) remained practically constant in that period. Despite the attractiveness of end-use devices running on electricity such as computers, which is typical of modern societies, the CO(2) emissions are bound to increase unless coal is replaced by less carbon emitting sources such as natural gas, renewables and nuclear energy. (C) 2011 Elsevier Ltd. All rights reserved.
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In a Nordic climate, space heating (SH) and domestic hot water (DHW) used in buildings constitute a considerable part of the total energy use in the country. For 2010, energy used for SH and DHW amounted to almost 90 TWh in Sweden which corresponds to 60 % of the energy used in the residential and service sector, or almost 24 % of the total final energy use for the country. Storing heat and cold with the use of thermal energy storage (TES) can be one way of increasing the energy efficiency of a building by opening up possibilities for alternative sources of heat or cold through a reduced mismatch between supply and demand. Thermal energy storage without the use of specific control systems are said to be passive and different applications using passive TES have been shown to increase energy efficiency and/or reduce power peaks of systems supplying the heating and cooling needs of buildings, as well as having an effect on the indoor climate. Results are however not consistent between studies and focus tend to be on the reduction of cooling energy or cooling power peaks. In this paper, passive TES introduced through an increased thermal mass in the building envelope to two single family houses with different insulation standard is investigated with building energy simulations. A Nordic climate is used and the focus of this study is both on the reduction of space heating demand and space heating power, as well as on reduction of excess temperatures in residential single family houses without active cooling systems. Care is taken to keep the building envelope characteristics other than the thermal mass equal for all cases so that any observations made can be derived to the change in thermal mass. Results show that increasing the sensible thermal mass in a single family house can reduce the heating demand only slightly (1-4 %) and reduce excess temperatures (temperatures above 24 degrees C) by up to 20 %. Adding a layer of PCM (phase change materials) to the light building construction can give similar reduction in heating demand and excess temperatures, however the phase change temperature is important for the results.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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This work presents a mathematical model for helping mills choose sugarcane varieties for planting. It maximizes crop residual biomass energy balance by considering the difference between generated and consumed energy in the process of transferring this biomass from the field to the processing center; it takes into account enterprise demand restrictions and cane planting area. For this full zero-one linear programming techniques were proposed. The model is viable for choosing sugarcane varieties that would benefit sugarcane production and industrial systems, by reducing crop residue and increasing final energy production. (c) 2006 Published by Elsevier Ltd.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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The behavior of the average energy for an ensemble of non-interacting particles is studied using scaling arguments in a dissipative time-dependent stadium-like billiard. The dynamics of the system is described by a four dimensional nonlinear mapping. The dissipation is introduced via inelastic collisions between the particles and the moving boundary. For different combinations of initial velocities and damping coefficients, the long time dynamics of the particles leads them to reach different states of final energy and to visit different attractors, which change as the dissipation is varied. The decay of the average energy of the particles, which is observed for a large range of restitution coefficients and different initial velocities, is described using scaling arguments. Since this system exhibits unlimited energy growth in the absence of dissipation, our results for the dissipative case give support to the principle that Fermi acceleration seems not to be a robust phenomenon. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.3699465]
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The aim of this technical report is to quantify alternative energy demand and supply scenarios for ten southern and eastern Mediterranean countries up to 2030. The report presents the model-based results of four alternative scenarios that are broadly in line with the MEDPRO scenario specifications on regional integration and cooperation with the EU. The report analyses the main implications of the scenarios in the following areas: • final energy demand by sector (industry, households, services, agriculture and transport); • the evolution of the power generation mix, the development of renewable energy sources and electricity exports to the EU; • primary energy production and the balance of trade for hydrocarbons; • energy-related CO2 emissions; and • power generation costs.
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Summary. Energy saving has been a stated policy objective of the EU since the 1970s. Presently, the 2020 target is a 20% reduction of EU energy consumption in comparison with current projections for 2020. This is one of the headline targets of the European Energy Strategy 2020 but efforts to achieve it remain slow and insufficient. The aim of this paper is to understand why this is happening. Firstly, this paper examines the reasons why public measures promoting energy efficiency are needed and what form these measures should optimally take (§ 1). Fortunately, over the last 20 years, much research has been done into the famous ‘energy efficiency gap’ (or ‘the energy efficiency paradox’), even if more remains to be done. Multiple explanations have been given: market failures, modelling flaws and behavioural obstacles. Each encompasses many complex aspects. Several types of instruments can be adopted to encourage energy efficiency: measures guaranteeing the correct pricing of energy are preferred, followed by taxes or tradable white certificates which in turn are preferred to standards or subsidies. Information programmes are also necessary. Secondly, the paper analyzes the evolution of the different programmes from 2000 onwards (§ 2). This reveals the extreme complexity of the subject. It deals with quite diverse topics: buildings, appliances, public sector, industry and transport. The market for energy efficiency is as diffuse as energy consumption patterns themselves. It is composed of many market actors who demand more efficient provision of energy services, and that suppliers of the necessary goods and know-how deliver this greater efficiency. Consumers in this market include individuals, businesses and governments, and market activities cover all energy-consuming sectors of the economy. Additionally, energy efficiency is the perfect example of a shared competence between the EU and the Member States. Lastly, the legal framework has steadily increased in complexity, and despite the successive energy efficiency programmes used to build this framework, it has become clear that the gap between the target and the results remains. The paper then examines whether the 2012/27/EU Directive adopted to improve the situation could bring better results. It briefly describes the content of this framework Directive, which accompanies and implements the latest energy efficiency programme (§ 3). Although the Directive is technically complex and maintains nonbinding energy efficiency targets, it certainly represents an improvement in several aspects. However, it is also saddled with a multiplicity of exemption clauses and interpretative documents (with no binding value) which weaken its provisions. Furthermore, alone, it will allow the achievement of only about 17.7% of final energy savings by 2020. The implementation process, which is essential, also remains fairly weak. The paper also gives a glimpse of the various EU instruments for financing energy efficiency projects (§ 4). Though useful, they do not indicate a strong priority. Fourthly, the paper tries to analyze the EU’s limited progress so far and gather a few suggestions for improvement. One thing seems to remain useful: targets which can be defined in various ways (§ 5). Basically, all this indicates that the EU energy efficiency strategy has so far failed to reach its targets, lacks coherence and remains ambiguous. In the new Commission’s proposals of 22 January 2014 – intended to define a new climate/energy package in the period from 2020 to 2030 – the approach to energy efficiency remains unclear. This is regrettable. Energy efficiency is the only instrument which allows the EU to reach simultaneously its three targets: sustainability, competitiveness and security. The final conclusion appears thus paradoxical. On the one hand, all existing studies indicate that the decarbonization of the EU economy will be absolutely impossible without some very serious improvements in energy efficiency. On the other hand, in reality energy efficiency has always been treated as a second zone priority. It is imperative to eliminate this contradiction.