[en] Despite the strong request coming from the CSP industry, the design and synthesis of new materials with enhanced heat capacity is still suffering from the lack of a fundamental knowledge on the heat capacity enhancement mechanisms. New materials obtained by adding nanoparticles to nitrates have been investigated, but almost exclusively from the experimental point of view. In this theoretical study we will illustrate, for the first time, the mechanisms generating the variation of heat capacity in nanomaterials (NMs) and, accordingly, we will give indications on the design criteria of new materials with improved thermal properties. Starting from a comprehensive set of molecular dynamics calculations, we analyse the results via ad hoc-developed relations on non-ideal mixtures of nanoparticles in bulky materials. These goals are reached by studying silica nanoparticles in nitrates, which are prototype materials for TES. The density profiles of the atoms at the silica/KNO₃ interface show the formation of liquid like interfaces in the solid phase, and of solid-like interfaces in the liquid phase. These characteristics of the interfaces translate in a cP enhancement of the solid nanomaterial, and in a cP decrease of the liquid nanomaterial with respect to the bulk suspending KNO₃

[en] The phase change materials (PCMs) have ability to store and release energy over a narrow range of temperature making these materials potential aspirants for energy redistribution. Microencapsulation of the PCM overcomes the limitations faced by the direct incorporation of the PCM into the base fluid for cool thermal energy storage applications. In this study, the microencapsulation of the dimethyl adipate as peM using organic melamine formaldehyde as shell material has been carried out through polymerization technique. The as-prepared microencapsulated PCM (MPCM) was characterized using the FESEM, FTIR, DSC and TGA techniques. The microstructural analysis carried out using FESEM as depicted in the article infer that, the MPCM being formed exhibited good surface morphology and the microparticles were almost spherical in shape with an average size of 2.8 μm

[en] Short communication

[en] Highlights: • The application of PCM in building was experimentally studied. • Weather forecast data were used in order to improve the energy saving. • The importance of an accurate weather forecast was investigated. • An electrical saving up to 90% per day was achieved. • Successful peak load shifting was achieved. - Abstract: This study experimentally investigated the application of weather forecasting in combination with the price-based control method for solar passive buildings. Two identical lightweight test huts were used for the experimental study, one finished with ordinary gypsum board and the other finished with PCM-impregnated gypsum boards. Based on the experimental results, the application of weather forecast data showed significant energy saving when PCM is used. In some days, an electrical energy saving up to 90% per day was achieved using the proposed method. The results also showed that the application of inaccurate weather forecasts can significantly deteriorate performance of the control system and even lead to more energy consumption in the PCM hut.

[en] Latent heat storage is one of the most efficient ways of storing thermal energy. Unlike the sensible heat storage method, the latent heat storage method provides much higher storage density, with a smaller temperature difference between storing and releasing heat. This paper reviews previous work on latent heat storage and provides an insight to recent efforts to develop new classes of phase change materials (PCMs) for use in energy storage. Three aspects have been the focus of this review: PCM materials, encapsulation and applications. There are large numbers of phase change materials that melt and solidify at a wide range of temperatures, making them attractive in a number of applications. Paraffin waxes are cheap and have moderate thermal energy storage density but low thermal conductivity and, hence, require large surface area. Hydrated salts have larger energy storage density and higher thermal conductivity but experience supercooling and phase segregation, and hence, their application requires the use of some nucleating and thickening agents. The main advantages of PCM encapsulation are providing large heat transfer area, reduction of the PCMs reactivity towards the outside environment and controlling the changes in volume of the storage materials as phase change occurs. The different applications in which the phase change method of heat storage can be applied are also reviewed in this paper. The problems associated with the application of PCMs with regards to the material and the methods used to contain them are also discussed

[en] Thermal energy storage is a technology under investigation since the early 1970s. Since then, numerous new applications have been found and much work has been done to bring this technology to the market. Nevertheless, the materials used either for latent or for sensible storage were mostly investigated 30 years ago, and the research has lead to improvement in their performance under different conditions of applications. In those years a significant number of new materials were developed in many fields other than storage and energy, but a great effort to characterize and classify these materials was done. Taking into account the fact that thousands of materials are known and a large number of new materials are developed every year, the authors use the methodology for materials selection developed by Prof. Ashby to give an overview of other materials suitable to be used in thermal energy storage. Sensible heat storage at temperatures between 150 and 200 C is defined as a case study and two different scenarios were considered: long term sensible heat storage and short term sensible heat storage. (author)

[en] A model has been solved in order to determine the thermal losses of a storage tank, where thermal energy is stored as sensible heat of a diathermic fluid at medium temperatures. A parametric analysis has been performed in order to evaluate the influence of various design parameters on the thermal discharge of the accumulator

[en] Short communication

[en] This article describes different energy storage methods, how they operate and are distributed as well as the risks associated with their installation, use and servicing and their maintenance/repair operations. Ways of preventing occupational risks are described for electrochemical energy storage, which is a form of storage enabling a very wide range of applications and uses (stationary or portable storage). Many employees are potentially exposed to risks related to this technology for which incidents and accidents are regularly reported. (authors)

[en] As the largest renewable energy source, hydropower is essential to the sustainability of the global energy market. However, a considerable amount of water can be lost in the form of evaporation from the associated multipurpose reservoirs, and hence enlarge the blue water footprint (BWF) of hydropower in a warming climate. To facilitate the sustainable management of both water and energy resources under the impact of climate change in the contiguous United States (CONUS), the BWF values of 143 major multipurpose reservoirs were evaluated during the historical period (1985–2014) and two future periods (2020–2049 and 2070–2099). The historical reservoir evaporation loss was calculated using the Landsat-based reservoir surface area and a new evaporation rate algorithm that considers the heat storage effect. Future projections of runoff availability, hydropower generation, and reservoir evaporation were estimated based on the downscaled climate model ensemble from phase 5 of the Coupled Model Intercomparison Project. It was found that the BWF for the CONUS is highly spatially heterogeneous, with an average value of 26.2 m³ MWh⁻¹ in the historical period. In the future, the BWF values are projected to increase under both Representative Concentration Pathway (RCP) 4.5 and 8.5 scenarios. This is especially noticeable under RCP 8.5, which has an average BWF value of 30.2 m³ MWh⁻¹ for 2070–2099 (increasing by 15.3% from 26.2 m³ MWh⁻¹). The uncertainty ranges increase even more, from 3.4 m³ MWh⁻¹ during 2020–2049 to 5.7 m³ MWh⁻¹ during 2070–2099. These findings can benefit water and energy resources management in identifying suitable environmental, economic, operational, and investment strategies for multipurpose reservoirs in a changing environment. (letter)