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AbstractDecarbonising the energy system requires high shares of variable renewable generation and sector coupling like power to heat. In addition to heat supply, heat pumps can be used in future energy systems to provide flexibility to the electricity system by using the thermal storage potential of the building stock and buffer tanks to shift electricity demand to hours of high renewable electricity production. Bridging the gap between two methodological approaches, we coupled a detailed building technology operation model and the open-source energy system model Balmorel to evaluate the flexibility potential that decentral heat pumps can provide to the electricity system. Austria in the year 2030 serves as an example of a 100% renewable-based electricity system (at an annual national balance). Results show that system benefits from heat pump flexibility are relatively limited in extent and concentrated on short-term flexibility. Flexible heat pumps reduce system cost, CO2 emissions, and photovoltaics and wind curtailment in all scenarios. The amount of electricity shifted in the assessed standard flexibility scenario is 194 GWhel and accounts for about 20% of the available flexible heat pump electricity demand. A comparison of different modelling approaches and a deterministic sensitivity analysis of key input parameters complement the modelling. The most important input parameters impacting heat pump flexibility are the flexible capacity (determined by installed capacity and share of control), shifting time limitations, and cost assumptions for the flexibility provided. Heat pump flexibility contributes more to increasing low residual loads (up to 22% in the assessed scenarios) than decreasing residual load peaks. Wind power integration benefits more from heat pump flexibility than photovoltaics because of the temporal correlation between heat demand and wind generation.

In this study, the thermal performance of a compact heat sink thermoelectric cooling module with water, nanofluid, and ferrofluid as the coolants is investigated experimentally. The TiO2 nanofluid and Fe3O4 ferrofluid were tested at concentrations of 0.005% and 0.015%, respectively. The dummy battery pack was filled with water under a constant temperature and represented as a heat load. The results reveal that the Fe3O4 ferrofluid showed a maximum heat transfer rate 11.17% and 12.57% higher, respectively, than that of the TiO2 nanofluid and water. The TiO2 nanofluid and Fe3O4 ferrofluid with a 0.015% concentration enhanced the Peltier effect by lowering the contribution of the Fourier effect of the thermoelectric cooler (TEC), decreasing the temperature difference of the TEC cooling module by 4.6% and 9.6%, respectively, which decreases the thermal resistance of the heat sink by 7% and 14%, respectively. More importantly, the use of nanofluids and ferrofluids with a 0.015% concentration as coolants increased the pressure drop significantly, by 0.5 kPa and 2.7 kPa, respectively, compared with water.

The objectives of this study are to experimentally investigate the effect of meandering turn numbers on thermal performance and to predict the optimum meandering turn number of vertical and horizontal closed-loop pulsating heat pipes (CLPHP). The CLPHPs were made from a copper capillary tube with internal diameter of 2.0 mm. The CLPHPs were bent into undulating tubes with various meandering turn numbers, such as 5, 7, 10, 16, and 30. Each set of the CLPHPs had different evaporator section lengths of 50 mm and 150 mm. Heat input was supplied to the CLPHP by allowing the flow of distilled water as the heating medium through the evaporator section. The adiabatic section temperature was constantly controlled at 50°C. It could be concluded that the optimum meandering turn number of vertical CLPHPs with an evaporator section length of 50 mm is 10 for both R123 and water, and the optimum meandering turn numbers of vertical CLPHPs with an evaporator section length of 150 mm are 5 and 10, respectively, for R123 and water. However, the optimum meandering turn number of the horizontal CLPHP could not be found since the heat flux directly varies with the turn number. In addition, the correlation to predict the optimum meandering turn number of the vertical CLPHP was successfully established.

SummaryEnvironmentally extended multiregional input‐output (EE MRIO) tables have emerged as a key framework to provide a comprehensive description of the global economy and analyze its effects on the environment. Of the available EE MRIO databases, EXIOBASE stands out as a database compatible with the System of Environmental‐Economic Accounting (SEEA) with a high sectorial detail matched with multiple social and environmental satellite accounts. In this paper, we present the latest developments realized with EXIOBASE 3—a time series of EE MRIO tables ranging from 1995 to 2011 for 44 countries (28 EU member plus 16 major economies) and five rest of the world regions. EXIOBASE 3 builds upon the previous versions of EXIOBASE by using rectangular supply‐use tables (SUTs) in a 163 industry by 200 products classification as the main building blocks. In order to capture structural changes, economic developments, as reported by national statistical agencies, were imposed on the available, disaggregated SUTs from EXIOBASE 2. These initial estimates were further refined by incorporating detailed data on energy, agricultural production, resource extraction, and bilateral trade. EXIOBASE 3 inherits the high level of environmental stressor detail from its precursor, with further improvement in the level of detail for resource extraction. To account for the expansion of the European Union (EU), EXIOBASE 3 was developed with the full EU28 country set (including the new member state Croatia). EXIOBASE 3 provides a unique tool for analyzing the dynamics of environmental pressures of economic activities over time.

