Life cycle assessment of thermochemical energy storage integration concepts for a concentrating solar power plant

Abstract

This paper presents an original life cycle assessment (LCA) of a concentrating solar power (CSP) plant with thermochemical energy storage (TCES). The studied CSP plant is a hypothetic solar tower plant with a Rankine power cycle, and the TCES material used is calcium hydroxide. Based on three proposed TCES integration concepts, detailed sizing and the associated emission inventory are performed for four main groups that constitute the CSP plant, including the solar field, the solar tower, the storage system and the power cycle. Various midpoint impact categories are evaluated using the IMPACT 2002+ method embedded in the SimaPro 7.3 software. A sensitivity analysis is performed to identify the most influencing elements of the CSP plant on the environmental impacts. LCA results show that the CSP plant with different TCES integration alternatives has comparable global warming potential (approximately 11 kg CO 2.eq /MWh) and energy payback time (approximately 4 months). The additional environmental burden due to the addition of the TCES system is relatively small (about 30%). The use of calcium hydroxide for the TCES has noticeable midpoint impacts on the respiratory inorganics, the terrestrial ecotoxicity and the mineral extraction. Solar field group (heliostat mirrors) is generally the most sensitive and environmental impacting factor of the CSP installation. The Turbine integration concept has the smallest environmental impacts among the three concepts proposed.

Life Cycle Assessment (LCA) of a Concentrating Solar Power (CSP) Plant in Tower Configuration with and without Thermal Energy Storage (TES)

“…Therefore, since the environmental impact generated by the TES & HTF systems was mainly provided by the mixture of nitrate salts, the impact of the salt nitrates was studied in depth. The literature shows that their environmental impact could be different if synthetic molten salts or mined salts are considered [7,8].…”

“…Given the high contribution of the nitrate salts and the fact that they can be from mines (which represent at least 60% of the market share used in TES [7,8,21]) or synthetized by chemical reactions, this was evaluated, showing that the salts with lowest impact were those coming from mines (20% lower than when synthetic products were used), even when long transportation was considered. This brings a new view to the selection of the type of salts to use in a CSP plant.…”

“…Whitaker et al [7] evaluated greenhouse gas (GHG) emissions, water consumption, cumulative energy demand (CED), and energy payback time (EPBT) for reference design of a tower CSP plant hypothetically located in the United States, whose characteristics were derived from previous research by Sandia National Laboratories on molten salt tower plant designs in conjunction with operational plant modeling work performed by the National Renewable Energy Laborory (NREL). Pelay et al [8] presented a LCA of a hypothetical tower CSP plant with a Rankine power cycle with thermochemical energy storage (TCES) with calcium hydroxide. The result of the comparison of the LCA with the reference plant without storage concluded that the additional environmental impact due to the TCES system was relatively small.…”

Salt Hydrates for Thermochemical Storage of Solar Energy: Modeling the Case Study of Calcium Oxalate Monohydrate Dehydration/Rehydration under Suspension Reactor Conditions

“…A way to partially overcome these issues is to refer to the concentrated solar power (CSP) technology. − It relies on the concentration of solar energy by the use of optical sun-tracking mirrors (heliostats); hence, reflecting and concentrating sunlight to a receiver plant. Here, solar thermal energy is collected by a thermal energy carrier (a fluid or a solid) that is used for the conversion of energy into, e.g., electricity.…”

A Review on the Performance Indicators and Influencing Factors for the Thermocline Thermal Energy Storage Systems

“…Taking the concentrated solar power (CSP) as an example, heat is provided by the solar field, and the integration of thermal energy storage (TES) module allows the plant output be not strictly dependent on the solar irradiation in time, which can greatly improve the output stability and dispatchability [4,5]. In fact, the TES module is of critical importance for the solar thermal conversion systems, which significantly affects the overall performance [6,7].…”