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Abstract In the electricity production sector, geothermal energy is considered a reliable energy source because of its independence of seasonal, climatic and geographical conditions. Low-temperature geothermal wells present a huge potential of exploitation, as the development of binary cycles and the technological improvement in drilling make this heat source a competitive solution for electricity generated distribution and self-consumption. The Organic Rankine Cycle (ORC) is currently the best solution to convert heat into electricity using low enthalpy heat sources. The ORC technology is already mature and widespread for medium and large-scale power plants, applying for geothermal, solar, biomass or waste heat recovery exploitation. Micro-scale ORC applications are still not diffused in the market: the system layout, the working fluid selection and the expander architecture can significantly vary depending on the specific realization requirements, thus a standard configuration has not established yet. In this paper, a particular case study of a micro-ORC power system using a geothermal well is presented. The application in analysis is a plug-and-play ORC facility, currently installed and operating in a pool centre. The system layout and the main components are described. The heat source is a geothermal well, which continuously supplies (by pressure difference) liquid water at a temperature lower than 60 °C to a binary Rankine cycle working with R134a. The ORC system is driven by a prototypal radial-piston expander and adopts an external-gear feed pump and a recuperative cycle. It is developed for working continuously, delivering the generated electricity directly into the grid. The facility is provided with temperature, pressure and electric power sensors for monitoring the operation and for a preliminary evaluation of the performance. The global efficiency of expander and feed pump and the ORC net efficiency have been evaluated at the regular working conditions of the geothermal well, showing values equal to, respectively, 53 %, 41 % and 4.4 %.

AbstractA parametric analysis for an innovative prototype of passive building, located in south Italy and for residential use, has been conducted to evaluate the thermal energy requirements for heating and cooling applications. The investigation was addressed by considering also the aspect of sustainability, by employing natural materials such as dry sand and wood fibre, and the correspondent effects on the energy performances of the envelope. These materials are usually available on site; they increase the building thermal capacity, which represents a crucial aspect for hot climates, and finally could even be reused after building disposal. The construction system based on the completely dry assembling technique makes the exploitation of the mentioned materials possible. The results of the parametric study were obtained by means of the Design Builder dynamic software, by investigating the glazed surfaces, the control of solar radiation and the exploitation of nocturnal free-cooling. A parametric study allowed for optimization of the envelope, by respecting the limit values of 15 kWh/m2 suggested by the standard passivhaus in its extended formulation for warm climates.

AbstractSwitchable windows are glazing technologies that exhibit dynamic optical properties and may thus be used to improve the energy performance of buildings. A window system based on a thermotropic glass pane was tested both in the laboratory and by means of an outdoor test cell facility.In this paper the full optical and thermal characterization of this glazing technology is presented. Experiments and data analysis led to the characterization of the behaviour of the thermotropic glazing both when this technology is used alone (single glass pane) and when it is integrated in a multilayer fenestration (a triple glazed unit).

AbstractThe efficiency of Geothermal Heat Pumps (GHPs) strongly depends on the site-specific parameters of the ground, which should therefore be mapped for the rational planning of shallow geothermal installations. In this paper, a case study is presented for the potentiality assessment of low enthalpy geothermal energy in the Province of Cuneo, a district of 6900 km2 in Piedmont, NW Italy. The available information on the geology, stratigraphy, hydrogeology, climate etc. were processed and mapped, and conclusions were drawn on the geothermal suitability and productivity of different areas of the territory surveyed.

Abstract In recent years, Distributed Energy Systems (DESs) have been recognized as a good option for sustainable development of future energy systems. With growing environmental concerns, design optimization of DESs through economic assessments only is not sufficient. To achieve long-run sustainability of energy supply, the key idea of this paper is to investigate exergy assessments in DES design optimization to attain rational use of energy resources while considering energy qualities of supply and demand. By using low-temperature sources for low-quality thermal demand, the waste of high-quality energy can be reduced, and the overall exergy efficiency can be increased. Based on a pre-established superstructure, the aim is to determine numbers and sizes of energy devices in the DES and the corresponding operation strategies. A multi-objective linear problem is formulated to reduce the total annual cost and increase the overall exergy efficiency. The Pareto frontier is found to provide different design options for planners based on economic and sustainability priorities, through minimizing a weighted-sum of the total annual cost and primary exergy input, by using branch-and-cut. Numerical results demonstrate that different optimized DES configurations can be found according to the two objectives. Moreover, results also show that the total annual cost and primary exergy input are reduced by 20% - 30% as compared with conventional energy supply systems.

AbstractThe forecasted energy production of oil sands operations in Alberta in the year 2030 were optimised under CO2 emissions constraints, using a mixed integer linear optimisation model. The model features a variety of technologies (with and without CO2 capture), including coal and natural gas power plants, IGCC, and oxyfuel plants. Hydrogen production technologies are steam methane reforming and coal gasification. The optimization is executed at increasing CO2 emissions reduction levels, yielding unique infrastructures that satisfy the energy demands of the oil sands industry at minimal cost. The economic and environmental impacts of the optimally chosen technologies on the forecasted operations of the oil sands industry in 2030 are thus determined.The maximum CO2 emissions reduction attainable by using CCS in the oil sands industry in 2030 is 39% with respect to a business-as-usual baseline. This CO2 reduction results in an energy cost increase of roughly 20% for synthetic crude and 2% for bitumen production. CO2 reductions ranging from 0–35% can be attained by optimising the energy infrastructures, yielding energy production cost reductions between 9%–18%. The maximum CO2 intensity reduction is 46% for synthetic crude and less than 3% for bitumen. Energy conversion and CO2 capture account for the bulk of the energy costs for synthetic crude whereas transport and storage combined contribute between 2.6% and 5% over the entire range of CO2 reductions.The optimal energy production technologies are strongly dependent on the CO2 reduction targets. Power production without capture, predominantly NGCC and supercritical coal technology, is optimal at CO2 reduction levels of up to 30%. At higher CO2 reductions, only NGCC with capture and Oxyfuel plants are optimal. H2 production via coal gasification is optimal for CO2 reduction levels of 35% and lower. Above 35% reduction, steam methane reforming with capture is the dominant technology.