Comparative LCA of Two Thermal Energy Storage Systems for Shams1 Concentrated Solar Power Plant: Molten Salt vs. Concrete

Abstract

Abstract-Thermal energy storage (TES) for concentrated solar power (CSP) is gaining popularity because it has the potential to increase the hours of electricity production from the CSP technology. In this Study, we conducted a comparative life cycle assessment (LCA) of two TES technologies (concrete and molten salt) for Shams-1 CSP plant in United Arab Emirates. Eco-Indicator 99 was employed to model the environmental impact per 800MWhe produced. Results obtained show that concrete TES has a greater environmental impact than molten salt TES, with fossil fuel being the largest impact contributor in both cases. A sensitivity analysis in which different scenarios were considered showed a reduction in environmental impact when waste recycling and transportation changes are incorporated. Based on the results obtained, incorporating molten salt TES in Shams 1 will have a lower environmental impact than the use of concrete TES.Index Terms-Concentrated solar power plant, concrete storage, life cycle assessment, molten salt storage, thermal energy storage. I. INTRODUCTIONSince the beginning of the industrial revolution, the atmospheric concentration of carbon dioxide has increased alarmingly by about 30%, due to human activities such as combustion of fossil fuels [1]. In Australia for example, electricity generation accounts for 45% of the carbon dioxide emission [2]. There is a need to reduce the quantity of CO 2 emission in order to mitigate its global warming effect. Hence, the development of renewable sources of electricity becomes relevant as the global requirement for electricity increases.Electricity generation using Concentrated Solar Power (CSP) is a relatively new technology that utilizes solar thermal energy to produce electricity. In this system, highly reflective mirrors are employed to concentrate the Direct Normal Irradiance (DNI) of sunlight on receivers, through which Heat Transfer Fluid (HTF) is pumped. Afterwards, the HTF transfers the acquired heat to a steam generator to produce steam, which is used in a Rankine Cycle Steam Turbine for electricity generation [3].Since the HTF is thermally stable and suitable for operations up to 400 o C [4], the temperature of the generated steam cannot exceed 380 o C. In order to increase the efficiency of the Rankine thermal cycle, CSP-natural gas hybridization can be used (Fig. 1). In this process, a booster heater is used to superheat the steam from 380 o C to 540 o C [5]. Fig. 1. Schematics of the hybrid CSP-natural gas plant [13] The four configurations employed in CSP plants are Parabolic Trough, Solar Fresnel, Stand Alone Solar Dish, and Central Tower [3]. CSP mirrors are usually installed with a solar tracking system to ensure optimal capture of solar radiation [6]. Currently, the United States is the world leader in solar thermal power development, with 63% of the market share [7].One disadvantage of CSP technology is that thermal energy generation is subject to daily fluctuations in solar radiation. In order to mitigate the effect of these fluctuations, th...

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