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Emerging technologies and new intelligent management systems will be needed to rise to the energy challenges posed by buildings today. Thermally activated building systems (TABS) are attracting growing interest on the back of their energy savings potential. The TABS studied in this article, a new prefabricated panel designed for installation in residential building façades, was characterised by the high thermal inertia afforded by the phase change materials in its composition. The design and assessment of the potential savings derived from TABS require specific characterisation methodologies to estimate the amount of useful energy available to control the indoor environment. A two-stage approach was adopted for the TABS studied here with ``ideal'' operating control (the building is assumed to be at a constant desired temperature). The first stage involved a simplified method for characterising system behaviour based on performance maps developed from CFD simulations. Such maps can be used to quickly assess changes in system energy performance following on variations in design and operating parameters. In the second, the TABS was integrated into a building with a simplified model to assess monthly energy demand to evaluate the system potential for energy savings in representative types of Spanish single-family housing in different climate zones. The first-stage findings showed that given the system significant inertia, it discharged for several days, even when charging occurred only on the first, ensuring a wide operating range adaptable to renewable resource limitations. The analysis of potential, in turn, revealed that savings of over 40% in heating demand are possible even under the least favourable circumstances. ; This study was funded by Spanish Ministry of Economy and Competitiveness under the INPHASE (RTC-2015-3583-5) and DACAR (BIA2016-77431-C2-2-R), the European Regional Development Fund (ERDF) and the University of Seville under its Research Plan VI (VPPI-US). Prof. Cabeza would like to thank the Catalan Government for the quality accreditation given to her research group GREiA (2017 SGR 1537). GREiA is certified agent TECNIO in the category of technology developers from the Government of Catalonia. This work is partially supported by ICREA under the ICREA Academia programme.

AbstractCost-effective CO2 capture is essential for decarbonized cement production since it is one of the largest CO2 emission sources, where 60% of direct emissions are from CaCO3 decomposition and 40% are from fuel combustion. This work presents a low-carbon cement manufacturing process by integrating it with renewable energy for electric heating and thermal storage to replace the burning of fossil fuels in the conventional calciner. The low-carbon renewable energy reduces the indirect CO2 emissions from electricity consumption. The high-temperature CO2 is employed as the heat transfer fluid between the energy storage system and the calciner. In the proposed basic manufacturing process, the CO2 from the CaCO3 decomposition can be directly collected without energy-consuming separation since no impurities are introduced. Furthermore, the remaining CO2 from fuel combustion in the kiln can be captured through monoethanolamine (MEA) absorption using waste heat. In the two situations, the overall CO2 emissions can be reduced by 69.7% and 83.1%, respectively, including the indirect emissions of electricity consumption. The economic performance of different energy storage materials is investigated for materials selection. The proposed manufacturing process with a few high-temperature energy storage materials (BaCO3/BaO, SrCO3/SrO, Si, etc.) offers a higher CO2 emission reduction and lower cost than alternative carbon capture routes, i.e., oxyfuel. The cost of CO2 avoided as low as 39.27 $/t can be achieved by thermochemical energy storage with BaCO3/BaO at 1300 °C, which is superior to all alternative technologies evaluated in recent studies.

