977 resultados para 660501 Energy transformation


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Initiated in May 2011, several months after the Fukushima nuclear disaster, Germany’s energy transformation (Energiewende) has been presented as an irrevocable plan, and – due to the speed of change required – it represents a new quality in Germany’s energy strategy. Its main objectives include: nuclear energy being phased out by 2022, the development of renewable energy sources (OZE), the expansion of transmission networks, the construction of new conventional power plants and an improvement in energy efficiency.The cornerstone of the strategy is the development of renewable energy. Under Germany's amended renewable energy law, the proportion of renewable energy in electricity generation is supposed to increase steadily from the current level of around 20% to approximately 38% in 2020. In 2030, renewable energy is expected to account for 50% of electricity generation. This is expected to increase to 65% in 2040 and to as much as 80% in 2050. The impact of the Energiewende is not limited to the sphere of energy supplies. In the medium and long term, it will change not only to the way the German economy operates, but also the functioning of German society and the state. Facing difficulties with the expansion of transmission networks, the excessive cost of building wind farms, and problems with the stability of electricity supplies, especially during particularly cold winters, the federal government has so far tended to centralise power and limit the independence of the German federal states with regard to their respective energy policies, justifying this with the need for greater co-ordination. The Energiewende may also become the beginning of a "third industrial revolution", i.e. a transition to a green economy and a society based on sustainable development. This will require a new "social contract" that will redefine the relations between the state, society and the economy. Negotiating such a contract will be one of the greatest challenges for German policy in the coming years.

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The thermal degradation of high density polyethylene has been modelled by the random breakage of polymer bonds, using a set of population balance equations. A model was proposed in which the population balances were lumped into representative sizes so that the experimentally determined molecular weight distribution of the original polymer could be used as the initial condition. This model was then compared to two different cases of the unlumped population balance which assumed unimolecular initial distributions of 100 and 500 monomer units, respectively. The model that utilised the experimentally determined molecular weight distribution was found to best describe the experimental data. The model fits suggested a second mechanism in addition to random breakage at slow reaction rates. (c) 2005 Elsevier Ltd. All rights reserved.

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Calcium oxide has been identified to be one of the best candidates for CO2 capture in zero-emission power-generation systems. However, it suffers a well-known problem of loss-in-capacity (i.e., its capacity of CO2 capture decreases after it undergoes cycles of carbonation/decarbonation). This problem is a potential obstacle to the adoption of the new technologies. This paper proposes a method of fabricating a CaO-based adsorbent without the problem of loss-in-capacity. An adsorbent was fabricated using the method and tested on a thermogravimetric analyzer. It was shown that the sorbent attained a utilization efficiency of more than 90% after 9 cycles of carbonation/decarbonation.

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Experimental demonstrations and theoretical analyses of a new electromechanical energy conversion process which is made feasible only by the unique properties of superconductors are presented in this dissertation. This energy conversion process is characterized by a highly efficient direct energy transformation from microwave energy into mechanical energy or vice versa and can be achieved at high power level. It is an application of a well established physical principle known as the adiabatic theorem (Boltzmann-Ehrenfest theorem) and in this case time dependent superconducting boundaries provide the necessary interface between the microwave energy on one hand and the mechanical work on the other. The mechanism which brings about the conversion is another known phenomenon - the Doppler effect. The resonant frequency of a superconducting resonator undergoes continuous infinitesimal shifts when the resonator boundaries are adiabatically changed in time by an external mechanical mechanism. These small frequency shifts can accumulate coherently over an extended period of time to produce a macroscopic shift when the resonator remains resonantly excited throughout this process. In addition, the electromagnetic energy in s ide the resonator which is proportional to the oscillation frequency is al so accordingly changed so that a direct conversion between electromagnetic and mechanical energies takes place. The intrinsically high efficiency of this process is due to the electromechanical interactions involved in the conversion rather than a process of thermodynamic nature and therefore is not limited by the thermodynamic value.

A highly reentrant superconducting resonator resonating in the range of 90 to 160 MHz was used for demonstrating this new conversion technique. The resonant frequency was mechanically modulated at a rate of two kilohertz. Experimental results showed that the time evolution of the electromagnetic energy inside this frequency modulated (FM) superconducting resonator indeed behaved as predicted and thus demonstrated the unique features of this process. A proposed usage of FM superconducting resonators as electromechanical energy conversion devices is given along with some practical design considerations. This device seems to be very promising in producing high power (~10W/cm^3) microwave energy at 10 - 30 GHz.

Weakly coupled FM resonator system is also analytically studied for its potential applications. This system shows an interesting switching characteristic with which the spatial distribution of microwave energies can be manipulated by external means. It was found that if the modulation was properly applied, a high degree (>95%) of unidirectional energy transfer from one resonator to the other could be accomplished. Applications of this characteristic to fabricate high efficiency energy switching devices and high power microwave pulse generators are also found feasible with present superconducting technology.

