Browsing by Author "Larrain, Teresita"

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    Net energy analysis for concentrated solar power plants in northern Chile
    (PERGAMON-ELSEVIER SCIENCE LTD, 2012) Larrain, Teresita; Escobar, Rodrigo
    Chilean energy policy goals attempts to promote efficiency and sustainability in the energy system. These objectives have been considered in recent modifications to the electricity generation laws by establishing that generation companies must reach a quota of up to a 10% from renewable energy sources by 2024. Concentrated solar power (CSP) is an interesting alternative to help achieve those objectives, as it is estimated that northern Chile has high radiation levels, coupled with the high values of the local clearness index and flat land availability. However, from the sustainability point of view it seems necessary to assess if a CSP plant is effectively an energy source. Here we propose a hybrid solar power plant lifecycle model which through a net energy analysis obtains and analyzes the plant energy sustainability attributes such as net energy, energy return over investment and energy payback time. The stages of construction, operation, maintenance and decommissioning are considered in the lifecycle analysis. The model is then applied in order to determine good locations where to install a CSP plant in the Chilean Atacama Desert. Monthly means of solar radiation are used in order to estimate the solar fraction for a 100MW direct steam generation parabolic trough collector plant. The results indicate that solar power plants are effectively a net energy source for the analyzed locations, and that higher energy costs are related to the fossil fuel backup lifecycle. A relation is established between yearly radiation, energy return over investment and energy payback time. It is estimated that the net energy analysis is a useful tool for determining under which conditions a power plant becomes a net energy source and therefore a more convenient option from the sustainability point of view, and thus can be utilized in order to define best geographical locations and operation conditions for different renewable energy sources. The sustainability attributes are greatly enhanced when considering a solar-only operation mode, which highlights the advantages of using that configuration, and presents a case for the use of thermal energy storage systems rather than fossil fuel hybridization if a constant or dispatchable energy profile is required. (C) 2011 Elsevier Ltd. All rights reserved.
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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.