2010/2011 ; Since from the first Industrial Revolution, energy supply, which feeds human activities, has been characterized by consumption of fossil fuels such as coal, crude oil and gas. This supply model is heavely affected by a dramatic limitation, taht is the idea of feeding an infinite system (such as the human activities energy demand) with a finite (in terms of time) source - fossil fuels. Although this issue was already forecast in the early decades of the last century (e.g. G. Ciamician in The photochemistry of the Future, during The Ninth International Congress of Applied Chemistry - New York), it has been largely neglected until the first oil crisis in the 70s, when public eye become aware of the (social) issue coming from the oil dependence. The exponential growth of Earth population and the consequent increase of energy demand and the environmental and pollution issues that characterized last decades leaded large part of scientific and (marginally) politic community to focusing its endeavours to research of more efficient way of exploiting renewable sources and to the fillip of their usage. The main drawback, which affects the usage of renewable energies, is that the supply, whether it comes from the earth or the sun, is never constant. Day turns to night, winds die down and the geothermal heat from the crust of the earth, although seemingly constant, will eventually diminish. The capability of storing energy and release it on demand, therefore, plays a crucial role in the possibility of exploiting renewable energies. The main target of this PhD study is investigation and design of devices capable of collecting thermal energy. According to the idea of gathering the largest quantity of energy in the most efficient way, as storage strategies it has been decided to adopt the latent heat thermal storage method. Suitable materials for accomplishing this task are Phase Change Materials (PCMs); they are a class of materials capable of collecting and releasing a large amount of energy during melting and freezing process at a temperature that may be useful for anthropic activities, such as air heating&cooling, domestic hot water production, industrial processes and energy production. In this thesis in particular, the existence of a convergence point between the possibility to adopt nano-enhanced material into largely used devices (heat exchangers, boilers etc.) is explored. This research has been, therefore, performed focusing mainly onto two different aspects: the possibility of improving thermal properties (melting enthalpy) of PCMs by addiction of nano-enhancer materials and on the other hand design and development of systems which imply the usage of PCMs, eventually nano-doped. The structure of this thesis reflects the division of topics and every part represents one of these task: * in the first part, Phase Change Materials a general overview on the state of art of PCMs is presented. A brief description of strategies for thermal storage is discussed and a dissertation on different typologies of PCMs, main advantages and disadvantages coming from their usage is given. The discussion than continues analysing possible ways of modelling the thermal behaviour during melting or freezing process. Both the analytical and numerical approaches are treated; * in the second part, Nanotechnology and Phase Change Materials, dissertation on thermal variations induced by inclusion of carbon nano tubes is carried out. After a snapshot on the state of the art in the field of nano-doping of PCMs, procedures and results of four commercially available paraffin waxes doped with CNTs have been discussed; * in the third part, Design and Phase Change Materials, devices which exploit PCMs have been designed and (numerically) optimized. A panel heat exchanger, capable to accomplish requirements of modularity and short time heat release has been numerically studied and optimized by genetic algorithm; the possibility of using a nano-enhanced material has been explored. Then, a system for avoiding ice formation on pavement surface during winter time has been developed. PCM elements (pipes) embedded into asphalt concrete of road pavement have been modelled using a commercial FE code. 1D and 2D models have been used and coupled with weather data collected in Trieste during the first week of January 2009; * in the last part, Conclusions, final remarks and further developments are discussed. ; XXIV Ciclo ; 1982

The evolution of electric generation systems, according to relevant legislation, allows for the parallel evolution of the installed power capacity of renewable resources with the development of technologies for renewable resources, therefore optimizing the choice of energy mix from renewable resources by prioritizing the implementation of concentrating solar thermal plants. Thanks to their great potential, parabolic trough solar thermal power plants have become the most widely spread type of electricity generation by renewable solar energy. Nonetheless, the operation of the plant is not unique ; it must be adapted to the parameters of solar radiation and market behavior for each specific location. This work focuses on the search for the optimal strategies of operation by a mathematical model of a 50 MWe parabolic trough thermal power plant with thermal storage. The analysis of the different ways of operation throughout a whole year, including model verification via a currently operating plant, provides meaningful insights into the electricity generated. Focused to work under non-regulated electricity markets to adjust this type of technology to the European directives, the presented model of optimization allows for the adaptation of the curve of generation to the network demands and market prices, rising the profitability of the power plant. Thus, related to solar resources and market price, the economic benefit derived from the electricity production improves between 5.17% and 7.79%.