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The structure and frequencies of C12B24N24 have been calculated by means of an ab initio method. By comparing the average bond energies with C-60, the calculated results predict that the cage C12B24N24 is a stable molecule. The calculated results indicate that the cage molecule C12B24N24 has a relative large HOMO-LUMO energy gap and a low rigidity The structures and stability of six possible isomers of C2B4N4 are used to suggest a possible transformation path from the pentagon CB2N2 to the C12B24N24 materials. (C) 2001 John Wiley & Sons, Inc.

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In the early 1970 the community has started to realize that have as a main principle the industry one, with the oblivion of the people and health conditions and of the world in general, it could not be a guideline principle. The sea, as an energy source, has the characteristic of offering different types of exploitation, in this project the focus is on the wave energy. Over the last 15 years the Countries interested in the renewable energies grew. Therefore many devices have came out, first in the world of research, then in the commercial one; these converters are able to achieve an energy transformation into electrical energy. The purpose of this work is to analyze the efficiency of a new wave energy converter, called WavePiston, with the aim of determine the feasibility of its actual application in different wave conditions: from the energy sea state of the North Sea, to the more quiet of the Mediterranean Sea. The evaluation of the WavePiston is based on the experimental investigation conducted at the University of Aalborg, in Denmark; and on a numerical modelling of the device in question, to ascertain its efficiency regardless the laboratory results. The numerical model is able to predict the laboratory condition, but it is not yet a model which can be used for any installation, in fact no mooring or economical aspect are included yet. È dai primi anni del 1970 che si è iniziato a capire che il solo principio dell’industria con l’incuranza delle condizioni salutari delle persone e del mondo in generale non poteva essere un principio guida. Il mare, come fonte energetica, ha la caratteristica di offrire diverse tipologie di sfruttamento, in questo progetto è stata analizzata l’energia da onda. Negli ultimi 15 anni sono stati sempre più in aumento i Paesi interessati in questo ambito e di conseguenza, si sono affacciati, prima nel mondo della ricerca, poi in quello commerciale, sempre più dispositivi atti a realizzare questa trasformazione energetica. Di tali convertitori di energia ondosa ne esistono diverse classificazioni. Scopo di tale lavoro è analizzare l’efficienza di un nuovo convertitore di energia ondosa, chiamato WavePiston, al fine si stabilire la fattibilità di una sua reale applicazione in diverse condizioni ondose: dalle più energetiche del Mare del Nord, alle più quiete del Mar Mediterraneo. La valutazione sul WavePiston è basata sullo studio sperimentale condotto nell’Università di Aalborg, in Danimarca; e su di una modellazione numerica del dispositivo stesso, al fine di conoscerne l’efficienza a prescindere dalla possibilità di avere risultati di laboratorio. Il modello numerico è in grado di predirre le condizioni di laboratorio, ma non considera ancora elementi come gli ancoraggi o valutazione dei costi.

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One year after the events of Fukushima the implementation of the new German energy strategy adopted in the summer of 2011 is being verified. Business circles, experts and publicists are sounding the alarm. The tempo at which the German economy is being rearranged in order that it uses renewable energy sources is so that it has turned out to be an extremely difficult and expensive task. The implementation of the key guidelines of the new strategy, such as the development of the transmission networks and the construction of new conventional power plants, is meeting increasing resistance in the form of economic and legal difficulties. The development of the green technologies sector is also posing problems. The solar energy industry, for example, is excessively subsidised, whereas the subsidies for the construction of maritime wind farms are too low. At present, only those guidelines of the strategy which are evaluated as economically feasible by investors or which receive adequate financial support from the state have a chance of being carried through. The strategy may also turn out to be unsuccessful due to the lack of a comprehensive coordination of its implementation and the financial burden its introduction entails for both the public and the economy. In the immediate future, the German government will make efforts not only to revise its internal regulations in order to enable the realisation of the energy transformation; it is also likely to undertake a number of measures at the EU forum which will facilitate this realisation. One should expect that the German government will actively support the financing of both the development of the energy networks in EU member states and the development of renewable energy sources in the energy sector.

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In 2015 Ireland has arguably begun to make its first bold steps in confronting the challenges of energy transition, with the objective of a “low carbon, climate resilient and environmentally sustainable economy by the end of the
year 2050” expressed in the 2015 Climate Action and Low Carbon Development Bill and the 2015 Energy Bill acknowledging that energy transformation relied on a new breed of ‘energy citizens’. These represent the first formal articulation of Ireland’s ambition to engage in a radical, long-term and far-reaching transition process, and raises a myriad of questions over how this can be operationalised, resourced and whether it can maintain political momentum. A range of perspectives on these issues is provided in the growing body of literature on transition theories (Rotmans et al 2001, Markard et al 2012) and the inter-disciplinary EPA-funded CC Transitions project, based at Queen’s University Belfast, represents an attempt to translate this into the context of Ireland’s institutions and technological profile. By relating this to international research on sustainability transitions, which conceptualises transitions as multi-level, multi-phase and multi-actor processes, this paper will explore the opportunities of alternative pathways that could take Ireland towards a more progressing, inclusive and effective low carbon future. Drawing on a number of case studies it will highlight some of the capacities for transition required in Irish society: where these exist, how they are being built or enabled, and the barriers to wider social change.

