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Conversion System (conversion + system)

Distribution by Scientific Domains
Engineering27%
Chemistry27%
Polymers and Materials Science18%

Kinds of Conversion System

  • energy conversion system
    		•

    Selected Abstracts

    Short-term scheduling of a wind generation and hydrogen storage in the electricity market

    EUROPEAN TRANSACTIONS ON ELECTRICAL POWER, Issue 5 2010
    G. Tina
    Abstract Intermittent renewable energy sources (RES) are promising to be the future of electricity generation. In particular wind generation, owing to its stochastic behaviour, has to be carefully managed. Its lack of sufficient predictability decreases the energy value in the current framework of electrical markets, therefore, beyond a certain threshold; this kind of generation into the electrical system represents a problem for the transmission system operator (TSO) during its despatching service. The coupling of wind energy conversion system (WECS) with a storage medium (i.e. hydrogen) could improve the programmability of such generation plants in electrical markets. In this paper, an economical optimization tool has been developed in order to find the short-term scheduling so as to maximize the economic revenues in the day-ahead electricity market of a storage plant coupled with a wind farm. This tool needs as input the forecasts of both wind generation power and market prices, obtained with the adoption of pre-processing input data algorithm based on different methods that involve both statistical and probabilistic approaches. Copyright © 2009 John Wiley & Sons, Ltd. [source]

    Bio-inspired Photoelectric Conversion Based on Smart-Gating Nanochannels

    ADVANCED FUNCTIONAL MATERIALS, Issue 16 2010
    Liping Wen
    Abstract Inspired by the light-driven, cross-membrane proton pump of biological systems, a photoelectric conversion system based on a smart-gating, proton-driven nanochannel is constructed. In this system, solar energy is the only source of cross-membrane proton motive force that induces a diffusion potential and photocurrent flowing through the external circuit. Although the obtained photoelectric conversion performance is lower than that of conventional solid photovoltaic devices, it is believed that higher efficiencies can be generated by enhancing the protonation capacity of the photo-acid molecules, optimizing the membrane, and synthesizing high-performance photosensitive molecules. This type of facile and environmentally friendly photoelectric conversion has potential applications for future energy demands such as the production of power for in vivo medical devices. [source]

    Implications of system expansion for the assessment of well-to-wheel CO2 emissions from biomass-based transportation

    INTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 13 2010
    Elisabeth Wetterlund
    Abstract In this paper we show the effects of expanding the system when evaluating well-to-wheel (WTW) CO2 emissions for biomass-based transportation, to include the systems surrounding the biomass conversion system. Four different cases are considered: DME via black liquor gasification (BLG), methanol via gasification of solid biomass, lignocellulosic ethanol and electricity from a biomass integrated gasification combined cycle (BIGCC) used in a battery-powered electric vehicle (BPEV). All four cases are considered with as well as without carbon capture and storage (CCS). System expansion is used consistently for all flows. The results are compared with results from a conventional WTW study that only uses system expansion for certain co-product flows. It is shown that when expanding the system, biomass-based transportation does not necessarily contribute to decreased CO2 emissions and the results from this study in general indicate considerably lower CO2 mitigation potential than do the results from the conventional study used for comparison. It is shown that of particular importance are assumptions regarding future biomass use, as by expanding the system, future competition for biomass feedstock can be taken into account by assuming an alternative biomass usage. Assumptions regarding other surrounding systems, such as the transportation and the electricity systems are also shown to be of significance. Of the four studied cases without CCS, BIGCC with the electricity used in a BPEV is the only case that consistently shows a potential for CO2 reduction when alternative use of biomass is considered. Inclusion of CCS is not a guarantee for achieving CO2 reduction, and in general the system effects are equivalent or larger than the effects of CCS. DME from BLG generally shows the highest CO2 emission reduction potential for the biofuel cases. However, neither of these options for biomass-based transportation can alone meet the needs of the transport sector. Therefore, a broader palette of solutions, including different production routes, different fuels and possibly also CCS, will be needed. Copyright © 2009 John Wiley & Sons, Ltd. [source]

    Light-driven Hydrogen Production by a Hybrid Complex of a [NiFe]-Hydrogenase and the Cyanobacterial Photosystem I

    PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 3 2006
    Masaki Ihara
    ABSTRACT In order to generate renewable and clean fuels, increasing efforts are focused on the exploitation of photosynthetic microorganisms for the production of molecular hydrogen from water and light. In this study we engineered a ,hard-wired' protein complex consisting of a hydrogenase and photosystem I (hydrogenase-PSI complex) as a direct light-to-hydrogen conversion system. The key component was an artificial fusion protein composed of the membrane-bound [NiFe] hydrogenase from the ,-proteobacterium Ralstonia eutropha H16 and the peripheral PSI subunit PsaE of the cyanobacterium Thermosy-nechococcus elongatus. The resulting hydrogenase-PsaE fusion protein associated with PsaE-free PSI spontaneously, thereby forming a hydrogenase-PSI complex as confirmed by sucrosegradient ultracentrifuge and immunoblot analysis. The hydrogenase-PSI complex displayed light-driven hydrogen production at a rate of 0.58 ,mol H2· mg chlorophyll,1· h,1. The complex maintained its accessibility to the native electron acceptor ferredoxin. This study provides the first example of a light-driven enzymatic reaction by an artificial complex between a redox enzyme and photosystem I and represents an important step on the way to design a photosynthetic organism that efficiently converts solar energy and water into hydrogen. [source]

    Design of an energy conversion system with decomposition of H2O and CO2 using ferrites

    PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 12 2004
    H. C. Shin
    Abstract The energy conversion system was designed in order to reduce the green-house effect and to get energy resources by decomposition of CO2 and H2O. This system is consisted of two parts, one is CO2 decomposition with the reduced ferrite by H2 and the other is H2O decomposition with reduced ferrite by CH4. CH4 could be synthesized in this system by methanation reaction using carbon, which was deposited on the ferrite surface in the CO2 decomposition process. Also, CH4 was used as reducing gas to reduce the ferrite for H2O decomposition. H2O was decomposed by oxidation of oxygen-deficient ferrite. In this energy conversion system, the reduced Cu-ferrite easily decomposed CO2 and H2O into the useful gases such as CO and H2, respectively. Cu-ferrite is a suitable material to apply to this system because it showed excellent redox reactivity on the energy conversions. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

    Light-Driven Thermoelectric Conversion Based on a Carbon Nanotube,Ionic Liquid Gel Composite

    CHEMSUSCHEM CHEMISTRY AND SUSTAINABILITY, ENERGY & MATERIALS, Issue 8 2009
    Eijiro Miyako Dr.
    A photoinduced thermoelectric conversion system based on single-walled carbon nanotube,room temperature ionic liquid composite gels is reported. These new types of gel-based near-infrared laser-driven thermoelectric convertors generate high electrical energy. [source]

    Assessment of Fuel-Cell-Based Passenger Cars

    FUEL CELLS, Issue 3 2004
    T. Grube
    Abstract Highly efficient energy conversion systems with fuel cells for vehicles, as well as for stationary and portable applications, are currently being discussed all over the world. Fuel cell technology is expected to help reduce primary energy demand and emissions of limited and climate-relevant pollutants. The high flexibility of fuel cell systems with respect to energy carriers opens up possibilities of modifying the energy sector in the long term. Introducing new fuels based on low-carbon, or in the long term carbon-free, energy carriers can contribute to reducing greenhouse gas emissions as well as locally and regionally active atmospheric pollutants. The use of hydrogen as feed gas for fuel cells on the basis of it being a non-fossil, renewable energy, leads to special benefits with respect to conserving resources and climate protection, but at present still represents a medium- to long-term prospect. A major milestone on the road to market success for all energy conversion systems with fuel cells is the reduction of costs. The definition of the ,appropriate" fuel represents a serious obstacle to the market introduction of fuel-cell-powered vehicles. Presenting data from a well-to-wheel analysis of various vehicle fuel systems at FZJ this article aims to discuss the potential benefits of future vehicle concepts with fuel cells in terms of primary energy use and greenhouse gas emissions. Results from a comparison of international studies on this subject will be used to identify relevant assumptions that lead to different answers in the evaluation process. [source]

    Local Electrochemical Functionality in Energy Storage Materials and Devices by Scanning Probe Microscopies: Status and Perspectives

    ADVANCED MATERIALS, Issue 35 2010
    Sergei V. Kalinin
    Abstract Energy storage and conversion systems are an integral component of emerging green technologies, including mobile electronic devices, automotive, and storage components of solar and wind energy economics. Despite the rapidly expanding manufacturing capabilities and wealth of phenomenological information on the macroscopic device behaviors, the microscopic mechanisms underpinning battery and fuel cell operations in the nanometer,micrometer range are virtually unknown. This lack of information is due to the dearth of experimental techniques capable of addressing elementary mechanisms involved in battery operation, including electronic and ion transport, vacancy injection, and interfacial reactions, on the nanometer scale. In this article, a brief overview of scanning probe microscopy (SPM) methods addressing nanoscale electrochemical functionalities is provided and compared with macroscopic electrochemical methods. Future applications of emergent SPM methods, including near field optical, electromechanical, microwave, and thermal probes and combined SPM-(S)TEM (scanning transmission electron microscopy) methods in energy storage and conversion materials are discussed. [source]

    Performance analysis of a variable structure controller for power regulation of WECS operating in the stall region

    INTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 15 2001
    H. De Battista
    Abstract This paper deals with power regulation in variable speed wind energy conversion systems. The importance of power control in the stall region is stressed. This mode of operation is characterized by a non-minimum phase behaviour. A variable structure controller is described that provides stability by means of speed feedback and is robust to grid disturbances and model uncertainties. Performance of the controller is investigated. A compromise arises in the design of the speed feedback gain between high and low frequency wind components rejection. Furthermore, a cut-off frequency of the wind velocity measurement is obtained that minimizes the effect of turbulence on power regulation. Simulation results are presented, corroborating the features of the control strategy. Copyright © 2001 John Wiley & Sons, Ltd. [source]

    The Role of Chemistry in the Energy Challenge

    CHEMSUSCHEM CHEMISTRY AND SUSTAINABILITY, ENERGY & MATERIALS, Issue 2 2010
    Robert Schlögl Prof.
    Chemistry with its key targets of providing materials and processes for conversion of matter is at the center stage of the energy challenge. Most energy conversion systems work on (bio)chemical energy carriers and require for their use suitable process and material solutions. The enormous scale of their application demands optimization beyond the incremental improvement of empirical discoveries. Knowledge-based systematic approaches are mandatory to arrive at scalable and sustainable solutions. Chemistry for energy, "ENERCHEM" contributes in many ways already today to the use of fossil energy carriers. Optimization of these processes exemplified by catalysis for fuels and chemicals production or by solid-state lightning can contribute in the near future substantially to the dual challenge of energy use and climate protection being in fact two sides of the same challenge. The paper focuses on the even greater role that ENERCHEM will have to play in the era of renewable energy systems where the storage of solar energy in chemical carries and batteries is a key requirement. A multidisciplinary and diversified approach is suggested to arrive at a stable and sustainable system of energy conversion processes. The timescales for transformation of the present energy scenario will be decades and the resources will be of global economic dimensions. ENERCHEM will have to provide the reliable basis for such technologies based on deep functional understanding. [source]