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Science, Open Communication and Sustainable Development
Sustainability 2010, 2(5), 1389-1407; doi:10.3390/su2051389

Some Sustainability Aspects of Energy Conversion in Urban Electric Trains

2,* , 1
1 Faculty of Electromechanical and Environmental Engineering, University of Craiova, Romania 2 Faculty of Engineering and Applied Science, University of Ontario Institute of Technology, 2000 Simcoe Street North, Oshawa, Ontario, L1H 7K4, Canada 3 Electrical Vehicles Department, ROMDATA AQ, Craiova, Romania
* Author to whom correspondence should be addressed.
Received: 1 April 2010 / Revised: 30 April 2010 / Accepted: 6 May 2010 / Published: 17 May 2010
(This article belongs to the Special Issue Advanced Forum for Sustainable Development)
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The paper illustrates some aspects of energy conversion processes during underground electric train operation. Energy conversion processes are explained using exergy, in order to support transport system sustainability. Loss of exergy reflects a loss of potential of energy to do work. Following the notion that life in Nature demonstrates sustainable energy conversion, we approach the sustainability of urban transportation systems according to the model of an ecosystem. The presentation steps based on an industrial ecosystem metabolism include describing the urban electric railway system as an industrial ecosystem with its limits and components, defining system operation regimes, and assessing the equilibrium points of the system for two reference frames. For an electric train, exergy losses can be related to the energy flows during dynamic processes, and exergy conversion in these processes provides a meaningful measure of the industrial (i.e., transportation) ecosystem efficiency. As a validation of the theoretical results, a case study is analyzed for three underground urban electric train types REU-U, REU-M, REU-G operating in the Bucharest Underground Railway System (METROREX). The main experimental results are presented and processed, and relevant diagrams are constructed. It is determined that there is great potential for improving the performance of rail systems and increasing their sustainability. For instance, power converters and efficient anti-skid systems can ensure optimum traction and minimum electricity use, and the recovered energy in electric braking can be used by other underground trains, increasing exergy efficiency, although caution must be exercised when doing so to avoid reducing the efficiency of the overall system.
Keywords: urban electric transportation; sustainability; electric train; energy conversion; exergy; induction motor; industrial ecology urban electric transportation; sustainability; electric train; energy conversion; exergy; induction motor; industrial ecology
This is an open access article distributed under the Creative Commons Attribution License (CC BY) which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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Nicola, D.A.; Rosen, M.A.; Bulucea, C.A.; Brandusa, C. Some Sustainability Aspects of Energy Conversion in Urban Electric Trains. Sustainability 2010, 2, 1389-1407.

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