Net energy analysis for concentrated solar power plants in northern Chile. http://dx.doi.org/10.1016/j.renene.2011.10.015

Abstract

Chilean energy policy goals attempts to promote efficiency and sustainability in the energy system. Theseobjectives have been considered in recent modifications to the electricity generation laws by establishingthat 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 isestimated that northern Chile has high radiation levels, coupled with the high values of the localclearness index and flat land availability. However, from the sustainability point of view it seemsnecessary to assess if a CSP plant is effectively an energy source. Here we propose a hybrid solar powerplant lifecycle model which through a net energy analysis obtains and analyzes the plant energysustainability attributes such as net energy, energy return over investment and energy payback time. Thestages of construction, operation, maintenance and decommissioning are considered in the lifecycleanalysis. The model is then applied in order to determine good locations where to install a CSP plant inthe Chilean Atacama Desert. Monthly means of solar radiation are used in order to estimate the solarfraction for a 100MW direct steam generation parabolic trough collector plant. The results indicate thatsolar power plants are effectively a net energy source for the analyzed locations, and that higher energycosts 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 isa useful tool for determining under which conditions a power plant becomes a net energy source andtherefore a more convenient option from the sustainability point of view, and thus can be utilized inorder to define best geographical locations and operation conditions for different renewable energysources. The sustainability attributes are greatly enhanced when considering a solar-only operationmode, which highlights the advantages of using that configuration, and presents a case for the use ofthermal energy storage systems rather than fossil fuel hybridization if a constant or dispatchable energyprofile is required.