The accumulation of dust on any given photovoltaic (PV) module surface depends on the type of dust, environment, surroundings, weather, module properties, and its installation design. In this research, equations were developed for the preliminary evaluation and comparison of the reduction in power from PV modules because of dust soiling. Use of these equations shows that dust accumulation decreases solar irradiance and thus the power output of modules, and that there is a linear relationship between the power output degradation and density or amount of accumulated dust. The equations can be used to conduct analysis of average photon energy and the PV module power output reduction from accumulated dust. The study also showed that type of PV module can also affect the degree of power output reduction. The amorphous silicon PV modules are more affected compared to poly crystalline silicon PV modules as the latter has a spectrum response which still has the range that can produce full energy and therefore, dust soiling has lesser impact on them. PV power plants should regularly clean the modules, if not, production of electricity decreases, and so too the revenue from selling electricity, making the payback of the power plant longer.

AbstractChemical looping combustion is a highly efficient CO2 separation technology without direct contact between combustion air and fuel. A metal oxide is used as an oxygen carrier in dual fluidized beds to generate clean CO2. The use of biomass is the focus of current research because of the possibility of negative CO2 emissions and the utilization of biogenic carbon. The most commonly proposed OC are natural ores and residues, but complete combustion has not yet been achieved. In this work, the direct utilization of CLC exhaust gas for methane synthesis as an alternative route was investigated, where the gas components CO, CH4 and H2 are not disadvantageous but benefit the reactions in a methanation step. The whole process chain, the coupling of an 80 kWth pilot plant with gas cleaning and a 10 kW fluidized bed methanation unit were for this purpose established. As OC, ilmenite enhanced with limestone was used, combusting bark pellets in autothermal operation at over 1000 °C reaching high combustion efficiencies of up to 91.7%. The fuel reactor exhaust gas was mixed with hydrogen in the methanation reactor at 360 °C and converted with a methane yield of up to 97.3%. The study showed especially high carbon utilization efficiencies of 97% compared to competitor technologies. Based on the experimental results, a scale-up concept study showed the high potential of the combination of the technologies concerning the total efficiency and the adaptability to grid injection. Graphical Abstract

Nowadays, as environmental awareness is key issue among researchers, scientific community is looking for natural materials as they are biodegradable, low cost, eco-friendly and also safe for health. Researchers and academicians have found many natural fibers and studied their properties for their sustainable applications in various possible sectors, and studies are also going on. So, in that context several natural fiber like jute, sisal, banana, pineapple, flax, hemp, kenaf, bamboo, cornstalk waste, coir, etc. have been successfully utilized as a reinforcing material in polymer composites by replacing man made synthetic fiber. Apart from traditional natural fibers, scientific community is also looking for locally available natural fibers across the globe in different geographical locations for successful reinforcement in polymer matrix. This will not only decrease burden on traditional fibers and but also at the same time it would be helpful to enrich the rural economy. Natural fiber based composites can be used in different areas such as auto motive industry, construction industry, sports industry and food industry. This study is related with extraction, characterization, surface treatment thermal analysis and activation energy of different uncommon natural fibers available at different geographical locations worldwide. The purpose of this study is to provide a comprehensive knowledge on extraction techniques, treatment methodologies, and properties of these uncommon natural fibers so that these novel materials can be utilized efficiently as a reinforcing material in different polymer matrix. Discussions on traditional natural fibers like Bagasse, Wheat straw, Coir, Pineapple, Banana etc. have been compiled extensively in various review papers but compilation on these new uncommon natural fibers is rare. Thermal analysis along with activation energy evaluation is another aspect which has been given emphasis in discussion because this is also a very important examination to evaluate the thermal stability of these natural fibers.