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Gasification is an energy transformation process in which solid fuel undergoes thermochemical conversion to produce gaseous fuel, and the two most important criteria involved in such process to evaluate the performance, economics and sustainability of the technology are: the total available energy (exergy) and the energy conserved (energy efficiency). Current study focuses on the energy and exergy analysis of the oxy-steam gasification and comparing with air gasification to optimize the H-2 yield, efficiency and syngas energy density. Casuarina wood is used as a fuel, and mixture of oxygen and steam in different proportion and amount is used as a gasifying media. The results are analysed with respect to varying equivalence ratio and steam to biomass ratio (SBR). Elemental mass balance technique is employed to ensure the validity of results. First and second law thermodynamic analysis is used towards time evaluation of energy and exergy analysis. Different component of energy input and output has been studied carefully to understand the influence of varying SBR on the availability of energy and irreversibility in the system to minimize the losses with change in input parameters for optimum performance. The energy and exergy losses (irreversibility) for oxy-steam gasification system are compared with the results of air gasification, and losses are found to be lower in oxy-steam thermal conversion; which has been argued and reasoned due to the presence of N-2 in the air-gasification. The maximum exergy efficiency of 85% with energy efficiency of 82% is achieved at SBR of 0.75 on the molar basis. It has been observed that increase in SBR results in lower exergy and energy efficiency, and it is argued to be due to the high energy input in steam generation and subsequent losses in the form of physical exergy of steam in the product gas, which alone accounts for over 18% in exergy input and 8.5% in exergy of product gas at SBR of 2.7. Carbon boundary point (CBP), is identified at the SBR of 1.5, and water gas shift (WGS) reaction plays a crucial role in H-2 enrichment after carbon boundary point (CBP) is reached. Effects of SBR and CBP on the H-2/CO ratio is analysed and discussed from the perspective of energy as well as the reaction chemistry. Energy density of syngas and energy efficiency is favoured at lower SBR but higher SBR favours H-2 rich gas at the expense of efficiency. Copyright (C) 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

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Following an account of factors influencing the biological productivity of reservoirs in India, details are given of energy transformation through primary production. An ecosystem approach to the management of reservoir fisheries is discussed, considering also socio-economic factors to be taken into account.

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Sustainable water use is seriously compromised in the North China Plain (NCP) due to the huge water requirements of agriculture, the largest use of water resources. An integrated approach which combines the ecosystem model with emergy analysis is presented to determine the optimum quantity of irrigation for sustainable development in irrigated cropping systems. Since the traditional emergy method pays little attention to the dynamic interaction among components of the ecological system and dynamic emergy accounting is in its infancy, it is hard to evaluate the cropping system in hypothetical situations or in response to specific changes. In order to solve this problem, an ecosystem model (Vegetation Interface Processes (VIP) model) is introduced for emergy analysis to describe the production processes. Some raw data, collected by investigating or observing in conventional emergy analysis, may be calculated by the VIP model in the new approach. To demonstrate the advantage of this new approach, we use it to assess the wheat-maize rotation cropping system at different irrigation levels and derive the optimum quantity of irrigation according to the index of ecosystem sustainable development in NCP. The results show, the optimum quantity of irrigation in this region should be 240-330 mm per year in the wheat system and no irrigation in the maize system, because with this quantity of irrigation the rotation crop system reveals: best efficiency in energy transformation (transformity = 6.05E + 4 sej/J); highest sustainability (renewability = 25%); lowest environmental impact (environmental loading ratio = 3.5) and the greatest sustainability index (Emergy Sustainability Index = 0.47) compared with the system in other irrigation amounts. This study demonstrates that application of the new approach is broader than the conventional emergy analysis and the new approach is helpful in optimizing resources allocation, resource-savings and maintaining agricultural sustainability.

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From the angle of energy transformation an equation was obtained for the brittle transition in polymer blends. The effects of interparticle distance, temperature and strain rate on the brittle-tough transition in polymer blends were characterized by this equation. The calculations show that, for this transition: (1) increasing temperature and decreasing interparticle distance are equivalent and the shift factor increases with increasing temperature; (2) decreasing strain rate and decreasing interparticle distance have equivalent effects on the transition; (3) the strain rate must be optimum in order to find the brittle-tough transition phenomena for a given temperature region. (C) 1998 Published by Elsevier Science Ltd. All rights reserved.

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Bathyal and abyssal epibenthic holothurians have a layer of bacteria lying over the tentacular epidermis and below the cuticle. Thus the tentacles of deep-sea holothurians may provide ideal conditions for subcuticular bacteria. These bacteria appear to be regulated by phagocytosis, which, together with pinocytosis would facilitate transfer of bacterial metabolites to the holothurian. Their abundance suggests a previously unknown pathway for energy transformation and assimilation of particular significance in an environment where food is limiting.