Browsing by Author "Vergara, Julio"

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    Performance model to assist solar thermal power plant siting in northern Chile based on backup fuel consumption
    (PERGAMON-ELSEVIER SCIENCE LTD, 2010) Larrain, Teresita; Escobar, Rodrigo; Vergara, Julio
    In response to environmental awareness, Chile introduced sustainability goals in its electricity law. Power producers must deliver 5% from renewable sources by 2010 and 10% by 2024. The Chilean desert has a large available surface with one of the highest radiation levels and clearest skies in the World. These factors imply that solar power is an option for this task. However, a commercial plant requires a fossil fuel system to backup the sunlight intermittency. The authors developed a thermodynamical model to estimate the backup fraction needed in a 100 MW hybrid -solar-fossil- parabolic trough power plant. This paper presents the model aiming to predicting the performance and exploring its usefulness in assisting site selection among four locations. Since solar radiation data are only available in a monthly average, we introduced two approaches to feed the model. One data set provided an average month with identical days throughout and the other one considered an artificial month of different daylight profiles on an hourly basis for the same monthly average. We recommend a best plant location based on minimum fossil fuel backup, contributing to optimal siting from the energy perspective. Utilities will refine their policy goals more closely when a precise solar energy data set becomes available. (C) 2010 Elsevier Ltd. All rights reserved.
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    Sustainable energy for the marine sector
    (ELSEVIER SCI LTD, 2012) Vergara, Julio; McKesson, Chris; Walczak, Magdalena
    Most scientists agree that climate change is affected by anthropogenic factors, and measures to reduce carbon dioxide emissions are being considered among countries. The maritime transportation sector must bear its share of responsibility for adopting corrective innovative measures on a global scale. The authors projected the energy consumption and emissions of different marine transportation types in 2050 and applied the model of stabilization wedges to explore activities and technologies to deduce policies that would lead to sustainable marine propulsion. Three percent of the global emissions reductions -about 44 GtCO(2)/y- required to stabilize the temperature under 2 degrees C above current levels must come from the maritime sector. To meet a reduction target of this segment, about 1.67 GtCO(2)/y in 2050, we propose a range of technologies that include mission refinement, resistance reduction, prime mover and propulsion innovation, and new fuels. The authors find that the goal is partially attainable and proposes the balance to be delivered by dedicated land-based synfuel refineries that use carbon dioxide from coal power plants and hydrogen produced from sustainable sources, an approach that would extend the lifecycle of conventional prime movers. We await the adoption of suitable technologies to reduce the emissions in the maritime sector. (C) 2012 Elsevier Ltd. All rights reserved.
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    Vibration-assisted laser welding: Frequency and amplitude vibration effect on the microhardness of A36 steel
    (2022) Vidal, Juan G.; Barrionuevo, German O.; Ramos Grez, Jorge; Vergara, Julio; Mullo, Jose L.