The evolution of electric generation systems, according to relevant legislation, allows for the parallel evolution of the installed power capacity of renewable resources with the development of technologies for renewable resources, therefore optimizing the choice of energy mix from renewable resources by prioritizing the implementation of concentrating solar thermal plants. Thanks to their great potential, parabolic trough solar thermal power plants have become the most widely spread type of electricity generation by renewable solar energy. Nonetheless, the operation of the plant is not unique; it must be adapted to the parameters of solar radiation and market behavior for each specific location. This work focuses on the search for the optimal strategies of operation by a mathematical model of a 50 MWe parabolic trough thermal power plant with thermal storage. The analysis of the different ways of operation throughout a whole year, including model verification via a currently operating plant, provides meaningful insights into the electricity generated. Focused to work under non-regulated electricity markets to adjust this type of technology to the European directives, the presented model of optimization allows for the adaptation of the curve of generation to the network demands and market prices, rising the profitability of the power plant. Thus, related to solar resources and market price, the economic benefit derived from the electricity production improves between 5.17% and 7.79%.

Abstract. This work was part of the European Union's Horizon 2020 Making-City program aiming to increase information regarding the positive energy districts. In this study as part of the project, possible use of phase change materials (PCM) in thermal storage was studied to increase its capacity by adding encapsulated materials to the conventional hot water tank. Although the use of PCMs has been studied previously, there still is a need for more practical research regarding the increase of energy content and its discharge properties. Therefore, we studied the theory of PCMs, commercial availability, theoretical viability, and practical viability of PCMs to set up practical test equipment to monitor temperature changes and to measure their efficiency in increasing the energy content. Four different PCM materials from multiple commercial PCM producers were tested in comparable tests with temperature measured in the function of time. Encapsulated PCMs were selected as they have been suggested to be the best option to nullify the negative properties according to previous studies. Increased energy gained by using the PCM was calculated for thermal storage based on previous studies and using commercial materials technical specifications. Finally, practical testing equipment was made to test PCMs and compare the results with theoretical calculations. All selected materials were tested in four different temperatures 70, 67.5, 65, and 62.5 °C with three cycles for each temperature. All experiments had consistent PCM/water volume relation (1/3) with additional control tests containing just water. After the automated test cycles were finished, temperature data with 30 seconds intervals were collected. Although, the mean temperature showed that all PCMs increased the overall energy content of the storage, the amount of latent energy stored differed as well as thermal conduction rates. The results revealed that compared to the control test with water, the highest calculated energy increase was in the range of 28 to 37 % depending on test temperature, which was lower in comparison to the expected theoretical energy increase.

Phase change materials (PCM) are able to store thermal energy when becoming liquids and to release it when freezing. Recently the use of PCM materials for thermal energy storage (TES) at high temperature for Concentrated Solar Power (CSP) technology has been widely studied. One of the main investigated problems is the improvement of their low thermal conductivity. This paper looks at the current state of research in the particular field of thermal conductivity enhancement (TCE) mechanisms of PCM to be used as TES. This work considers a numerical approach to evaluate the performance of a group of TCE solutions composed by particular configurations of two of the principal TCE systems found on the literature: finned pipes and conductive foams. The cases are compared against a single PCM case, used as reference. Three different grades of graphite foams have been studied, presenting a charge time 100 times lower than the reference case for the same capacity. For fins two materials are analyzed: carbon steel and aluminum. The charge times of fin cases are from 3 to 15 times faster, depending on the amount and type of material employed. The internal mechanisms are analyzed to understand the results and locate possible improvement. ; The research leading to these results has received funding from CDTI Thesto (ITC-20111050) innterconecta Thesto). The work partially funded by the Spanish government (ENE2011-28269-C03-02 and ENE2015-64117-C5-1-R). The authors would like to thank the Catalan Government for the quality accreditation given to the research group GREA (2014 SGR 123). The research leading to these results has received funding from the European Union's Seventh Framework Programme (FP7/ 2007e2013) under grant agreement n PIRSES-GA-2013-610692 (INNOSTORAGE) and from the European Union's Horizon 2020 research and innovation programme under grant agreement No 657466 (INPATH-TES).