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In 2008, following its R&D strategy roadmap for Concentrated Solar Power, Abengoa designed, built and tested a unique Molten Salts pilot plant at the representative scale of 8 MWhth, coupled with a trough oil loop. The objectives of this project were based on evaluating the technology at a scale at which the results are sufficiently representative of the real circumstances facing a commercial plant that utilizes this storage technology. To this end, the MS-TES plant was brought into operation on January 19th, 2009, been the first demo plant of indirect double tank storage in operation in the world. Key points such a material corrosion, analysis of possible leakage points, calculation of performance or true efficiency of the storage (including a thorough assessment of thermal losses) and analysis of plant operation are the lines that have been analysed at this plant. Operational aspects such as the mechanical assembling, the pre-heating, the filling up and plant performance were deeply addressed. Key components as the storage tanks, the heat exchanger, the molten salts pumps, the heat-tracing systems or valves and instrumentation were tested. In this first paper, the description and commissioning of the plant is presented together a set of lessons learnt to be applied at the commercial plant scale.

The metropolitan cities of developed countries comprise more than 50% of the global population and consume over 60% of the world's energy. Many governments plan to enhance their energy infrastructure and the electricity supply–demand reliability of their energy sources. Among them, South Korea's government has developed electricity generation facilities, most of which use renewable resources such as photovoltaic and wind energy. This study determines the optimal renewable electricity generation configuration for one of the largest metropolitan cities in South Korea, Busan metropolitan city. A simulation using 2013 Busan electricity demand data produces this optimal configuration, which includes photovoltaic panels, wind facilities, converters, and batteries with $0.399 of COE (Cost of Electricity) and 100% of renewable fractions. Both the study's practical limitations and implications are discussed.

Abstract Storage and transport of temperature sensitive products have become an important issue worldwide. The enhancement of thermal performance of cold application is under investigation and implementing thermal energy storage (TES) systems by using phase change materials (PCM) is one of the solutions to better storage. Hence, the selection of the suitable PCM for each specific application is an important matter. In this paper, a TES system using PCM for low temperature applications such as commercial freezers is studied. A set of PCM formulations based on ammonium chloride – water binary system were tested and analyzed to provide information useful for the selection of PCM with regards to their melting range, latent heat, stability under cycling, and cost. Thermal cycling was conducted to determine the thermal reliability of the PCM and the thermal properties were determined using differential scanning calorimetry (DSC) analysis.

Abstract The present work compares the environmental impact of three different thermal energy storage (TES) systems for solar power plants. A Life Cycle Assessment (LCA) for these systems is developed: sensible heat storage both in solid (high temperature concrete) and liquid (molten salts) thermal storage media, and latent heat storage which uses phase change material (PCM). The aim of this paper is to analyze if the energy savings related to the stored energy of the different systems are enough to balance the environmental impact produced during the manufacturing and operation phase of each storage system. Some hypothetical scenarios are studied using LCA methodology to point out the differences between each TES system. The system based on solid media, due to his simplicity, shows the lowest environmental impact per kWh stored of all three systems compared. In addition, the liquid media (molten salts) shows the highest impact per kWh stored because it needs more material and complex equipment.

Abstract Among the research activities that aim at reducing energy consumption in buildings and their impact on the environment is an experimental set-up that has several house-shaped cubicles constructed in Puigverd de Lleida (Spain). Assessing the environmental impact through studying the manufacturing, operational and disposal phases of these cubicles have been done in previous research. The objective of this paper is to investigate the use of esters as PCM in order to estimate its environmental impact in building envelopes in comparison to the use of paraffin or salt hydrates through a theoretical study. The evaluation of the environmental impact of this type of PCM material is conducted using Life Cycle Assessment (LCA) based on the Eco-indicator 99 method. It is found that the impact of ester used as PCM presents slightly better results than the case of using salt hydrates during the manufacturing impact. On the other hand, the use of salt hydrates or ester as PCM in the cubicles results in an impact reduction of 9% and 10.5% respectively, compared to the case of using paraffin.

Abstract Sandwich panels are a good option as building materials, as they offer excellent characteristics in a modular system. The goal of this study was to demonstrate the feasibility of using the microencapsulated PCM (Micronal BASF) in sandwich panels to increase their thermal inertia and to reduce the energy demand of the final buildings. In this paper, to manufacture the sandwich panel with microencapsulated PCM three different methods were tested. In case 1, the PCM was added mixing the microencapsulated PCM with one of the components of the polyurethane. In the other two cases, the PCM was added either a step before (case 2) or a step after (case 3) to the addition of the polyurethane to the metal sheets. The results show that in case 1 the effect of PCM was overlapped by a possible increase in thermal conductivity, but an increase of thermal inertia was found in case 3. In case 2, different results were obtained due to the poor distribution of the PCM. Some samples showed the effect of the PCM (higher thermal inertia), and other samples results were similar to the conventional sandwich panel. In both cases (2 and 3), it is required to industrialize the process to improve the results.

Solar energy can be efficiently used if thermal energy storage systems are accordingly designed to match availability and demand. Thermal energy storage by thermochemical materials (TCM) is very attractive since these materials present a high storage density. Therefore, compact systems can be designed to provide both heating and cooling in dwellings. One of the main drawbacks of the TCM is corrosion with metals in contact. Hence, the objective of this study is to present the obtained results of an immersion corrosion test following ASTM G1 simulating an open TCM reactor, under humidity and temperature defined conditions. Four common metals: copper, aluminum, stainless steel 316, and carbon steel, and five TCM: CaCl2, Na2S, CaO, MgSO4, and MgCl2, were studied. Aluminum and copper show severe corrosion when combined with Na2S, aluminum corrosion is more significant since the specimen was totally destroyed after 3 weeks. Stainless steel 316 is recommended to be used as a metal container material when storing all tested TCM.

The goal of this study is to implement and to test a thermal energy storage (TES) system using different phase change materials (PCM) for solar cooling applications. A high temperature pilot plant able to test different types of TES systems and materials was designed and built at the University of Lleida (Spain). This pilot plant is composed mainly by three parts: heating system, cooling system, and different storage tanks. The pilot plant uses synthetic thermal oil as heat transfer fluid (HTF) and has a working temperature range from 100 to 400 C. Two different PCM were selected after a deep study of the requirements of a real solar cooling plant and the available materials in the market through literature review and DSC analysis. Finally D-mannitol with phase change temperature of 167 C and hydroquinone which has a melting temperature of 172.2 C were used at pilot plant scale. For both PCM, no hysteresis was detected, and at pilot plant only D-mannitol showed subcooling even though both showed it during the DSC analysis. An effective heat transfer coefficient between the storage material and the heat transfer fluid (HTF) was calculated. For the same boundary conditions, the energy stored by D-mannitol was higher than that for hydroquinone. Moreover, D-mannitol has polymorphism that needs to be taken into account when the material is used as PCM, but experiments in this paper showed that polymorphism did not interfere its performance as PCM.