• Energy Research
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Abstract This work reports a detailed experimental study that is aimed at investigating the Thermal Energy Storage (TES) performance of cementitious systems containing Microencapsulated Phase Change Materials (MPCMs). New spherical-shaped test specimens for TES measurements were produced following an innovative casting technique, developed at the Institut fur Werkstoffe im Bauwesen – TU Darmstadt. Three water-to-cement ratios and three MPCMs volume fractions, leading to a total of nine different mixtures, were investigated. The thermal experiments were accompanied by mechanical tests to observe the effect MPCMs have on the resulting strengths in both compression and bending. The analysis and discussion of the TES results are employed for calibrating an enthalpy-based model. The experimental data have been applied to evaluate the corresponding temperature-based material parameters like specific heat, conductivity, or more in general, the energy storage capacity of a system under transient heat conduction conditions.

Many developing countries face a dilemma between meeting the intensive growth in electricity demand, broadening an electricity access, as well as tackling climate change. The use of renewable energy is considered as an option for meeting both electrification and climate change objectives. In this study, long-term forecasting of electricity supply for the Java-Bali power system – the main power system in Indonesia – is presented. The forecasts take into consideration the Indonesian government policy of increasing the share of new and renewable energy in the national energy mix up to 23% by 2025 and 30% by 2050. After a systematic review of energy system models, we perform the analysis of the Java-Bali power system expansion using the Long-range Energy Alternative Planning system (LEAP) model. Three scenarios are developed over the planning horizon (2016-2050) including the business as usual scenario (BAU), the renewable energy scenario (REN) and the optimization scenario (OPT). The results of the three scenarios are analyzed in terms of the changes in resource/technology deployment, CO2 emissions and total costs.

Green tea catechins mixed with caffeine have been proposed as adjuvants for maintaining or enhancing energy expenditure and for increasing fat oxidation, in the context of prevention and treatment of obesity. These catechins-caffeine mixtures seem to counteract the decrease in metabolic rate that occurs during weight loss. Their effects are of particular importance during weight maintenance after weight loss. Other metabolic targets may be fat absorption and the gut microbiota composition, but these effects still need further investigation in combination with weight loss. Limitations for the effects of green tea catechins are moderating factors such as genetic predisposition related to COMT-activity, habitual caffeine intake, and ingestion combined with dietary protein. In conclusion, a mixture of green tea catechins and caffeine has a beneficial effect on body-weight management, especially by sustained energy expenditure, fat oxidation, and preservation of fat free body-mass, after energy restriction induced body-weight loss, when taking the limitations into account.

Abstract Microgrids integrating local renewable energy sources at low-voltage level show promising potentials in realizing a reliable, efficient, and clean supply of electricity. Further improvements are expected when such a microgrid is operated based on direct current (dc) instead of alternating current (ac) infrastructure for power distribution commonly in use today. Our study aims to systemically quantify the gap between environmental impacts of microgrids at building level using the case study of power distribution within office buildings. For this purpose, a scalable comparative life cycle assessment (LCA) is conducted based on a technical bottom-up analysis of differences between ac and dc microgrids. Particularly, our approach combines the micro-level assessment of required power electronic components with the macro-level requirements for daily operation derived from a generic grid model. The results indicate that the environmental impacts of employed power electronics are substantially reduced by operating a microgrid based on dc power distribution infrastructure. Our sensitivity analyses show that efficient dc microgrids particularly lead to savings in climate change impact emissions. In addition, our study shows that the state-of-the-art scaling rules of power electronics currently used in LCAs leads to inaccurate results. In contrast, the proposed methodology applies a more technical approach, which enables a detailed analysis of the environmental impacts of power electronic components at system level. Thus, it provides the foundation for an evaluation criterion for a comprehensive assessment of technological changes within the framework of energy policy objectives.

Abstract Public participation is often part of planning and decision-making processes relating to the German energy transformation (Energiewende). Factors influencing the active involvement of individuals have not been fully investigated, although these factors may impact the outcome of participatory decision making. However, a few concepts are discussed relating to what kind of people participate in governance processes: political efficacy, place attachment, value orientation, and sociodemographic characteristics. We further assumed that the aspects of attitudes toward renewable energy technologies, general knowledge about environment and energy, specific knowledge about electricity-generating technologies, personality strength, and living situation might influence people's participation in planning and decision making related to energy issues. In this study, we examine the relevance of these concepts based on a survey for which (n=) 2400 respondents were recruited from an access panel to build up a quota sample on the three crossed characteristics: gender, age, and school education. Many of the respondents are aware of participation options but very few become actively engaged in participation processes. The multivariate analyses conducted showed that attitudes towards renewable energy technologies, value orientation towards nature, political efficacy, personality strength, and individuals' specific knowledge have a strong influence on whether someone becomes actively involved or not.

Head objective of the paper is to create and stimulate a Novel Dual Stator Sandwiched Rotor Hybrid Magnetic Pole Six-Phase PMSG (NDSSRHMPSP-PMSG) for harnessing wind power. Wind energy is the most optimized plan for innovation since it erases the need of water and is eco-accommodating and can be a superior option for expanded energy usage. A multiphase PMSG is a superior alternative for wind energy utilization. The two-fold rotor-stator setup upgrades the machine’s voltage regulation as well as its dependability and execution. The designed NDSSRHMPSPPMSG possesses novelty in terms of its magnet structure. A Hybrid Magnetic Pole (HMP) is inserted into the rotatory portions. The concept of HMP introduces the combination of V-Shaped Magnets (VSM) and Multi-Layer Embedded Magnets (MLEM). This remarkable combination of two different magnetic formation provides a higher flux density and contributes towards an efficient operation of the proposed system. To construct the generator optimally and for evaluation, magnetostatic and transient setups are used. Because of proper examination, it may be very well presumed that the proposed novel framework is legitimate and effective.